AioContext: introduce aio_prepare
This will be used to implement socket polling on Windows.
On Windows, select() and g_poll() are completely different;
sockets are polled with select() before calling g_poll,
and the g_poll must be nonblocking if select() says a
socket is ready.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/aio-posix.c b/aio-posix.c
index 0936b4f..d3ac06e 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -100,6 +100,11 @@
(IOHandler *)io_read, NULL, notifier);
}
+bool aio_prepare(AioContext *ctx)
+{
+ return false;
+}
+
bool aio_pending(AioContext *ctx)
{
AioHandler *node;
diff --git a/aio-win32.c b/aio-win32.c
index fd52686..4542270 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -76,6 +76,11 @@
aio_notify(ctx);
}
+bool aio_prepare(AioContext *ctx)
+{
+ return false;
+}
+
bool aio_pending(AioContext *ctx)
{
AioHandler *node;
diff --git a/async.c b/async.c
index 293a52a..a99e7f6 100644
--- a/async.c
+++ b/async.c
@@ -188,6 +188,11 @@
/* We assume there is no timeout already supplied */
*timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
+
+ if (aio_prepare(ctx)) {
+ *timeout = 0;
+ }
+
return *timeout == 0;
}
diff --git a/include/block/aio.h b/include/block/aio.h
index 7ba3e96..ef4197b 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -205,7 +205,14 @@
void qemu_bh_delete(QEMUBH *bh);
/* Return whether there are any pending callbacks from the GSource
- * attached to the AioContext.
+ * attached to the AioContext, before g_poll is invoked.
+ *
+ * This is used internally in the implementation of the GSource.
+ */
+bool aio_prepare(AioContext *ctx);
+
+/* Return whether there are any pending callbacks from the GSource
+ * attached to the AioContext, after g_poll is invoked.
*
* This is used internally in the implementation of the GSource.
*/
