new file mode 100644
@@ -0,0 +1,46 @@
+/*
+ * Simple transactions API
+ *
+ * Copyright (c) 2020 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/>.
+ */
+
+#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 */
new file mode 100644
@@ -0,0 +1,81 @@
+/*
+ * Simple transactions API
+ *
+ * Copyright (c) 2020 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"
+
+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);
+}
@@ -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'))
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 <vsementsov@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