From: Alexandru Ardelean <aardelean@riverbed.com>
Date: Thu, 5 May 2016 11:03:30 +0000 (+0300)
Subject: cli: register event handler first, then do lookup
X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fubus.git;a=commitdiff_plain;h=312448a5b147c221836827a7a641e76a4514db44;ds=sidebyside

cli: register event handler first, then do lookup

We seem to be getting timeout for ubus wait_for calls
every now and then.

And it's not reliably reproducible.
Looking at the code the only thing that would look like
a potetntial reason, is that between the ubus_lookup() and
ubus_register_event_handler() calls, there's a very narrow
window where the event would get sent out and we would not
get it, thus having to timeout.

It doesn't look like registering the event handler first
is a big problem for the whole wait_check_object() logic.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
---

diff --git a/cli.c b/cli.c
index c5cbfc3..080f953 100644
--- a/cli.c
+++ b/cli.c
@@ -293,17 +293,20 @@ static int ubus_cli_wait_for(struct ubus_context *ctx, int argc, char **argv)
 	uloop_init();
 	ubus_add_uloop(ctx);
 
-	ret = ubus_lookup(ctx, NULL, wait_list_cb, &data);
+	ret = ubus_register_event_handler(ctx, &data.ev, "ubus.object.add");
 	if (ret)
 		return ret;
 
 	if (!data.n_pending)
 		return ret;
 
-	ret = ubus_register_event_handler(ctx, &data.ev, "ubus.object.add");
+	ret = ubus_lookup(ctx, NULL, wait_list_cb, &data);
 	if (ret)
 		return ret;
 
+	if (!data.n_pending)
+		return ret;
+
 	uloop_timeout_set(&data.timeout, timeout * 1000);
 	uloop_run();
 	uloop_done();