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

Add locks for sequence's to ensure that there is only one writer or many readers

Browse Source 
This is needed for MyISAM and other storage engines which normally
relies on THR_LOCK's to ensure that one is not writing the same block
one could be reading from.
This commit is contained in:
Monty
2017-05-29 16:08:11 +03:00
parent d7e3120da8
commit 7e5bd1500f
6 changed files with 97 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
sql/ha_sequence.cc
View File

@ -48,7 +48,7 @@ handlerton *sql_sequence_hton;
*/
ha_sequence::ha_sequence(handlerton *hton, TABLE_SHARE *share)
:handler(hton, share), sequence_locked(0)
:handler(hton, share), write_locked(0)
{
sequence= share->sequence;
DBUG_ASSERT(share->sequence);
@ -179,7 +179,7 @@ int ha_sequence::create(const char *name, TABLE *form,
@retval != 0 Failure
NOTES:
sequence_locked is set if we are called from SEQUENCE::next_value
write_locked is set if we are called from SEQUENCE::next_value
In this case the mutex is already locked and we should not update
the sequence with 'buf' as the sequence object is already up to date.
*/
@ -188,6 +188,7 @@ int ha_sequence::write_row(uchar *buf)
{
int error;
sequence_definition tmp_seq;
bool sequence_locked;
DBUG_ENTER("ha_sequence::write_row");
DBUG_ASSERT(table->record[0] == buf);
@ -200,7 +201,8 @@ int ha_sequence::write_row(uchar *buf)
if (unlikely(sequence->initialized != SEQUENCE::SEQ_READY_TO_USE))
DBUG_RETURN(HA_ERR_WRONG_COMMAND);
if (!sequence_locked) // If not from next_value()
sequence_locked= write_locked;
if (!write_locked) // If not from next_value()
{
/*
User tries to write a full row directly to the sequence table with
@ -224,14 +226,13 @@ int ha_sequence::write_row(uchar *buf)
tmp_seq.read_fields(table);
if (tmp_seq.check_and_adjust(0))
DBUG_RETURN(HA_ERR_SEQUENCE_INVALID_DATA);
}
/*
Lock sequence to ensure that no one can come in between
while sequence, table and binary log are updated.
*/
if (!sequence_locked) // If not from next_value()
sequence->lock();
/*
Lock sequence to ensure that no one can come in between
while sequence, table and binary log are updated.
*/
sequence->write_lock(table);
}
if (!(error= file->update_first_row(buf)))
{
@ -246,7 +247,7 @@ int ha_sequence::write_row(uchar *buf)
sequence->all_values_used= 0;
if (!sequence_locked)
sequence->unlock();
sequence->write_unlock(table);
DBUG_RETURN(error);
}