From c9b49d28563487e76169c7749b309244cabc70bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Barbosa?= <joao.paulo.barbosa@gmail.com>
Date: Wed, 17 Jun 2020 10:47:29 +0100
Subject: wallet: Handle concurrent wallet loading

Github-Pull: #19300
Rebased-From: b9971ae5853c1d62e09d976a8705f4f731290d85
---
 src/wallet/wallet.cpp | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 4394b2748a..af3f958349 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -101,9 +101,11 @@ std::unique_ptr<interfaces::Handler> HandleLoadWallet(LoadWalletFn load_wallet)
     return interfaces::MakeHandler([it] { LOCK(cs_wallets); g_load_wallet_fns.erase(it); });
 }
 
+static Mutex g_loading_wallet_mutex;
 static Mutex g_wallet_release_mutex;
 static std::condition_variable g_wallet_release_cv;
-static std::set<std::string> g_unloading_wallet_set;
+static std::set<std::string> g_loading_wallet_set GUARDED_BY(g_loading_wallet_mutex);
+static std::set<std::string> g_unloading_wallet_set GUARDED_BY(g_wallet_release_mutex);
 
 // Custom deleter for shared_ptr<CWallet>.
 static void ReleaseWallet(CWallet* wallet)
@@ -147,7 +149,8 @@ void UnloadWallet(std::shared_ptr<CWallet>&& wallet)
     }
 }
 
-std::shared_ptr<CWallet> LoadWallet(interfaces::Chain& chain, const WalletLocation& location, std::string& error, std::vector<std::string>& warnings)
+namespace {
+std::shared_ptr<CWallet> LoadWalletInternal(interfaces::Chain& chain, const WalletLocation& location, std::string& error, std::vector<std::string>& warnings)
 {
     try {
         if (!CWallet::Verify(chain, location, false, error, warnings)) {
@@ -168,6 +171,19 @@ std::shared_ptr<CWallet> LoadWallet(interfaces::Chain& chain, const WalletLocati
         return nullptr;
     }
 }
+} // namespace
+
+std::shared_ptr<CWallet> LoadWallet(interfaces::Chain& chain, const WalletLocation& location, std::string& error, std::vector<std::string>& warnings)
+{
+    auto result = WITH_LOCK(g_loading_wallet_mutex, return g_loading_wallet_set.insert(location.GetName()));
+    if (!result.second) {
+        error = "Wallet already being loading.";
+        return nullptr;
+    }
+    auto wallet = LoadWalletInternal(chain, location, error, warnings);
+    WITH_LOCK(g_loading_wallet_mutex, g_loading_wallet_set.erase(result.first));
+    return wallet;
+}
 
 std::shared_ptr<CWallet> LoadWallet(interfaces::Chain& chain, const std::string& name, std::string& error, std::vector<std::string>& warnings)
 {
-- 
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