Merge #14437: Refactor: Start to separate wallet from node

081accb875 Pass chain locked variables where needed (Russell Yanofsky)
79d579f4e1 Remove uses of cs_main in wallet code (Russell Yanofsky)
ea961c3d72 Remove direct node->wallet calls in init.cpp (Russell Yanofsky)
8db11dd0b1 Pass chain and client variables where needed (Russell Yanofsky)
7e2e62cf7c Add skeleton chain and client classes (Russell Yanofsky)

Pull request description:

  This creates an incomplete [`Chain`](https://github.com/ryanofsky/bitcoin/blob/pr/wipc-sep/src/interfaces/chain.h) interface in [`src/interfaces/`](https://github.com/ryanofsky/bitcoin/tree/pr/wipc-sep/src/interfaces) and begins to update wallet code to use it.

  #10973 builds on this, changing the wallet to use the new interface to access chain state, instead of using CBlockIndex pointers and global variables like `chainActive`.

Tree-SHA512: 6ef05a4d8ebf57f2ad71835e4d970c9c59e34057e39e48cee76b887492c2fee907e3f6a74a9861e5a9f97cdc6823f4865ebc41ec556ab371ebca1b664c20dbea

33 files changed, 715 insertions, 365 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 6852ef408a..8dd0d31839 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -125,6 +125,7 @@ BITCOIN_CORE_H = \
   index/txindex.h \
   indirectmap.h \
   init.h \
+  interfaces/chain.h \
   interfaces/handler.h \
   interfaces/node.h \
   interfaces/wallet.h \
@@ -233,6 +234,7 @@ libbitcoin_server_a_SOURCES = \
   httpserver.cpp \
   index/base.cpp \
   index/txindex.cpp \
+  interfaces/chain.cpp \
   interfaces/handler.cpp \
   interfaces/node.cpp \
   init.cpp \
@@ -465,6 +467,7 @@ endif
 bitcoind_LDADD = \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_WALLET) \
+  $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index decdadfb26..8552ed34fd 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <bench/bench.h>
+#include <interfaces/chain.h>
 #include <wallet/wallet.h>
 #include <wallet/coinselection.h>
 
@@ -33,7 +34,8 @@ static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<Ou
 // (https://github.com/bitcoin/bitcoin/issues/7883#issuecomment-224807484)
 static void CoinSelection(benchmark::State& state)
 {
-    const CWallet wallet(WalletLocation(), WalletDatabase::CreateDummy());
+    auto chain = interfaces::MakeChain();
+    const CWallet wallet(*chain, WalletLocation(), WalletDatabase::CreateDummy());
     LOCK(wallet.cs_wallet);
 
     // Add coins.
@@ -57,7 +59,8 @@ static void CoinSelection(benchmark::State& state)
 }
 
 typedef std::set<CInputCoin> CoinSet;
-static const CWallet testWallet(WalletLocation(), WalletDatabase::CreateDummy());
+static auto testChain = interfaces::MakeChain();
+static const CWallet testWallet(*testChain, WalletLocation(), WalletDatabase::CreateDummy());
 std::vector<std::unique_ptr<CWalletTx>> wtxn;
 
 // Copied from src/wallet/test/coinselector_tests.cpp
diff --git a/src/bitcoind.cpp b/src/bitcoind.cpp
index c6e2a7c20a..1306ba3821 100644
--- a/src/bitcoind.cpp
+++ b/src/bitcoind.cpp
@@ -11,6 +11,7 @@
 #include <clientversion.h>
 #include <compat.h>
 #include <fs.h>
+#include <interfaces/chain.h>
 #include <rpc/server.h>
 #include <init.h>
 #include <noui.h>
@@ -58,6 +59,9 @@ static void WaitForShutdown()
 //
 static bool AppInit(int argc, char* argv[])
 {
+    InitInterfaces interfaces;
+    interfaces.chain = interfaces::MakeChain();
+
     bool fRet = false;
 
     //
@@ -164,7 +168,7 @@ static bool AppInit(int argc, char* argv[])
             // If locking the data directory failed, exit immediately
             return false;
         }
-        fRet = AppInitMain();
+        fRet = AppInitMain(interfaces);
     }
     catch (const std::exception& e) {
         PrintExceptionContinue(&e, "AppInit()");
@@ -178,7 +182,7 @@ static bool AppInit(int argc, char* argv[])
     } else {
         WaitForShutdown();
     }
-    Shutdown();
+    Shutdown(interfaces);
 
     return fRet;
 }
diff --git a/src/dummywallet.cpp b/src/dummywallet.cpp
index 2a9b297029..9211a7596b 100644
--- a/src/dummywallet.cpp
+++ b/src/dummywallet.cpp
@@ -14,13 +14,7 @@ public:
     bool HasWalletSupport() const override {return false;}
     void AddWalletOptions() const override;
     bool ParameterInteraction() const override {return true;}
-    void RegisterRPC(CRPCTable &) const override {}
-    bool Verify() const override {return true;}
-    bool Open() const override {LogPrintf("No wallet support compiled in!\n"); return true;}
-    void Start(CScheduler& scheduler) const override {}
-    void Flush() const override {}
-    void Stop() const override {}
-    void Close() const override {}
+    void Construct(InitInterfaces& interfaces) const override {LogPrintf("No wallet support compiled in!\n");}
 };
 
 void DummyWalletInit::AddWalletOptions() const
diff --git a/src/init.cpp b/src/init.cpp
index d54d4a8782..3ab97be329 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -19,6 +19,7 @@
 #include <fs.h>
 #include <httpserver.h>
 #include <httprpc.h>
+#include <interfaces/chain.h>
 #include <index/txindex.h>
 #include <key.h>
 #include <validation.h>
@@ -32,6 +33,7 @@
 #include <rpc/server.h>
 #include <rpc/register.h>
 #include <rpc/blockchain.h>
+#include <rpc/util.h>
 #include <script/standard.h>
 #include <script/sigcache.h>
 #include <scheduler.h>
@@ -157,7 +159,7 @@ void Interrupt()
     }
 }
 
-void Shutdown()
+void Shutdown(InitInterfaces& interfaces)
 {
     LogPrintf("%s: In progress...\n", __func__);
     static CCriticalSection cs_Shutdown;
@@ -176,7 +178,9 @@ void Shutdown()
     StopREST();
     StopRPC();
     StopHTTPServer();
-    g_wallet_init_interface.Flush();
+    for (const auto& client : interfaces.chain_clients) {
+        client->flush();
+    }
     StopMapPort();
 
     // Because these depend on each-other, we make sure that neither can be
@@ -239,7 +243,9 @@ void Shutdown()
         pcoinsdbview.reset();
         pblocktree.reset();
     }
-    g_wallet_init_interface.Stop();
+    for (const auto& client : interfaces.chain_clients) {
+        client->stop();
+    }
 
 #if ENABLE_ZMQ
     if (g_zmq_notification_interface) {
@@ -259,7 +265,7 @@ void Shutdown()
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     GetMainSignals().UnregisterWithMempoolSignals(mempool);
-    g_wallet_init_interface.Close();
+    interfaces.chain_clients.clear();
     globalVerifyHandle.reset();
     ECC_Stop();
     LogPrintf("%s: done\n", __func__);
@@ -1158,7 +1164,7 @@ bool AppInitLockDataDirectory()
     return true;
 }
 
-bool AppInitMain()
+bool AppInitMain(InitInterfaces& interfaces)
 {
     const CChainParams& chainparams = Params();
     // ********************************************************* Step 4a: application initialization
@@ -1221,11 +1227,20 @@ bool AppInitMain()
     GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
     GetMainSignals().RegisterWithMempoolSignals(mempool);
 
+    // Create client interfaces for wallets that are supposed to be loaded
+    // according to -wallet and -disablewallet options. This only constructs
+    // the interfaces, it doesn't load wallet data. Wallets actually get loaded
+    // when load() and start() interface methods are called below.
+    g_wallet_init_interface.Construct(interfaces);
+
     /* Register RPC commands regardless of -server setting so they will be
      * available in the GUI RPC console even if external calls are disabled.
      */
     RegisterAllCoreRPCCommands(tableRPC);
-    g_wallet_init_interface.RegisterRPC(tableRPC);
+    for (const auto& client : interfaces.chain_clients) {
+        client->registerRpcs();
+    }
+    g_rpc_interfaces = &interfaces;
 #if ENABLE_ZMQ
     RegisterZMQRPCCommands(tableRPC);
 #endif
@@ -1243,7 +1258,11 @@ bool AppInitMain()
     }
 
     // ********************************************************* Step 5: verify wallet database integrity
-    if (!g_wallet_init_interface.Verify()) return false;
+    for (const auto& client : interfaces.chain_clients) {
+        if (!client->verify()) {
+            return false;
+        }
+    }
 
     // ********************************************************* Step 6: network initialization
     // Note that we absolutely cannot open any actual connections
@@ -1562,7 +1581,11 @@ bool AppInitMain()
     }
 
     // ********************************************************* Step 9: load wallet
-    if (!g_wallet_init_interface.Open()) return false;
+    for (const auto& client : interfaces.chain_clients) {
+        if (!client->load()) {
+            return false;
+        }
+    }
 
     // ********************************************************* Step 10: data directory maintenance
 
@@ -1708,7 +1731,9 @@ bool AppInitMain()
     SetRPCWarmupFinished();
     uiInterface.InitMessage(_("Done loading"));
 
-    g_wallet_init_interface.Start(scheduler);
+    for (const auto& client : interfaces.chain_clients) {
+        client->start(scheduler);
+    }
 
     return true;
 }
diff --git a/src/init.h b/src/init.h
index b106353d08..1c59ca069e 100644
--- a/src/init.h
+++ b/src/init.h
@@ -10,8 +10,17 @@
 #include <string>
 #include <util/system.h>
 
-class CScheduler;
-class CWallet;
+namespace interfaces {
+class Chain;
+class ChainClient;
+} // namespace interfaces
+
+//! Pointers to interfaces used during init and destroyed on shutdown.
+struct InitInterfaces
+{
+    std::unique_ptr<interfaces::Chain> chain;
+    std::vector<std::unique_ptr<interfaces::ChainClient>> chain_clients;
+};
 
 namespace boost
 {
@@ -20,7 +29,7 @@ class thread_group;
 
 /** Interrupt threads */
 void Interrupt();
-void Shutdown();
+void Shutdown(InitInterfaces& interfaces);
 //!Initialize the logging infrastructure
 void InitLogging();
 //!Parameter interaction: change current parameters depending on various rules
@@ -54,7 +63,7 @@ bool AppInitLockDataDirectory();
  * @note This should only be done after daemonization. Call Shutdown() if this function fails.
  * @pre Parameters should be parsed and config file should be read, AppInitLockDataDirectory should have been called.
  */
-bool AppInitMain();
+bool AppInitMain(InitInterfaces& interfaces);
 
 /**
  * Setup the arguments for gArgs
diff --git a/src/interfaces/README.md b/src/interfaces/README.md
index e93b91d23c..57d41df746 100644
--- a/src/interfaces/README.md
+++ b/src/interfaces/README.md
@@ -4,7 +4,7 @@ The following interfaces are defined here:
 
 * [`Chain`](chain.h) — used by wallet to access blockchain and mempool state. Added in [#10973](https://github.com/bitcoin/bitcoin/pull/10973).
 
-* [`Chain::Client`](chain.h) — used by node to start & stop `Chain` clients. Added in [#10973](https://github.com/bitcoin/bitcoin/pull/10973).
+* [`ChainClient`](chain.h) — used by node to start & stop `Chain` clients. Added in [#10973](https://github.com/bitcoin/bitcoin/pull/10973).
 
 * [`Node`](node.h) — used by GUI to start & stop bitcoin node. Added in [#10244](https://github.com/bitcoin/bitcoin/pull/10244).
 
diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
new file mode 100644
index 0000000000..2571a91031
--- /dev/null
+++ b/src/interfaces/chain.cpp
@@ -0,0 +1,44 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <interfaces/chain.h>
+
+#include <sync.h>
+#include <util/system.h>
+#include <validation.h>
+
+#include <memory>
+#include <utility>
+
+namespace interfaces {
+namespace {
+
+class LockImpl : public Chain::Lock
+{
+};
+
+class LockingStateImpl : public LockImpl, public UniqueLock<CCriticalSection>
+{
+    using UniqueLock::UniqueLock;
+};
+
+class ChainImpl : public Chain
+{
+public:
+    std::unique_ptr<Chain::Lock> lock(bool try_lock) override
+    {
+        auto result = MakeUnique<LockingStateImpl>(::cs_main, "cs_main", __FILE__, __LINE__, try_lock);
+        if (try_lock && result && !*result) return {};
+        // std::move necessary on some compilers due to conversion from
+        // LockingStateImpl to Lock pointer
+        return std::move(result);
+    }
+    std::unique_ptr<Chain::Lock> assumeLocked() override { return MakeUnique<LockImpl>(); }
+};
+
+} // namespace
+
+std::unique_ptr<Chain> MakeChain() { return MakeUnique<ChainImpl>(); }
+
+} // namespace interfaces
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
new file mode 100644
index 0000000000..fe5658de4b
--- /dev/null
+++ b/src/interfaces/chain.h
@@ -0,0 +1,84 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_INTERFACES_CHAIN_H
+#define BITCOIN_INTERFACES_CHAIN_H
+
+#include <memory>
+#include <string>
+#include <vector>
+
+class CScheduler;
+
+namespace interfaces {
+
+//! Interface for giving wallet processes access to blockchain state.
+class Chain
+{
+public:
+    virtual ~Chain() {}
+
+    //! Interface for querying locked chain state, used by legacy code that
+    //! assumes state won't change between calls. New code should avoid using
+    //! the Lock interface and instead call higher-level Chain methods
+    //! that return more information so the chain doesn't need to stay locked
+    //! between calls.
+    class Lock
+    {
+    public:
+        virtual ~Lock() {}
+    };
+
+    //! Return Lock interface. Chain is locked when this is called, and
+    //! unlocked when the returned interface is freed.
+    virtual std::unique_ptr<Lock> lock(bool try_lock = false) = 0;
+
+    //! Return Lock interface assuming chain is already locked. This
+    //! method is temporary and is only used in a few places to avoid changing
+    //! behavior while code is transitioned to use the Chain::Lock interface.
+    virtual std::unique_ptr<Lock> assumeLocked() = 0;
+};
+
+//! Interface to let node manage chain clients (wallets, or maybe tools for
+//! monitoring and analysis in the future).
+class ChainClient
+{
+public:
+    virtual ~ChainClient() {}
+
+    //! Register rpcs.
+    virtual void registerRpcs() = 0;
+
+    //! Check for errors before loading.
+    virtual bool verify() = 0;
+
+    //! Load saved state.
+    virtual bool load() = 0;
+
+    //! Start client execution and provide a scheduler.
+    virtual void start(CScheduler& scheduler) = 0;
+
+    //! Save state to disk.
+    virtual void flush() = 0;
+
+    //! Shut down client.
+    virtual void stop() = 0;
+};
+
+//! Return implementation of Chain interface.
+std::unique_ptr<Chain> MakeChain();
+
+//! Return implementation of ChainClient interface for a wallet client. This
+//! function will be undefined in builds where ENABLE_WALLET is false.
+//!
+//! Currently, wallets are the only chain clients. But in the future, other
+//! types of chain clients could be added, such as tools for monitoring,
+//! analysis, or fee estimation. These clients need to expose their own
+//! MakeXXXClient functions returning their implementations of the ChainClient
+//! interface.
+std::unique_ptr<ChainClient> MakeWalletClient(Chain& chain, std::vector<std::string> wallet_filenames);
+
+} // namespace interfaces
+
+#endif // BITCOIN_INTERFACES_CHAIN_H
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index 490c456e6e..1919e16a66 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -9,6 +9,7 @@
 #include <chain.h>
 #include <chainparams.h>
 #include <init.h>
+#include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <interfaces/wallet.h>
 #include <net.h>
@@ -50,6 +51,8 @@ namespace {
 
 class NodeImpl : public Node
 {
+public:
+    NodeImpl() { m_interfaces.chain = MakeChain(); }
     bool parseParameters(int argc, const char* const argv[], std::string& error) override
     {
         return gArgs.ParseParameters(argc, argv, error);
@@ -68,11 +71,11 @@ class NodeImpl : public Node
         return AppInitBasicSetup() && AppInitParameterInteraction() && AppInitSanityChecks() &&
                AppInitLockDataDirectory();
     }
-    bool appInitMain() override { return AppInitMain(); }
+    bool appInitMain() override { return AppInitMain(m_interfaces); }
     void appShutdown() override
     {
         Interrupt();
-        Shutdown();
+        Shutdown(m_interfaces);
     }
     void startShutdown() override { StartShutdown(); }
     bool shutdownRequested() override { return ShutdownRequested(); }
@@ -291,6 +294,7 @@ class NodeImpl : public Node
                     GuessVerificationProgress(Params().TxData(), block));
             }));
     }
+    InitInterfaces m_interfaces;
 };
 
