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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.
Note that we have to use | here to ensure that all calls are made.
*/
/*
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);
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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