aio: prepare for introducing GSource-based dispatch

This adds a GPollFD to each AioHandler.  It will then be possible to
attach these GPollFDs to a GSource, and from there to the main loop.
aio_wait examines the GPollFDs and avoids calling select() if any
is set (similar to what it does if bottom halves are available).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/qemu-aio.h b/qemu-aio.h
index f19201e..ac24896 100644
--- a/qemu-aio.h
+++ b/qemu-aio.h
@@ -133,6 +133,13 @@ void qemu_bh_delete(QEMUBH *bh);
  * outstanding AIO operations have been completed or cancelled. */
 void aio_flush(AioContext *ctx);
 
+/* Return whether there are any pending callbacks from the GSource
+ * attached to the AioContext.
+ *
+ * This is used internally in the implementation of the GSource.
+ */
+bool aio_pending(AioContext *ctx);
+
 /* Progress in completing AIO work to occur.  This can issue new pending
  * aio as a result of executing I/O completion or bh callbacks.
  *