 } // namespace
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index 14c6bd0330..672a557d41 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -7,12 +7,16 @@
 #include <amount.h>
 #include <chain.h>
 #include <consensus/validation.h>
+#include <init.h>
+#include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <net.h>
 #include <policy/feerate.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <primitives/transaction.h>
+#include <rpc/server.h>
+#include <scheduler.h>
 #include <script/ismine.h>
 #include <script/standard.h>
 #include <support/allocators/secure.h>
@@ -20,10 +24,18 @@
 #include <timedata.h>
 #include <ui_interface.h>
 #include <uint256.h>
+#include <util/system.h>
 #include <validation.h>
 #include <wallet/feebumper.h>
 #include <wallet/fees.h>
+#include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
+#include <wallet/walletutil.h>
+
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
 
 namespace interfaces {
 namespace {
@@ -41,7 +53,8 @@ public:
         WalletOrderForm order_form,
         std::string& reject_reason) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         CValidationState state;
         if (!m_wallet.CommitTransaction(m_tx, std::move(value_map), std::move(order_form), m_key, g_connman.get(), state)) {
             reject_reason = state.GetRejectReason();
@@ -56,7 +69,7 @@ public:
 };
 
 //! Construct wallet tx struct.
-static WalletTx MakeWalletTx(CWallet& wallet, const CWalletTx& wtx) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+WalletTx MakeWalletTx(interfaces::Chain::Lock& locked_chain, CWallet& wallet, const CWalletTx& wtx)
 {
     WalletTx result;
     result.tx = wtx.tx;
@@ -74,7 +87,7 @@ static WalletTx MakeWalletTx(CWallet& wallet, const CWalletTx& wtx) EXCLUSIVE_LO
                                                       IsMine(wallet, result.txout_address.back()) :
                                                       ISMINE_NO);
     }
-    result.credit = wtx.GetCredit(ISMINE_ALL);
+    result.credit = wtx.GetCredit(locked_chain, ISMINE_ALL);
     result.debit = wtx.GetDebit(ISMINE_ALL);
     result.change = wtx.GetChange();
     result.time = wtx.GetTxTime();
@@ -84,32 +97,38 @@ static WalletTx MakeWalletTx(CWallet& wallet, const CWalletTx& wtx) EXCLUSIVE_LO
 }
 
 //! Construct wallet tx status struct.
-static WalletTxStatus MakeWalletTxStatus(const CWalletTx& wtx) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+WalletTxStatus MakeWalletTxStatus(interfaces::Chain::Lock& locked_chain, const CWalletTx& wtx)
 {
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+
     WalletTxStatus result;
     auto mi = ::mapBlockIndex.find(wtx.hashBlock);
     CBlockIndex* block = mi != ::mapBlockIndex.end() ? mi->second : nullptr;
     result.block_height = (block ? block->nHeight : std::numeric_limits<int>::max());
-    result.blocks_to_maturity = wtx.GetBlocksToMaturity();
-    result.depth_in_main_chain = wtx.GetDepthInMainChain();
+    result.blocks_to_maturity = wtx.GetBlocksToMaturity(locked_chain);
+    result.depth_in_main_chain = wtx.GetDepthInMainChain(locked_chain);
     result.time_received = wtx.nTimeReceived;
     result.lock_time = wtx.tx->nLockTime;
     result.is_final = CheckFinalTx(*wtx.tx);
-    result.is_trusted = wtx.IsTrusted();
+    result.is_trusted = wtx.IsTrusted(locked_chain);
     result.is_abandoned = wtx.isAbandoned();
     result.is_coinbase = wtx.IsCoinBase();
-    result.is_in_main_chain = wtx.IsInMainChain();
+    result.is_in_main_chain = wtx.IsInMainChain(locked_chain);
     return result;
 }
 
 //! Construct wallet TxOut struct.
-static WalletTxOut MakeWalletTxOut(CWallet& wallet, const CWalletTx& wtx, int n, int depth) EXCLUSIVE_LOCKS_REQUIRED(cs_main, wallet.cs_wallet)
+WalletTxOut MakeWalletTxOut(interfaces::Chain::Lock& locked_chain,
+    CWallet& wallet,
+    const CWalletTx& wtx,
+    int n,
+    int depth) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
 {
     WalletTxOut result;
     result.txout = wtx.tx->vout[n];
     result.time = wtx.GetTxTime();
     result.depth_in_main_chain = depth;
-    result.is_spent = wallet.IsSpent(wtx.GetHash(), n);
+    result.is_spent = wallet.IsSpent(locked_chain, wtx.GetHash(), n);
     return result;
 }
 
@@ -197,22 +216,26 @@ public:
     }
     void lockCoin(const COutPoint& output) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.LockCoin(output);
     }
     void unlockCoin(const COutPoint& output) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.UnlockCoin(output);
     }
     bool isLockedCoin(const COutPoint& output) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.IsLockedCoin(output.hash, output.n);
     }
     void listLockedCoins(std::vector<COutPoint>& outputs) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.ListLockedCoins(outputs);
     }
     std::unique_ptr<PendingWalletTx> createTransaction(const std::vector<CRecipient>& recipients,
@@ -222,9 +245,10 @@ public:
         CAmount& fee,
         std::string& fail_reason) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         auto pending = MakeUnique<PendingWalletTxImpl>(m_wallet);
-        if (!m_wallet.CreateTransaction(recipients, pending->m_tx, pending->m_key, fee, change_pos,
+        if (!m_wallet.CreateTransaction(*locked_chain, recipients, pending->m_tx, pending->m_key, fee, change_pos,
                 fail_reason, coin_control, sign)) {
             return {};
         }
@@ -233,8 +257,9 @@ public:
     bool transactionCanBeAbandoned(const uint256& txid) override { return m_wallet.TransactionCanBeAbandoned(txid); }
     bool abandonTransaction(const uint256& txid) override
     {
-        LOCK2(cs_main, m_wallet.cs_wallet);
-        return m_wallet.AbandonTransaction(txid);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
+        return m_wallet.AbandonTransaction(*locked_chain, txid);
     }
     bool transactionCanBeBumped(const uint256& txid) override
     {
@@ -262,7 +287,8 @@ public:
     }
     CTransactionRef getTx(const uint256& txid) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         auto mi = m_wallet.mapWallet.find(txid);
         if (mi != m_wallet.mapWallet.end()) {
             return mi->second.tx;
@@ -271,20 +297,22 @@ public:
     }
     WalletTx getWalletTx(const uint256& txid) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         auto mi = m_wallet.mapWallet.find(txid);
         if (mi != m_wallet.mapWallet.end()) {
-            return MakeWalletTx(m_wallet, mi->second);
+            return MakeWalletTx(*locked_chain, m_wallet, mi->second);
         }
         return {};
     }
     std::vector<WalletTx> getWalletTxs() override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         std::vector<WalletTx> result;
         result.reserve(m_wallet.mapWallet.size());
         for (const auto& entry : m_wallet.mapWallet) {
-            result.emplace_back(MakeWalletTx(m_wallet, entry.second));
+            result.emplace_back(MakeWalletTx(*locked_chain, m_wallet, entry.second));
         }
         return result;
     }
@@ -292,7 +320,7 @@ public:
         interfaces::WalletTxStatus& tx_status,
         int& num_blocks) override
     {
-        TRY_LOCK(::cs_main, locked_chain);
+        auto locked_chain = m_wallet.chain().lock(true /* try_lock */);
         if (!locked_chain) {
             return false;
         }
@@ -305,7 +333,7 @@ public:
             return false;
         }
         num_blocks = ::chainActive.Height();
-        tx_status = MakeWalletTxStatus(mi->second);
+        tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
         return true;
     }
     WalletTx getWalletTxDetails(const uint256& txid,
@@ -314,14 +342,15 @@ public:
         bool& in_mempool,
         int& num_blocks) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         auto mi = m_wallet.mapWallet.find(txid);
         if (mi != m_wallet.mapWallet.end()) {
             num_blocks = ::chainActive.Height();
             in_mempool = mi->second.InMempool();
             order_form = mi->second.vOrderForm;
-            tx_status = MakeWalletTxStatus(mi->second);
-            return MakeWalletTx(m_wallet, mi->second);
+            tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
+            return MakeWalletTx(*locked_chain, m_wallet, mi->second);
         }
         return {};
     }
@@ -341,7 +370,7 @@ public:
     }
     bool tryGetBalances(WalletBalances& balances, int& num_blocks) override
     {
-        TRY_LOCK(cs_main, locked_chain);
+        auto locked_chain = m_wallet.chain().lock(true /* try_lock */);
         if (!locked_chain) return false;
         TRY_LOCK(m_wallet.cs_wallet, locked_wallet);
         if (!locked_wallet) {
@@ -358,49 +387,55 @@ public:
     }
     isminetype txinIsMine(const CTxIn& txin) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.IsMine(txin);
     }
     isminetype txoutIsMine(const CTxOut& txout) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.IsMine(txout);
     }
     CAmount getDebit(const CTxIn& txin, isminefilter filter) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.GetDebit(txin, filter);
     }
     CAmount getCredit(const CTxOut& txout, isminefilter filter) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         return m_wallet.GetCredit(txout, filter);
     }
     CoinsList listCoins() override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         CoinsList result;
-        for (const auto& entry : m_wallet.ListCoins()) {
+        for (const auto& entry : m_wallet.ListCoins(*locked_chain)) {
             auto& group = result[entry.first];
             for (const auto& coin : entry.second) {
-                group.emplace_back(
-                    COutPoint(coin.tx->GetHash(), coin.i), MakeWalletTxOut(m_wallet, *coin.tx, coin.i, coin.nDepth));
+                group.emplace_back(COutPoint(coin.tx->GetHash(), coin.i),
+                    MakeWalletTxOut(*locked_chain, m_wallet, *coin.tx, coin.i, coin.nDepth));
             }
         }
         return result;
     }
     std::vector<WalletTxOut> getCoins(const std::vector<COutPoint>& outputs) override
     {
-        LOCK2(::cs_main, m_wallet.cs_wallet);
+        auto locked_chain = m_wallet.chain().lock();
+        LOCK(m_wallet.cs_wallet);
         std::vector<WalletTxOut> result;
         result.reserve(outputs.size());
         for (const auto& output : outputs) {
             result.emplace_back();
             auto it = m_wallet.mapWallet.find(output.hash);
             if (it != m_wallet.mapWallet.end()) {
-                int depth = it->second.GetDepthInMainChain();
+                int depth = it->second.GetDepthInMainChain(*locked_chain);
                 if (depth >= 0) {
-                    result.back() = MakeWalletTxOut(m_wallet, it->second, output.n, depth);
+                    result.back() = MakeWalletTxOut(*locked_chain, m_wallet, it->second, output.n, depth);
                 }
             }
         }
@@ -456,8 +491,32 @@ public:
     CWallet& m_wallet;
 };
 
+class WalletClientImpl : public ChainClient
+{
+public:
+    WalletClientImpl(Chain& chain, std::vector<std::string> wallet_filenames)
+        : m_chain(chain), m_wallet_filenames(std::move(wallet_filenames))
+    {
+    }
+    void registerRpcs() override { return RegisterWalletRPCCommands(::tableRPC); }
+    bool verify() override { return VerifyWallets(m_chain, m_wallet_filenames); }
+    bool load() override { return LoadWallets(m_chain, m_wallet_filenames); }
+    void start(CScheduler& scheduler) override { return StartWallets(scheduler); }
+    void flush() override { return FlushWallets(); }
+    void stop() override { return StopWallets(); }
+    ~WalletClientImpl() override { UnloadWallets(); }
+
+    Chain& m_chain;
+    std::vector<std::string> m_wallet_filenames;
+};
+
 } // namespace
 
 std::unique_ptr<Wallet> MakeWallet(const std::shared_ptr<CWallet>& wallet) { return MakeUnique<WalletImpl>(wallet); }
 
+std::unique_ptr<ChainClient> MakeWalletClient(Chain& chain, std::vector<std::string> wallet_filenames)
+{
+    return MakeUnique<WalletClientImpl>(chain, std::move(wallet_filenames));
+}
+
 } // namespace interfaces
diff --git a/src/qt/test/addressbooktests.cpp b/src/qt/test/addressbooktests.cpp
index 0cabb5f0be..3e414df1f0 100644
--- a/src/qt/test/addressbooktests.cpp
+++ b/src/qt/test/addressbooktests.cpp
@@ -2,6 +2,7 @@
 #include <qt/test/util.h>
 #include <test/test_bitcoin.h>
 
+#include <interfaces/chain.h>
 #include <interfaces/node.h>
 #include <qt/addressbookpage.h>
 #include <qt/addresstablemodel.h>
@@ -56,7 +57,8 @@ void EditAddressAndSubmit(
 void TestAddAddressesToSendBook()
 {
     TestChain100Setup test;
-    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateMock());
+    auto chain = interfaces::MakeChain();
+    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateMock());
     bool firstRun;
     wallet->LoadWallet(firstRun);
 
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index 12dbf922f1..f02fd8aea7 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -1,6 +1,7 @@
 #include <qt/test/wallettests.h>
 #include <qt/test/util.h>
 
+#include <interfaces/chain.h>
 #include <interfaces/node.h>
 #include <base58.h>
 #include <qt/bitcoinamountfield.h>
@@ -132,7 +133,8 @@ void TestGUI()
     for (int i = 0; i < 5; ++i) {
         test.CreateAndProcessBlock({}, GetScriptForRawPubKey(test.coinbaseKey.GetPubKey()));
     }
-    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateMock());
+    auto chain = interfaces::MakeChain();
+    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateMock());
     bool firstRun;
     wallet->LoadWallet(firstRun);
     {
@@ -141,7 +143,7 @@ void TestGUI()
         wallet->AddKeyPubKey(test.coinbaseKey, test.coinbaseKey.GetPubKey());
     }
     {
-        LOCK(cs_main);
+        auto locked_chain = wallet->chain().lock();
         WalletRescanReserver reserver(wallet.get());
         reserver.reserve();
         wallet->ScanForWalletTransactions(chainActive.Genesis(), nullptr, reserver, true);
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 7960311154..51b4e44aed 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -9,6 +9,7 @@
 #include <consensus/validation.h>
 #include <core_io.h>
 #include <index/txindex.h>
+#include <init.h>
 #include <keystore.h>
 #include <validation.h>
 #include <validationinterface.h>
@@ -20,6 +21,7 @@
 #include <primitives/transaction.h>
 #include <rpc/rawtransaction.h>
 #include <rpc/server.h>
+#include <rpc/util.h>
 #include <script/script.h>
 #include <script/script_error.h>
 #include <script/sign.h>
@@ -754,7 +756,7 @@ static UniValue combinerawtransaction(const JSONRPCRequest& request)
     return EncodeHexTx(mergedTx);
 }
 
-UniValue SignTransaction(CMutableTransaction& mtx, const UniValue& prevTxsUnival, CBasicKeyStore *keystore, bool is_temp_keystore, const UniValue& hashType)
+UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, const UniValue& prevTxsUnival, CBasicKeyStore *keystore, bool is_temp_keystore, const UniValue& hashType)
 {
     // Fetch previous transactions (inputs):
     CCoinsView viewDummy;
@@ -969,7 +971,7 @@ static UniValue signrawtransactionwithkey(const JSONRPCRequest& request)
         keystore.AddKey(key);
     }
 
-    return SignTransaction(mtx, request.params[2], &keystore, true, request.params[3]);
+    return SignTransaction(*g_rpc_interfaces->chain, mtx, request.params[2], &keystore, true, request.params[3]);
 }
 
