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[PULL 08/39] util: add transactions.c
From: |
Kevin Wolf |
Subject: |
[PULL 08/39] util: add transactions.c |
Date: |
Fri, 30 Apr 2021 12:51:16 +0200 |
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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>
---
include/qemu/transactions.h | 63 ++++++++++++++++++++++++
util/transactions.c | 96 +++++++++++++++++++++++++++++++++++++
MAINTAINERS | 6 +++
util/meson.build | 1 +
4 files changed, 166 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..92c5965235
--- /dev/null
+++ b/include/qemu/transactions.h
@@ -0,0 +1,63 @@
+/*
+ * Simple transactions API
+ *
+ * Copyright (c) 2021 Virtuozzo International GmbH.
+ *
+ * Author:
+ * Vladimir Sementsov-Ogievskiy <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/>.
+ *
+ *
+ * = Generic transaction API =
+ *
+ * The intended usage is the following: you create "prepare" functions, which
+ * represents the actions. They will usually have Transaction* argument, and
+ * call tran_add() to register finalization callbacks. For finalization
+ * callbacks, prepare corresponding TransactionActionDrv structures.
+ *
+ * Then, when you need to make a transaction, create an empty Transaction by
+ * tran_create(), call your "prepare" functions on it, and finally call
+ * tran_abort() or tran_commit() to finalize the transaction by corresponding
+ * finalization actions in reverse order.
+ */
+
+#ifndef QEMU_TRANSACTIONS_H
+#define QEMU_TRANSACTIONS_H
+
+#include <gmodule.h>
+
+typedef struct TransactionActionDrv {
+ void (*abort)(void *opaque);
+ void (*commit)(void *opaque);
+ void (*clean)(void *opaque);
+} TransactionActionDrv;
+
+typedef struct Transaction Transaction;
+
+Transaction *tran_new(void);
+void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque);
+void tran_abort(Transaction *tran);
+void tran_commit(Transaction *tran);
+
+static inline void tran_finalize(Transaction *tran, int ret)
+{
+ if (ret < 0) {
+ tran_abort(tran);
+ } else {
+ tran_commit(tran);
+ }
+}
+
+#endif /* QEMU_TRANSACTIONS_H */
diff --git a/util/transactions.c b/util/transactions.c
new file mode 100644
index 0000000000..d0bc9a3e73
--- /dev/null
+++ b/util/transactions.c
@@ -0,0 +1,96 @@
+/*
+ * 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);
+}
diff --git a/MAINTAINERS b/MAINTAINERS
index 36055f14c5..4c05ff8bba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2532,6 +2532,12 @@ M: Vladimir Sementsov-Ogievskiy
<vsementsov@virtuozzo.com>
S: Maintained
F: scripts/simplebench/
+Transactions helper
+M: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+S: Maintained
+F: include/qemu/transactions.h
+F: util/transactions.c
+
QAPI
M: Markus Armbruster <armbru@redhat.com>
M: Michael Roth <michael.roth@amd.com>
diff --git a/util/meson.build b/util/meson.build
index 510765cde4..97fad44105 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'))
util_ss.add(files('yank.c'))
--
2.30.2
- [PULL 00/39] Block layer patches, Kevin Wolf, 2021/04/30
- [PULL 01/39] tests/test-bdrv-graph-mod: add test_parallel_exclusive_write, Kevin Wolf, 2021/04/30
- [PULL 02/39] tests/test-bdrv-graph-mod: add test_parallel_perm_update, Kevin Wolf, 2021/04/30
- [PULL 04/39] block: bdrv_append(): don't consume reference, Kevin Wolf, 2021/04/30
- [PULL 03/39] tests/test-bdrv-graph-mod: add test_append_greedy_filter, Kevin Wolf, 2021/04/30
- [PULL 06/39] block: drop ctx argument from bdrv_root_attach_child, Kevin Wolf, 2021/04/30
- [PULL 05/39] block: BdrvChildClass: add .get_parent_aio_context handler, Kevin Wolf, 2021/04/30
- [PULL 07/39] block: make bdrv_reopen_{prepare,commit,abort} private, Kevin Wolf, 2021/04/30
- [PULL 08/39] util: add transactions.c,
Kevin Wolf <=
- [PULL 09/39] block: bdrv_refresh_perms: check for parents permissions conflict, Kevin Wolf, 2021/04/30
- [PULL 11/39] block: rewrite bdrv_child_try_set_perm() using bdrv_refresh_perms(), Kevin Wolf, 2021/04/30
- [PULL 10/39] block: refactor bdrv_child* permission functions, Kevin Wolf, 2021/04/30
- [PULL 12/39] block: inline bdrv_child_*() permission functions calls, Kevin Wolf, 2021/04/30
- [PULL 13/39] block: use topological sort for permission update, Kevin Wolf, 2021/04/30
- [PULL 14/39] block: add bdrv_drv_set_perm transaction action, Kevin Wolf, 2021/04/30
- [PULL 15/39] block: add bdrv_list_* permission update functions, Kevin Wolf, 2021/04/30
- [PULL 17/39] block: fix bdrv_replace_node_common, Kevin Wolf, 2021/04/30
- [PULL 19/39] block: add bdrv_attach_child_noperm() transaction action, Kevin Wolf, 2021/04/30
- [PULL 18/39] block: add bdrv_attach_child_common() transaction action, Kevin Wolf, 2021/04/30