Merge #10973: Refactor: separate wallet from node

d358466de Remove remaining wallet accesses to node globals (Russell Yanofsky)
b1b2b2389 Remove use of CCoinsViewMemPool::GetCoin in wallet code (Russell Yanofsky)
4e4d9e9f8 Remove use of CRPCTable::appendCommand in wallet code (Russell Yanofsky)
91868e628 Remove use CValidationInterface in wallet code (Russell Yanofsky)

Pull request description:

  This PR is the last in a chain of PRs (#14437, #14711, and #15288) that make the wallet code access node state through an abstract [`Chain`](https://github.com/ryanofsky/bitcoin/blob/pr/wipc-sep/src/interfaces/chain.h) class in [`src/interfaces/`](https://github.com/ryanofsky/bitcoin/tree/pr/wipc-sep/src/interfaces) instead of using global variables like `cs_main`, `chainActive`, and `g_connman`. After this PR, wallet code no longer accesses global variables declared outside the wallet directory, and no longer calls functions accessing those globals (as verified by the `hide-globals` script in #10244).

  This PR and the previous PRs have been refactoring changes that do not affect behavior. Previous PRs have consisted of lots of mechanical changes like:

  ```diff
  -    wtx.nTimeReceived = GetAdjustedTime();
  +    wtx.nTimeReceived = m_chain->getAdjustedTime();
  ```

  This PR is smaller, but less mechanical. It replaces last few bits of wallet code that access node state directly (through `CValidationInterface`, `CRPCTable`, and `CCoinsViewMemPool` interfaces) with code that uses the `Chain` interface.

  These changes allow followup PR #10102 (multiprocess gui & wallet PR) to work without any significant updates to wallet code. Additionally they:

  * Provide a single place to describe the interface between wallet and node code.
  * Can make better wallet testing possible, because the `Chain` object consists of virtual methods that can be overloaded for mocking. (This could be used to test edge cases in the rescan code, for example).

Tree-SHA512: e6291d8a3c50bdff18a9c8ad11e729beb30b5b7040d7aaf31ba678800b4a97b2dd2be76340b1e5c01fe2827d67d37ed1bb4c8380cf8ed653aadfea003e9b22e7

10 files changed, 73 insertions, 66 deletions

diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index a1c3a21d4b..ef7f3be728 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -123,16 +123,17 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
     // The wallet uses a conservative WALLET_INCREMENTAL_RELAY_FEE value to
     // future proof against changes to network wide policy for incremental relay
     // fee that our node may not be aware of.
+    CFeeRate nodeIncrementalRelayFee = wallet->chain().relayIncrementalFee();
     CFeeRate walletIncrementalRelayFee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);
-    if (::incrementalRelayFee > walletIncrementalRelayFee) {
-        walletIncrementalRelayFee = ::incrementalRelayFee;
+    if (nodeIncrementalRelayFee > walletIncrementalRelayFee) {
+        walletIncrementalRelayFee = nodeIncrementalRelayFee;
     }
 
     if (total_fee > 0) {
-        CAmount minTotalFee = nOldFeeRate.GetFee(maxNewTxSize) + ::incrementalRelayFee.GetFee(maxNewTxSize);
+        CAmount minTotalFee = nOldFeeRate.GetFee(maxNewTxSize) + nodeIncrementalRelayFee.GetFee(maxNewTxSize);
         if (total_fee < minTotalFee) {
             errors.push_back(strprintf("Insufficient totalFee, must be at least %s (oldFee %s + incrementalFee %s)",
-                                                                FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxNewTxSize)), FormatMoney(::incrementalRelayFee.GetFee(maxNewTxSize))));
+                                                                FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxNewTxSize)), FormatMoney(nodeIncrementalRelayFee.GetFee(maxNewTxSize))));
             return Result::INVALID_PARAMETER;
         }
         CAmount requiredFee = GetRequiredFee(*wallet, maxNewTxSize);
@@ -159,9 +160,10 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
     }
 