 UniValue signrawtransaction(const JSONRPCRequest& request)
diff --git a/src/rpc/rawtransaction.h b/src/rpc/rawtransaction.h
index 924611ed5a..52d701d1c3 100644
--- a/src/rpc/rawtransaction.h
+++ b/src/rpc/rawtransaction.h
@@ -9,8 +9,12 @@ class CBasicKeyStore;
 struct CMutableTransaction;
 class UniValue;
 
+namespace interfaces {
+class Chain;
+} // namespace interfaces
+
 /** Sign a transaction with the given keystore and previous transactions */
-UniValue SignTransaction(CMutableTransaction& mtx, const UniValue& prevTxs, CBasicKeyStore *keystore, bool tempKeystore, const UniValue& hashType);
+UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, const UniValue& prevTxs, CBasicKeyStore *keystore, bool tempKeystore, const UniValue& hashType);
 
 /** Create a transaction from univalue parameters */
 CMutableTransaction ConstructTransaction(const UniValue& inputs_in, const UniValue& outputs_in, const UniValue& locktime, const UniValue& rbf);
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 8a66191a6a..ef2d14b90e 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -9,6 +9,8 @@
 #include <tinyformat.h>
 #include <util/strencodings.h>
 
+InitInterfaces* g_rpc_interfaces = nullptr;
+
 // Converts a hex string to a public key if possible
 CPubKey HexToPubKey(const std::string& hex_in)
 {
diff --git a/src/rpc/util.h b/src/rpc/util.h
index 0a3a156e45..e21b5ba22a 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -17,6 +17,12 @@
 class CKeyStore;
 class CPubKey;
 class CScript;
+struct InitInterfaces;
+
+//! Pointers to interfaces that need to be accessible from RPC methods. Due to
+//! limitations of the RPC framework, there's currently no direct way to pass in
+//! state to RPC method implementations.
+extern InitInterfaces* g_rpc_interfaces;
 
 CPubKey HexToPubKey(const std::string& hex_in);
 CPubKey AddrToPubKey(CKeyStore* const keystore, const std::string& addr_in);
diff --git a/src/test/rpc_tests.cpp b/src/test/rpc_tests.cpp
index a49796d6f4..121b72a5f7 100644
--- a/src/test/rpc_tests.cpp
+++ b/src/test/rpc_tests.cpp
@@ -4,8 +4,11 @@
 
 #include <rpc/server.h>
 #include <rpc/client.h>
+#include <rpc/util.h>
 
 #include <core_io.h>
+#include <init.h>
+#include <interfaces/chain.h>
 #include <key_io.h>
 #include <netbase.h>
 
@@ -112,10 +115,14 @@ BOOST_AUTO_TEST_CASE(rpc_rawsign)
     std::string notsigned = r.get_str();
     std::string privkey1 = "\"KzsXybp9jX64P5ekX1KUxRQ79Jht9uzW7LorgwE65i5rWACL6LQe\"";
     std::string privkey2 = "\"Kyhdf5LuKTRx4ge69ybABsiUAWjVRK4XGxAKk2FQLp2HjGMy87Z4\"";
+    InitInterfaces interfaces;
+    interfaces.chain = interfaces::MakeChain();
+    g_rpc_interfaces = &interfaces;
     r = CallRPC(std::string("signrawtransactionwithkey ")+notsigned+" [] "+prevout);
     BOOST_CHECK(find_value(r.get_obj(), "complete").get_bool() == false);
     r = CallRPC(std::string("signrawtransactionwithkey ")+notsigned+" ["+privkey1+","+privkey2+"] "+prevout);
     BOOST_CHECK(find_value(r.get_obj(), "complete").get_bool() == true);
+    g_rpc_interfaces = nullptr;
 }
 
 BOOST_AUTO_TEST_CASE(rpc_createraw_op_return)
diff --git a/src/threadsafety.h b/src/threadsafety.h
index 47e6b2ea38..33acddc65c 100644
--- a/src/threadsafety.h
+++ b/src/threadsafety.h
@@ -54,4 +54,15 @@
 #define ASSERT_EXCLUSIVE_LOCK(...)
 #endif // __GNUC__
 
+// Utility class for indicating to compiler thread analysis that a mutex is
+// locked (when it couldn't be determined otherwise).
+struct SCOPED_LOCKABLE LockAnnotation
+{
+    template <typename Mutex>
+    explicit LockAnnotation(Mutex& mutex) EXCLUSIVE_LOCK_FUNCTION(mutex)
+    {
+    }
+    ~LockAnnotation() UNLOCK_FUNCTION() {}
+};
+
 #endif // BITCOIN_THREADSAFETY_H
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index 5eb70cd7a5..7a71aea715 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <consensus/validation.h>
+#include <interfaces/chain.h>
 #include <wallet/coincontrol.h>
 #include <wallet/feebumper.h>
 #include <wallet/fees.h>
@@ -18,7 +19,7 @@
 
 //! Check whether transaction has descendant in wallet or mempool, or has been
 //! mined, or conflicts with a mined transaction. Return a feebumper::Result.
-static feebumper::Result PreconditionChecks(const CWallet* wallet, const CWalletTx& wtx, std::vector<std::string>& errors) EXCLUSIVE_LOCKS_REQUIRED(cs_main, wallet->cs_wallet)
+static feebumper::Result PreconditionChecks(interfaces::Chain::Lock& locked_chain, const CWallet* wallet, const CWalletTx& wtx, std::vector<std::string>& errors) EXCLUSIVE_LOCKS_REQUIRED(wallet->cs_wallet)
 {
     if (wallet->HasWalletSpend(wtx.GetHash())) {
         errors.push_back("Transaction has descendants in the wallet");
@@ -34,7 +35,7 @@ static feebumper::Result PreconditionChecks(const CWallet* wallet, const CWallet
         }
     }
 
-    if (wtx.GetDepthInMainChain() != 0) {
+    if (wtx.GetDepthInMainChain(locked_chain) != 0) {
         errors.push_back("Transaction has been mined, or is conflicted with a mined transaction");
         return feebumper::Result::WALLET_ERROR;
     }
@@ -64,19 +65,21 @@ namespace feebumper {
 
 bool TransactionCanBeBumped(const CWallet* wallet, const uint256& txid)
 {
-    LOCK2(cs_main, wallet->cs_wallet);
+    auto locked_chain = wallet->chain().lock();
+    LOCK(wallet->cs_wallet);
     const CWalletTx* wtx = wallet->GetWalletTx(txid);
     if (wtx == nullptr) return false;
 
     std::vector<std::string> errors_dummy;
-    feebumper::Result res = PreconditionChecks(wallet, *wtx, errors_dummy);
+    feebumper::Result res = PreconditionChecks(*locked_chain, wallet, *wtx, errors_dummy);
     return res == feebumper::Result::OK;
 }
 
 Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoinControl& coin_control, CAmount total_fee, std::vector<std::string>& errors,
                          CAmount& old_fee, CAmount& new_fee, CMutableTransaction& mtx)
 {
-    LOCK2(cs_main, wallet->cs_wallet);
+    auto locked_chain = wallet->chain().lock();
+    LOCK(wallet->cs_wallet);
     errors.clear();
     auto it = wallet->mapWallet.find(txid);
     if (it == wallet->mapWallet.end()) {
@@ -85,7 +88,7 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
     }
     const CWalletTx& wtx = it->second;
 
-    Result result = PreconditionChecks(wallet, wtx, errors);
+    Result result = PreconditionChecks(*locked_chain, wallet, wtx, errors);
     if (result != Result::OK) {
         return result;
     }
@@ -212,13 +215,15 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
 }
 
 bool SignTransaction(CWallet* wallet, CMutableTransaction& mtx) {
-    LOCK2(cs_main, wallet->cs_wallet);
+    auto locked_chain = wallet->chain().lock();
+    LOCK(wallet->cs_wallet);
     return wallet->SignTransaction(mtx);
 }
 
 Result CommitTransaction(CWallet* wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<std::string>& errors, uint256& bumped_txid)
 {
-    LOCK2(cs_main, wallet->cs_wallet);
+    auto locked_chain = wallet->chain().lock();
+    LOCK(wallet->cs_wallet);
     if (!errors.empty()) {
         return Result::MISC_ERROR;
     }
@@ -230,7 +235,7 @@ Result CommitTransaction(CWallet* wallet, const uint256& txid, CMutableTransacti
     CWalletTx& oldWtx = it->second;
 
     // make sure the transaction still has no descendants and hasn't been mined in the meantime
-    Result result = PreconditionChecks(wallet, oldWtx, errors);
+    Result result = PreconditionChecks(*locked_chain, wallet, oldWtx, errors);
     if (result != Result::OK) {
         return result;
     }
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 456422d004..14d811c6cd 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -5,6 +5,7 @@
 
 #include <chainparams.h>
 #include <init.h>
+#include <interfaces/chain.h>
 #include <net.h>
 #include <scheduler.h>
 #include <outputtype.h>
@@ -28,28 +29,8 @@ public:
     //! Wallets parameter interaction
     bool ParameterInteraction() const override;
 
-    //! Register wallet RPCs.
-    void RegisterRPC(CRPCTable &tableRPC) const override;
-
-    //! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
-    //  This function will perform salvage on the wallet if requested, as long as only one wallet is
-    //  being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
-    bool Verify() const override;
-
-    //! Load wallet databases.
-    bool Open() const override;
-
-    //! Complete startup of wallets.
-    void Start(CScheduler& scheduler) const override;
-
-    //! Flush all wallets in preparation for shutdown.
-    void Flush() const override;
-
-    //! Stop all wallets. Wallets will be flushed first.
-    void Stop() const override;
-
-    //! Close all wallets.
-    void Close() const override;
+    //! Add wallets that should be opened to list of init interfaces.
+    void Construct(InitInterfaces& interfaces) const override;
 };
 
 const WalletInitInterface& g_wallet_init_interface = WalletInit();
@@ -99,7 +80,6 @@ bool WalletInit::ParameterInteraction() const
         return true;
     }
 
-    gArgs.SoftSetArg("-wallet", "");
     const bool is_multiwallet = gArgs.GetArgs("-wallet").size() > 1;
 
     if (gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY) && gArgs.SoftSetBoolArg("-walletbroadcast", false)) {
@@ -165,21 +145,8 @@ bool WalletInit::ParameterInteraction() const
     return true;
 }
 
-void WalletInit::RegisterRPC(CRPCTable &t) const
-{
-    if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
-        return;
-    }
-
-    RegisterWalletRPCCommands(t);
-}
-
-bool WalletInit::Verify() const
+bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
 {
-    if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
-        return true;
-    }
-
     if (gArgs.IsArgSet("-walletdir")) {
         fs::path wallet_dir = gArgs.GetArg("-walletdir", "");
         boost::system::error_code error;
@@ -200,8 +167,6 @@ bool WalletInit::Verify() const
 
     uiInterface.InitMessage(_("Verifying wallet(s)..."));
 
-    std::vector<std::string> wallet_files = gArgs.GetArgs("-wallet");
-
     // Parameter interaction code should have thrown an error if -salvagewallet
     // was enabled with more than wallet file, so the wallet_files size check
     // here should have no effect.
@@ -219,7 +184,7 @@ bool WalletInit::Verify() const
 
         std::string error_string;
         std::string warning_string;
-        bool verify_success = CWallet::Verify(location, salvage_wallet, error_string, warning_string);
+        bool verify_success = CWallet::Verify(chain, location, salvage_wallet, error_string, warning_string);
         if (!error_string.empty()) InitError(error_string);
         if (!warning_string.empty()) InitWarning(warning_string);
         if (!verify_success) return false;
@@ -228,15 +193,20 @@ bool WalletInit::Verify() const
     return true;
 }
 
-bool WalletInit::Open() const
+void WalletInit::Construct(InitInterfaces& interfaces) const
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         LogPrintf("Wallet disabled!\n");
-        return true;
+        return;
     }
+    gArgs.SoftSetArg("-wallet", "");
+    interfaces.chain_clients.emplace_back(interfaces::MakeWalletClient(*interfaces.chain, gArgs.GetArgs("-wallet")));
+}
 
-    for (const std::string& walletFile : gArgs.GetArgs("-wallet")) {
-        std::shared_ptr<CWallet> pwallet = CWallet::CreateWalletFromFile(WalletLocation(walletFile));
+bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
+{
+    for (const std::string& walletFile : wallet_files) {
+        std::shared_ptr<CWallet> pwallet = CWallet::CreateWalletFromFile(chain, WalletLocation(walletFile));
         if (!pwallet) {
             return false;
         }
@@ -246,7 +216,7 @@ bool WalletInit::Open() const
     return true;
 }
 
-void WalletInit::Start(CScheduler& scheduler) const
+void StartWallets(CScheduler& scheduler)
 {
     for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
         pwallet->postInitProcess();
@@ -256,21 +226,21 @@ void WalletInit::Start(CScheduler& scheduler) const
     scheduler.scheduleEvery(MaybeCompactWalletDB, 500);
 }
 
-void WalletInit::Flush() const
+void FlushWallets()
 {
     for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
         pwallet->Flush(false);
     }
 }
 
-void WalletInit::Stop() const
+void StopWallets()
 {
     for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
         pwallet->Flush(true);
     }
 }
 
-void WalletInit::Close() const
+void UnloadWallets()
 {
     for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
         RemoveWallet(pwallet);
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 2a4cf0147e..e1e4fc51fe 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chain.h>
+#include <interfaces/chain.h>
 #include <key_io.h>
 #include <rpc/server.h>
 #include <validation.h>
@@ -133,7 +134,8 @@ UniValue importprivkey(const JSONRPCRequest& request)
     WalletRescanReserver reserver(pwallet);
     bool fRescan = true;
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
 
         EnsureWalletIsUnlocked(pwallet);
 
@@ -305,7 +307,8 @@ UniValue importaddress(const JSONRPCRequest& request)
         fP2SH = request.params[3].get_bool();
 
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
 
         CTxDestination dest = DecodeDestination(request.params[0].get_str());
         if (IsValidDestination(dest)) {
@@ -362,7 +365,7 @@ UniValue importprunedfunds(const JSONRPCRequest& request)
     unsigned int txnIndex = 0;
     if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) == merkleBlock.header.hashMerkleRoot) {
 
-        LOCK(cs_main);
+        auto locked_chain = pwallet->chain().lock();
         const CBlockIndex* pindex = LookupBlockIndex(merkleBlock.header.GetHash());
         if (!pindex || !chainActive.Contains(pindex)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
@@ -382,7 +385,8 @@ UniValue importprunedfunds(const JSONRPCRequest& request)
     wtx.nIndex = txnIndex;
     wtx.hashBlock = merkleBlock.header.GetHash();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (pwallet->IsMine(*wtx.tx)) {
         pwallet->AddToWallet(wtx, false);
@@ -412,7 +416,8 @@ UniValue removeprunedfunds(const JSONRPCRequest& request)
             + HelpExampleRpc("removeprunedfunds", "\"a8d0c0184dde994a09ec054286f1ce581bebf46446a512166eae7628734ea0a5\"")
         );
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     uint256 hash(ParseHashV(request.params[0], "txid"));
     std::vector<uint256> vHash;
@@ -483,7 +488,8 @@ UniValue importpubkey(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey is not a valid public key");
 
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
 
         for (const auto& dest : GetAllDestinationsForKey(pubKey)) {
             ImportAddress(pwallet, dest, strLabel);
@@ -535,7 +541,8 @@ UniValue importwallet(const JSONRPCRequest& request)
     int64_t nTimeBegin = 0;
     bool fGood = true;
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
 
         EnsureWalletIsUnlocked(pwallet);
 
@@ -653,7 +660,8 @@ UniValue dumpprivkey(const JSONRPCRequest& request)
             + HelpExampleRpc("dumpprivkey", "\"myaddress\"")
         );
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     EnsureWalletIsUnlocked(pwallet);
 
@@ -700,7 +708,8 @@ UniValue dumpwallet(const JSONRPCRequest& request)
             + HelpExampleRpc("dumpwallet", "\"test\"")
         );
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     EnsureWalletIsUnlocked(pwallet);
 
