Backport of:

------------------------------------------------------------
revno: 2630.4.11
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Tue 2008-05-27 21:31:53 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  After review fixes in progress.

  Changed mysql_lock_tables() to be no longer responsible for
  reopening table if waiting for the lock on it was aborted.
  This allows to get rid of several annoying functions.

sql/ha_ndbcluster_binlog.cc

@@ -2391,7 +2391,7 @@ int ndb_add_ndb_binlog_index(THD *thd, void *_row)
       goto add_ndb_binlog_index_err;
     }
 
-    if (lock_tables(thd, &binlog_tables, 1, &need_reopen))
+    if (lock_tables(thd, &binlog_tables, 1, 0, &need_reopen))
     {
       if (need_reopen)
       {

sql/lock.cc

@@ -94,31 +94,6 @@ static int lock_external(THD *thd, TABLE **table,uint count);
 static int unlock_external(THD *thd, TABLE **table,uint count);
 static void print_lock_error(int error, const char *);
 
-/*
-  Lock tables.
-
-  SYNOPSIS
-    mysql_lock_tables()
-    thd                         The current thread.
-    tables                      An array of pointers to the tables to lock.
-    count                       The number of tables to lock.
-    flags                       Options:
-      MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK      Ignore a global read lock
-      MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY      Ignore SET GLOBAL READ_ONLY
-      MYSQL_LOCK_IGNORE_FLUSH                 Ignore a flush tables.
-      MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN        Instead of reopening altered
-                                              or dropped tables by itself,
-                                              mysql_lock_tables() should
-                                              notify upper level and rely
-                                              on caller doing this.
-    need_reopen                 Out parameter, TRUE if some tables were altered
-                                or deleted and should be reopened by caller.
-
-  RETURN
-    A lock structure pointer on success.
-    NULL on error or if some tables should be reopen.
-*/
-
 /* Map the return value of thr_lock to an error from errmsg.txt */
 static int thr_lock_errno_to_mysql[]=
 { 0, 1, ER_LOCK_WAIT_TIMEOUT, ER_LOCK_DEADLOCK };
@@ -247,6 +222,28 @@ static void reset_lock_data_and_free(MYSQL_LOCK **mysql_lock)
 }
 
 
+/**
+   Lock tables.
+
+   @param thd          The current thread.
+   @param tables       An array of pointers to the tables to lock.
+   @param count        The number of tables to lock.
+   @param flags        Options:
+                 MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK Ignore a global read lock
+                 MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY Ignore SET GLOBAL READ_ONLY
+                 MYSQL_LOCK_IGNORE_FLUSH            Ignore a flush tables.
+   @param need_reopen  Out parameter, TRUE if some tables were altered
+                       or deleted and should be reopened by caller.
+
+   @note Caller of this function should always be ready to handle request to
+         reopen table unless there are external invariants which guarantee
+         that such thing won't be needed (for example we are obtaining lock
+         on table on which we already have exclusive metadata lock).
+
+   @retval  A lock structure pointer on success.
+   @retval  NULL on error or if some tables should be reopen.
+*/
+
 MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
                               uint flags, bool *need_reopen)
 {
@@ -330,7 +327,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
       my_error(rc, MYF(0));
       break;
     }
-    else if (rc == 1)                           /* aborted */
+    else if (rc == 1)                           /* aborted or killed */
     {
       thd->some_tables_deleted=1;		// Try again
       sql_lock->lock_count= 0;                  // Locks are already freed
@@ -339,8 +336,9 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
     else if (!thd->some_tables_deleted || (flags & MYSQL_LOCK_IGNORE_FLUSH))
     {
       /*
-        Thread was killed or lock aborted. Let upper level close all
-        used tables and retry or give error.
+        Success and nobody set thd->some_tables_deleted to force reopen
+        or we were called with MYSQL_LOCK_IGNORE_FLUSH so such attempts
+        should be ignored.
       */
       break;
     }
@@ -366,13 +364,9 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
     */
     reset_lock_data_and_free(&sql_lock);
 retry:
-    if (flags & MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN)
-    {
-      *need_reopen= TRUE;
-      break;
-    }
-    if (wait_for_tables(thd))
-      break;					// Couldn't open tables
+    /* Let upper level close all used tables and retry or give error. */
+    *need_reopen= TRUE;
+    break;
   }
   thd_proc_info(thd, 0);
   if (thd->killed)

sql/log_event_old.cc

@@ -1461,7 +1461,8 @@ int Old_rows_log_event::do_apply_event(Relay_log_info const *rli)
     lex_start(thd);
 