     // Check that in all cases the new fee doesn't violate maxTxFee
-     if (new_fee > maxTxFee) {
+     const CAmount max_tx_fee = wallet->chain().maxTxFee();
+     if (new_fee > max_tx_fee) {
          errors.push_back(strprintf("Specified or calculated fee %s is too high (cannot be higher than maxTxFee %s)",
-                               FormatMoney(new_fee), FormatMoney(maxTxFee)));
+                               FormatMoney(new_fee), FormatMoney(max_tx_fee)));
          return Result::WALLET_ERROR;
      }
 
diff --git a/src/wallet/fees.cpp b/src/wallet/fees.cpp
index 545adaebc1..560c86a70a 100644
--- a/src/wallet/fees.cpp
+++ b/src/wallet/fees.cpp
@@ -22,8 +22,9 @@ CAmount GetMinimumFee(const CWallet& wallet, unsigned int nTxBytes, const CCoinC
 {
     CAmount fee_needed = GetMinimumFeeRate(wallet, coin_control, feeCalc).GetFee(nTxBytes);
     // Always obey the maximum
-    if (fee_needed > maxTxFee) {
-        fee_needed = maxTxFee;
+    const CAmount max_tx_fee = wallet.chain().maxTxFee();
+    if (fee_needed > max_tx_fee) {
+        fee_needed = max_tx_fee;
         if (feeCalc) feeCalc->reason = FeeReason::MAXTXFEE;
     }
     return fee_needed;
@@ -31,7 +32,7 @@ CAmount GetMinimumFee(const CWallet& wallet, unsigned int nTxBytes, const CCoinC
 
 CFeeRate GetRequiredFeeRate(const CWallet& wallet)
 {
-    return std::max(wallet.m_min_fee, ::minRelayTxFee);
+    return std::max(wallet.m_min_fee, wallet.chain().relayMinFee());
 }
 
 CFeeRate GetMinimumFeeRate(const CWallet& wallet, const CCoinControl& coin_control, FeeCalculation* feeCalc)
@@ -96,6 +97,6 @@ CFeeRate GetDiscardRate(const CWallet& wallet)
     // Don't let discard_rate be greater than longest possible fee estimate if we get a valid fee estimate
     discard_rate = (discard_rate == CFeeRate(0)) ? wallet.m_discard_rate : std::min(discard_rate, wallet.m_discard_rate);
     // Discard rate must be at least dustRelayFee
-    discard_rate = std::max(discard_rate, ::dustRelayFee);
+    discard_rate = std::max(discard_rate, wallet.chain().relayDustFee());
     return discard_rate;
 }
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 7ad343c15f..76a7eaa681 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -153,7 +153,7 @@ bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wal
 
     LogPrintf("Using wallet directory %s\n", GetWalletDir().string());
 
-    uiInterface.InitMessage(_("Verifying wallet(s)..."));
+    chain.initMessage(_("Verifying wallet(s)..."));
 
     // Parameter interaction code should have thrown an error if -salvagewallet
     // was enabled with more than wallet file, so the wallet_files size check
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 684d900478..6c3b5a49dc 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -595,11 +595,11 @@ UniValue importwallet(const JSONRPCRequest& request)
 
