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Making FLUSH TABLES WITH READ LOCK block COMMITs of existing transactions,

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in a deadlock-free manner. This splits locking the global read lock in two steps.
This fixes a consequence of this bug, known as:
BUG#4953 'mysqldump --master-data may report incorrect binlog position if using InnoDB'
And a test.


sql/handler.cc:
  making COMMIT wait if FLUSH TABLES WITH READ LOCK happened.
sql/lock.cc:
  an additional stage so that FLUSH TABLES WITH READ LOCK blocks COMMIT:
  make_global_read_lock_block_commit():
  taking the global read lock is TWO steps (2nd step is optional; without
  it, COMMIT of existing transactions will be allowed):
  lock_global_read_lock() THEN make_global_read_lock_block_commit().
sql/mysql_priv.h:
  new argument to wait_if_global_read_lock()
sql/sql_class.h:
  THD::global_read_lock now an uint to reflect the 2 steps of global read lock (does not block COMMIT / does)
sql/sql_db.cc:
  update for new prototype
sql/sql_parse.cc:
  implementing the two steps of global read lock so that FLUSH TABLES WITH READ LOCK can block COMMIT without deadlocking with COMMITs.
This commit is contained in:
unknown 2004-08-20 16:35:23 +02:00
commit cd8054d431
9 changed files with 154 additions and 21 deletions
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4
sql/sql_db.cc
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@ -42,7 +42,7 @@ int mysql_create_db(THD *thd, char *db, uint create_options, bool silent)
VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
// do not create database if another thread is holding read lock
if (wait_if_global_read_lock(thd,0))
if (wait_if_global_read_lock(thd, 0, 1))
{
error= -1;
goto exit2;
@ -146,7 +146,7 @@ int mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
// do not drop database if another thread is holding read lock
if (wait_if_global_read_lock(thd,0))
if (wait_if_global_read_lock(thd, 0, 1))
{
error= -1;
goto exit2;