LOCK_thread_count and COND_thread_count removed from wsrep modules (#1197)

Refactored wsrep patch to not use LOCK_thread_count and COND_thread_count anymore.
This has partially been replaced by using old LOCK_wsrep_slave_threads mutex.
For slave thread count change waiting, new COND_wsrep_slave_threads signal has been added

Added LOCK_wsrep_cluster_config mutex to control that cluster address change cannot happen in parallel

Protected wsrep_slave_threads variable changes with LOCK_cluster_config mutex
This is for avoiding concurrent slave thread count and cluster joining operations to happen

Fixes according to Teemu's review

1 files changed, 6 insertions, 5 deletions

diff --git a/sql/wsrep_var.cc b/sql/wsrep_var.cc
index d091348f481..d73daf7c9f8 100644
--- a/sql/wsrep_var.cc
+++ b/sql/wsrep_var.cc
@@ -478,23 +478,24 @@ bool wsrep_cluster_address_update (sys_var *self, THD* thd, enum_var_type type)
      Note: releasing LOCK_global_system_variables may cause race condition, if 
      there can be several concurrent clients changing wsrep_provider
   */
+  WSREP_DEBUG("wsrep_cluster_address_update: %s", wsrep_cluster_address);
   mysql_mutex_unlock(&LOCK_global_system_variables);
   wsrep_stop_replication(thd);
 
-
   if (wsrep_start_replication())
   {
     wsrep_create_rollbacker();
     wsrep_create_appliers(wsrep_slave_threads);
   }
-
   /* locking order to be enforced is:
      1. LOCK_global_system_variables
-     2. LOCK_wsrep_slave_threads
+     2. LOCK_wsrep_cluster_config
+     => have to juggle mutexes to comply with this
   */
-  mysql_mutex_unlock(&LOCK_wsrep_slave_threads);
+
+  mysql_mutex_unlock(&LOCK_wsrep_cluster_config);
   mysql_mutex_lock(&LOCK_global_system_variables);
-  mysql_mutex_lock(&LOCK_wsrep_slave_threads);
+  mysql_mutex_lock(&LOCK_wsrep_cluster_config);
 
   return false;
 }