     while ((error= lock_tables(thd, rli->tables_to_lock,
-                               rli->tables_to_lock_count, &need_reopen)))
+                               rli->tables_to_lock_count, 0,
+                               &need_reopen)))
     {
       if (!need_reopen)
       {

sql/mysql_priv.h

@@ -1241,8 +1241,6 @@ thr_lock_type read_lock_type_for_table(THD *thd, TABLE *table);
 void close_data_files_and_morph_locks(THD *thd, const char *db,
                                       const char *table_name);
 void close_handle_and_leave_table_as_lock(TABLE *table);
-bool wait_for_tables(THD *thd);
-bool table_is_used(TABLE *table, bool wait_for_name_lock);
 void unlock_locked_tables(THD *thd);
 void execute_init_command(THD *thd, sys_var_str *init_command_var,
 			  rw_lock_t *var_mutex);
@@ -1476,22 +1474,24 @@ void wait_for_condition(THD *thd, pthread_mutex_t *mutex,
                         pthread_cond_t *cond);
 int open_tables(THD *thd, TABLE_LIST **tables, uint *counter, uint flags);
 /* open_and_lock_tables with optional derived handling */
-int open_and_lock_tables_derived(THD *thd, TABLE_LIST *tables, bool derived);
+int open_and_lock_tables_derived(THD *thd, TABLE_LIST *tables, bool derived,
+                                 uint flags);
 /* simple open_and_lock_tables without derived handling */
 inline int simple_open_n_lock_tables(THD *thd, TABLE_LIST *tables)
 {
-  return open_and_lock_tables_derived(thd, tables, FALSE);
+  return open_and_lock_tables_derived(thd, tables, FALSE, 0);
 }
 /* open_and_lock_tables with derived handling */
 inline int open_and_lock_tables(THD *thd, TABLE_LIST *tables)
 {
-  return open_and_lock_tables_derived(thd, tables, TRUE);
+  return open_and_lock_tables_derived(thd, tables, TRUE, 0);
 }
 /* simple open_and_lock_tables without derived handling for single table */
 TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
                                 thr_lock_type lock_type);
 bool open_normal_and_derived_tables(THD *thd, TABLE_LIST *tables, uint flags);
-int lock_tables(THD *thd, TABLE_LIST *tables, uint counter, bool *need_reopen);
+int lock_tables(THD *thd, TABLE_LIST *tables, uint counter, uint flags,
+                bool *need_reopen);
 int decide_logging_format(THD *thd, TABLE_LIST *tables);
 TABLE *open_temporary_table(THD *thd, const char *path, const char *db,
 			    const char *table_name, bool link_in_list);
@@ -2045,10 +2045,9 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count,
 /* mysql_lock_tables() and open_table() flags bits */
 #define MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK      0x0001
 #define MYSQL_LOCK_IGNORE_FLUSH                 0x0002
-#define MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN        0x0004
-#define MYSQL_OPEN_TEMPORARY_ONLY               0x0008
-#define MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY      0x0010
-#define MYSQL_LOCK_PERF_SCHEMA                  0x0020
+#define MYSQL_OPEN_TEMPORARY_ONLY               0x0004
+#define MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY      0x0008
+#define MYSQL_LOCK_PERF_SCHEMA                  0x0010
 
 void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock);
 void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock);

sql/sql_handler.cc

@@ -519,8 +519,7 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
   */
   thd->open_tables= thd->handler_tables;
 
-  lock= mysql_lock_tables(thd, &tables->table, 1,
-                          MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN, &need_reopen);
+  lock= mysql_lock_tables(thd, &tables->table, 1, 0, &need_reopen);
 
   /* restore previous context */
   thd->open_tables= backup_open_tables;

sql/sql_insert.cc

@@ -1817,6 +1817,7 @@ class Delayed_insert :public ilink {
   inline uint lock_count() { return locks_in_memory; }
 
   TABLE* get_local_table(THD* client_thd);
+  bool open_and_lock_table();
   bool handle_inserts(void);
 };
 
