[PATCH 14/14] libxl: ao: Timeouts are cancellable

[Ian Jackson <ian.jackson@eu.citrix.com>]

Make libxl__ev_time* register with the cancellation machinery, so that
libxl_ao_cancel can cancel any operation which has a timeout.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
---
 tools/libxl/libxl_event.c    |   27 +++++++++++++++++++++++++++
 tools/libxl/libxl_internal.h |    3 ++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/tools/libxl/libxl_event.c b/tools/libxl/libxl_event.c
index e982858..8f85162 100644
--- a/tools/libxl/libxl_event.c
+++ b/tools/libxl/libxl_event.c
@@ -292,6 +292,8 @@ static int time_register_finite(libxl__gc *gc, libxl__ev_time *ev,
 
 static void time_deregister(libxl__gc *gc, libxl__ev_time *ev)
 {
+    libxl__ao_cancellable_deregister(&ev->cancel);
+
     if (!ev->infinite) {
         struct timeval right_away = { 0, 0 };
         if (ev->nexus) /* only set if app provided hooks */
@@ -314,6 +316,23 @@ static void time_done_debug(libxl__gc *gc, const char *func,
 #endif
 }
 
+static void time_cancelled(libxl__egc *egc, libxl__ao_cancellable *canc, int rc)
+{
+    libxl__ev_time *ev = CONTAINER_OF(canc, *ev, cancel);
+    EGC_GC;
+
+    time_deregister(gc, ev);
+    DBG("ev_time=%p cancelled", ev);
+    ev->func(egc, ev, &ev->abs, rc);
+}
+
+static int time_register_cancel(libxl__ao *ao, libxl__ev_time *ev)
+{
+    ev->cancel.ao = ao;
+    ev->cancel.callback = time_cancelled;
+    return libxl__ao_cancellable_register(&ev->cancel);
+}
+
 int libxl__ev_time_register_abs(libxl__ao *ao, libxl__ev_time *ev,
                                 libxl__ev_time_callback *func,
                                 struct timeval absolute)
@@ -326,6 +345,9 @@ int libxl__ev_time_register_abs(libxl__ao *ao, libxl__ev_time *ev,
     DBG("ev_time=%p register abs=%lu.%06lu",
         ev, (unsigned long)absolute.tv_sec, (unsigned long)absolute.tv_usec);
 
+    rc = time_register_cancel(ao, ev);
+    if (rc) goto out;
+
     rc = time_register_finite(gc, ev, absolute);
     if (rc) goto out;
 
@@ -333,6 +355,7 @@ int libxl__ev_time_register_abs(libxl__ao *ao, libxl__ev_time *ev,
 
     rc = 0;
  out:
+    libxl__ao_cancellable_deregister(&ev->cancel);
     time_done_debug(gc,__func__,ev,rc);
     CTX_UNLOCK;
     return rc;
@@ -351,6 +374,9 @@ int libxl__ev_time_register_rel(libxl__ao *ao, libxl__ev_time *ev,
 
     DBG("ev_time=%p register ms=%d", ev, milliseconds);
 
+    rc = time_register_cancel(ao, ev);
+    if (rc) goto out;
+
     if (milliseconds < 0) {
         ev->infinite = 1;
     } else {
@@ -365,6 +391,7 @@ int libxl__ev_time_register_rel(libxl__ao *ao, libxl__ev_time *ev,
     rc = 0;
 
  out:
+    libxl__ao_cancellable_deregister(&ev->cancel);
     time_done_debug(gc,__func__,ev,rc);
     CTX_UNLOCK;
     return rc;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 951a77d..927f67e 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -218,6 +218,7 @@ struct libxl__ev_time {
     LIBXL_TAILQ_ENTRY(libxl__ev_time) entry;
     struct timeval abs;
     libxl__osevent_hook_nexus *nexus;
+    libxl__ao_cancellable cancel;
 };
 
 typedef struct libxl__ev_xswatch libxl__ev_xswatch;
@@ -790,7 +791,7 @@ _hidden int libxl__ev_time_modify_abs(libxl__gc*, libxl__ev_time *ev,
                                       struct timeval);
 _hidden void libxl__ev_time_deregister(libxl__gc*, libxl__ev_time *ev);
 static inline void libxl__ev_time_init(libxl__ev_time *ev)
-                { ev->func = 0; }
+                { ev->func = 0; libxl__ao_cancellable_init(&ev->cancel); }
 static inline int libxl__ev_time_isregistered(const libxl__ev_time *ev)
                 { return !!ev->func; }
 
-- 
1.7.10.4