[PATCH] cmdserver: add command to get pid of server handling current connection

[Pierre-Yves David]

On 10/17/2014 03:12 PM, Idan Kamara wrote:
> On Fri, Oct 17, 2014 at 2:29 PM, Pierre-Yves David
> <pierre-yves.david at ens-lyon.org> wrote:
>>
>>
>> On 10/17/2014 08:39 AM, Yuya Nishihara wrote:
>>>
>>> # HG changeset patch
>>> # User Yuya Nishihara <yuya at tcha.org>
>>> # Date 1413556690 -32400
>>> #      Fri Oct 17 23:38:10 2014 +0900
>>> # Node ID 1b432767e0829aba65a8f63bdcdb3bb9cabbce4f
>>> # Parent  840be5ca03e1db16ba994e55597771c418166c97
>>> cmdserver: add command to get pid of server handling current connection
>>>
>>> Since unix-mode server forks child process per request, client cannot know
>>> the pid of the server, which is necessary to send SIGINT for example.
>>>
>>> Though Linux has getsockopt(SO_PEERCRED), it cannot be used because the
>>> server
>>> fork()s after accept().  So commandserver should provide "getpid" command.
>>
>>
>> I'm not super excited about this, but I can see why this is necessary.
>>
>> I've a bit confused about how you get:
>>
>> (1) the child processing your request to reply to the same one
>> (2) the child processing your request to reply to this as it is blocked
>> replying to the request.
>
> I believe the idea here is that a client connected to a socket mode server
> wants a way to interrupt it by sending it a SIGINT, for which it needs its
> pid.
>
> So the flow is:
>
> 1) client connects to server
> 2) client runs command that hangs
> 3) user interrupts hung client
> 4) client sig handler can interrupt server since it now has its pid

I got the main goal. But there is soem fork business going on. Is there 
a fork per connection of a fork per request ? if it is per connection I 
asssumes we have to get the pid at connection time for later use,

-- 
Pierre-Yves David