@@ -2292,6 +2293,42 @@ void kill_delayed_threads(void)
 }
 
 
+/**
+   Open and lock table for use by delayed thread and check that
+   this table is suitable for delayed inserts.
+
+   @retval FALSE - Success.
+   @retval TRUE  - Failure.
+*/
+
+bool Delayed_insert::open_and_lock_table()
+{
+  if (!(table= open_n_lock_single_table(&thd, &table_list,
+                                        TL_WRITE_DELAYED)))
+  {
+    thd.fatal_error();				// Abort waiting inserts
+    return TRUE;
+  }
+  if (!(table->file->ha_table_flags() & HA_CAN_INSERT_DELAYED))
+  {
+    my_error(ER_DELAYED_NOT_SUPPORTED, MYF(ME_FATALERROR),
+             table_list.table_name);
+    return TRUE;
+  }
+  if (table->triggers)
+  {
+    /*
+      Table has triggers. This is not an error, but we do
+      not support triggers with delayed insert. Terminate the delayed
+      thread without an error and thus request lock upgrade.
+    */
+    return TRUE;
+  }
+  table->copy_blobs= 1;
+  return FALSE;
+}
+
+
 /*
  * Create a new delayed insert thread
 */
@@ -2354,29 +2391,8 @@ pthread_handler_t handle_delayed_insert(void *arg)
 
     alloc_mdl_locks(&di->table_list, thd->mem_root);
 
-    /* Open table */
-    if (!(di->table= open_n_lock_single_table(thd, &di->table_list,
-                                              TL_WRITE_DELAYED)))
-    {
-      thd->fatal_error();				// Abort waiting inserts
-      goto err;
-    }
-    if (!(di->table->file->ha_table_flags() & HA_CAN_INSERT_DELAYED))
-    {
-      my_error(ER_DELAYED_NOT_SUPPORTED, MYF(ME_FATALERROR),
-               di->table_list.table_name);
-      goto err;
-    }
-    if (di->table->triggers)
-    {
-      /*
-        Table has triggers. This is not an error, but we do
-        not support triggers with delayed insert. Terminate the delayed
-        thread without an error and thus request lock upgrade.
-      */
+    if (di->open_and_lock_table())
       goto err;
-    }
-    di->table->copy_blobs=1;
 
     /* Tell client that the thread is initialized */
     pthread_cond_signal(&di->cond_client);
@@ -2450,7 +2466,7 @@ pthread_handler_t handle_delayed_insert(void *arg)
 
       if (di->tables_in_use && ! thd->lock)
       {
-        bool not_used;
+        bool need_reopen;
         /*
           Request for new delayed insert.
           Lock the table, but avoid to be blocked by a global read lock.
@@ -2463,11 +2479,29 @@ pthread_handler_t handle_delayed_insert(void *arg)
         */
         if (! (thd->lock= mysql_lock_tables(thd, &di->table, 1,
                                             MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK,
-                                            &not_used)))
+                                            &need_reopen)))
         {
-          /* Fatal error */
-          di->dead= 1;
-          thd->killed= THD::KILL_CONNECTION;
+          if (need_reopen)
+          {
+            /*
+              We were waiting to obtain TL_WRITE_DELAYED (probably due to
+              someone having or requesting TL_WRITE_ALLOW_READ) and got
+              aborted. Try to reopen table and if it fails die.
+            */
+            close_thread_tables(thd);
+            di->table= 0;
+            if (di->open_and_lock_table())
+            {
+              di->dead= 1;
+              thd->killed= THD::KILL_CONNECTION;
+            }
+          }
+          else
+          {
+            /* Fatal error */
+            di->dead= 1;
+            thd->killed= THD::KILL_CONNECTION;
+          }
         }
         pthread_cond_broadcast(&di->cond_client);
       }
@@ -3533,6 +3567,12 @@ static TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info,
 
   table->reginfo.lock_type=TL_WRITE;
   hooks->prelock(&table, 1);                    // Call prelock hooks
+  /*
+    mysql_lock_tables() below should never fail with request to reopen table
+    since it won't wait for the table lock (we have exclusive metadata lock on
+    the table) and thus can't get aborted and since it ignores other threads
+    setting THD::some_tables_deleted thanks to MYSQL_LOCK_IGNORE_FLUSH.
+  */
   if (! ((*lock)= mysql_lock_tables(thd, &table, 1,
                                     MYSQL_LOCK_IGNORE_FLUSH, &not_used)) ||
         hooks->postlock(&table, 1))

sql/sql_update.cc

@@ -222,7 +222,7 @@ int mysql_update(THD *thd,
       /* convert to multiupdate */
       DBUG_RETURN(2);
     }
-    if (!lock_tables(thd, table_list, table_count, &need_reopen))
+    if (!lock_tables(thd, table_list, table_count, 0, &need_reopen))
       break;
     if (!need_reopen)
       DBUG_RETURN(1);
@@ -1099,7 +1099,7 @@ int mysql_multi_update_prepare(THD *thd)
 
   /* now lock and fill tables */
   if (!thd->stmt_arena->is_stmt_prepare() &&
-      lock_tables(thd, table_list, table_count, &need_reopen))
+      lock_tables(thd, table_list, table_count, 0, &need_reopen))
   {
     if (!need_reopen)
       DBUG_RETURN(TRUE);