include/qemu/transactions.h

   1 /*
   2  * Simple transactions API
   3  *
   4  * Copyright (c) 2021 Virtuozzo International GmbH.
   5  *
   6  * Author:
   7  *  Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  21  *
  22  *
  23  * = Generic transaction API =
  24  *
  25  * The intended usage is the following: you create "prepare" functions, which
  26  * represents the actions. They will usually have Transaction* argument, and
  27  * call tran_add() to register finalization callbacks. For finalization
  28  * callbacks, prepare corresponding TransactionActionDrv structures.
  29  *
  30  * Then, when you need to make a transaction, create an empty Transaction by
  31  * tran_create(), call your "prepare" functions on it, and finally call
  32  * tran_abort() or tran_commit() to finalize the transaction by corresponding
  33  * finalization actions in reverse order.
  34  *
  35  * The clean() functions registered by the drivers in a transaction are called
  36  * last, after all abort() or commit() functions have been called.
  37  */
  38
  39 #ifndef QEMU_TRANSACTIONS_H
  40 #define QEMU_TRANSACTIONS_H
  41
  42 #include <gmodule.h>
  43
  44 typedef struct TransactionActionDrv {
  45     void (*abort)(void *opaque);
  46     void (*commit)(void *opaque);
  47     void (*clean)(void *opaque);
  48 } TransactionActionDrv;
  49
  50 typedef struct Transaction Transaction;
  51
  52 Transaction *tran_new(void);
  53 void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque);
  54 void tran_abort(Transaction *tran);
  55 void tran_commit(Transaction *tran);
  56
  57 static inline void tran_finalize(Transaction *tran, int ret)
  58 {
  59     if (ret < 0) {
  60         tran_abort(tran);
  61     } else {
  62         tran_commit(tran);
  63     }
  64 }
  65
  66 #endif /* QEMU_TRANSACTIONS_H */