qemu/util/transactions.c
Vladimir Sementsov-Ogievskiy 8cad15b156 util: add transactions.c
Add simple transaction API to use in further update of block graph
operations.

Supposed usage is:

- "prepare" is main function of the action and it should make the main
  effect of the action to be visible for the following actions, keeping
  possibility of roll-back, saving necessary things in action state,
  which is prepended to the action list (to do that, prepare func
  should call tran_add()). So, driver struct doesn't include "prepare"
  field, as it is supposed to be called directly.

- commit/rollback is supposed to be called for the list of action
  states, to commit/rollback all the actions in reverse order

- When possible "commit" should not make visible effect for other
  actions, which make possible transparent logical interaction between
  actions.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-9-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-04-30 12:27:47 +02:00

97 lines
2.2 KiB
C

/*
* Simple transactions API
*
* Copyright (c) 2021 Virtuozzo International GmbH.
*
* Author:
* Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/transactions.h"
#include "qemu/queue.h"
typedef struct TransactionAction {
TransactionActionDrv *drv;
void *opaque;
QSLIST_ENTRY(TransactionAction) entry;
} TransactionAction;
struct Transaction {
QSLIST_HEAD(, TransactionAction) actions;
};
Transaction *tran_new(void)
{
Transaction *tran = g_new(Transaction, 1);
QSLIST_INIT(&tran->actions);
return tran;
}
void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque)
{
TransactionAction *act;
act = g_new(TransactionAction, 1);
*act = (TransactionAction) {
.drv = drv,
.opaque = opaque
};
QSLIST_INSERT_HEAD(&tran->actions, act, entry);
}
void tran_abort(Transaction *tran)
{
TransactionAction *act, *next;
QSLIST_FOREACH_SAFE(act, &tran->actions, entry, next) {
if (act->drv->abort) {
act->drv->abort(act->opaque);
}
if (act->drv->clean) {
act->drv->clean(act->opaque);
}
g_free(act);
}
g_free(tran);
}
void tran_commit(Transaction *tran)
{
TransactionAction *act, *next;
QSLIST_FOREACH_SAFE(act, &tran->actions, entry, next) {
if (act->drv->commit) {
act->drv->commit(act->opaque);
}
if (act->drv->clean) {
act->drv->clean(act->opaque);
}
g_free(act);
}
g_free(tran);
}