Remove direct node->wallet calls in init.cpp

Route calls during node initialization and shutdown that would happen between a
node process and wallet processes through the serializable `Chain::Client`
interface, rather than `WalletInitInterface` which is now simpler and only
deals with early initialization and parameter interaction.

This commit mostly does not change behavior. The only change is that the
"Wallet disabled!" and "No wallet support compiled in!" messages are now logged
earlier during startup.

11 files changed, 114 insertions, 85 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index e2727ac522..8dd0d31839 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -467,6 +467,7 @@ endif
 bitcoind_LDADD = \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_WALLET) \
+  $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
diff --git a/src/dummywallet.cpp b/src/dummywallet.cpp
index fa232d2dd0..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(interfaces::Chain& chain) const override {return true;}
-    bool Open(interfaces::Chain& chain) 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 88d4d059f9..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>
@@ -177,7 +178,9 @@ void Shutdown(InitInterfaces& interfaces)
     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
@@ -240,7 +243,9 @@ void Shutdown(InitInterfaces& interfaces)
         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) {
@@ -260,7 +265,7 @@ void Shutdown(InitInterfaces& interfaces)
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     GetMainSignals().UnregisterWithMempoolSignals(mempool);
-    g_wallet_init_interface.Close();
+    interfaces.chain_clients.clear();
     globalVerifyHandle.reset();
     ECC_Stop();
     LogPrintf("%s: done\n", __func__);
@@ -1222,11 +1227,19 @@ bool AppInitMain(InitInterfaces& interfaces)
     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);
@@ -1245,7 +1258,11 @@ bool AppInitMain(InitInterfaces& interfaces)
     }
 
     // ********************************************************* Step 5: verify wallet database integrity
-    if (!g_wallet_init_interface.Verify(*interfaces.chain)) 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
@@ -1564,7 +1581,11 @@ bool AppInitMain(InitInterfaces& interfaces)
     }
 
     // ********************************************************* Step 9: load wallet
-    if (!g_wallet_init_interface.Open(*interfaces.chain)) return false;
+    for (const auto& client : interfaces.chain_clients) {
+        if (!client->load()) {
+            return false;
+        }
+    }
 
     // ********************************************************* Step 10: data directory maintenance
 
@@ -1710,7 +1731,9 @@ bool AppInitMain(InitInterfaces& interfaces)
     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/interfaces/chain.h b/src/interfaces/chain.h
index 8a40cb4cda..30bc9f5f73 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -9,6 +9,8 @@
 #include <string>
 #include <vector>
 
+class CScheduler;
+
 namespace interfaces {
 
 //! Interface for giving wallet processes access to blockchain state.
@@ -24,6 +26,24 @@ 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.
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index e9f4669f4d..a29440ee4a 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -7,6 +7,7 @@
 #include <amount.h>
 #include <chain.h>
 #include <consensus/validation.h>
+#include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <net.h>
@@ -14,6 +15,8 @@
 #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>
@@ -25,7 +28,9 @@
 #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>
@@ -470,6 +475,13 @@ public:
         : 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;
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 5ae9304904..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(interfaces::Chain& chain) const override;
-
-    //! Load wallet databases.
-    bool Open(interfaces::Chain& chain) 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(interfaces::Chain& chain) 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(interfaces::Chain& chain) 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.
@@ -228,14 +193,19 @@ bool WalletInit::Verify(interfaces::Chain& chain) const
     return true;
 }
 
-bool WalletInit::Open(interfaces::Chain& chain) 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")) {
+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(interfaces::Chain& chain) 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/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 97f4b0926f..cd47b31da1 100644
--- a/src/wallet/test/init_test_fixture.h
+++ b/src/wallet/test/init_test_fixture.h
@@ -18,6 +18,7 @@ struct InitWalletDirTestingSetup: public BasicTestingSetup {
     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 b28f22f1b8..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(*m_chain);
+    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(*m_chain);
+    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(*m_chain);
+    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(*m_chain);
+    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(*m_chain);
+    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(*m_chain);
+    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(*m_chain);
+    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/wallet.h b/src/wallet/wallet.h
index 32cd462c4c..2fb2140ac7 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -37,6 +37,27 @@ namespace interfaces {
 class Chain;
 } // namespace interfaces
 
+
+//! 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();
diff --git a/src/walletinitinterface.h b/src/walletinitinterface.h
index fb6dcf60d0..22aca65990 100644
--- a/src/walletinitinterface.h
+++ b/src/walletinitinterface.h
@@ -9,10 +9,7 @@
 
 class CScheduler;
 class CRPCTable;
-
-namespace interfaces {
-class Chain;
-} // namespace interfaces
+struct InitInterfaces;
 
 class WalletInitInterface {
 public:
@@ -22,20 +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(interfaces::Chain& chain) const = 0;
-    /** Open wallets*/
-    virtual bool Open(interfaces::Chain& chain) 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() {}
 };