POSIX: allow WaitableEvents to be deleted while watching them.

On Windows, one can close a HANDLE which is currently being waited on. The MSDN
documentation says that the resulting behaviour is 'undefined', but it doesn't
crash. Currently, on POSIX, one couldn't use WaitableEventWatcher to watch an
event which gets deleted. This mismatch has bitten us several times now.

This patch allows WaitableEvents to be deleted while a WaitableEventWatcher is
still watching them. It applies only to watchers, the usual Wait() and
WaitMany() calls still require that all their target be valid until the end of
the call.

http://crbug.com/8809

Review URL: http://codereview.chromium.org/53026


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12459 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 1 deletions

diff --git a/base/waitable_event_watcher.h b/base/waitable_event_watcher.h
index 1b49944..94c3fdb 100644
--- a/base/waitable_event_watcher.h
+++ b/base/waitable_event_watcher.h
@@ -11,11 +11,11 @@
 #include "base/object_watcher.h"
 #else
 #include "base/message_loop.h"
+#include "base/waitable_event.h"
 #endif
 
 namespace base {
 
-class WaitableEvent;
 class Flag;
 class AsyncWaiter;
 class AsyncCallbackTask;
@@ -51,6 +51,9 @@ class AsyncCallbackTask;
 // occurs just before a WaitableEventWatcher is deleted. There is currently no
 // safe way to stop watching an automatic reset WaitableEvent without possibly
 // missing a signal.
+//
+// NOTE: you /are/ allowed to delete the WaitableEvent while still waiting on
+// it with a Watcher. It will act as if the event was never signaled.
 // -----------------------------------------------------------------------------
 
 class WaitableEventWatcher
@@ -140,6 +143,7 @@ class WaitableEventWatcher
   scoped_refptr<Flag> cancel_flag_;
   AsyncWaiter* waiter_;
   AsyncCallbackTask* callback_task_;
+  scoped_refptr<WaitableEvent::WaitableEventKernel> kernel_;
 #endif
 };