add back in double check on connection

Author: ttstarck

lib/fibered_mysql2/fibered_database_connection_pool.rb

@@ -204,10 +204,6 @@ def with_connection
       def current_thread
         Fiber.current
       end
-
-      def connection
-        cached_connections[current_connection_id] ||= checkout
-      end
     end
 
     if ::ActiveRecord.gem_version < "7.1"
@@ -243,6 +239,23 @@ def checkout(checkout_timeout = @checkout_timeout)
       end
       super
     end
+
+    # Invoca patch to ensure that we are using the current fiber's connection.
+    def connection
+      # this is correctly done double-checked locking
+      # (ThreadSafe::Cache's lookups have volatile semantics)
+      if (result = cached_connections[current_connection_id])
+        result
+      else
+        synchronize do
+          if (result = cached_connections[current_connection_id])
+            result
+          else
+            cached_connections[current_connection_id] = checkout
+          end
+        end
+      end
+    end
   end
 end
 

lib/fibered_mysql2/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module FiberedMysql2
-  VERSION = "0.4.0.pre.tstarck.1"
+  VERSION = "0.4.0.pre.tstarck.2"
 end