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/* Copyright (C) 2007 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include "maria_def.h"
#include "trnman.h"
/**
@brief writes a COMMIT record to log and commits transaction in memory
@param trn transaction
@return Operation status
@retval 0 ok
@retval 1 error (disk error or out of memory)
*/
int ma_commit(TRN *trn)
{
int res;
LSN commit_lsn;
LEX_CUSTRING log_array[TRANSLOG_INTERNAL_PARTS];
DBUG_ENTER("ma_commit");
if (trn->undo_lsn == 0) /* no work done, rollback (cheaper than commit) */
DBUG_RETURN(trnman_rollback_trn(trn));
/*
- if COMMIT record is written before trnman_commit_trn():
if Checkpoint comes in the middle it will see trn is not committed,
then if crash, Recovery might roll back trn (if min(rec_lsn) is after
COMMIT record) and this is not an issue as
* transaction's updates were not made visible to other transactions
* "commit ok" was not sent to client
Alternatively, Recovery might commit trn (if min(rec_lsn) is before COMMIT
record), which is ok too. All in all it means that "trn committed" is not
100% equal to "COMMIT record written".
- if COMMIT record is written after trnman_commit_trn():
if crash happens between the two, trn will be rolled back which is an
issue (transaction's updates were made visible to other transactions).
So we need to go the first way.
*/
/*
We do not store "thd->transaction.xid_state.xid" for now, it will be
needed only when we support XA.
*/
res= (translog_write_record(&commit_lsn, LOGREC_COMMIT,
trn, NULL, 0,
sizeof(log_array)/sizeof(log_array[0]),
log_array, NULL, NULL) ||
translog_flush(commit_lsn) ||
trnman_commit_trn(trn));
/*
Note: if trnman_commit_trn() fails above, we have already
written the COMMIT record, so Checkpoint and Recovery will see the
transaction as committed.
*/
DBUG_RETURN(res);
}
/**
@brief Writes a COMMIT record for a transaciton associated with a file
@param info Maria handler
@return Operation status
@retval 0 ok
@retval # error (disk error or out of memory)
*/
int maria_commit(MARIA_HA *info)
{
return info->s->now_transactional ? ma_commit(info->trn) : 0;
}
/**
@brief Starts a transaction on a file handle
@param info Maria handler
@return Operation status
@retval 0 ok
@retval # Error code.
*/
int maria_begin(MARIA_HA *info)
{
DBUG_ENTER("maria_begin");
if (info->s->now_transactional)
{
TRN *trn;
struct st_my_thread_var *mysys_var= my_thread_var;
trn= trnman_new_trn(&mysys_var->mutex,
&mysys_var->suspend,
(char*) &mysys_var + STACK_DIRECTION *1024*128);
if (unlikely(!trn))
DBUG_RETURN(HA_ERR_OUT_OF_MEM);
DBUG_PRINT("info", ("TRN set to 0x%lx", (ulong) trn));
info->trn= trn;
}
DBUG_RETURN(0);
}
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