[libvirt PATCH v4 5/9] virobject: Introduce VIR_WITH_OBJECT_LOCK_GUARD

[Tim Wiederhake]

Modeled after "WITH_QEMU_LOCK_GUARD" (see qemu's include/qemu/lockable.h).
Uses "__LINE__" instead of "__COUNTER__", as the latter is a GNU extension.

See comment for typical usage.

Signed-off-by: Tim Wiederhake <twiederh at redhat.com>
---
 src/util/virobject.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/util/virobject.h b/src/util/virobject.h
index dc1ce66a4f..595076bda7 100644
--- a/src/util/virobject.h
+++ b/src/util/virobject.h
@@ -148,3 +148,23 @@ virObjectListFree(void *list);
 void
 virObjectListFreeCount(void *list,
                        size_t count);
+
+/**
+ * VIR_WITH_OBJECT_LOCK_GUARD:
+ *
+ * This macro defines a lock scope such that entering the scope takes the lock
+ * and leaving the scope releases the lock. Return statements are allowed
+ * within the scope and release the lock. Break and continue statements leave
+ * the scope early and release the lock.
+ *
+ *     virObjectLockable *lockable = ...;
+ *
+ *     VIR_WITH_OBJECT_LOCK_GUARD(lockable) {
+ *         // `lockable` is locked, and released automatically on scope exit
+ *         ...
+ *     }
+ */
+#define VIR_WITH_OBJECT_LOCK_GUARD(o) \
+    for (g_auto(virLockGuard) CONCAT(var, __LINE__) = virObjectLockGuard(o); \
+         CONCAT(var, __LINE__).mutex; \
+         CONCAT(var, __LINE__).mutex = (virLockGuardUnlock(& CONCAT(var, __LINE__)), NULL))
-- 
2.31.1