From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff King <peff@peff.net>
Subject: Re: [PATCH 1/2] daemon: add tests
Date: Wed, 4 Jan 2012 21:51:54 -0500
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Cc: Junio C Hamano <gitster@pobox.com>,
	Clemens Buchacher <drizzd@aon.at>, git@vger.kernel.org,
	Jonathan Nieder <jrnieder@gmail.com>,
	Erik Faye-Lund <kusmabite@gmail.com>,
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	=?utf-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy <pclouds@gmail.com>
To: Jakub Narebski <jnareb@gmail.com>
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On Wed, Jan 04, 2012 at 06:24:16PM -0800, Jakub Narebski wrote:

> Jeff King <peff@peff.net> writes:
> 
> > As a side note, it looks like we just start the daemon with "git daemon
> > &". Doesn't that create a race condition with the tests which
> > immediately try to access it (i.e., the first test may run before the
> > daemon actually opens the socket)?
> 
> Hmmm... perhaps the trick that git-instaweb does for "plackup" web
> server would be of use here, waiting for socket to be ready?

It looks like it busy loops, which is kind of ugly.

The credential-cache helper has a similar problem. It wants to kick off
a daemon if one is not already running, and then connect to it. So the
daemon does:

  printf("ok\n");
  fclose(stdout);

when it has set up the socket, and the client does:

  r = read_in_full(daemon.out, buf, sizeof(buf));
  if (r < 0)
          die_errno("unable to read result code from cache daemon");
  if (r != 3 || memcmp(buf, "ok\n", 3))
          die("cache daemon did not start: %.*s", r, buf);
  /* now we can connect over the socket */

We could probably add a "--notify-when-ready" option to git-daemon to
do something similar.

-Peff