aio: add aio_notify

With this change async.c does not rely anymore on any service from
main-loop.c, i.e. it is completely self-contained.

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/qemu-aio.h b/qemu-aio.h
index aedf66cfa1..2354617ed1 100644
--- a/qemu-aio.h
+++ b/qemu-aio.h
@@ -62,6 +62,9 @@ typedef struct AioContext {
      * no callbacks are removed while we're walking and dispatching callbacks.
      */
     int walking_bh;
+
+    /* Used for aio_notify.  */
+    EventNotifier notifier;
 } AioContext;
 
 /* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
@@ -102,6 +105,21 @@ void aio_context_unref(AioContext *ctx);
 QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque);
 
 /**
+ * aio_notify: Force processing of pending events.
+ *
+ * Similar to signaling a condition variable, aio_notify forces
+ * aio_wait to exit, so that the next call will re-examine pending events.
+ * The caller of aio_notify will usually call aio_wait again very soon,
+ * or go through another iteration of the GLib main loop.  Hence, aio_notify
+ * also has the side effect of recalculating the sets of file descriptors
+ * that the main loop waits for.
+ *
+ * Calling aio_notify is rarely necessary, because for example scheduling
+ * a bottom half calls it already.
+ */
+void aio_notify(AioContext *ctx);
+
+/**
  * aio_bh_poll: Poll bottom halves for an AioContext.
  *
  * These are internal functions used by the QEMU main loop.