Use finalization feature so bufferevents can avoid deadlocks

Since the bufferevents' events are now EV_FINALIZE (name pending),
they won't deadlock.  To clean up properly, though, we must use the
finalization feature.

This patch also split bufferevent deallocation into an "unlink" step
that happens fast, and a "destruct" step that happens after
finalization.

More work is needed: there needs to be a way to specify a finalizer
for the bufferevent's argument itself.  Also, this finalizer business
makes lots of the reference counting we were doing unnecessary.

Also, more testing is needed.

1 files changed, 18 insertions, 0 deletions

diff --git a/buffer.c b/buffer.c
index 7c35a69b..860ba0dc 100644
--- a/buffer.c
+++ b/buffer.c
@@ -3345,3 +3345,21 @@ evbuffer_cb_unsuspend(struct evbuffer *buffer, struct evbuffer_cb_entry *cb)
 }
 #endif
 
+int
+evbuffer_get_callbacks_(struct evbuffer *buffer, struct event_callback **cbs,
+    int max_cbs)
+{
+	int r = 0;
+	EVBUFFER_LOCK(buffer);
+	if (buffer->deferred_cbs) {
+		if (max_cbs < 1) {
+			r = -1;
+			goto done;
+		}
+		cbs[0] = &buffer->deferred;
+		r = 1;
+	}
+done:
+	EVBUFFER_UNLOCK(buffer);
+	return r;
+}