Merge #13063: Use shared pointer to retain wallet instance

80b4910f7d87983f50047074c3c2397b0a5c4e92 wallet: Use shared pointer to retain wallet instance (João Barbosa)

Pull request description:

  Currently there are 3 places where it makes sense to retain a wallet shared pointer:
   - `vpwallets`;
   - `interfaces::Wallet` interface instance - used by the UI;
   - wallet RPC functions - given by `GetWalletForJSONRPCRequest`.

  The way it is now it is possible to have, for instance, listunspent RPC and in parallel unload the wallet (once #13111 is merged) without blocking. Once the RPC finishes, the shared pointer will release the wallet.

  It is also possible to get all existing wallets without blocking because the caller keeps a local list of shared pointers.

  This is mostly relevant for wallet unloading.

  This PR replaces #11402.

Tree-SHA512: b7e37c7e1ab56626085afe2d40b1628e8d4f0dbda08df01b7e618ecd2d894ce9b83d4219443f444ba889096286eff002f163cb0a48f37063b62e9ba4ccfa6cce

1 files changed, 14 insertions, 17 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 1e67e09e00..5fb1d68092 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -36,23 +36,23 @@
 #include <boost/algorithm/string/replace.hpp>
 
 static CCriticalSection cs_wallets;
-static std::vector<CWallet*> vpwallets GUARDED_BY(cs_wallets);
+static std::vector<std::shared_ptr<CWallet>> vpwallets GUARDED_BY(cs_wallets);
 
-bool AddWallet(CWallet* wallet)
+bool AddWallet(const std::shared_ptr<CWallet>& wallet)
 {
     LOCK(cs_wallets);
     assert(wallet);
-    std::vector<CWallet*>::const_iterator i = std::find(vpwallets.begin(), vpwallets.end(), wallet);
+    std::vector<std::shared_ptr<CWallet>>::const_iterator i = std::find(vpwallets.begin(), vpwallets.end(), wallet);
     if (i != vpwallets.end()) return false;
     vpwallets.push_back(wallet);
     return true;
 }
 
-bool RemoveWallet(CWallet* wallet)
+bool RemoveWallet(const std::shared_ptr<CWallet>& wallet)
 {
     LOCK(cs_wallets);
     assert(wallet);
-    std::vector<CWallet*>::iterator i = std::find(vpwallets.begin(), vpwallets.end(), wallet);
+    std::vector<std::shared_ptr<CWallet>>::iterator i = std::find(vpwallets.begin(), vpwallets.end(), wallet);
     if (i == vpwallets.end()) return false;
     vpwallets.erase(i);
     return true;
@@ -64,16 +64,16 @@ bool HasWallets()
     return !vpwallets.empty();
 }
 
-std::vector<CWallet*> GetWallets()
+std::vector<std::shared_ptr<CWallet>> GetWallets()
 {
     LOCK(cs_wallets);
     return vpwallets;
 }
 
-CWallet* GetWallet(const std::string& name)
+std::shared_ptr<CWallet> GetWallet(const std::string& name)
 {
     LOCK(cs_wallets);
-    for (CWallet* wallet : vpwallets) {
+    for (const std::shared_ptr<CWallet>& wallet : vpwallets) {
         if (wallet->GetName() == name) return wallet;
     }
     return nullptr;
@@ -3201,8 +3201,6 @@ DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
     if (nLoadWalletRet != DBErrors::LOAD_OK)
         return nLoadWalletRet;
 
-    uiInterface.LoadWallet(this);
-
     return DBErrors::LOAD_OK;
 }
 
@@ -4038,7 +4036,7 @@ bool CWallet::Verify(std::string wallet_file, bool salvage_wallet, std::string&
     return WalletBatch::VerifyDatabaseFile(wallet_path, warning_string, error_string);
 }
 
-CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path& path)
+std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(const std::string& name, const fs::path& path)
 {
     const std::string& walletFile = name;
 
@@ -4060,10 +4058,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
 
     int64_t nStart = GetTimeMillis();
     bool fFirstRun = true;
-    // Make a temporary wallet unique pointer so memory doesn't get leaked if
-    // wallet creation fails.
-    auto temp_wallet = MakeUnique<CWallet>(name, WalletDatabase::Create(path));
-    CWallet* walletInstance = temp_wallet.get();
+    std::shared_ptr<CWallet> walletInstance = std::make_shared<CWallet>(name, WalletDatabase::Create(path));
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DBErrors::LOAD_OK)
     {
@@ -4092,6 +4087,8 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
         }
     }
 
+    uiInterface.LoadWallet(walletInstance);
+
     int prev_version = walletInstance->nWalletVersion;
     if (gArgs.GetBoolArg("-upgradewallet", fFirstRun))
     {
@@ -4304,7 +4301,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
 
         nStart = GetTimeMillis();
         {
-            WalletRescanReserver reserver(walletInstance);
+            WalletRescanReserver reserver(walletInstance.get());
             if (!reserver.reserve()) {
                 InitError(_("Failed to rescan the wallet during initialization"));
                 return nullptr;
@@ -4342,7 +4339,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
     }
 
     // Register with the validation interface. It's ok to do this after rescan since we're still holding cs_main.
-    RegisterValidationInterface(temp_wallet.release());
+    RegisterValidationInterface(walletInstance.get());
 
     walletInstance->SetBroadcastTransactions(gArgs.GetBoolArg("-walletbroadcast", DEFAULT_WALLETBROADCAST));