         // Use uiInterface.ShowProgress instead of pwallet.ShowProgress because pwallet.ShowProgress has a cancel button tied to AbortRescan which
         // we don't want for this progress bar showing the import progress. uiInterface.ShowProgress does not have a cancel button.
-        uiInterface.ShowProgress(strprintf("%s " + _("Importing..."), pwallet->GetDisplayName()), 0, false); // show progress dialog in GUI
+        pwallet->chain().showProgress(strprintf("%s " + _("Importing..."), pwallet->GetDisplayName()), 0, false); // show progress dialog in GUI
         std::vector<std::tuple<CKey, int64_t, bool, std::string>> keys;
         std::vector<std::pair<CScript, int64_t>> scripts;
         while (file.good()) {
-            uiInterface.ShowProgress("", std::max(1, std::min(50, (int)(((double)file.tellg() / (double)nFilesize) * 100))), false);
+            pwallet->chain().showProgress("", std::max(1, std::min(50, (int)(((double)file.tellg() / (double)nFilesize) * 100))), false);
             std::string line;
             std::getline(file, line);
             if (line.empty() || line[0] == '#')
@@ -637,13 +637,13 @@ UniValue importwallet(const JSONRPCRequest& request)
         file.close();
         // We now know whether we are importing private keys, so we can error if private keys are disabled
         if (keys.size() > 0 && pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
-            uiInterface.ShowProgress("", 100, false); // hide progress dialog in GUI
+            pwallet->chain().showProgress("", 100, false); // hide progress dialog in GUI
             throw JSONRPCError(RPC_WALLET_ERROR, "Importing wallets is disabled when private keys are disabled");
         }
         double total = (double)(keys.size() + scripts.size());
         double progress = 0;
         for (const auto& key_tuple : keys) {
-            uiInterface.ShowProgress("", std::max(50, std::min(75, (int)((progress / total) * 100) + 50)), false);
+            pwallet->chain().showProgress("", std::max(50, std::min(75, (int)((progress / total) * 100) + 50)), false);
             const CKey& key = std::get<0>(key_tuple);
             int64_t time = std::get<1>(key_tuple);
             bool has_label = std::get<2>(key_tuple);
@@ -668,7 +668,7 @@ UniValue importwallet(const JSONRPCRequest& request)
             progress++;
         }
         for (const auto& script_pair : scripts) {
-            uiInterface.ShowProgress("", std::max(50, std::min(75, (int)((progress / total) * 100) + 50)), false);
+            pwallet->chain().showProgress("", std::max(50, std::min(75, (int)((progress / total) * 100) + 50)), false);
             const CScript& script = script_pair.first;
             int64_t time = script_pair.second;
             CScriptID id(script);
@@ -687,10 +687,10 @@ UniValue importwallet(const JSONRPCRequest& request)
             }
             progress++;
         }
-        uiInterface.ShowProgress("", 100, false); // hide progress dialog in GUI
+        pwallet->chain().showProgress("", 100, false); // hide progress dialog in GUI
         pwallet->UpdateTimeFirstKey(nTimeBegin);
     }
-    uiInterface.ShowProgress("", 100, false); // hide progress dialog in GUI
+    pwallet->chain().showProgress("", 100, false); // hide progress dialog in GUI
     RescanWallet(*pwallet, reserver, nTimeBegin, false /* update */);
     pwallet->MarkDirty();
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 31a3209a49..fa7604b695 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2367,8 +2367,8 @@ static UniValue settxfee(const JSONRPCRequest& request)
     CFeeRate tx_fee_rate(nAmount, 1000);
     if (tx_fee_rate == 0) {
         // automatic selection
-    } else if (tx_fee_rate < ::minRelayTxFee) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", ::minRelayTxFee.ToString()));
+    } else if (tx_fee_rate < pwallet->chain().relayMinFee()) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", pwallet->chain().relayMinFee().ToString()));
     } else if (tx_fee_rate < pwallet->m_min_fee) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than wallet min fee (%s)", pwallet->m_min_fee.ToString()));
     }
@@ -4156,8 +4156,8 @@ static const CRPCCommand commands[] =
 };
 // clang-format on
 
-void RegisterWalletRPCCommands(CRPCTable &t)
+void RegisterWalletRPCCommands(interfaces::Chain& chain, std::vector<std::unique_ptr<interfaces::Handler>>& handlers)
 {
     for (unsigned int vcidx = 0; vcidx < ARRAYLEN(commands); vcidx++)
-        t.appendCommand(commands[vcidx].name, &commands[vcidx]);
+        handlers.emplace_back(chain.handleRpc(commands[vcidx]));
 }
diff --git a/src/wallet/rpcwallet.h b/src/wallet/rpcwallet.h
index 58053bde59..7cf607ccc7 100644
--- a/src/wallet/rpcwallet.h
+++ b/src/wallet/rpcwallet.h
@@ -5,7 +5,9 @@
 #ifndef BITCOIN_WALLET_RPCWALLET_H
 #define BITCOIN_WALLET_RPCWALLET_H
 
