database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

Remove the unnecessary method handlerton::release_temporary_latches()

Browse Source 
The sole purpose of handlerton::release_temporary_latches and its wrapper
function was to release the InnoDB adaptive hash index latch
(btr_search_latch).

When the btr_search_latch was split into an array of latches
in MySQL 5.7.8 as part of the Oracle Bug#20985298 fix, the "caching"
of the latch across storage engine API calls was removed. As part of that,
the function trx_search_latch_release_if_reserved() was changed to an
assertion and the function trx_reserve_search_latch_if_not_reserved()
was removed, and handlerton::release_temporary_latches() practically
became a no-op.

Note: MDEV-12121 replaced the function
trx_search_latch_release_if_reserved()
with the more appropriately named macro trx_assert_no_search_latch().
This commit is contained in:
Marko Mäkelä
2017-06-16 11:05:09 +03:00
parent 6b71b3e348
commit e5980bf1b1
11 changed files with 9 additions and 197 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
sql/handler.cc
View File

@ -2015,44 +2015,6 @@ commit_checkpoint_notify_ha(handlerton *hton, void *cookie)
}
/**
@details
This function should be called when MySQL sends rows of a SELECT result set
or the EOF mark to the client. It releases a possible adaptive hash index
S-latch held by thd in InnoDB and also releases a possible InnoDB query
FIFO ticket to enter InnoDB. To save CPU time, InnoDB allows a thd to
keep them over several calls of the InnoDB handler interface when a join
is executed. But when we let the control to pass to the client they have
to be released because if the application program uses mysql_use_result(),
it may deadlock on the S-latch if the application on another connection
performs another SQL query. In MySQL-4.1 this is even more important because
there a connection can have several SELECT queries open at the same time.
@param thd the thread handle of the current connection
@return
always 0
*/
int ha_release_temporary_latches(THD *thd)
{
Ha_trx_info *info;
/*
Note that below we assume that only transactional storage engines
may need release_temporary_latches(). If this will ever become false,
we could iterate on thd->open_tables instead (and remove duplicates
as if (!seen[hton->slot]) { seen[hton->slot]=1; ... }).
*/
for (info= thd->transaction.stmt.ha_list; info; info= info->next())
{
handlerton *hton= info->ht();
if (hton && hton->release_temporary_latches)
hton->release_temporary_latches(hton, thd);
}
return 0;
}
/**
Check if all storage engines used in transaction agree that after
rollback to savepoint it is safe to release MDL locks acquired after