Merge bitcoin/bitcoin#25491: wallet: use Mutex for g_sqlite_mutex instead of GlobalMutex

4163093d6374e865dc57e33dbea0e7e359062e0a wallet: use Mutex for g_sqlite_mutex instead of GlobalMutex (Vasil Dimov)

Pull request description:

  Using `Mutex` provides stronger guarantee than `GlobalMutex` wrt Clang's
  thread safety analysis. Thus it is better to reduce the usage of
  `GlobalMutex` in favor of `Mutex`.

  Using `Mutex` for `g_sqlite_mutex` is ok because its usage is limited in
  `wallet/sqlite.cpp` and it does not require propagating the negative
  annotations to not relevant code.

ACKs for top commit:
  achow101:
    ACK 4163093d6374e865dc57e33dbea0e7e359062e0a
  hebasto:
    re-ACK 4163093d6374e865dc57e33dbea0e7e359062e0a
  TheCharlatan:
    ACK 4163093d6374e865dc57e33dbea0e7e359062e0a

Tree-SHA512: 4913bcb8437ecf0e6b6cb781d02a6d24ffb4bf3e2e1899fa60785eab41c4c65dbdd9600bcb696290c873661b873ad61e5a4c4f205b7e66fdef2ae17c676cd12f

1 files changed, 11 insertions, 1 deletions

diff --git a/src/wallet/sqlite.h b/src/wallet/sqlite.h
index c6745d7a7e..5745a1d4cf 100644
--- a/src/wallet/sqlite.h
+++ b/src/wallet/sqlite.h
@@ -5,6 +5,7 @@
 #ifndef BITCOIN_WALLET_SQLITE_H
 #define BITCOIN_WALLET_SQLITE_H
 
+#include <sync.h>
 #include <wallet/db.h>
 
 #include <sqlite3.h>
@@ -69,7 +70,16 @@ private:
 
     const std::string m_file_path;
 
-    void Cleanup() noexcept;
+    /**
+     * This mutex protects SQLite initialization and shutdown.
+     * sqlite3_config() and sqlite3_shutdown() are not thread-safe (sqlite3_initialize() is).
+     * Concurrent threads that execute SQLiteDatabase::SQLiteDatabase() should have just one
+     * of them do the init and the rest wait for it to complete before all can proceed.
+     */
+    static Mutex g_sqlite_mutex;
+    static int g_sqlite_count GUARDED_BY(g_sqlite_mutex);
+
+    void Cleanup() noexcept EXCLUSIVE_LOCKS_REQUIRED(!g_sqlite_mutex);
 
 public:
     SQLiteDatabase() = delete;