8cad15b156
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>
64 lines
2 KiB
C
64 lines
2 KiB
C
/*
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* Simple transactions API
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*
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* Copyright (c) 2021 Virtuozzo International GmbH.
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*
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* Author:
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* Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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* = Generic transaction API =
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*
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* The intended usage is the following: you create "prepare" functions, which
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* represents the actions. They will usually have Transaction* argument, and
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* call tran_add() to register finalization callbacks. For finalization
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* callbacks, prepare corresponding TransactionActionDrv structures.
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*
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* Then, when you need to make a transaction, create an empty Transaction by
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* tran_create(), call your "prepare" functions on it, and finally call
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* tran_abort() or tran_commit() to finalize the transaction by corresponding
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* finalization actions in reverse order.
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*/
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#ifndef QEMU_TRANSACTIONS_H
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#define QEMU_TRANSACTIONS_H
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#include <gmodule.h>
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typedef struct TransactionActionDrv {
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void (*abort)(void *opaque);
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void (*commit)(void *opaque);
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void (*clean)(void *opaque);
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} TransactionActionDrv;
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typedef struct Transaction Transaction;
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Transaction *tran_new(void);
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void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque);
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void tran_abort(Transaction *tran);
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void tran_commit(Transaction *tran);
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static inline void tran_finalize(Transaction *tran, int ret)
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{
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if (ret < 0) {
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tran_abort(tran);
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} else {
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tran_commit(tran);
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}
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}
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#endif /* QEMU_TRANSACTIONS_H */
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