@@ -723,7 +732,7 @@ UniValue dumpwallet(const JSONRPCRequest& request)
 
     std::map<CTxDestination, int64_t> mapKeyBirth;
     const std::map<CKeyID, int64_t>& mapKeyPool = pwallet->GetAllReserveKeys();
-    pwallet->GetKeyBirthTimes(mapKeyBirth);
+    pwallet->GetKeyBirthTimes(*locked_chain, mapKeyBirth);
 
     std::set<CScriptID> scripts = pwallet->GetCScripts();
     // TODO: include scripts in GetKeyBirthTimes() output instead of separate
@@ -1134,7 +1143,8 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
     int64_t nLowestTimestamp = 0;
     UniValue response(UniValue::VARR);
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
         EnsureWalletIsUnlocked(pwallet);
 
         // Verify all timestamps are present before importing any keys.
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 45d4b5bceb..5a89448e02 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -8,6 +8,8 @@
 #include <consensus/validation.h>
 #include <core_io.h>
 #include <httpserver.h>
+#include <init.h>
+#include <interfaces/chain.h>
 #include <validation.h>
 #include <key_io.h>
 #include <net.h>
@@ -89,9 +91,9 @@ void EnsureWalletIsUnlocked(CWallet * const pwallet)
     }
 }
 
-static void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+static void WalletTxToJSON(interfaces::Chain& chain, interfaces::Chain::Lock& locked_chain, const CWalletTx& wtx, UniValue& entry)
 {
-    int confirms = wtx.GetDepthInMainChain();
+    int confirms = wtx.GetDepthInMainChain(locked_chain);
     entry.pushKV("confirmations", confirms);
     if (wtx.IsCoinBase())
         entry.pushKV("generated", true);
@@ -101,7 +103,7 @@ static void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry) EXCLUSIVE_LOCK
         entry.pushKV("blockindex", wtx.nIndex);
         entry.pushKV("blocktime", LookupBlockIndex(wtx.hashBlock)->GetBlockTime());
     } else {
-        entry.pushKV("trusted", wtx.IsTrusted());
+        entry.pushKV("trusted", wtx.IsTrusted(locked_chain));
     }
     uint256 hash = wtx.GetHash();
     entry.pushKV("txid", hash.GetHex());
@@ -290,7 +292,7 @@ static UniValue setlabel(const JSONRPCRequest& request)
 }
 
 
-static CTransactionRef SendMoney(CWallet * const pwallet, const CTxDestination &address, CAmount nValue, bool fSubtractFeeFromAmount, const CCoinControl& coin_control, mapValue_t mapValue)
+static CTransactionRef SendMoney(interfaces::Chain::Lock& locked_chain, CWallet * const pwallet, const CTxDestination &address, CAmount nValue, bool fSubtractFeeFromAmount, const CCoinControl& coin_control, mapValue_t mapValue)
 {
     CAmount curBalance = pwallet->GetBalance();
 
@@ -317,7 +319,7 @@ static CTransactionRef SendMoney(CWallet * const pwallet, const CTxDestination &
     CRecipient recipient = {scriptPubKey, nValue, fSubtractFeeFromAmount};
     vecSend.push_back(recipient);
     CTransactionRef tx;
-    if (!pwallet->CreateTransaction(vecSend, tx, reservekey, nFeeRequired, nChangePosRet, strError, coin_control)) {
+    if (!pwallet->CreateTransaction(locked_chain, vecSend, tx, reservekey, nFeeRequired, nChangePosRet, strError, coin_control)) {
         if (!fSubtractFeeFromAmount && nValue + nFeeRequired > curBalance)
             strError = strprintf("Error: This transaction requires a transaction fee of at least %s", FormatMoney(nFeeRequired));
         throw JSONRPCError(RPC_WALLET_ERROR, strError);
@@ -373,7 +375,8 @@ static UniValue sendtoaddress(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     CTxDestination dest = DecodeDestination(request.params[0].get_str());
     if (!IsValidDestination(dest)) {
@@ -415,7 +418,7 @@ static UniValue sendtoaddress(const JSONRPCRequest& request)
 
     EnsureWalletIsUnlocked(pwallet);
 
-    CTransactionRef tx = SendMoney(pwallet, dest, nAmount, fSubtractFeeFromAmount, coin_control, std::move(mapValue));
+    CTransactionRef tx = SendMoney(*locked_chain, pwallet, dest, nAmount, fSubtractFeeFromAmount, coin_control, std::move(mapValue));
     return tx->GetHash().GetHex();
 }
 
@@ -455,10 +458,11 @@ static UniValue listaddressgroupings(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     UniValue jsonGroupings(UniValue::VARR);
-    std::map<CTxDestination, CAmount> balances = pwallet->GetAddressBalances();
+    std::map<CTxDestination, CAmount> balances = pwallet->GetAddressBalances(*locked_chain);
     for (const std::set<CTxDestination>& grouping : pwallet->GetAddressGroupings()) {
         UniValue jsonGrouping(UniValue::VARR);
         for (const CTxDestination& address : grouping)
@@ -508,7 +512,8 @@ static UniValue signmessage(const JSONRPCRequest& request)
             + HelpExampleRpc("signmessage", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", \"my message\"")
         );
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     EnsureWalletIsUnlocked(pwallet);
 
@@ -574,7 +579,9 @@ static UniValue getreceivedbyaddress(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     // Bitcoin address
     CTxDestination dest = DecodeDestination(request.params[0].get_str());
@@ -600,7 +607,7 @@ static UniValue getreceivedbyaddress(const JSONRPCRequest& request)
 
         for (const CTxOut& txout : wtx.tx->vout)
             if (txout.scriptPubKey == scriptPubKey)
-                if (wtx.GetDepthInMainChain() >= nMinDepth)
+                if (wtx.GetDepthInMainChain(*locked_chain) >= nMinDepth)
                     nAmount += txout.nValue;
     }
 
@@ -641,7 +648,9 @@ static UniValue getreceivedbylabel(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     // Minimum confirmations
     int nMinDepth = 1;
@@ -663,7 +672,7 @@ static UniValue getreceivedbylabel(const JSONRPCRequest& request)
         {
             CTxDestination address;
             if (ExtractDestination(txout.scriptPubKey, address) && IsMine(*pwallet, address) && setAddress.count(address)) {
-                if (wtx.GetDepthInMainChain() >= nMinDepth)
+                if (wtx.GetDepthInMainChain(*locked_chain) >= nMinDepth)
                     nAmount += txout.nValue;
             }
         }
@@ -707,7 +716,8 @@ static UniValue getbalance(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     const UniValue& dummy_value = request.params[0];
     if (!dummy_value.isNull() && dummy_value.get_str() != "*") {
@@ -745,7 +755,8 @@ static UniValue getunconfirmedbalance(const JSONRPCRequest &request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     return ValueFromAmount(pwallet->GetUnconfirmedBalance());
 }
@@ -806,7 +817,8 @@ static UniValue sendmany(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (pwallet->GetBroadcastTransactions() && !g_connman) {
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
@@ -892,7 +904,7 @@ static UniValue sendmany(const JSONRPCRequest& request)
     int nChangePosRet = -1;
     std::string strFailReason;
     CTransactionRef tx;
-    bool fCreated = pwallet->CreateTransaction(vecSend, tx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
+    bool fCreated = pwallet->CreateTransaction(*locked_chain, vecSend, tx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
     if (!fCreated)
         throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, strFailReason);
     CValidationState state;
@@ -945,7 +957,8 @@ static UniValue addmultisigaddress(const JSONRPCRequest& request)
         throw std::runtime_error(msg);
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     std::string label;
     if (!request.params[2].isNull())
@@ -996,8 +1009,10 @@ struct tallyitem
     }
 };
 
-static UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool by_label) EXCLUSIVE_LOCKS_REQUIRED(cs_main, pwallet->cs_wallet)
+static UniValue ListReceived(interfaces::Chain::Lock& locked_chain, CWallet * const pwallet, const UniValue& params, bool by_label) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)
 {
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+
     // Minimum confirmations
     int nMinDepth = 1;
     if (!params[0].isNull())
@@ -1031,7 +1046,7 @@ static UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bo
         if (wtx.IsCoinBase() || !CheckFinalTx(*wtx.tx))
             continue;
 
-        int nDepth = wtx.GetDepthInMainChain();
+        int nDepth = wtx.GetDepthInMainChain(locked_chain);
         if (nDepth < nMinDepth)
             continue;
 
@@ -1185,9 +1200,10 @@ static UniValue listreceivedbyaddress(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
-    return ListReceived(pwallet, request.params, false);
+    return ListReceived(*locked_chain, pwallet, request.params, false);
 }
 
 static UniValue listreceivedbylabel(const JSONRPCRequest& request)
@@ -1229,9 +1245,10 @@ static UniValue listreceivedbylabel(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
-    return ListReceived(pwallet, request.params, true);
+    return ListReceived(*locked_chain, pwallet, request.params, true);
 }
 
 static void MaybePushAddress(UniValue & entry, const CTxDestination &dest)
@@ -1251,7 +1268,7 @@ static void MaybePushAddress(UniValue & entry, const CTxDestination &dest)
  * @param  ret        The UniValue into which the result is stored.
  * @param  filter     The "is mine" filter bool.
  */
-static void ListTransactions(CWallet* const pwallet, const CWalletTx& wtx, int nMinDepth, bool fLong, UniValue& ret, const isminefilter& filter) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+static void ListTransactions(interfaces::Chain::Lock& locked_chain, CWallet* const pwallet, const CWalletTx& wtx, int nMinDepth, bool fLong, UniValue& ret, const isminefilter& filter)
 {
     CAmount nFee;
     std::list<COutputEntry> listReceived;
@@ -1279,14 +1296,14 @@ static void ListTransactions(CWallet* const pwallet, const CWalletTx& wtx, int n
             entry.pushKV("vout", s.vout);
             entry.pushKV("fee", ValueFromAmount(-nFee));
             if (fLong)
-                WalletTxToJSON(wtx, entry);
+                WalletTxToJSON(pwallet->chain(), locked_chain, wtx, entry);
             entry.pushKV("abandoned", wtx.isAbandoned());
             ret.push_back(entry);
         }
     }
 
     // Received
-    if (listReceived.size() > 0 && wtx.GetDepthInMainChain() >= nMinDepth)
+    if (listReceived.size() > 0 && wtx.GetDepthInMainChain(locked_chain) >= nMinDepth)
     {
         for (const COutputEntry& r : listReceived)
         {
@@ -1301,9 +1318,9 @@ static void ListTransactions(CWallet* const pwallet, const CWalletTx& wtx, int n
             MaybePushAddress(entry, r.destination);
             if (wtx.IsCoinBase())
             {
-                if (wtx.GetDepthInMainChain() < 1)
+                if (wtx.GetDepthInMainChain(locked_chain) < 1)
                     entry.pushKV("category", "orphan");
-                else if (wtx.IsImmatureCoinBase())
+                else if (wtx.IsImmatureCoinBase(locked_chain))
                     entry.pushKV("category", "immature");
                 else
                     entry.pushKV("category", "generate");
@@ -1318,7 +1335,7 @@ static void ListTransactions(CWallet* const pwallet, const CWalletTx& wtx, int n
             }
             entry.pushKV("vout", r.vout);
             if (fLong)
-                WalletTxToJSON(wtx, entry);
+                WalletTxToJSON(pwallet->chain(), locked_chain, wtx, entry);
             ret.push_back(entry);
         }
     }
@@ -1405,7 +1422,8 @@ UniValue listtransactions(const JSONRPCRequest& request)
     UniValue ret(UniValue::VARR);
 
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
 
         const CWallet::TxItems & txOrdered = pwallet->wtxOrdered;
 
@@ -1413,7 +1431,7 @@ UniValue listtransactions(const JSONRPCRequest& request)
         for (CWallet::TxItems::const_reverse_iterator it = txOrdered.rbegin(); it != txOrdered.rend(); ++it)
         {
             CWalletTx *const pwtx = (*it).second;
-            ListTransactions(pwallet, *pwtx, 0, true, ret, filter);
+            ListTransactions(*locked_chain, pwallet, *pwtx, 0, true, ret, filter);
             if ((int)ret.size() >= (nCount+nFrom)) break;
         }
     }
@@ -1505,7 +1523,8 @@ static UniValue listsinceblock(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     const CBlockIndex* pindex = nullptr;    // Block index of the specified block or the common ancestor, if the block provided was in a deactivated chain.
     const CBlockIndex* paltindex = nullptr; // Block index of the specified block, even if it's in a deactivated chain.
@@ -1548,8 +1567,8 @@ static UniValue listsinceblock(const JSONRPCRequest& request)
     for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         CWalletTx tx = pairWtx.second;
 
-        if (depth == -1 || tx.GetDepthInMainChain() < depth) {
-            ListTransactions(pwallet, tx, 0, true, transactions, filter);
+        if (depth == -1 || tx.GetDepthInMainChain(*locked_chain) < depth) {
+            ListTransactions(*locked_chain, pwallet, tx, 0, true, transactions, filter);
         }
     }
 
@@ -1566,7 +1585,7 @@ static UniValue listsinceblock(const JSONRPCRequest& request)
             if (it != pwallet->mapWallet.end()) {
                 // We want all transactions regardless of confirmation count to appear here,
                 // even negative confirmation ones, hence the big negative.
-                ListTransactions(pwallet, it->second, -100000000, true, removed, filter);
+                ListTransactions(*locked_chain, pwallet, it->second, -100000000, true, removed, filter);
             }
         }
         paltindex = paltindex->pprev;
@@ -1640,7 +1659,8 @@ static UniValue gettransaction(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     uint256 hash(ParseHashV(request.params[0], "txid"));
 
@@ -1656,7 +1676,7 @@ static UniValue gettransaction(const JSONRPCRequest& request)
     }
     const CWalletTx& wtx = it->second;
 
-    CAmount nCredit = wtx.GetCredit(filter);
+    CAmount nCredit = wtx.GetCredit(*locked_chain, filter);
     CAmount nDebit = wtx.GetDebit(filter);
     CAmount nNet = nCredit - nDebit;
     CAmount nFee = (wtx.IsFromMe(filter) ? wtx.tx->GetValueOut() - nDebit : 0);
@@ -1665,10 +1685,10 @@ static UniValue gettransaction(const JSONRPCRequest& request)
     if (wtx.IsFromMe(filter))
         entry.pushKV("fee", ValueFromAmount(nFee));
 
-    WalletTxToJSON(wtx, entry);
+    WalletTxToJSON(pwallet->chain(), *locked_chain, wtx, entry);
 
     UniValue details(UniValue::VARR);
-    ListTransactions(pwallet, wtx, 0, false, details, filter);
+    ListTransactions(*locked_chain, pwallet, wtx, 0, false, details, filter);
     entry.pushKV("details", details);
 
     std::string strHex = EncodeHexTx(*wtx.tx, RPCSerializationFlags());
@@ -1707,14 +1727,15 @@ static UniValue abandontransaction(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     uint256 hash(ParseHashV(request.params[0], "txid"));
 
     if (!pwallet->mapWallet.count(hash)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid or non-wallet transaction id");
     }
-    if (!pwallet->AbandonTransaction(hash)) {
+    if (!pwallet->AbandonTransaction(*locked_chain, hash)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not eligible for abandonment");
     }
 
@@ -1746,7 +1767,8 @@ static UniValue backupwallet(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     std::string strDest = request.params[0].get_str();
     if (!pwallet->BackupWallet(strDest)) {
@@ -1782,7 +1804,8 @@ static UniValue keypoolrefill(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_WALLET_ERROR, "Error: Private keys are disabled for this wallet");
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     // 0 is interpreted by TopUpKeyPool() as the default keypool size given by -keypool
     unsigned int kpSize = 0;
@@ -1833,7 +1856,8 @@ static UniValue walletpassphrase(const JSONRPCRequest& request)
         );
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletpassphrase was called.");
@@ -1911,7 +1935,8 @@ static UniValue walletpassphrasechange(const JSONRPCRequest& request)
         );
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletpassphrasechange was called.");
@@ -1967,7 +1992,8 @@ static UniValue walletlock(const JSONRPCRequest& request)
         );
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (!pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletlock was called.");
@@ -2013,7 +2039,8 @@ static UniValue encryptwallet(const JSONRPCRequest& request)
         );
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an encrypted wallet, but encryptwallet was called.");
@@ -2087,7 +2114,8 @@ static UniValue lockunspent(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     RPCTypeCheckArgument(request.params[0], UniValue::VBOOL);
 