+#include <memory>
 #include <string>
+#include <vector>
 
 class CRPCTable;
 class CWallet;
@@ -14,7 +16,12 @@ class UniValue;
 struct PartiallySignedTransaction;
 class CTransaction;
 
-void RegisterWalletRPCCommands(CRPCTable &t);
+namespace interfaces {
+class Chain;
+class Handler;
+}
+
+void RegisterWalletRPCCommands(interfaces::Chain& chain, std::vector<std::unique_ptr<interfaces::Handler>>& handlers);
 
 /**
  * Figures out what wallet, if any, to use for a JSONRPCRequest.
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index a5fb1db86c..6a051214a9 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -13,12 +13,7 @@ WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
 {
     bool fFirstRun;
     m_wallet.LoadWallet(fFirstRun);
-    RegisterValidationInterface(&m_wallet);
+    m_wallet.m_chain_notifications_handler = m_chain->handleNotifications(m_wallet);
 
-    RegisterWalletRPCCommands(tableRPC);
-}
-
-WalletTestingSetup::~WalletTestingSetup()
-{
-    UnregisterValidationInterface(&m_wallet);
+    m_chain_client->registerRpcs();
 }
diff --git a/src/wallet/test/wallet_test_fixture.h b/src/wallet/test/wallet_test_fixture.h
index e6fe8c9473..dcfbc55f94 100644
--- a/src/wallet/test/wallet_test_fixture.h
+++ b/src/wallet/test/wallet_test_fixture.h
@@ -17,9 +17,9 @@
  */
 struct WalletTestingSetup: public TestingSetup {
     explicit WalletTestingSetup(const std::string& chainName = CBaseChainParams::MAIN);
-    ~WalletTestingSetup();
 
     std::unique_ptr<interfaces::Chain> m_chain = interfaces::MakeChain();
+    std::unique_ptr<interfaces::ChainClient> m_chain_client = interfaces::MakeWalletClient(*m_chain, {});
     CWallet m_wallet;
 };
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index de686b0ddf..95756f988f 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -96,7 +96,7 @@ static void ReleaseWallet(CWallet* wallet)
     wallet->WalletLogPrintf("Releasing wallet\n");
     wallet->BlockUntilSyncedToCurrentChain();
     wallet->Flush();
-    UnregisterValidationInterface(wallet);
+    wallet->m_chain_notifications_handler.reset();
     delete wallet;
     // Wallet is now released, notify UnloadWallet, if any.
     {
@@ -1243,7 +1243,8 @@ void CWallet::TransactionRemovedFromMempool(const CTransactionRef &ptx) {
     }
 }
 
-void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex *pindex, const std::vector<CTransactionRef>& vtxConflicted) {
+void CWallet::BlockConnected(const CBlock& block, const std::vector<CTransactionRef>& vtxConflicted) {
+    const uint256& block_hash = block.GetHash();
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
     // TODO: Temporarily ensure that mempool removals are notified before
@@ -1258,19 +1259,19 @@ void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const
         SyncTransaction(ptx, {} /* block hash */, 0 /* position in block */);
         TransactionRemovedFromMempool(ptx);
     }
-    for (size_t i = 0; i < pblock->vtx.size(); i++) {
-        SyncTransaction(pblock->vtx[i], pindex->GetBlockHash(), i);
-        TransactionRemovedFromMempool(pblock->vtx[i]);
+    for (size_t i = 0; i < block.vtx.size(); i++) {
+        SyncTransaction(block.vtx[i], block_hash, i);
+        TransactionRemovedFromMempool(block.vtx[i]);
     }
 
-    m_last_block_processed = pindex->GetBlockHash();
+    m_last_block_processed = block_hash;
 }
 
