[PATCH 3 of 4 stateful-chg] commandserver: add a heartbeat method to servicehandler

[Yuya Nishihara]

On Sat, 6 May 2017 16:39:16 -0700, Jun Wu wrote:
> # HG changeset patch
> # User Jun Wu <quark at fb.com>
> # Date 1493527390 25200
> #      Sat Apr 29 21:43:10 2017 -0700
> # Node ID ba6bc72d245d779c8951d50eddca1bea9b1b802a
> # Parent  1adb2037f0d1f8dc2b84b3804a763ec4c70c00ac
> # Available At https://bitbucket.org/quark-zju/hg-draft
> #              hg pull https://bitbucket.org/quark-zju/hg-draft -r ba6bc72d245d
> commandserver: add a heartbeat method to servicehandler
> 
> This allows chg to do extra things periodically, like checking if there are
> repos needed to be preloaded.
> 
> diff --git a/mercurial/commandserver.py b/mercurial/commandserver.py
> --- a/mercurial/commandserver.py
> +++ b/mercurial/commandserver.py
> @@ -417,4 +417,8 @@ class unixservicehandler(object):
>          os.unlink(address)
>  
> +    def heartbeat(self):
> +        """Called periodically before fork"""
> +        pass
> +
>      def shouldexit(self):
>          """True if server should shut down; checked per pollinterval"""
> @@ -486,4 +490,6 @@ class unixforkingservice(object):
>                  self._unlinksocket()
>                  exiting = True
> +            else:
> +                h.heartbeat()

Looks okay, but this breaks chg.