Merge lp:~vkolesnikov/pbxt/pbxt-bug-489088 into lp:pbxt

[Vladimir Kolesnikov]

[Paul McCullagh (paul-mccullagh)]

Hi Vlad,

Could you please add a release note.

[Vladimir Kolesnikov (vkolesnikov)]

done!

[lp:~vkolesnikov/pbxt/pbxt-bug-489088]

744. By Vladimir Kolesnikov on 2009-11-30

added a release note

=== modified file 'ChangeLog'
--- ChangeLog	2009-11-25 15:02:05 +0000
+++ ChangeLog	2009-11-30 14:30:26 +0000
@@ -1,6 +1,10 @@
 PBXT Release Notes
 ==================
 
+------- 1.0.09g RC3 - not yet released
+
+RN290: Fixed bug #489088: On shutdown MySQL reports: [Warning] Plugin 'PBXT' will be forced to shutdown
+
 ------- 1.0.09f RC3 - 2009-11-25
 
 RN290: Fixed bug #345524: pbxt does not compile on 64 bit windows. Currently atomic operations are not supported on this platform.
 
=== modified file 'src/myxt_xt.cc'
--- src/myxt_xt.cc	2009-11-27 14:12:44 +0000
+++ src/myxt_xt.cc	2009-11-30 14:30:26 +0000
@@ -3093,12 +3093,23 @@
 		return NULL;
 	}
 
-	if (!(new_thd = new THD())) {
+	if (!(new_thd = new THD)) {
 		my_thread_end();
 		xt_register_error(XT_REG_CONTEXT, XT_ERR_MYSQL_ERROR, 0, "Unable to create MySQL thread (THD)");
 		return NULL;
 	}
 
+	/*
+	 * If PBXT is the default storage engine, then creating any THD objects will add extra 
+	 * references to the PBXT plugin object and will effectively deadlock the plugin so 
+	 * that server will have to force plugin shutdown. To avoid deadlocking and forced shutdown 
+	 * we must dereference the plugin after creating THD objects.
+	 */
+	LEX_STRING& plugin_name = (*new_thd->variables.table_plugin)->name;
+	if ((plugin_name.length == 4) && (strncmp(plugin_name.str, "PBXT", plugin_name.length) == 0)) {
+		(*new_thd->variables.table_plugin)->ref_count--;
+	}
+
 	new_thd->thread_stack = (char *) &new_thd;
 	new_thd->store_globals();
 	lex_start(new_thd);
@@ -3134,6 +3145,17 @@
 	close_thread_tables(thd);
 #endif
 
+	/*
+	 * In myxt_create_thread we decremented plugin ref-count to avoid dead-locking.
+	 * Here we need to increment ref-count to avoid assertion failures.
+	 */
+	if (thd->variables.table_plugin) {
+		LEX_STRING& plugin_name = (*thd->variables.table_plugin)->name;
+		if ((plugin_name.length == 4) && (strncmp(plugin_name.str, "PBXT", plugin_name.length) == 0)) {
+			(*thd->variables.table_plugin)->ref_count++;
+		}
+	}
+	
 	delete thd;
 
 	/* Remember that we don't have a THD */