-void CWallet::BlockDisconnected(const std::shared_ptr<const CBlock>& pblock) {
+void CWallet::BlockDisconnected(const CBlock& block) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
-    for (const CTransactionRef& ptx : pblock->vtx) {
+    for (const CTransactionRef& ptx : block.vtx) {
         SyncTransaction(ptx, {} /* block hash */, 0 /* position in block */);
     }
 }
@@ -1297,7 +1298,7 @@ void CWallet::BlockUntilSyncedToCurrentChain() {
     // ...otherwise put a callback in the validation interface queue and wait
     // for the queue to drain enough to execute it (indicating we are caught up
     // at least with the time we entered this function).
-    SyncWithValidationInterfaceQueue();
+    chain().waitForNotifications();
 }
 
 
@@ -1790,7 +1791,7 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
             progress_end = chain().guessVerificationProgress(stop_block.IsNull() ? tip_hash : stop_block);
         }
         double progress_current = progress_begin;
-        while (block_height && !fAbortRescan && !ShutdownRequested()) {
+        while (block_height && !fAbortRescan && !chain().shutdownRequested()) {
             if (*block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
                 ShowProgress(strprintf("%s " + _("Rescanning..."), GetDisplayName()), std::max(1, std::min(99, (int)((progress_current - progress_begin) / (progress_end - progress_begin) * 100))));
             }
@@ -1852,7 +1853,7 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
         if (block_height && fAbortRescan) {
             WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n", *block_height, progress_current);
             result.status = ScanResult::USER_ABORT;
-        } else if (block_height && ShutdownRequested()) {
+        } else if (block_height && chain().shutdownRequested()) {
             WalletLogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", *block_height, progress_current);
             result.status = ScanResult::USER_ABORT;
         }
@@ -2137,7 +2138,7 @@ std::vector<uint256> CWallet::ResendWalletTransactionsBefore(interfaces::Chain::
     return result;
 }
 
-void CWallet::ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman)
+void CWallet::ResendWalletTransactions(interfaces::Chain::Lock& locked_chain, int64_t nBestBlockTime)
 {
     // Do this infrequently and randomly to avoid giving away
     // that these are our transactions.
@@ -2155,8 +2156,7 @@ void CWallet::ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman
 
     // Rebroadcast unconfirmed txes older than 5 minutes before the last
     // block was found:
-    auto locked_chain = chain().assumeLocked();  // Temporary. Removed in upcoming lock cleanup
-    std::vector<uint256> relayed = ResendWalletTransactionsBefore(*locked_chain, nBestBlockTime-5*60);
+    std::vector<uint256> relayed = ResendWalletTransactionsBefore(locked_chain, nBestBlockTime-5*60);
     if (!relayed.empty())
         WalletLogPrintf("%s: rebroadcast %u unconfirmed transactions\n", __func__, relayed.size());
 }
@@ -2310,7 +2310,6 @@ CAmount CWallet::GetAvailableBalance(const CCoinControl* coinControl) 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);
 
     vCoins.clear();
@@ -2420,7 +2419,6 @@ void CWallet::AvailableCoins(interfaces::Chain::Lock& locked_chain, std::vector<
 
 std::map<CTxDestination, std::vector<COutput>> CWallet::ListCoins(interfaces::Chain::Lock& locked_chain) const
 {
-    AssertLockHeld(cs_main);
     AssertLockHeld(cs_wallet);
 
     std::map<CTxDestination, std::vector<COutput>> result;
@@ -2692,13 +2690,13 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
     return true;
 }
 