@@ -2136,7 +2164,7 @@ static UniValue lockunspent(const JSONRPCRequest& request)
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout index out of bounds");
         }
 
-        if (pwallet->IsSpent(outpt.hash, outpt.n)) {
+        if (pwallet->IsSpent(*locked_chain, outpt.hash, outpt.n)) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expected unspent output");
         }
 
@@ -2197,7 +2225,8 @@ static UniValue listlockunspent(const JSONRPCRequest& request)
             + HelpExampleRpc("listlockunspent", "")
         );
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     std::vector<COutPoint> vOutpts;
     pwallet->ListLockedCoins(vOutpts);
@@ -2238,7 +2267,8 @@ static UniValue settxfee(const JSONRPCRequest& request)
         );
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     CAmount nAmount = AmountFromValue(request.params[0]);
     CFeeRate tx_fee_rate(nAmount, 1000);
@@ -2293,7 +2323,8 @@ static UniValue getwalletinfo(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     UniValue obj(UniValue::VOBJ);
 
@@ -2420,11 +2451,11 @@ static UniValue loadwallet(const JSONRPCRequest& request)
     }
 
     std::string warning;
-    if (!CWallet::Verify(location, false, error, warning)) {
+    if (!CWallet::Verify(*g_rpc_interfaces->chain, location, false, error, warning)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet file verification failed: " + error);
     }
 
-    std::shared_ptr<CWallet> const wallet = CWallet::CreateWalletFromFile(location);
+    std::shared_ptr<CWallet> const wallet = CWallet::CreateWalletFromFile(*g_rpc_interfaces->chain, location);
     if (!wallet) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet loading failed.");
     }
@@ -2472,11 +2503,11 @@ static UniValue createwallet(const JSONRPCRequest& request)
     }
 
     // Wallet::Verify will check if we're trying to create a wallet with a duplication name.
-    if (!CWallet::Verify(location, false, error, warning)) {
+    if (!CWallet::Verify(*g_rpc_interfaces->chain, location, false, error, warning)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet file verification failed: " + error);
     }
 
-    std::shared_ptr<CWallet> const wallet = CWallet::CreateWalletFromFile(location, (disable_privatekeys ? (uint64_t)WALLET_FLAG_DISABLE_PRIVATE_KEYS : 0));
+    std::shared_ptr<CWallet> const wallet = CWallet::CreateWalletFromFile(*g_rpc_interfaces->chain, location, (disable_privatekeys ? (uint64_t)WALLET_FLAG_DISABLE_PRIVATE_KEYS : 0));
     if (!wallet) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet creation failed.");
     }
@@ -2562,13 +2593,14 @@ static UniValue resendwallettransactions(const JSONRPCRequest& request)
     if (!g_connman)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     if (!pwallet->GetBroadcastTransactions()) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Error: Wallet transaction broadcasting is disabled with -walletbroadcast");
     }
 
-    std::vector<uint256> txids = pwallet->ResendWalletTransactionsBefore(GetTime(), g_connman.get());
+    std::vector<uint256> txids = pwallet->ResendWalletTransactionsBefore(*locked_chain, GetTime(), g_connman.get());
     UniValue result(UniValue::VARR);
     for (const uint256& txid : txids)
     {
@@ -2699,8 +2731,9 @@ static UniValue listunspent(const JSONRPCRequest& request)
     UniValue results(UniValue::VARR);
     std::vector<COutput> vecOutputs;
     {
-        LOCK2(cs_main, pwallet->cs_wallet);
-        pwallet->AvailableCoins(vecOutputs, !include_unsafe, nullptr, nMinimumAmount, nMaximumAmount, nMinimumSumAmount, nMaximumCount, nMinDepth, nMaxDepth);
+        auto locked_chain = pwallet->chain().lock();
+        LOCK(pwallet->cs_wallet);
+        pwallet->AvailableCoins(*locked_chain, vecOutputs, !include_unsafe, nullptr, nMinimumAmount, nMaximumAmount, nMinimumSumAmount, nMaximumCount, nMinDepth, nMaxDepth);
     }
 
     LOCK(pwallet->cs_wallet);
@@ -3018,10 +3051,11 @@ UniValue signrawtransactionwithwallet(const JSONRPCRequest& request)
     }
 
     // Sign the transaction
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
     EnsureWalletIsUnlocked(pwallet);
 
-    return SignTransaction(mtx, request.params[1], pwallet, false, request.params[2]);
+    return SignTransaction(pwallet->chain(), mtx, request.params[1], pwallet, false, request.params[2]);
 }
 
 static UniValue bumpfee(const JSONRPCRequest& request)
@@ -3123,7 +3157,8 @@ static UniValue bumpfee(const JSONRPCRequest& request)
     // the user could have gotten from another RPC command prior to now
     pwallet->BlockUntilSyncedToCurrentChain();
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
     EnsureWalletIsUnlocked(pwallet);
 
 
@@ -3263,7 +3298,7 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
     CBlockIndex *pindexStop = nullptr;
     CBlockIndex *pChainTip = nullptr;
     {
-        LOCK(cs_main);
+        auto locked_chain = pwallet->chain().lock();
         pindexStart = chainActive.Genesis();
         pChainTip = chainActive.Tip();
 
@@ -3287,7 +3322,7 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
 
     // We can't rescan beyond non-pruned blocks, stop and throw an error
     if (fPruneMode) {
-        LOCK(cs_main);
+        auto locked_chain = pwallet->chain().lock();
         CBlockIndex *block = pindexStop ? pindexStop : pChainTip;
         while (block && block->nHeight >= pindexStart->nHeight) {
             if (!(block->nStatus & BLOCK_HAVE_DATA)) {
@@ -3687,7 +3722,8 @@ UniValue sethdseed(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Cannot set a new HD seed while still in Initial Block Download");
     }
 
-    LOCK2(cs_main, pwallet->cs_wallet);
+    auto locked_chain = pwallet->chain().lock();
+    LOCK(pwallet->cs_wallet);
 
     // Do not do anything to non-HD wallets
     if (!pwallet->IsHDEnabled()) {
diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
index a9464870ea..5c65acf601 100644
--- a/src/wallet/test/coinselector_tests.cpp
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -28,7 +28,8 @@ std::vector<std::unique_ptr<CWalletTx>> wtxn;
 typedef std::set<CInputCoin> CoinSet;
 
 static std::vector<COutput> vCoins;
-static CWallet testWallet(WalletLocation(), WalletDatabase::CreateDummy());
+static auto testChain = interfaces::MakeChain();
+static CWallet testWallet(*testChain, WalletLocation(), WalletDatabase::CreateDummy());
 static CAmount balance = 0;
 
 CoinEligibilityFilter filter_standard(1, 6, 0);
diff --git a/src/wallet/test/init_test_fixture.cpp b/src/wallet/test/init_test_fixture.cpp
index 1453029c9c..3b828d57f9 100644
--- a/src/wallet/test/init_test_fixture.cpp
+++ b/src/wallet/test/init_test_fixture.cpp
@@ -8,6 +8,8 @@
 
 InitWalletDirTestingSetup::InitWalletDirTestingSetup(const std::string& chainName): BasicTestingSetup(chainName)
 {
+    m_chain_client = MakeWalletClient(*m_chain, {});
+
     std::string sep;
     sep += fs::path::preferred_separator;
 
diff --git a/src/wallet/test/init_test_fixture.h b/src/wallet/test/init_test_fixture.h
index 5684adbece..cd47b31da1 100644
--- a/src/wallet/test/init_test_fixture.h
+++ b/src/wallet/test/init_test_fixture.h
@@ -5,6 +5,7 @@
 #ifndef BITCOIN_WALLET_TEST_INIT_TEST_FIXTURE_H
 #define BITCOIN_WALLET_TEST_INIT_TEST_FIXTURE_H
 
+#include <interfaces/chain.h>
 #include <test/test_bitcoin.h>
 
 
@@ -16,6 +17,8 @@ struct InitWalletDirTestingSetup: public BasicTestingSetup {
     fs::path m_datadir;
     fs::path m_cwd;
     std::map<std::string, fs::path> m_walletdir_path_cases;
+    std::unique_ptr<interfaces::Chain> m_chain = interfaces::MakeChain();
+    std::unique_ptr<interfaces::ChainClient> m_chain_client;
 };
 
 #endif // BITCOIN_WALLET_TEST_INIT_TEST_FIXTURE_H
diff --git a/src/wallet/test/init_tests.cpp b/src/wallet/test/init_tests.cpp
index 7048547b2b..5852d3ef84 100644
--- a/src/wallet/test/init_tests.cpp
+++ b/src/wallet/test/init_tests.cpp
@@ -17,7 +17,7 @@ BOOST_FIXTURE_TEST_SUITE(init_tests, InitWalletDirTestingSetup)
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_default)
 {
     SetWalletDir(m_walletdir_path_cases["default"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == true);
     fs::path walletdir = gArgs.GetArg("-walletdir", "");
     fs::path expected_path = fs::canonical(m_walletdir_path_cases["default"]);
@@ -27,7 +27,7 @@ BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_default)
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_custom)
 {
     SetWalletDir(m_walletdir_path_cases["custom"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == true);
     fs::path walletdir = gArgs.GetArg("-walletdir", "");
     fs::path expected_path = fs::canonical(m_walletdir_path_cases["custom"]);
@@ -37,28 +37,28 @@ BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_custom)
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_does_not_exist)
 {
     SetWalletDir(m_walletdir_path_cases["nonexistent"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == false);
 }
 
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_is_not_directory)
 {
     SetWalletDir(m_walletdir_path_cases["file"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == false);
 }
 
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_is_not_relative)
 {
     SetWalletDir(m_walletdir_path_cases["relative"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == false);
 }
 
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_no_trailing)
 {
     SetWalletDir(m_walletdir_path_cases["trailing"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == true);
     fs::path walletdir = gArgs.GetArg("-walletdir", "");
     fs::path expected_path = fs::canonical(m_walletdir_path_cases["default"]);
@@ -68,7 +68,7 @@ BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_no_trailing)
 BOOST_AUTO_TEST_CASE(walletinit_verify_walletdir_no_trailing2)
 {
     SetWalletDir(m_walletdir_path_cases["trailing2"]);
-    bool result = g_wallet_init_interface.Verify();
+    bool result = m_chain_client->verify();
     BOOST_CHECK(result == true);
     fs::path walletdir = gArgs.GetArg("-walletdir", "");
     fs::path expected_path = fs::canonical(m_walletdir_path_cases["default"]);
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index d42209ab15..a5fb1db86c 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -9,7 +9,7 @@
 #include <wallet/rpcwallet.h>
 
 WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
-    TestingSetup(chainName), m_wallet(WalletLocation(), WalletDatabase::CreateMock())
+    TestingSetup(chainName), m_wallet(*m_chain, WalletLocation(), WalletDatabase::CreateMock())
 {
     bool fFirstRun;
     m_wallet.LoadWallet(fFirstRun);
diff --git a/src/wallet/test/wallet_test_fixture.h b/src/wallet/test/wallet_test_fixture.h
index ff8ec32b03..e6fe8c9473 100644
--- a/src/wallet/test/wallet_test_fixture.h
+++ b/src/wallet/test/wallet_test_fixture.h
@@ -7,6 +7,8 @@
 
 #include <test/test_bitcoin.h>
 
+#include <interfaces/chain.h>
+#include <interfaces/wallet.h>
 #include <wallet/wallet.h>
 
 #include <memory>
@@ -17,6 +19,7 @@ struct WalletTestingSetup: public TestingSetup {
     explicit WalletTestingSetup(const std::string& chainName = CBaseChainParams::MAIN);
     ~WalletTestingSetup();
 
+    std::unique_ptr<interfaces::Chain> m_chain = interfaces::MakeChain();
     CWallet m_wallet;
 };
 
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 269a916829..c6aac8aad5 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -11,6 +11,7 @@
 #include <vector>
 
 #include <consensus/validation.h>
+#include <interfaces/chain.h>
 #include <rpc/server.h>
 #include <test/test_bitcoin.h>
 #include <validation.h>
@@ -34,6 +35,8 @@ static void AddKey(CWallet& wallet, const CKey& key)
 
 BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
 {
+    auto chain = interfaces::MakeChain();
+
     // Cap last block file size, and mine new block in a new block file.
     CBlockIndex* const nullBlock = nullptr;
     CBlockIndex* oldTip = chainActive.Tip();
@@ -41,12 +44,12 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
     CBlockIndex* newTip = chainActive.Tip();
 
-    LOCK(cs_main);
+    auto locked_chain = chain->lock();
 
     // Verify ScanForWalletTransactions picks up transactions in both the old
     // and new block files.
     {
-        CWallet wallet(WalletLocation(), WalletDatabase::CreateDummy());
+        CWallet wallet(*chain, WalletLocation(), WalletDatabase::CreateDummy());
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
@@ -61,7 +64,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // Verify ScanForWalletTransactions only picks transactions in the new block
     // file.
     {
-        CWallet wallet(WalletLocation(), WalletDatabase::CreateDummy());
+        CWallet wallet(*chain, WalletLocation(), WalletDatabase::CreateDummy());
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
@@ -73,7 +76,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // before the missing block, and success for a key whose creation time is
     // after.
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateDummy());
+        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateDummy());
         AddWallet(wallet);
         UniValue keys;
         keys.setArray();
@@ -115,6 +118,8 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
 // than or equal to key birthday.
 BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 {
+    auto chain = interfaces::MakeChain();
+
     // Create two blocks with same timestamp to verify that importwallet rescan
     // will pick up both blocks, not just the first.
     const int64_t BLOCK_TIME = chainActive.Tip()->GetBlockTimeMax() + 5;
@@ -128,13 +133,13 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     SetMockTime(KEY_TIME);
     m_coinbase_txns.emplace_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
 
-    LOCK(cs_main);
+    auto locked_chain = chain->lock();
 
     std::string backup_file = (SetDataDir("importwallet_rescan") / "wallet.backup").string();
 
     // Import key into wallet and call dumpwallet to create backup file.
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateDummy());
+        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateDummy());
         LOCK(wallet->cs_wallet);
         wallet->mapKeyMetadata[coinbaseKey.GetPubKey().GetID()].nCreateTime = KEY_TIME;
         wallet->AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
@@ -150,7 +155,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     // Call importwallet RPC and verify all blocks with timestamps >= BLOCK_TIME
     // were scanned, and no prior blocks were scanned.
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateDummy());
+        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateDummy());
 
         JSONRPCRequest request;
         request.params.setArray();
@@ -180,21 +185,23 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 // debit functions.
 BOOST_FIXTURE_TEST_CASE(coin_mark_dirty_immature_credit, TestChain100Setup)
 {
-    CWallet wallet(WalletLocation(), WalletDatabase::CreateDummy());
+    auto chain = interfaces::MakeChain();
+    CWallet wallet(*chain, WalletLocation(), WalletDatabase::CreateDummy());
     CWalletTx wtx(&wallet, m_coinbase_txns.back());
-    LOCK2(cs_main, wallet.cs_wallet);
+    auto locked_chain = chain->lock();
+    LOCK(wallet.cs_wallet);
     wtx.hashBlock = chainActive.Tip()->GetBlockHash();
     wtx.nIndex = 0;
 
     // Call GetImmatureCredit() once before adding the key to the wallet to
     // cache the current immature credit amount, which is 0.
-    BOOST_CHECK_EQUAL(wtx.GetImmatureCredit(), 0);
+    BOOST_CHECK_EQUAL(wtx.GetImmatureCredit(*locked_chain), 0);
 
