Shared/Database: Improve dead-lock error handling

Improve dead-lock error handling by making sure only 1 thread at time retries to execute a transaction so they don't keep dead-locking each other.

2 files changed, 5 insertions, 0 deletions

diff --git a/src/server/shared/Database/Transaction.cpp b/src/server/shared/Database/Transaction.cpp
index b83b787a106..9f36d198bde 100644
--- a/src/server/shared/Database/Transaction.cpp
+++ b/src/server/shared/Database/Transaction.cpp
@@ -19,6 +19,8 @@
 #include "Transaction.h"
 #include <mysqld_error.h>
 
+std::mutex TransactionTask::_deadlockLock;
+
 //- Append a raw ad-hoc query to the transaction
 void Transaction::Append(const char* sql)
 {
@@ -81,6 +83,8 @@ bool TransactionTask::Execute()
 
     if (errorCode == ER_LOCK_DEADLOCK)
     {
+        // Make sure only 1 async thread retries a transaction so they don't keep dead-locking each other
+        std::lock_guard<std::mutex> lock(_deadlockLock);
         uint8 loopBreaker = 5;  // Handle MySQL Errno 1213 without extending deadlock to the core itself
         for (uint8 i = 0; i < loopBreaker; ++i)
             if (!m_conn->ExecuteTransaction(m_trans))
diff --git a/src/server/shared/Database/Transaction.h b/src/server/shared/Database/Transaction.h
index cf6aa98b386..83d59006ddc 100644
--- a/src/server/shared/Database/Transaction.h
+++ b/src/server/shared/Database/Transaction.h
@@ -66,6 +66,7 @@ class TransactionTask : public SQLOperation
         bool Execute() override;
 
         SQLTransaction m_trans;
+        static std::mutex _deadlockLock;
 };
 
 #endif