-static bool IsCurrentForAntiFeeSniping(interfaces::Chain::Lock& locked_chain)
+static bool IsCurrentForAntiFeeSniping(interfaces::Chain& chain, interfaces::Chain::Lock& locked_chain)
 {
-    if (IsInitialBlockDownload()) {
+    if (chain.isInitialBlockDownload()) {
         return false;
     }
     constexpr int64_t MAX_ANTI_FEE_SNIPING_TIP_AGE = 8 * 60 * 60; // in seconds
-    if (chainActive.Tip()->GetBlockTime() < (GetTime() - MAX_ANTI_FEE_SNIPING_TIP_AGE)) {
+    if (locked_chain.getBlockTime(*locked_chain.getHeight()) < (GetTime() - MAX_ANTI_FEE_SNIPING_TIP_AGE)) {
         return false;
     }
     return true;
@@ -2708,7 +2706,7 @@ static bool IsCurrentForAntiFeeSniping(interfaces::Chain::Lock& locked_chain)
  * Return a height-based locktime for new transactions (uses the height of the
  * current chain tip unless we are not synced with the current chain
  */
-static uint32_t GetLocktimeForNewTransaction(interfaces::Chain::Lock& locked_chain)
+static uint32_t GetLocktimeForNewTransaction(interfaces::Chain& chain, interfaces::Chain::Lock& locked_chain)
 {
     uint32_t const height = locked_chain.getHeight().get_value_or(-1);
     uint32_t locktime;
@@ -2732,7 +2730,7 @@ static uint32_t GetLocktimeForNewTransaction(interfaces::Chain::Lock& locked_cha
     // enough, that fee sniping isn't a problem yet, but by implementing a fix
     // now we ensure code won't be written that makes assumptions about
     // nLockTime that preclude a fix later.
-    if (IsCurrentForAntiFeeSniping(locked_chain)) {
+    if (IsCurrentForAntiFeeSniping(chain, locked_chain)) {
         locktime = height;
 
         // Secondly occasionally randomly pick a nLockTime even further back, so
@@ -2806,7 +2804,7 @@ bool CWallet::CreateTransaction(interfaces::Chain::Lock& locked_chain, const std
 
     CMutableTransaction txNew;
 
-    txNew.nLockTime = GetLocktimeForNewTransaction(locked_chain);
+    txNew.nLockTime = GetLocktimeForNewTransaction(chain(), locked_chain);
 
     FeeCalculation feeCalc;
     CAmount nFeeNeeded;
@@ -2902,7 +2900,7 @@ bool CWallet::CreateTransaction(interfaces::Chain::Lock& locked_chain, const std
                     // Include the fee cost for outputs. Note this is only used for BnB right now
                     coin_selection_params.tx_noinputs_size += ::GetSerializeSize(txout, PROTOCOL_VERSION);
 
-                    if (IsDust(txout, ::dustRelayFee))
+                    if (IsDust(txout, chain().relayDustFee()))
                     {
                         if (recipient.fSubtractFeeFromAmount && nFeeRet > 0)
                         {
@@ -3003,7 +3001,7 @@ bool CWallet::CreateTransaction(interfaces::Chain::Lock& locked_chain, const std
 
                 // If we made it here and we aren't even able to meet the relay fee on the next pass, give up
                 // because we must be at the maximum allowed fee.
-                if (nFeeNeeded < ::minRelayTxFee.GetFee(nBytes))
+                if (nFeeNeeded < chain().relayMinFee().GetFee(nBytes))
                 {
                     strFailReason = _("Transaction too large for fee policy");
                     return false;
@@ -4280,9 +4278,9 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(interfaces::Chain& chain,
                               _("This is the transaction fee you will pay if you send a transaction."));
         }
         walletInstance->m_pay_tx_fee = CFeeRate(nFeePerK, 1000);
-        if (walletInstance->m_pay_tx_fee < ::minRelayTxFee) {
+        if (walletInstance->m_pay_tx_fee < chain.relayMinFee()) {
             chain.initError(strprintf(_("Invalid amount for -paytxfee=<amount>: '%s' (must be at least %s)"),
-                gArgs.GetArg("-paytxfee", ""), ::minRelayTxFee.ToString()));
+                gArgs.GetArg("-paytxfee", ""), chain.relayMinFee().ToString()));
             return nullptr;
         }
     }
@@ -4384,8 +4382,8 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(interfaces::Chain& chain,
 
     chain.loadWallet(interfaces::MakeWallet(walletInstance));
 