     // Invalidate the cached value, add the key, and make sure a new immature
     // credit amount is calculated.
     wtx.MarkDirty();
     wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
-    BOOST_CHECK_EQUAL(wtx.GetImmatureCredit(), 50*COIN);
+    BOOST_CHECK_EQUAL(wtx.GetImmatureCredit(*locked_chain), 50*COIN);
 }
 
 static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64_t blockTime)
@@ -204,7 +211,7 @@ static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64
     SetMockTime(mockTime);
     CBlockIndex* block = nullptr;
     if (blockTime > 0) {
-        LOCK(cs_main);
+        auto locked_chain = wallet.chain().lock();
         auto inserted = mapBlockIndex.emplace(GetRandHash(), new CBlockIndex);
         assert(inserted.second);
         const uint256& hash = inserted.first->first;
@@ -273,7 +280,7 @@ public:
     ListCoinsTestingSetup()
     {
         CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
-        wallet = MakeUnique<CWallet>(WalletLocation(), WalletDatabase::CreateMock());
+        wallet = MakeUnique<CWallet>(*m_chain, WalletLocation(), WalletDatabase::CreateMock());
         bool firstRun;
         wallet->LoadWallet(firstRun);
         AddKey(*wallet, coinbaseKey);
@@ -295,7 +302,7 @@ public:
         int changePos = -1;
         std::string error;
         CCoinControl dummy;
-        BOOST_CHECK(wallet->CreateTransaction({recipient}, tx, reservekey, fee, changePos, error, dummy));
+        BOOST_CHECK(wallet->CreateTransaction(*m_locked_chain, {recipient}, tx, reservekey, fee, changePos, error, dummy));
         CValidationState state;
         BOOST_CHECK(wallet->CommitTransaction(tx, {}, {}, reservekey, nullptr, state));
         CMutableTransaction blocktx;
@@ -311,6 +318,8 @@ public:
         return it->second;
     }
 
+    std::unique_ptr<interfaces::Chain> m_chain = interfaces::MakeChain();
+    std::unique_ptr<interfaces::Chain::Lock> m_locked_chain = m_chain->assumeLocked();  // Temporary. Removed in upcoming lock cleanup
     std::unique_ptr<CWallet> wallet;
 };
 
@@ -323,7 +332,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
     std::map<CTxDestination, std::vector<COutput>> list;
     {
         LOCK2(cs_main, wallet->cs_wallet);
-        list = wallet->ListCoins();
+        list = wallet->ListCoins(*m_locked_chain);
     }
     BOOST_CHECK_EQUAL(list.size(), 1U);
     BOOST_CHECK_EQUAL(boost::get<CKeyID>(list.begin()->first).ToString(), coinbaseAddress);
@@ -339,7 +348,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
     AddTx(CRecipient{GetScriptForRawPubKey({}), 1 * COIN, false /* subtract fee */});
     {
         LOCK2(cs_main, wallet->cs_wallet);
-        list = wallet->ListCoins();
+        list = wallet->ListCoins(*m_locked_chain);
     }
     BOOST_CHECK_EQUAL(list.size(), 1U);
     BOOST_CHECK_EQUAL(boost::get<CKeyID>(list.begin()->first).ToString(), coinbaseAddress);
@@ -349,7 +358,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
     {
         LOCK2(cs_main, wallet->cs_wallet);
         std::vector<COutput> available;
-        wallet->AvailableCoins(available);
+        wallet->AvailableCoins(*m_locked_chain, available);
         BOOST_CHECK_EQUAL(available.size(), 2U);
     }
     for (const auto& group : list) {
@@ -361,14 +370,14 @@ BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
     {
         LOCK2(cs_main, wallet->cs_wallet);
         std::vector<COutput> available;
-        wallet->AvailableCoins(available);
+        wallet->AvailableCoins(*m_locked_chain, available);
         BOOST_CHECK_EQUAL(available.size(), 0U);
     }
     // Confirm ListCoins still returns same result as before, despite coins
     // being locked.
     {
         LOCK2(cs_main, wallet->cs_wallet);
-        list = wallet->ListCoins();
+        list = wallet->ListCoins(*m_locked_chain);
     }
     BOOST_CHECK_EQUAL(list.size(), 1U);
     BOOST_CHECK_EQUAL(boost::get<CKeyID>(list.begin()->first).ToString(), coinbaseAddress);
@@ -377,7 +386,8 @@ BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
 
 BOOST_FIXTURE_TEST_CASE(wallet_disableprivkeys, TestChain100Setup)
 {
-    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(WalletLocation(), WalletDatabase::CreateDummy());
+    auto chain = interfaces::MakeChain();
+    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(*chain, WalletLocation(), WalletDatabase::CreateDummy());
     wallet->SetWalletFlag(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
     BOOST_CHECK(!wallet->TopUpKeyPool(1000));
     CPubKey pubkey;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 2ea9f45462..8ea4c5c495 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -11,6 +11,7 @@
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <fs.h>
+#include <interfaces/chain.h>
 #include <key.h>
 #include <key_io.h>
 #include <keystore.h>
@@ -593,7 +594,7 @@ void CWallet::SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator> ran
  * Outpoint is spent if any non-conflicted transaction
  * spends it:
  */
-bool CWallet::IsSpent(const uint256& hash, unsigned int n) const
+bool CWallet::IsSpent(interfaces::Chain::Lock& locked_chain, const uint256& hash, unsigned int n) const
 {
     const COutPoint outpoint(hash, n);
     std::pair<TxSpends::const_iterator, TxSpends::const_iterator> range;
@@ -604,7 +605,7 @@ bool CWallet::IsSpent(const uint256& hash, unsigned int n) const
         const uint256& wtxid = it->second;
         std::map<uint256, CWalletTx>::const_iterator mit = mapWallet.find(wtxid);
         if (mit != mapWallet.end()) {
-            int depth = mit->second.GetDepthInMainChain();
+            int depth = mit->second.GetDepthInMainChain(locked_chain);
             if (depth > 0  || (depth == 0 && !mit->second.isAbandoned()))
                 return true; // Spent
         }
@@ -1005,9 +1006,10 @@ bool CWallet::AddToWalletIfInvolvingMe(const CTransactionRef& ptx, const CBlockI
 
 bool CWallet::TransactionCanBeAbandoned(const uint256& hashTx) const
 {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
     const CWalletTx* wtx = GetWalletTx(hashTx);
-    return wtx && !wtx->isAbandoned() && wtx->GetDepthInMainChain() == 0 && !wtx->InMempool();
+    return wtx && !wtx->isAbandoned() && wtx->GetDepthInMainChain(*locked_chain) == 0 && !wtx->InMempool();
 }
 
 void CWallet::MarkInputsDirty(const CTransactionRef& tx)
@@ -1020,9 +1022,10 @@ void CWallet::MarkInputsDirty(const CTransactionRef& tx)
     }
 }
 
-bool CWallet::AbandonTransaction(const uint256& hashTx)
+bool CWallet::AbandonTransaction(interfaces::Chain::Lock& locked_chain, const uint256& hashTx)
 {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain_recursive = chain().lock();  // Temporary. Removed in upcoming lock cleanup
+    LOCK(cs_wallet);
 
     WalletBatch batch(*database, "r+");
 
@@ -1033,7 +1036,7 @@ bool CWallet::AbandonTransaction(const uint256& hashTx)
     auto it = mapWallet.find(hashTx);
     assert(it != mapWallet.end());
     CWalletTx& origtx = it->second;
-    if (origtx.GetDepthInMainChain() != 0 || origtx.InMempool()) {
+    if (origtx.GetDepthInMainChain(locked_chain) != 0 || origtx.InMempool()) {
         return false;
     }
 
@@ -1046,7 +1049,7 @@ bool CWallet::AbandonTransaction(const uint256& hashTx)
         auto it = mapWallet.find(now);
         assert(it != mapWallet.end());
         CWalletTx& wtx = it->second;
-        int currentconfirm = wtx.GetDepthInMainChain();
+        int currentconfirm = wtx.GetDepthInMainChain(locked_chain);
         // If the orig tx was not in block, none of its spends can be
         assert(currentconfirm <= 0);
         // if (currentconfirm < 0) {Tx and spends are already conflicted, no need to abandon}
@@ -1077,7 +1080,8 @@ bool CWallet::AbandonTransaction(const uint256& hashTx)
 
 void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)
 {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     int conflictconfirms = 0;
     CBlockIndex* pindex = LookupBlockIndex(hashBlock);
@@ -1106,7 +1110,7 @@ void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)
         auto it = mapWallet.find(now);
         assert(it != mapWallet.end());
         CWalletTx& wtx = it->second;
-        int currentconfirm = wtx.GetDepthInMainChain();
+        int currentconfirm = wtx.GetDepthInMainChain(*locked_chain);
         if (conflictconfirms < currentconfirm) {
             // Block is 'more conflicted' than current confirm; update.
             // Mark transaction as conflicted with this block.
@@ -1140,7 +1144,8 @@ void CWallet::SyncTransaction(const CTransactionRef& ptx, const CBlockIndex *pin
 }
 
 void CWallet::TransactionAddedToMempool(const CTransactionRef& ptx) {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
     SyncTransaction(ptx);
 
     auto it = mapWallet.find(ptx->GetHash());
@@ -1158,7 +1163,8 @@ void CWallet::TransactionRemovedFromMempool(const CTransactionRef &ptx) {
 }
 
 void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex *pindex, const std::vector<CTransactionRef>& vtxConflicted) {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
     // TODO: Temporarily ensure that mempool removals are notified before
     // connected transactions.  This shouldn't matter, but the abandoned
     // state of transactions in our wallet is currently cleared when we
@@ -1180,7 +1186,8 @@ void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const
 }
 
 void CWallet::BlockDisconnected(const std::shared_ptr<const CBlock>& pblock) {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     for (const CTransactionRef& ptx : pblock->vtx) {
         SyncTransaction(ptx);
@@ -1199,7 +1206,7 @@ void CWallet::BlockUntilSyncedToCurrentChain() {
         // We could also take cs_wallet here, and call m_last_block_processed
         // protected by cs_wallet instead of cs_main, but as long as we need
         // cs_main here anyway, it's easier to just call it cs_main-protected.
-        LOCK(cs_main);
+        auto locked_chain = chain().lock();
         const CBlockIndex* initialChainTip = chainActive.Tip();
 
         if (m_last_block_processed && m_last_block_processed->GetAncestor(initialChainTip->nHeight) == initialChainTip) {
@@ -1600,7 +1607,7 @@ int64_t CWallet::RescanFromTime(int64_t startTime, const WalletRescanReserver& r
     // to be scanned.
     CBlockIndex* startBlock = nullptr;
     {
-        LOCK(cs_main);
+        auto locked_chain = chain().lock();
         startBlock = chainActive.FindEarliestAtLeast(startTime - TIMESTAMP_WINDOW);
         WalletLogPrintf("%s: Rescanning last %i blocks\n", __func__, startBlock ? chainActive.Height() - startBlock->nHeight + 1 : 0);
     }
@@ -1652,7 +1659,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
         double progress_begin;
         double progress_end;
         {
-            LOCK(cs_main);
+            auto locked_chain = chain().lock();
             progress_begin = GuessVerificationProgress(chainParams.TxData(), pindex);
             if (pindexStop == nullptr) {
                 tip = chainActive.Tip();
@@ -1674,7 +1681,8 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
 
             CBlock block;
             if (ReadBlockFromDisk(block, pindex, Params().GetConsensus())) {
-                LOCK2(cs_main, cs_wallet);
+                auto locked_chain = chain().lock();
+                LOCK(cs_wallet);
                 if (pindex && !chainActive.Contains(pindex)) {
                     // Abort scan if current block is no longer active, to prevent
                     // marking transactions as coming from the wrong block.
@@ -1691,7 +1699,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, CBlock
                 break;
             }
             {
-                LOCK(cs_main);
+                auto locked_chain = chain().lock();
                 pindex = chainActive.Next(pindex);
                 progress_current = GuessVerificationProgress(chainParams.TxData(), pindex);
                 if (pindexStop == nullptr && tip != chainActive.Tip()) {
@@ -1716,7 +1724,8 @@ void CWallet::ReacceptWalletTransactions()
     // If transactions aren't being broadcasted, don't let them into local mempool either
     if (!fBroadcastTransactions)
         return;
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
     std::map<int64_t, CWalletTx*> mapSorted;
 
     // Sort pending wallet transactions based on their initial wallet insertion order
@@ -1726,7 +1735,7 @@ void CWallet::ReacceptWalletTransactions()
         CWalletTx& wtx = item.second;
         assert(wtx.GetHash() == wtxid);
 
-        int nDepth = wtx.GetDepthInMainChain();
+        int nDepth = wtx.GetDepthInMainChain(*locked_chain);
 
         if (!wtx.IsCoinBase() && (nDepth == 0 && !wtx.isAbandoned())) {
             mapSorted.insert(std::make_pair(wtx.nOrderPos, &wtx));
@@ -1737,18 +1746,18 @@ void CWallet::ReacceptWalletTransactions()
     for (const std::pair<const int64_t, CWalletTx*>& item : mapSorted) {
         CWalletTx& wtx = *(item.second);
         CValidationState state;
-        wtx.AcceptToMemoryPool(maxTxFee, state);
+        wtx.AcceptToMemoryPool(*locked_chain, maxTxFee, state);
     }
 }
 
-bool CWalletTx::RelayWalletTransaction(CConnman* connman)
+bool CWalletTx::RelayWalletTransaction(interfaces::Chain::Lock& locked_chain, CConnman* connman)
 {
     assert(pwallet->GetBroadcastTransactions());
-    if (!IsCoinBase() && !isAbandoned() && GetDepthInMainChain() == 0)
+    if (!IsCoinBase() && !isAbandoned() && GetDepthInMainChain(locked_chain) == 0)
     {
         CValidationState state;
         /* GetDepthInMainChain already catches known conflicts. */
-        if (InMempool() || AcceptToMemoryPool(maxTxFee, state)) {
+        if (InMempool() || AcceptToMemoryPool(locked_chain, maxTxFee, state)) {
             pwallet->WalletLogPrintf("Relaying wtx %s\n", GetHash().ToString());
             if (connman) {
                 CInv inv(MSG_TX, GetHash());
@@ -1806,10 +1815,10 @@ CAmount CWalletTx::GetDebit(const isminefilter& filter) const
     return debit;
 }
 
-CAmount CWalletTx::GetCredit(const isminefilter& filter) const
+CAmount CWalletTx::GetCredit(interfaces::Chain::Lock& locked_chain, const isminefilter& filter) const
 {
     // Must wait until coinbase is safely deep enough in the chain before valuing it
-    if (IsImmatureCoinBase())
+    if (IsImmatureCoinBase(locked_chain))
         return 0;
 
     CAmount credit = 0;
@@ -1839,9 +1848,9 @@ CAmount CWalletTx::GetCredit(const isminefilter& filter) const
     return credit;
 }
 
-CAmount CWalletTx::GetImmatureCredit(bool fUseCache) const
+CAmount CWalletTx::GetImmatureCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache) const
 {
-    if (IsImmatureCoinBase() && IsInMainChain()) {
+    if (IsImmatureCoinBase(locked_chain) && IsInMainChain(locked_chain)) {
         if (fUseCache && fImmatureCreditCached)
             return nImmatureCreditCached;
         nImmatureCreditCached = pwallet->GetCredit(*tx, ISMINE_SPENDABLE);
@@ -1852,13 +1861,13 @@ CAmount CWalletTx::GetImmatureCredit(bool fUseCache) const
     return 0;
 }
 
-CAmount CWalletTx::GetAvailableCredit(bool fUseCache, const isminefilter& filter) const
+CAmount CWalletTx::GetAvailableCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache, const isminefilter& filter) const
 {
     if (pwallet == nullptr)
         return 0;
 
     // Must wait until coinbase is safely deep enough in the chain before valuing it
-    if (IsImmatureCoinBase())
+    if (IsImmatureCoinBase(locked_chain))
         return 0;
 
     CAmount* cache = nullptr;
@@ -1880,7 +1889,7 @@ CAmount CWalletTx::GetAvailableCredit(bool fUseCache, const isminefilter& filter
     uint256 hashTx = GetHash();
     for (unsigned int i = 0; i < tx->vout.size(); i++)
     {
-        if (!pwallet->IsSpent(hashTx, i))
+        if (!pwallet->IsSpent(locked_chain, hashTx, i))
         {
             const CTxOut &txout = tx->vout[i];
             nCredit += pwallet->GetCredit(txout, filter);
@@ -1897,9 +1906,9 @@ CAmount CWalletTx::GetAvailableCredit(bool fUseCache, const isminefilter& filter
     return nCredit;
 }
 
