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:
  lock_tables() now also accepts set of options to be passed to
  mysql_lock_tables().
sql/lock.cc:
  Changed mysql_lock_tables() always requests caller to reopen
  table instead doing this on its own when waiting for lock was
  aborted. This allows us to get rid of several functions which
  were used in rare cases and significantly complicated our life.
sql/log_event_old.cc:
  lock_tables() now also accepts set of options to be passed
  to mysql_lock_tables().
sql/mysql_priv.h:
  Now mysql_lock_tables() always requests caller to reopen
  table instead doing this on its own when waiting for lock was
  aborted. So we no longer need wait_for_tables() and
  table_is_used() functions and MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN
  flag.
  open_and_lock_table_derived() and lock_tables() now accept
  options to be passed to open_tables() and mysql_lock_tables()
  calls.
sql/sql_base.cc:
  Since now mysql_lock_tables() always requests caller to
  reopen table instead doing this on its own when waiting for
  lock was aborted we no longer need wait_for_tables(),
  table_is_used() and close_old_data_files() functions.
  open_and_lock_table_derived() and lock_tables() now accept
  options to be passed to open_tables() and mysql_lock_tables()
  calls. This was needed in order to get rid of redundant code
  in open_system_tables_for_read() function.
sql/sql_handler.cc:
  mysql_lock_tables() is now always requests reopen if waiting
  for lock is aborted. MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN flag
  was removed.
sql/sql_insert.cc:
  handle_delayed_insert():
  Since mysql_lock_tables() is no longer responsible for
  reopening tables when waiting for lock was aborted we have
  to handle such situation outside of this function. To simplify
  this extracted code opening table for delayed insert thread to
  separate method of Delayed_insert class.
sql/sql_update.cc:
  lock_tables() now also accepts set of options to be passed
  to mysql_lock_tables().

1 files changed, 29 insertions, 35 deletions

diff --git a/sql/lock.cc b/sql/lock.cc
index 0c8c3095844..38b2d22f91f 100644
--- a/sql/lock.cc
+++ b/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)