-    // Register with the validation interface. It's ok to do this after rescan since we're still holding cs_main.
-    RegisterValidationInterface(walletInstance.get());
+    // Register with the validation interface. It's ok to do this after rescan since we're still holding locked_chain.
+    walletInstance->m_chain_notifications_handler = chain.handleNotifications(*walletInstance);
 
     walletInstance->SetBroadcastTransactions(gArgs.GetBoolArg("-walletbroadcast", DEFAULT_WALLETBROADCAST));
 
@@ -4445,8 +4443,6 @@ int CMerkleTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
     if (hashUnset())
         return 0;
 
-    AssertLockHeld(cs_main);
-
     return locked_chain.getBlockDepth(hashBlock) * (nIndex == -1 ? -1 : 1);
 }
 
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index ea196c8799..86448efcaf 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -8,6 +8,7 @@
 
 #include <amount.h>
 #include <interfaces/chain.h>
+#include <interfaces/handler.h>
 #include <outputtype.h>
 #include <policy/feerate.h>
 #include <streams.h>
@@ -505,7 +506,7 @@ public:
     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 "EXCLUSIVE_LOCKS_REQUIRED(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(interfaces::Chain::Lock& locked_chain, bool fUseCache=true, const isminefilter& filter=ISMINE_SPENDABLE) const NO_THREAD_SAFETY_ANALYSIS;
@@ -637,7 +638,7 @@ class WalletRescanReserver; //forward declarations for ScanForWalletTransactions
  * A CWallet is an extension of a keystore, which also maintains a set of transactions and balances,
  * and provides the ability to create new transactions.
  */
-class CWallet final : public CCryptoKeyStore, public CValidationInterface
+class CWallet final : public CCryptoKeyStore, private interfaces::Chain::Notifications
 {
 private:
     std::atomic<bool> fAbortRescan{false};
@@ -808,6 +809,9 @@ public:
 
     std::set<COutPoint> setLockedCoins GUARDED_BY(cs_wallet);
 
+    /** Registered interfaces::Chain::Notifications handler. */
+    std::unique_ptr<interfaces::Handler> m_chain_notifications_handler;
+
     /** Interface for accessing chain state. */
     interfaces::Chain& chain() const { return m_chain; }
 
@@ -920,8 +924,8 @@ public:
     bool AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose=true);
     void LoadToWallet(const CWalletTx& wtxIn) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void TransactionAddedToMempool(const CTransactionRef& tx) override;
-    void BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex *pindex, const std::vector<CTransactionRef>& vtxConflicted) override;
-    void BlockDisconnected(const std::shared_ptr<const CBlock>& pblock) override;
+    void BlockConnected(const CBlock& block, const std::vector<CTransactionRef>& vtxConflicted) override;
+    void BlockDisconnected(const CBlock& block) override;
     int64_t RescanFromTime(int64_t startTime, const WalletRescanReserver& reserver, bool update);
 
     struct ScanResult {
@@ -942,7 +946,7 @@ public:
     ScanResult ScanForWalletTransactions(const uint256& first_block, const uint256& last_block, const WalletRescanReserver& reserver, bool fUpdate);
     void TransactionRemovedFromMempool(const CTransactionRef &ptx) override;
     void ReacceptWalletTransactions();
-    void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman) override EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    void ResendWalletTransactions(interfaces::Chain::Lock& locked_chain, int64_t nBestBlockTime) override;
     // ResendWalletTransactionsBefore may only be called if fBroadcastTransactions!
     std::vector<uint256> ResendWalletTransactionsBefore(interfaces::Chain::Lock& locked_chain, int64_t nTime);
     CAmount GetBalance(const isminefilter& filter=ISMINE_SPENDABLE, const int min_depth=0) const;
@@ -1220,6 +1224,8 @@ public:
 
     /** Add a KeyOriginInfo to the wallet */
     bool AddKeyOrigin(const CPubKey& pubkey, const KeyOriginInfo& info);
+
+    friend struct WalletTestingSetup;
 };
 
 /** A key allocated from the key pool. */