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authorPaolo Bonzini <pbonzini@redhat.com>2013-09-25 14:20:59 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2013-10-17 17:30:55 +0200
commitc7c4d063f50f0de980d99f02e055722227d703bc (patch)
tree8ddfd7aa65bfb93a1c77d1edfa0f4c5576cad52e /util/qemu-thread-win32.c
parentcb365646a942ed58aae053064b2048a415337ba2 (diff)
qemu-thread: add QemuEvent
This emulates Win32 manual-reset events using futexes or conditional variables. Typical ways to use them are with multi-producer, single-consumer data structures, to test for a complex condition whose elements come from different threads: for (;;) { qemu_event_reset(ev); ... test complex condition ... if (condition is true) { break; } qemu_event_wait(ev); } Or more efficiently (but with some duplication): ... evaluate condition ... while (!condition) { qemu_event_reset(ev); ... evaluate condition ... if (!condition) { qemu_event_wait(ev); ... evaluate condition ... } } QemuEvent provides a very fast userspace path in the common case when no other thread is waiting, or the event is not changing state. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'util/qemu-thread-win32.c')
-rw-r--r--util/qemu-thread-win32.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index 517878dcc1..27a5217769 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -227,6 +227,32 @@ void qemu_sem_wait(QemuSemaphore *sem)
}
}
+void qemu_event_init(QemuEvent *ev, bool init)
+{
+ /* Manual reset. */
+ ev->event = CreateEvent(NULL, TRUE, init, NULL);
+}
+
+void qemu_event_destroy(QemuEvent *ev)
+{
+ CloseHandle(ev->event);
+}
+
+void qemu_event_set(QemuEvent *ev)
+{
+ SetEvent(ev->event);
+}
+
+void qemu_event_reset(QemuEvent *ev)
+{
+ ResetEvent(ev->event);
+}
+
+void qemu_event_wait(QemuEvent *ev)
+{
+ WaitForSingleObject(ev->event, INFINITE);
+}
+
struct QemuThreadData {
/* Passed to win32_start_routine. */
void *(*start_routine)(void *);