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MDEV-12882 - Assertion failed in MDL_context::upgrade_shared_lock

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Relaxed assertion (in MySQL it was removed).
For "LOCK TABLES t1 WRITE CONCURRENT, t1 READ" upgrade lock to weakest
existing suitable lock, which is MDL_SHARED_NO_READ_WRITE.
This commit is contained in:
Sergey Vojtovich 2017-06-22 17:35:36 +04:00
parent 0d69d313a1
commit dd710e7552
4 changed files with 49 additions and 3 deletions
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22
mysql-test/r/mdl.result Normal file
View File

@ -0,0 +1,22 @@
#
# MDEV-12882 - Assertion `mdl_ticket->m_type == MDL_SHARED_UPGRADABLE ||
# mdl_ticket->m_type == MDL_SHARED_NO_WRITE ||
# mdl_ticket->m_type == MDL_SHARED_NO_READ_WRITE ||
# mdl_ticket->m_type == MDL_SHARED_READ'
# failed in MDL_context::upgrade_shared_lock
#
CREATE TABLE t1(a INT) ENGINE=InnoDB;
LOCK TABLES t1 WRITE CONCURRENT, t1 AS t2 READ;
SELECT * FROM information_schema.metadata_lock_info;
THREAD_ID LOCK_MODE LOCK_DURATION LOCK_TYPE TABLE_SCHEMA TABLE_NAME
9 MDL_INTENTION_EXCLUSIVE NULL Global read lock
9 MDL_SHARED_NO_READ_WRITE NULL Table metadata lock test t1
UNLOCK TABLES;
LOCK TABLES t1 AS t2 READ, t1 WRITE CONCURRENT;
SELECT * FROM information_schema.metadata_lock_info;
THREAD_ID LOCK_MODE LOCK_DURATION LOCK_TYPE TABLE_SCHEMA TABLE_NAME
9 MDL_INTENTION_EXCLUSIVE NULL Global read lock
9 MDL_SHARED_WRITE NULL Table metadata lock test t1
9 MDL_SHARED_READ_ONLY NULL Table metadata lock test t1
UNLOCK TABLES;
DROP TABLE t1;

19
mysql-test/t/mdl.test Normal file
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@ -0,0 +1,19 @@
--source include/have_metadata_lock_info.inc
--source include/have_innodb.inc
--echo #
--echo # MDEV-12882 - Assertion `mdl_ticket->m_type == MDL_SHARED_UPGRADABLE ||
--echo # mdl_ticket->m_type == MDL_SHARED_NO_WRITE ||
--echo # mdl_ticket->m_type == MDL_SHARED_NO_READ_WRITE ||
--echo # mdl_ticket->m_type == MDL_SHARED_READ'
--echo # failed in MDL_context::upgrade_shared_lock
--echo #
CREATE TABLE t1(a INT) ENGINE=InnoDB;
LOCK TABLES t1 WRITE CONCURRENT, t1 AS t2 READ;
SELECT * FROM information_schema.metadata_lock_info;
UNLOCK TABLES;
LOCK TABLES t1 AS t2 READ, t1 WRITE CONCURRENT;
SELECT * FROM information_schema.metadata_lock_info;
UNLOCK TABLES;
DROP TABLE t1;

5
sql/mdl.cc
View File

@ -2320,11 +2320,12 @@ MDL_context::upgrade_shared_lock(MDL_ticket *mdl_ticket,
if (mdl_ticket->has_stronger_or_equal_type(new_type))
DBUG_RETURN(FALSE);
/* Only allow upgrades from SHARED_UPGRADABLE/NO_WRITE/NO_READ_WRITE/READ */
/* Only allow upgrades from UPGRADABLE/NO_WRITE/NO_READ_WRITE/READ/WRITE */
DBUG_ASSERT(mdl_ticket->m_type == MDL_SHARED_UPGRADABLE ||
mdl_ticket->m_type == MDL_SHARED_NO_WRITE ||
mdl_ticket->m_type == MDL_SHARED_NO_READ_WRITE ||
mdl_ticket->m_type == MDL_SHARED_READ);
mdl_ticket->m_type == MDL_SHARED_READ ||
mdl_ticket->m_type == MDL_SHARED_WRITE);
mdl_xlock_request.init(&mdl_ticket->m_lock->key, new_type,
MDL_TRANSACTION);

6
sql/sql_parse.cc
View File

@ -2787,6 +2787,7 @@ retry:
! table->prelocking_placeholder &&
table->table->file->lock_count() == 0)
{
enum enum_mdl_type lock_type;
/*
In case when LOCK TABLE ... READ LOCAL was issued for table with
storage engine which doesn't support READ LOCAL option and doesn't
@ -2799,9 +2800,12 @@ retry:
deadlock_handler.init();
thd->push_internal_handler(&deadlock_handler);
lock_type= table->table->mdl_ticket->get_type() == MDL_SHARED_WRITE ?
MDL_SHARED_NO_READ_WRITE : MDL_SHARED_READ_ONLY;
bool result= thd->mdl_context.upgrade_shared_lock(
table->table->mdl_ticket,
MDL_SHARED_READ_ONLY,
lock_type,
thd->variables.lock_wait_timeout);
thd->pop_internal_handler();