-CAmount CWalletTx::GetImmatureWatchOnlyCredit(const bool fUseCache) const
+CAmount CWalletTx::GetImmatureWatchOnlyCredit(interfaces::Chain::Lock& locked_chain, const bool fUseCache) const
 {
-    if (IsImmatureCoinBase() && IsInMainChain()) {
+    if (IsImmatureCoinBase(locked_chain) && IsInMainChain(locked_chain)) {
         if (fUseCache && fImmatureWatchCreditCached)
             return nImmatureWatchCreditCached;
         nImmatureWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
@@ -1924,12 +1933,14 @@ bool CWalletTx::InMempool() const
     return fInMempool;
 }
 
-bool CWalletTx::IsTrusted() const
+bool CWalletTx::IsTrusted(interfaces::Chain::Lock& locked_chain) const
 {
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+
     // Quick answer in most cases
     if (!CheckFinalTx(*tx))
         return false;
-    int nDepth = GetDepthInMainChain();
+    int nDepth = GetDepthInMainChain(locked_chain);
     if (nDepth >= 1)
         return true;
     if (nDepth < 0)
@@ -1964,7 +1975,7 @@ bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const
         return CTransaction(tx1) == CTransaction(tx2);
 }
 
-std::vector<uint256> CWallet::ResendWalletTransactionsBefore(int64_t nTime, CConnman* connman)
+std::vector<uint256> CWallet::ResendWalletTransactionsBefore(interfaces::Chain::Lock& locked_chain, int64_t nTime, CConnman* connman)
 {
     std::vector<uint256> result;
 
@@ -1983,7 +1994,7 @@ std::vector<uint256> CWallet::ResendWalletTransactionsBefore(int64_t nTime, CCon
     for (const std::pair<const unsigned int, CWalletTx*>& item : mapSorted)
     {
         CWalletTx& wtx = *item.second;
-        if (wtx.RelayWalletTransaction(connman))
+        if (wtx.RelayWalletTransaction(locked_chain, connman))
             result.push_back(wtx.GetHash());
     }
     return result;
@@ -2007,7 +2018,8 @@ void CWallet::ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman
 
     // Rebroadcast unconfirmed txes older than 5 minutes before the last
     // block was found:
-    std::vector<uint256> relayed = ResendWalletTransactionsBefore(nBestBlockTime-5*60, connman);
+    auto locked_chain = chain().assumeLocked();  // Temporary. Removed in upcoming lock cleanup
+    std::vector<uint256> relayed = ResendWalletTransactionsBefore(*locked_chain, nBestBlockTime-5*60, connman);
     if (!relayed.empty())
         WalletLogPrintf("%s: rebroadcast %u unconfirmed transactions\n", __func__, relayed.size());
 }
@@ -2027,12 +2039,13 @@ CAmount CWallet::GetBalance(const isminefilter& filter, const int min_depth) con
 {
     CAmount nTotal = 0;
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         for (const auto& entry : mapWallet)
         {
             const CWalletTx* pcoin = &entry.second;
-            if (pcoin->IsTrusted() && pcoin->GetDepthInMainChain() >= min_depth) {
-                nTotal += pcoin->GetAvailableCredit(true, filter);
+            if (pcoin->IsTrusted(*locked_chain) && pcoin->GetDepthInMainChain(*locked_chain) >= min_depth) {
+                nTotal += pcoin->GetAvailableCredit(*locked_chain, true, filter);
             }
         }
     }
@@ -2044,12 +2057,13 @@ CAmount CWallet::GetUnconfirmedBalance() const
 {
     CAmount nTotal = 0;
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         for (const auto& entry : mapWallet)
         {
             const CWalletTx* pcoin = &entry.second;
-            if (!pcoin->IsTrusted() && pcoin->GetDepthInMainChain() == 0 && pcoin->InMempool())
-                nTotal += pcoin->GetAvailableCredit();
+            if (!pcoin->IsTrusted(*locked_chain) && pcoin->GetDepthInMainChain(*locked_chain) == 0 && pcoin->InMempool())
+                nTotal += pcoin->GetAvailableCredit(*locked_chain);
         }
     }
     return nTotal;
@@ -2059,11 +2073,12 @@ CAmount CWallet::GetImmatureBalance() const
 {
     CAmount nTotal = 0;
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         for (const auto& entry : mapWallet)
         {
             const CWalletTx* pcoin = &entry.second;
-            nTotal += pcoin->GetImmatureCredit();
+            nTotal += pcoin->GetImmatureCredit(*locked_chain);
         }
     }
     return nTotal;
@@ -2073,12 +2088,13 @@ CAmount CWallet::GetUnconfirmedWatchOnlyBalance() const
 {
     CAmount nTotal = 0;
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         for (const auto& entry : mapWallet)
         {
             const CWalletTx* pcoin = &entry.second;
-            if (!pcoin->IsTrusted() && pcoin->GetDepthInMainChain() == 0 && pcoin->InMempool())
-                nTotal += pcoin->GetAvailableCredit(true, ISMINE_WATCH_ONLY);
+            if (!pcoin->IsTrusted(*locked_chain) && pcoin->GetDepthInMainChain(*locked_chain) == 0 && pcoin->InMempool())
+                nTotal += pcoin->GetAvailableCredit(*locked_chain, true, ISMINE_WATCH_ONLY);
         }
     }
     return nTotal;
@@ -2088,11 +2104,12 @@ CAmount CWallet::GetImmatureWatchOnlyBalance() const
 {
     CAmount nTotal = 0;
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         for (const auto& entry : mapWallet)
         {
             const CWalletTx* pcoin = &entry.second;
-            nTotal += pcoin->GetImmatureWatchOnlyCredit();
+            nTotal += pcoin->GetImmatureWatchOnlyCredit(*locked_chain);
         }
     }
     return nTotal;
@@ -2106,13 +2123,15 @@ CAmount CWallet::GetImmatureWatchOnlyBalance() const
 // trusted.
 CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth) const
 {
-    LOCK2(cs_main, cs_wallet);
+    LockAnnotation lock(::cs_main); // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     CAmount balance = 0;
     for (const auto& entry : mapWallet) {
         const CWalletTx& wtx = entry.second;
-        const int depth = wtx.GetDepthInMainChain();
-        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.IsImmatureCoinBase()) {
+        const int depth = wtx.GetDepthInMainChain(*locked_chain);
+        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.IsImmatureCoinBase(*locked_chain)) {
             continue;
         }
 
@@ -2139,11 +2158,12 @@ CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth) cons
 
 CAmount CWallet::GetAvailableBalance(const CCoinControl* coinControl) const
 {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     CAmount balance = 0;
     std::vector<COutput> vCoins;
-    AvailableCoins(vCoins, true, coinControl);
+    AvailableCoins(*locked_chain, vCoins, true, coinControl);
     for (const COutput& out : vCoins) {
         if (out.fSpendable) {
             balance += out.tx->tx->vout[out.i].nValue;
@@ -2152,7 +2172,7 @@ CAmount CWallet::GetAvailableBalance(const CCoinControl* coinControl) const
     return balance;
 }
 
-void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const CCoinControl *coinControl, const CAmount &nMinimumAmount, const CAmount &nMaximumAmount, const CAmount &nMinimumSumAmount, const uint64_t nMaximumCount, const int nMinDepth, const int nMaxDepth) const
+void CWallet::AvailableCoins(interfaces::Chain::Lock& locked_chain, std::vector<COutput> &vCoins, bool fOnlySafe, const CCoinControl *coinControl, const CAmount &nMinimumAmount, const CAmount &nMaximumAmount, const CAmount &nMinimumSumAmount, const uint64_t nMaximumCount, const int nMinDepth, const int nMaxDepth) const
 {
     AssertLockHeld(cs_main);
     AssertLockHeld(cs_wallet);
@@ -2168,10 +2188,10 @@ void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const
         if (!CheckFinalTx(*pcoin->tx))
             continue;
 
-        if (pcoin->IsImmatureCoinBase())
+        if (pcoin->IsImmatureCoinBase(locked_chain))
             continue;
 
-        int nDepth = pcoin->GetDepthInMainChain();
+        int nDepth = pcoin->GetDepthInMainChain(locked_chain);
         if (nDepth < 0)
             continue;
 
@@ -2180,7 +2200,7 @@ void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const
         if (nDepth == 0 && !pcoin->InMempool())
             continue;
 
-        bool safeTx = pcoin->IsTrusted();
+        bool safeTx = pcoin->IsTrusted(locked_chain);
 
         // We should not consider coins from transactions that are replacing
         // other transactions.
@@ -2230,7 +2250,7 @@ void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const
             if (IsLockedCoin(entry.first, i))
                 continue;
 
-            if (IsSpent(wtxid, i))
+            if (IsSpent(locked_chain, wtxid, i))
                 continue;
 
             isminetype mine = IsMine(pcoin->tx->vout[i]);
@@ -2261,7 +2281,7 @@ void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const
     }
 }
 
-std::map<CTxDestination, std::vector<COutput>> CWallet::ListCoins() const
+std::map<CTxDestination, std::vector<COutput>> CWallet::ListCoins(interfaces::Chain::Lock& locked_chain) const
 {
     AssertLockHeld(cs_main);
     AssertLockHeld(cs_wallet);
@@ -2269,7 +2289,7 @@ std::map<CTxDestination, std::vector<COutput>> CWallet::ListCoins() const
     std::map<CTxDestination, std::vector<COutput>> result;
     std::vector<COutput> availableCoins;
 
-    AvailableCoins(availableCoins);
+    AvailableCoins(locked_chain, availableCoins);
 
     for (const COutput& coin : availableCoins) {
         CTxDestination address;
@@ -2284,7 +2304,7 @@ std::map<CTxDestination, std::vector<COutput>> CWallet::ListCoins() const
     for (const COutPoint& output : lockedCoins) {
         auto it = mapWallet.find(output.hash);
         if (it != mapWallet.end()) {
-            int depth = it->second.GetDepthInMainChain();
+            int depth = it->second.GetDepthInMainChain(locked_chain);
             if (depth >= 0 && output.n < it->second.tx->vout.size() &&
                 IsMine(it->second.tx->vout[output.n]) == ISMINE_SPENDABLE) {
                 CTxDestination address;
@@ -2499,11 +2519,12 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
 
     // Acquire the locks to prevent races to the new locked unspents between the
     // CreateTransaction call and LockCoin calls (when lockUnspents is true).
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     CReserveKey reservekey(this);
     CTransactionRef tx_new;
-    if (!CreateTransaction(vecSend, tx_new, reservekey, nFeeRet, nChangePosInOut, strFailReason, coinControl, false)) {
+    if (!CreateTransaction(*locked_chain, vecSend, tx_new, reservekey, nFeeRet, nChangePosInOut, strFailReason, coinControl, false)) {
         return false;
     }
 
@@ -2562,7 +2583,7 @@ OutputType CWallet::TransactionChangeType(OutputType change_type, const std::vec
     return m_default_address_type;
 }
 
-bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet,
+bool CWallet::CreateTransaction(interfaces::Chain::Lock& locked_chain, const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet,
                          int& nChangePosInOut, std::string& strFailReason, const CCoinControl& coin_control, bool sign)
 {
     CAmount nValue = 0;
@@ -2624,10 +2645,11 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
     int nBytes;
     {
         std::set<CInputCoin> setCoins;
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
         {
             std::vector<COutput> vAvailableCoins;
-            AvailableCoins(vAvailableCoins, true, &coin_control);
+            AvailableCoins(*locked_chain, vAvailableCoins, true, &coin_control);
             CoinSelectionParams coin_selection_params; // Parameters for coin selection, init with dummy
 
             // Create change script that will be used if we need change
@@ -2962,7 +2984,8 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
 bool CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm, CReserveKey& reservekey, CConnman* connman, CValidationState& state)
 {
     {
-        LOCK2(cs_main, cs_wallet);
+        auto locked_chain = chain().lock();
+        LOCK(cs_wallet);
 
         CWalletTx wtxNew(this, std::move(tx));
         wtxNew.mapValue = std::move(mapValue);
@@ -2995,11 +3018,11 @@ bool CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::ve
         if (fBroadcastTransactions)
         {
             // Broadcast
-            if (!wtx.AcceptToMemoryPool(maxTxFee, state)) {
+            if (!wtx.AcceptToMemoryPool(*locked_chain, maxTxFee, state)) {
                 WalletLogPrintf("CommitTransaction(): Transaction cannot be broadcast immediately, %s\n", FormatStateMessage(state));
                 // TODO: if we expect the failure to be long term or permanent, instead delete wtx from the wallet and return failure.
             } else {
-                wtx.RelayWalletTransaction(connman);
+                wtx.RelayWalletTransaction(*locked_chain, connman);
             }
         }
     }
@@ -3008,7 +3031,8 @@ bool CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::ve
 
 DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
 {
-    LOCK2(cs_main, cs_wallet);
+    auto locked_chain = chain().lock();
+    LOCK(cs_wallet);
 
     fFirstRunRet = false;
     DBErrors nLoadWalletRet = WalletBatch(*database,"cr+").LoadWallet(this);
@@ -3392,7 +3416,7 @@ int64_t CWallet::GetOldestKeyPoolTime()
     return oldestKey;
 }
 
-std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()
+std::map<CTxDestination, CAmount> CWallet::GetAddressBalances(interfaces::Chain::Lock& locked_chain)
 {
     std::map<CTxDestination, CAmount> balances;
 
@@ -3402,13 +3426,13 @@ std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()
         {
             const CWalletTx *pcoin = &walletEntry.second;
 
-            if (!pcoin->IsTrusted())
+            if (!pcoin->IsTrusted(locked_chain))
                 continue;
 
-            if (pcoin->IsImmatureCoinBase())
+            if (pcoin->IsImmatureCoinBase(locked_chain))
                 continue;
 
-            int nDepth = pcoin->GetDepthInMainChain();
+            int nDepth = pcoin->GetDepthInMainChain(locked_chain);
             if (nDepth < (pcoin->IsFromMe(ISMINE_ALL) ? 0 : 1))
                 continue;
 
@@ -3420,7 +3444,7 @@ std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()
                 if(!ExtractDestination(pcoin->tx->vout[i].scriptPubKey, addr))
                     continue;
 
-                CAmount n = IsSpent(walletEntry.first, i) ? 0 : pcoin->tx->vout[i].nValue;
+                CAmount n = IsSpent(locked_chain, walletEntry.first, i) ? 0 : pcoin->tx->vout[i].nValue;
 
                 if (!balances.count(addr))
                     balances[addr] = 0;
@@ -3645,7 +3669,7 @@ void CWallet::ListLockedCoins(std::vector<COutPoint>& vOutpts) const
 
 /** @} */ // end of Actions
 
-void CWallet::GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) const {
+void CWallet::GetKeyBirthTimes(interfaces::Chain::Lock& locked_chain, std::map<CTxDestination, int64_t> &mapKeyBirth) const {
     AssertLockHeld(cs_wallet); // mapKeyMetadata
     mapKeyBirth.clear();
 
@@ -3825,7 +3849,7 @@ void CWallet::MarkPreSplitKeys()
     }
 }
 
-bool CWallet::Verify(const WalletLocation& location, bool salvage_wallet, std::string& error_string, std::string& warning_string)
+bool CWallet::Verify(interfaces::Chain& chain, const WalletLocation& location, bool salvage_wallet, std::string& error_string, std::string& warning_string)
 {
     // Do some checking on wallet path. It should be either a:
     //
@@ -3866,7 +3890,7 @@ bool CWallet::Verify(const WalletLocation& location, bool salvage_wallet, std::s
 
     if (salvage_wallet) {
         // Recover readable keypairs:
-        CWallet dummyWallet(WalletLocation(), WalletDatabase::CreateDummy());
+        CWallet dummyWallet(chain, WalletLocation(), WalletDatabase::CreateDummy());
         std::string backup_filename;
         if (!WalletBatch::Recover(wallet_path, (void *)&dummyWallet, WalletBatch::RecoverKeysOnlyFilter, backup_filename)) {
             return false;
@@ -3876,7 +3900,7 @@ bool CWallet::Verify(const WalletLocation& location, bool salvage_wallet, std::s
     return WalletBatch::VerifyDatabaseFile(wallet_path, warning_string, error_string);
 }
 
-std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const WalletLocation& location, uint64_t wallet_creation_flags)
+std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(interfaces::Chain& chain, const WalletLocation& location, uint64_t wallet_creation_flags)
 {
     const std::string& walletFile = location.GetName();
 
