bzr commit into mysql-5.5-runtime branch (Dmitry.Lenev:3168)

[Dmitry Lenev]

#At file:///home/dlenev/src/bzr/mysql-5.5-rt-grl/ based on revid:dmitry.lenev@stripped

 3168 Dmitry Lenev	2010-10-19
      More changes to draft patch refactoring global read
      lock implementation. Makes GRL yet another type of
      metadata lock and thus exposes it to deadlock detector
      in MDL subsystem.
      
      Solves bugs #54673 "It takes too long to get readlock for
      'FLUSH TABLES WITH READ LOCK'" and #57006 "Deadlock between
      HANDLER and FLUSH TABLES WITH READ LOCK".
      
      Work-in-progress.

    modified:
      sql/lock.cc
      sql/sql_class.cc
      sql/sql_class.h
      sql/sql_insert.cc
=== modified file 'sql/lock.cc'
--- a/sql/lock.cc	2010-10-18 12:33:49 +0000
+++ b/sql/lock.cc	2010-10-19 13:31:53 +0000
@@ -1137,10 +1137,6 @@ bool Global_read_lock::make_global_read_
                                     thd->variables.lock_wait_timeout))
     DBUG_RETURN(TRUE);
 
-  /*
-    TODO/FIXME Ensure that this ticket is correctly placed after sentinel
-               when we are leaving LOCK TABLES mode.
-  */
   thd->mdl_context.move_ticket_after_trans_sentinel(mdl_request.ticket);
   m_mdl_blocks_commits_lock= mdl_request.ticket;
   m_state= GRL_ACQUIRED_AND_BLOCKS_COMMIT;
@@ -1148,6 +1144,22 @@ bool Global_read_lock::make_global_read_
   DBUG_RETURN(FALSE);
 }
 
+
+/**
+  Move tickets for metadata locks which are used to implement GRL after
+  transactional sentinel.
+
+  @param thd     Reference to thread.
+*/
+
+void Global_read_lock::move_tickets_after_trans_sentinel(THD *thd)
+{
+  if (m_mdl_global_shared_lock)
+    thd->mdl_context.move_ticket_after_trans_sentinel(m_mdl_global_shared_lock);
+  if (m_mdl_blocks_commits_lock)
+    thd->mdl_context.move_ticket_after_trans_sentinel(m_mdl_blocks_commits_lock);
+}
+
 /**
   @} (end of group Locking)
 */

=== modified file 'sql/sql_class.cc'
--- a/sql/sql_class.cc	2010-10-18 12:33:49 +0000
+++ b/sql/sql_class.cc	2010-10-19 13:31:53 +0000
@@ -3458,11 +3458,12 @@ void THD::set_mysys_var(struct st_my_thr
 void THD::leave_locked_tables_mode()
 {
   locked_tables_mode= LTM_NONE;
+  mdl_context.reset_trans_sentinel(NULL);
   /*
-    Make sure we don't release the global read lock when leaving LTM.
-    TODO/FIXME: Add handling of commit blocker!
+    Make sure we don't release the global read lock and commit blocker
+    when leaving LTM.
   */
-  mdl_context.reset_trans_sentinel(global_read_lock.global_shared_lock());
+  global_read_lock.move_tickets_after_trans_sentinel(this);
   /* Also ensure that we don't release metadata locks for open HANDLERs. */
   if (handler_tables_hash.records)
     mysql_ha_move_tickets_after_trans_sentinel(this);

=== modified file 'sql/sql_class.h'
--- a/sql/sql_class.h	2010-10-18 12:33:49 +0000
+++ b/sql/sql_class.h	2010-10-19 13:31:53 +0000
@@ -1350,7 +1350,7 @@ public:
   void release_protection_if_set(THD *thd);
   bool make_global_read_lock_block_commit(THD *thd);
   bool is_acquired() const { return m_state != GRL_NONE; }
-  MDL_ticket *global_shared_lock() const { return m_mdl_global_shared_lock; }
+  void move_tickets_after_trans_sentinel(THD *thd);
 private:
   enum_grl_state m_state;
   /**

=== modified file 'sql/sql_insert.cc'
--- a/sql/sql_insert.cc	2010-10-18 12:33:49 +0000
+++ b/sql/sql_insert.cc	2010-10-19 13:31:53 +0000
@@ -540,8 +540,6 @@ bool open_and_lock_for_insert_delayed(TH
     table to being inserted into inside the connection thread.
     If this goes ok, the tickets are cloned and added to the list of granted
     locks held by the handler thread.
-
-    TODO/FIXME: Handle release of protection against GRL.
   */
   if (thd->global_read_lock.can_acquire_protection())
     DBUG_RETURN(TRUE);
@@ -592,7 +590,12 @@ bool open_and_lock_for_insert_delayed(TH
     this or another tables (updating the same table is of course illegal,
     but such an attempt can be discovered only later during statement
     execution).
+
+    Move ticket protecting from a GRL to the front of ticket list.
+    This allows to find it quickly when this lock has to be released
+    at the end of statement.
   */
+  thd->mdl_context.move_ticket_to_front(protection_request.ticket);
 
   /*
     Reset the ticket in case we end up having to use normal insert and


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