bk commit into 5.1 tree (malff:1.2367)

[marc.alff]

Below is the list of changes that have just been committed into a local
5.1 repository of marcsql. When marcsql does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
For information on how to access the public repository
see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2006-11-30 18:48:16-07:00, malff@weblab.(none) +2 -0
  Merge malff@stripped:/home/bk/mysql-5.1-runtime
  into  weblab.(none):/home/marcsql/TREE/mysql-5.1-11733_topdown
  MERGE: 1.2353.1.25

  sql/handler.cc@stripped, 2006-11-30 18:48:12-07:00, malff@weblab.(none) +0 -0
    Auto merged
    MERGE: 1.278.1.2

  sql/set_var.cc@stripped, 2006-11-30 18:48:12-07:00, malff@weblab.(none) +0 -0
    Auto merged
    MERGE: 1.200.1.2

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	malff
# Host:	weblab.(none)
# Root:	/home/marcsql/TREE/mysql-5.1-11733_topdown/RESYNC

--- 1.283/sql/handler.cc	2006-11-30 18:48:21 -07:00
+++ 1.284/sql/handler.cc	2006-11-30 18:48:21 -07:00
@@ -692,6 +692,19 @@ int ha_commit_trans(THD *thd, bool all)
       ha_rollback_trans(thd, all);
       DBUG_RETURN(1);
     }
+
+    if (   is_real_trans
+        && opt_readonly
+        && ! (thd->security_ctx->master_access & SUPER_ACL)
+        && ! thd->slave_thread
+       )
+    {
+      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--read-only");
+      ha_rollback_trans(thd, all);
+      error= 1;
+      goto end;
+    }
+
     DBUG_EXECUTE_IF("crash_commit_before", abort(););
 
     /* Close all cursors that can not survive COMMIT */

--- 1.204/sql/set_var.cc	2006-11-30 18:48:21 -07:00
+++ 1.205/sql/set_var.cc	2006-11-30 18:48:21 -07:00
@@ -369,7 +369,7 @@ sys_var_thd_ulong       sys_preload_buff
                                               &SV::preload_buff_size);
 sys_var_thd_ulong	sys_read_buff_size("read_buffer_size",
 					   &SV::read_buff_size);
-sys_var_bool_ptr	sys_readonly("read_only", &opt_readonly);
+sys_var_opt_readonly    sys_readonly("read_only", &opt_readonly);
 sys_var_thd_ulong	sys_read_rnd_buff_size("read_rnd_buffer_size",
 					       &SV::read_rnd_buff_size);
 sys_var_thd_ulong	sys_div_precincrement("div_precision_increment",
@@ -3853,6 +3853,70 @@ bool sys_var_trust_routine_creators::upd
   warn_deprecated(thd);
   return sys_var_bool_ptr::update(thd, var);
 }
+
+bool sys_var_opt_readonly::update(THD *thd, set_var *var)
+{
+  bool result;
+
+  DBUG_ENTER("sys_var_opt_readonly::update");
+
+  /* Prevent self dead-lock */
+  if (thd->locked_tables || thd->active_transaction())
+  {
+    my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
+    DBUG_RETURN(true);
+  }
+
+  if (thd->global_read_lock)
+  {
+    /*
+      This connection already holds the global read lock.
+      This can be the case with:
+      - FLUSH TABLES WITH READ LOCK
+      - SET GLOBAL READ_ONLY = 1
+    */
+    result= sys_var_bool_ptr::update(thd, var);
+    DBUG_RETURN(result);
+  }
+
+  /*
+    Perform a 'FLUSH TABLES WITH READ LOCK'.
+    This is a 3 step process:
+    - [1] lock_global_read_lock()
+    - [2] close_cached_tables()
+    - [3] make_global_read_lock_block_commit()
+    [1] prevents new connections from obtaining tables locked for write.
+    [2] waits until all existing connections close their tables.
+    [3] prevents transactions from being committed.
+  */
+
+  if (lock_global_read_lock(thd))
+    DBUG_RETURN(true);
+
+  /*
+    This call will be blocked by any connection holding a READ or WRITE lock.
+    Ideally, we want to wait only for pending WRITE locks, but since:
+    con 1> LOCK TABLE T FOR READ;
+    con 2> LOCK TABLE T FOR WRITE; (blocked by con 1)
+    con 3> SET GLOBAL READ ONLY=1; (blocked by con 2)
+    can cause to wait on a read lock, it's required for the client application
+    to unlock everything, and acceptable for the server to wait on all locks.
+  */
+  if (close_cached_tables(thd, true, NULL, false))
+    goto end_with_read_lock;
+
+  if (result= make_global_read_lock_block_commit(thd))
+    goto end_with_read_lock;
+
+  /* Change the opt_readonly system variable, safe because the lock is held */
+  result= sys_var_bool_ptr::update(thd, var);
+
+end_with_read_lock:
+  /* Release the lock */
+  unlock_global_read_lock(thd);
+  DBUG_RETURN(result);
+}
+
 
 /* even session variable here requires SUPER, because of -#o,file */
 bool sys_var_thd_dbug::check(THD *thd, set_var *var)