@@ -3886,7 +3910,7 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const WalletLocation& loc
     if (gArgs.GetBoolArg("-zapwallettxes", false)) {
         uiInterface.InitMessage(_("Zapping all transactions from wallet..."));
 
-        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(location, WalletDatabase::Create(location.GetPath()));
+        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(chain, location, WalletDatabase::Create(location.GetPath()));
         DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
         if (nZapWalletRet != DBErrors::LOAD_OK) {
             InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
@@ -3900,7 +3924,7 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const WalletLocation& loc
     bool fFirstRun = true;
     // TODO: Can't use std::make_shared because we need a custom deleter but
     // should be possible to use std::allocate_shared.
-    std::shared_ptr<CWallet> walletInstance(new CWallet(location, WalletDatabase::Create(location.GetPath())), ReleaseWallet);
+    std::shared_ptr<CWallet> walletInstance(new CWallet(chain, location, WalletDatabase::Create(location.GetPath())), ReleaseWallet);
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DBErrors::LOAD_OK)
     {
@@ -4010,6 +4034,7 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const WalletLocation& loc
             return nullptr;
         }
 
+        auto locked_chain = chain.assumeLocked();  // Temporary. Removed in upcoming lock cleanup
         walletInstance->ChainStateFlushed(chainActive.GetLocator());
     } else if (wallet_creation_flags & WALLET_FLAG_DISABLE_PRIVATE_KEYS) {
         // Make it impossible to disable private keys after creation
@@ -4097,7 +4122,9 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const WalletLocation& loc
     // Try to top up keypool. No-op if the wallet is locked.
     walletInstance->TopUpKeyPool();
 
-    LOCK2(cs_main, walletInstance->cs_wallet);
+    LockAnnotation lock(::cs_main); // Temporary, for FindForkInGlobalIndex below. Removed in upcoming commit.
+    auto locked_chain = chain.lock();
+    LOCK(walletInstance->cs_wallet);
 
     CBlockIndex *pindexRescan = chainActive.Genesis();
     if (!gArgs.GetBoolArg("-rescan", false))
@@ -4232,7 +4259,7 @@ void CMerkleTx::SetMerkleBranch(const CBlockIndex* pindex, int posInBlock)
     nIndex = posInBlock;
 }
 
-int CMerkleTx::GetDepthInMainChain() const
+int CMerkleTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
 {
     if (hashUnset())
         return 0;
@@ -4247,23 +4274,25 @@ int CMerkleTx::GetDepthInMainChain() const
     return ((nIndex == -1) ? (-1) : 1) * (chainActive.Height() - pindex->nHeight + 1);
 }
 
-int CMerkleTx::GetBlocksToMaturity() const
+int CMerkleTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
 {
     if (!IsCoinBase())
         return 0;
-    int chain_depth = GetDepthInMainChain();
+    int chain_depth = GetDepthInMainChain(locked_chain);
     assert(chain_depth >= 0); // coinbase tx should not be conflicted
     return std::max(0, (COINBASE_MATURITY+1) - chain_depth);
 }
 
-bool CMerkleTx::IsImmatureCoinBase() const
+bool CMerkleTx::IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const
 {
     // note GetBlocksToMaturity is 0 for non-coinbase tx
-    return GetBlocksToMaturity() > 0;
+    return GetBlocksToMaturity(locked_chain) > 0;
 }
 
-bool CWalletTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState& state)
+bool CWalletTx::AcceptToMemoryPool(interfaces::Chain::Lock& locked_chain, const CAmount& nAbsurdFee, CValidationState& state)
 {
+    LockAnnotation lock(::cs_main); // Temporary, for AcceptToMemoryPool below. Removed in upcoming commit.
+
     // We must set fInMempool here - while it will be re-set to true by the
     // entered-mempool callback, if we did not there would be a race where a
     // user could call sendmoney in a loop and hit spurious out of funds errors
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 74eaa09506..f96798201f 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -7,6 +7,7 @@
 #define BITCOIN_WALLET_WALLET_H
 
 #include <amount.h>
+#include <interfaces/chain.h>
 #include <outputtype.h>
 #include <policy/feerate.h>
 #include <streams.h>
@@ -33,6 +34,26 @@
 #include <utility>
 #include <vector>
 
+//! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
+//  This function will perform salvage on the wallet if requested, as long as only one wallet is
+//  being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
+bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
+
+//! Load wallet databases.
+bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
+
+//! Complete startup of wallets.
+void StartWallets(CScheduler& scheduler);
+
+//! Flush all wallets in preparation for shutdown.
+void FlushWallets();
+
+//! Stop all wallets. Wallets will be flushed first.
+void StopWallets();
+
+//! Close all wallets.
+void UnloadWallets();
+
 bool AddWallet(const std::shared_ptr<CWallet>& wallet);
 bool RemoveWallet(const std::shared_ptr<CWallet>& wallet);
 bool HasWallets();
@@ -264,22 +285,22 @@ public:
      *  0  : in memory pool, waiting to be included in a block
      * >=1 : this many blocks deep in the main chain
      */
-    int GetDepthInMainChain() const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
-    bool IsInMainChain() const EXCLUSIVE_LOCKS_REQUIRED(cs_main) { return GetDepthInMainChain() > 0; }
+    int GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const;
+    bool IsInMainChain(interfaces::Chain::Lock& locked_chain) const { return GetDepthInMainChain(locked_chain) > 0; }
 
     /**
      * @return number of blocks to maturity for this transaction:
      *  0 : is not a coinbase transaction, or is a mature coinbase transaction
      * >0 : is a coinbase transaction which matures in this many blocks
      */
-    int GetBlocksToMaturity() const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    int GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const;
     bool hashUnset() const { return (hashBlock.IsNull() || hashBlock == ABANDON_HASH); }
     bool isAbandoned() const { return (hashBlock == ABANDON_HASH); }
     void setAbandoned() { hashBlock = ABANDON_HASH; }
 
     const uint256& GetHash() const { return tx->GetHash(); }
     bool IsCoinBase() const { return tx->IsCoinBase(); }
-    bool IsImmatureCoinBase() const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const;
 };
 
 //Get the marginal bytes of spending the specified output
@@ -458,14 +479,14 @@ public:
 
     //! filter decides which addresses will count towards the debit
     CAmount GetDebit(const isminefilter& filter) const;
-    CAmount GetCredit(const isminefilter& filter) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
-    CAmount GetImmatureCredit(bool fUseCache=true) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    CAmount GetCredit(interfaces::Chain::Lock& locked_chain, const isminefilter& filter) const;
+    CAmount GetImmatureCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache=true) const;
     // TODO: Remove "NO_THREAD_SAFETY_ANALYSIS" and replace it with the correct
     // annotation "EXCLUSIVE_LOCKS_REQUIRED(cs_main, pwallet->cs_wallet)". The
     // annotation "NO_THREAD_SAFETY_ANALYSIS" was temporarily added to avoid
     // having to resolve the issue of member access into incomplete type CWallet.
-    CAmount GetAvailableCredit(bool fUseCache=true, const isminefilter& filter=ISMINE_SPENDABLE) const NO_THREAD_SAFETY_ANALYSIS;
-    CAmount GetImmatureWatchOnlyCredit(const bool fUseCache=true) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    CAmount GetAvailableCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache=true, const isminefilter& filter=ISMINE_SPENDABLE) const NO_THREAD_SAFETY_ANALYSIS;
+    CAmount GetImmatureWatchOnlyCredit(interfaces::Chain::Lock& locked_chain, const bool fUseCache=true) const;
     CAmount GetChange() const;
 
     // Get the marginal bytes if spending the specified output from this transaction
@@ -486,15 +507,15 @@ public:
     bool IsEquivalentTo(const CWalletTx& tx) const;
 
     bool InMempool() const;
-    bool IsTrusted() const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool IsTrusted(interfaces::Chain::Lock& locked_chain) const;
 
     int64_t GetTxTime() const;
 
     // RelayWalletTransaction may only be called if fBroadcastTransactions!
-    bool RelayWalletTransaction(CConnman* connman) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool RelayWalletTransaction(interfaces::Chain::Lock& locked_chain, CConnman* connman);
 
     /** Pass this transaction to the mempool. Fails if absolute fee exceeds absurd fee. */
-    bool AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState& state) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool AcceptToMemoryPool(interfaces::Chain::Lock& locked_chain, const CAmount& nAbsurdFee, CValidationState& state);
 
     // TODO: Remove "NO_THREAD_SAFETY_ANALYSIS" and replace it with the correct
     // annotation "EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)". The annotation
@@ -676,6 +697,9 @@ private:
      */
     bool AddWatchOnly(const CScript& dest) override EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
+    /** Interface for accessing chain state. */
+    interfaces::Chain& m_chain;
+
     /** Wallet location which includes wallet name (see WalletLocation). */
     WalletLocation m_location;
 
@@ -737,7 +761,7 @@ public:
     unsigned int nMasterKeyMaxID = 0;
 
     /** Construct wallet with specified name and database implementation. */
-    CWallet(const WalletLocation& location, std::unique_ptr<WalletDatabase> database) : m_location(location), database(std::move(database))
+    CWallet(interfaces::Chain& chain, const WalletLocation& location, std::unique_ptr<WalletDatabase> database) : m_chain(chain), m_location(location), database(std::move(database))
     {
     }
 
@@ -759,6 +783,9 @@ public:
 
     std::set<COutPoint> setLockedCoins GUARDED_BY(cs_wallet);
 
+    /** Interface for accessing chain state. */
+    interfaces::Chain& chain() const { return m_chain; }
+
     const CWalletTx* GetWalletTx(const uint256& hash) const;
 
     //! check whether we are allowed to upgrade (or already support) to the named feature
@@ -767,12 +794,12 @@ public:
     /**
      * populate vCoins with vector of available COutputs.
      */
-    void AvailableCoins(std::vector<COutput>& vCoins, bool fOnlySafe=true, const CCoinControl *coinControl = nullptr, const CAmount& nMinimumAmount = 1, const CAmount& nMaximumAmount = MAX_MONEY, const CAmount& nMinimumSumAmount = MAX_MONEY, const uint64_t nMaximumCount = 0, const int nMinDepth = 0, const int nMaxDepth = 9999999) const EXCLUSIVE_LOCKS_REQUIRED(cs_main, cs_wallet);
+    void AvailableCoins(interfaces::Chain::Lock& locked_chain, std::vector<COutput>& vCoins, bool fOnlySafe=true, const CCoinControl *coinControl = nullptr, const CAmount& nMinimumAmount = 1, const CAmount& nMaximumAmount = MAX_MONEY, const CAmount& nMinimumSumAmount = MAX_MONEY, const uint64_t nMaximumCount = 0, const int nMinDepth = 0, const int nMaxDepth = 9999999) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Return list of available coins and locked coins grouped by non-change output address.
      */
-    std::map<CTxDestination, std::vector<COutput>> ListCoins() const EXCLUSIVE_LOCKS_REQUIRED(cs_main, cs_wallet);
+    std::map<CTxDestination, std::vector<COutput>> ListCoins(interfaces::Chain::Lock& locked_chain) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Find non-change parent output.
@@ -788,7 +815,7 @@ public:
     bool SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<OutputGroup> groups,
         std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CoinSelectionParams& coin_selection_params, bool& bnb_used) const;
 
-    bool IsSpent(const uint256& hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_main, cs_wallet);
+    bool IsSpent(interfaces::Chain::Lock& locked_chain, const uint256& hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::vector<OutputGroup> GroupOutputs(const std::vector<COutput>& outputs, bool single_coin) const;
 
     bool IsLockedCoin(uint256 hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
@@ -852,7 +879,7 @@ public:
     bool ChangeWalletPassphrase(const SecureString& strOldWalletPassphrase, const SecureString& strNewWalletPassphrase);
     bool EncryptWallet(const SecureString& strWalletPassphrase);
 
-    void GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    void GetKeyBirthTimes(interfaces::Chain::Lock& locked_chain, std::map<CTxDestination, int64_t> &mapKeyBirth) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     unsigned int ComputeTimeSmart(const CWalletTx& wtx) const;
 
     /**
@@ -874,7 +901,7 @@ public:
     void ReacceptWalletTransactions();
     void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman) override EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     // ResendWalletTransactionsBefore may only be called if fBroadcastTransactions!
-    std::vector<uint256> ResendWalletTransactionsBefore(int64_t nTime, CConnman* connman) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    std::vector<uint256> ResendWalletTransactionsBefore(interfaces::Chain::Lock& locked_chain, int64_t nTime, CConnman* connman);
     CAmount GetBalance(const isminefilter& filter=ISMINE_SPENDABLE, const int min_depth=0) const;
     CAmount GetUnconfirmedBalance() const;
     CAmount GetImmatureBalance() const;
@@ -897,7 +924,7 @@ public:
      * selected by SelectCoins(); Also create the change output, when needed
      * @note passing nChangePosInOut as -1 will result in setting a random position
      */
-    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosInOut,
+    bool CreateTransaction(interfaces::Chain::Lock& locked_chain, const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosInOut,
                            std::string& strFailReason, const CCoinControl& coin_control, bool sign = true);
     bool CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm, CReserveKey& reservekey, CConnman* connman, CValidationState& state);
 
@@ -956,7 +983,7 @@ public:
     const std::map<CKeyID, int64_t>& GetAllReserveKeys() const { return m_pool_key_to_index; }
 
     std::set<std::set<CTxDestination>> GetAddressGroupings() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    std::map<CTxDestination, CAmount> GetAddressBalances() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    std::map<CTxDestination, CAmount> GetAddressBalances(interfaces::Chain::Lock& locked_chain);
 
     std::set<CTxDestination> GetLabelAddresses(const std::string& label) const;
 
@@ -1051,16 +1078,16 @@ public:
     bool TransactionCanBeAbandoned(const uint256& hashTx) const;
 
     /* Mark a transaction (and it in-wallet descendants) as abandoned so its inputs may be respent. */
-    bool AbandonTransaction(const uint256& hashTx);
+    bool AbandonTransaction(interfaces::Chain::Lock& locked_chain, const uint256& hashTx);
 
     /** Mark a transaction as replaced by another transaction (e.g., BIP 125). */
     bool MarkReplaced(const uint256& originalHash, const uint256& newHash);
 
     //! Verify wallet naming and perform salvage on the wallet if required
-    static bool Verify(const WalletLocation& location, bool salvage_wallet, std::string& error_string, std::string& warning_string);
+    static bool Verify(interfaces::Chain& chain, const WalletLocation& location, bool salvage_wallet, std::string& error_string, std::string& warning_string);
 
     /* Initializes the wallet, returns a new CWallet instance or a null pointer in case of an error */
-    static std::shared_ptr<CWallet> CreateWalletFromFile(const WalletLocation& location, uint64_t wallet_creation_flags = 0);
+    static std::shared_ptr<CWallet> CreateWalletFromFile(interfaces::Chain& chain, const WalletLocation& location, uint64_t wallet_creation_flags = 0);
 
     /**
      * Wallet post-init setup
diff --git a/src/walletinitinterface.h b/src/walletinitinterface.h
index 6f12551273..22aca65990 100644
--- a/src/walletinitinterface.h
+++ b/src/walletinitinterface.h
@@ -9,6 +9,7 @@
 
 class CScheduler;
 class CRPCTable;
+struct InitInterfaces;
 
 class WalletInitInterface {
 public:
@@ -18,20 +19,8 @@ public:
     virtual void AddWalletOptions() const = 0;
     /** Check wallet parameter interaction */
     virtual bool ParameterInteraction() const = 0;
-    /** Register wallet RPC*/
-    virtual void RegisterRPC(CRPCTable &) const = 0;
-    /** Verify wallets */
-    virtual bool Verify() const = 0;
-    /** Open wallets*/
-    virtual bool Open() const = 0;
-    /** Start wallets*/
-    virtual void Start(CScheduler& scheduler) const = 0;
-    /** Flush Wallets*/
-    virtual void Flush() const = 0;
-    /** Stop Wallets*/
-    virtual void Stop() const = 0;
-    /** Close wallets */
-    virtual void Close() const = 0;
+    /** Add wallets that should be opened to list of init interfaces. */
+    virtual void Construct(InitInterfaces& interfaces) const = 0;
 
     virtual ~WalletInitInterface() {}
 };