lib/tevent: Add trace point callback

Set/get a single callback function to be invoked at various trace
points.  Define "before wait" and "after wait" trace points - more
trace points can be added later if required.

CTDB wants this to log long waits and events.

Pair-programmed-with: Amitay Isaacs <amitay@gmail.com>
Signed-off-by: Martin Schwenke <martin@meltin.net>
Signed-off-by: Stefan Metzmacher <metze@samba.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/tevent/tevent_internal.h b/lib/tevent/tevent_internal.h
index 472beb5c94..877510f9f4 100644
--- a/lib/tevent/tevent_internal.h
+++ b/lib/tevent/tevent_internal.h
@@ -258,6 +258,11 @@ struct tevent_context {
 		tevent_nesting_hook hook_fn;
 		void *hook_private;
 	} nesting;
+
+	struct {
+		tevent_trace_callback_t callback;
+		void *private_data;
+	} tracing;
 };
 
 
@@ -313,3 +318,6 @@ bool tevent_poll_init(void);
 #ifdef HAVE_EPOLL
 bool tevent_epoll_init(void);
 #endif
+
+void tevent_trace_point_callback(struct tevent_context *ev,
+				 enum tevent_trace_point);