Merge from mysql-5.5-runtime to mysql-5.5-bugteam

No conflicts

sql/sql_class.h

@@ -869,8 +869,8 @@ struct st_savepoint {
   char                *name;
   uint                 length;
   Ha_trx_info         *ha_list;
-  /** Last acquired lock before this savepoint was set. */
-  MDL_ticket     *mdl_savepoint;
+  /** State of metadata locks before this savepoint was set. */
+  MDL_savepoint        mdl_savepoint;
 };
 
 enum xa_states {XA_NOTR=0, XA_ACTIVE, XA_IDLE, XA_PREPARED, XA_ROLLBACK_ONLY};
@@ -1105,12 +1105,12 @@ class Open_tables_backup: public Open_tables_state
 public:
   /**
     When we backup the open tables state to open a system
-    table or tables, points at the last metadata lock
-    acquired before the backup. Is used to release
-    metadata locks on system tables after they are
+    table or tables, we want to save state of metadata
+    locks which were acquired before the backup. It is used
+    to release metadata locks on system tables after they are
     no longer used.
   */
-  MDL_ticket *mdl_system_tables_svp;
+  MDL_savepoint mdl_system_tables_svp;
 };
 
 /**
@@ -1383,26 +1383,43 @@ public:
   };
 
   Global_read_lock()
-    :m_protection_count(0), m_state(GRL_NONE), m_mdl_global_shared_lock(NULL)
+    : m_state(GRL_NONE),
+      m_mdl_global_shared_lock(NULL),
+      m_mdl_blocks_commits_lock(NULL)
   {}
 
   bool lock_global_read_lock(THD *thd);
   void unlock_global_read_lock(THD *thd);
-  bool wait_if_global_read_lock(THD *thd, bool abort_on_refresh,
-                                bool is_not_commit);
-  void start_waiting_global_read_lock(THD *thd);
+  /**
+    Check if this connection can acquire protection against GRL and
+    emit error if otherwise.
+  */
+  bool can_acquire_protection() const
+  {
+    if (m_state)
+    {
+      my_error(ER_CANT_UPDATE_WITH_READLOCK, MYF(0));
+      return TRUE;
+    }
+    return FALSE;
+  }
   bool make_global_read_lock_block_commit(THD *thd);
   bool is_acquired() const { return m_state != GRL_NONE; }
-  bool has_protection() const { return m_protection_count > 0; }
-  MDL_ticket *global_shared_lock() const { return m_mdl_global_shared_lock; }
+  void set_explicit_lock_duration(THD *thd);
 private:
-  uint           m_protection_count;            // GRL protection count
+  enum_grl_state m_state;
   /**
     In order to acquire the global read lock, the connection must
-    acquire a global shared metadata lock, to prohibit all DDL.
+    acquire shared metadata lock in GLOBAL namespace, to prohibit
+    all DDL.
   */
-  enum_grl_state m_state;
   MDL_ticket *m_mdl_global_shared_lock;
+  /**
+    Also in order to acquire the global read lock, the connection
+    must acquire a shared metadata lock in COMMIT namespace, to
+    prohibit commits.
+  */
+  MDL_ticket *m_mdl_blocks_commits_lock;
 };
 
 
@@ -2000,6 +2017,12 @@ public:
   DYNAMIC_ARRAY user_var_events;        /* For user variables replication */
   MEM_ROOT      *user_var_events_alloc; /* Allocate above array elements here */
 
+  /*
+    If checking this in conjunction with a wait condition, please
+    include a check after enter_cond() if you want to avoid a race
+    condition. For details see the implementation of awake(),
+    especially the "broadcast" part.
+  */
   enum killed_state
   {
     NOT_KILLED=0,
@@ -2258,6 +2281,20 @@ public:
   }
   void set_time_after_lock()  { utime_after_lock= my_micro_time(); }
   ulonglong current_utime()  { return my_micro_time(); }
+  /**
+   Update server status after execution of a top level statement.
+
+   Currently only checks if a query was slow, and assigns
+   the status accordingly.
+   Evaluate the current time, and if it exceeds the long-query-time
+   setting, mark the query as slow.
+  */
+  void update_server_status()
+  {
+    ulonglong end_utime_of_query= current_utime();
+    if (end_utime_of_query > utime_after_lock + variables.long_query_time)
+      server_status|= SERVER_QUERY_WAS_SLOW;
+  }
   inline ulonglong found_rows(void)
   {
     return limit_found_rows;
@@ -2749,7 +2786,7 @@ public:
   {
     DBUG_ASSERT(locked_tables_mode == LTM_NONE);
 
-    mdl_context.set_trans_sentinel();
+    mdl_context.set_explicit_duration_for_all_locks();
     locked_tables_mode= mode_arg;
   }
   void leave_locked_tables_mode();
@@ -3554,21 +3591,11 @@ public:
 */
 #define CF_DIAGNOSTIC_STMT        (1U << 8)
 
-/**
-  SQL statements that must be protected against impending global read lock
-  to prevent deadlock. This deadlock could otherwise happen if the statement
-  starts waiting for the GRL to go away inside mysql_lock_tables while at the
-  same time having "old" opened tables. The thread holding the GRL can be
-  waiting for these "old" opened tables to be closed, causing a deadlock
-  (FLUSH TABLES WITH READ LOCK).
- */
-#define CF_PROTECT_AGAINST_GRL  (1U << 10)
-
 /**
   Identifies statements that may generate row events
   and that may end up in the binary log.
 */
-#define CF_CAN_GENERATE_ROW_EVENTS (1U << 11)
+#define CF_CAN_GENERATE_ROW_EVENTS (1U << 9)
 
 /* Bits in server_command_flags */