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 list. 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 <vsement...@virtuozzo.com> --- include/qemu/transactions.h | 46 +++++++++++++++++++++ util/transactions.c | 81 +++++++++++++++++++++++++++++++++++++ util/meson.build | 1 + 3 files changed, 128 insertions(+) create mode 100644 include/qemu/transactions.h create mode 100644 util/transactions.c diff --git a/include/qemu/transactions.h b/include/qemu/transactions.h new file mode 100644 index 0000000000..db8fced65f --- /dev/null +++ b/include/qemu/transactions.h @@ -0,0 +1,46 @@ +/* + * Simple transactions API + * + * Copyright (c) 2020 Virtuozzo International GmbH. + * + * Author: + * Sementsov-Ogievskiy Vladimir <vsement...@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/>. + */ + +#ifndef QEMU_TRANSACTIONS_H +#define QEMU_TRANSACTIONS_H + +#include <gmodule.h> + +typedef struct BdrvActionDrv { + void (*abort)(void *opeque); + void (*commit)(void *opeque); + void (*clean)(void *opeque); +} BdrvActionDrv; + +void tran_prepend(GSList **list, BdrvActionDrv *drv, void *opaque); +void tran_abort(GSList *backup); +void tran_commit(GSList *backup); +static inline void tran_finalize(GSList *backup, int ret) +{ + if (ret < 0) { + tran_abort(backup); + } else { + tran_commit(backup); + } +} + +#endif /* QEMU_TRANSACTIONS_H */ diff --git a/util/transactions.c b/util/transactions.c new file mode 100644 index 0000000000..845d77fc16 --- /dev/null +++ b/util/transactions.c @@ -0,0 +1,81 @@ +/* + * Simple transactions API + * + * Copyright (c) 2020 Virtuozzo International GmbH. + * + * Author: + * Sementsov-Ogievskiy Vladimir <vsement...@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" + +typedef struct BdrvAction { + BdrvActionDrv *drv; + void *opaque; +} BdrvAction; + +void tran_prepend(GSList **list, BdrvActionDrv *drv, void *opaque) +{ + BdrvAction *act; + + act = g_new(BdrvAction, 1); + *act = (BdrvAction) { + .drv = drv, + .opaque = opaque + }; + + *list = g_slist_prepend(*list, act); +} + +void tran_abort(GSList *list) +{ + GSList *p; + + for (p = list; p != NULL; p = p->next) { + BdrvAction *act = p->data; + + if (act->drv->abort) { + act->drv->abort(act->opaque); + } + + if (act->drv->clean) { + act->drv->clean(act->opaque); + } + } + + g_slist_free_full(list, g_free); +} + +void tran_commit(GSList *list) +{ + GSList *p; + + for (p = list; p != NULL; p = p->next) { + BdrvAction *act = p->data; + + if (act->drv->commit) { + act->drv->commit(act->opaque); + } + + if (act->drv->clean) { + act->drv->clean(act->opaque); + } + } + + g_slist_free_full(list, g_free); +} diff --git a/util/meson.build b/util/meson.build index f359af0d46..8c7c28bd40 100644 --- a/util/meson.build +++ b/util/meson.build @@ -41,6 +41,7 @@ util_ss.add(files('qsp.c')) util_ss.add(files('range.c')) util_ss.add(files('stats64.c')) util_ss.add(files('systemd.c')) +util_ss.add(files('transactions.c')) util_ss.add(when: 'CONFIG_POSIX', if_true: files('drm.c')) util_ss.add(files('guest-random.c')) -- 2.21.3