-----Original Message-----
From: Burakov, Anatoly
Sent: Thursday, January 25, 2018 1:10 PM
To: Ananyev, Konstantin <konstantin.anan...@intel.com>; Tan, Jianfeng
<jianfeng....@intel.com>; dev@dpdk.org
Cc: Richardson, Bruce <bruce.richard...@intel.com>; tho...@monjalon.net
Subject: Re: [dpdk-dev] [PATCH v3 2/3] eal: add synchronous multi-process
communication
On 25-Jan-18 1:05 PM, Burakov, Anatoly wrote:
On 25-Jan-18 1:00 PM, Ananyev, Konstantin wrote:
-----Original Message-----
From: Burakov, Anatoly
Sent: Thursday, January 25, 2018 12:26 PM
To: Ananyev, Konstantin <konstantin.anan...@intel.com>; Tan, Jianfeng
<jianfeng....@intel.com>; dev@dpdk.org
Cc: Richardson, Bruce <bruce.richard...@intel.com>; tho...@monjalon.net
Subject: Re: [PATCH v3 2/3] eal: add synchronous multi-process
communication
On 25-Jan-18 12:19 PM, Ananyev, Konstantin wrote:
-----Original Message-----
From: Burakov, Anatoly
Sent: Thursday, January 25, 2018 12:00 PM
To: Tan, Jianfeng <jianfeng....@intel.com>; dev@dpdk.org
Cc: Richardson, Bruce <bruce.richard...@intel.com>; Ananyev,
Konstantin <konstantin.anan...@intel.com>; tho...@monjalon.net
Subject: Re: [PATCH v3 2/3] eal: add synchronous multi-process
communication
On the overall patch,
Reviewed-by: Anatoly Burakov <anatoly.bura...@intel.com>
For request(), returning number of replies received actually makes
sense, because now we get use the value to read our replies, if we
were
a primary process sending messages to secondary processes.
Yes, I also think it is good to return number of sends.
Then caller can compare number of sended requests with number of
received replies and decide should it be considered a failure or no.
Well, OK, that might make sense. However, i think it would've be of more
value to make the API consistent (0/-1 on success/failure) and put
number of sent messages into the reply, like number of received. I.e.
something like
struct reply {
int nb_sent;
int nb_received;
};
We do it for the latter already, so why not the former?
The question is what treat as success/failure?
Let say we sent 2 requests (of 3 possible), got back 1 response...
Should we consider it as success or failure?
I think "failure" is "something went wrong", not "secondary processes
didn't respond". For example, invalid parameters, or our socket suddenly
being closed, or some other error that prevents us from sending requests
to secondaries.
As far as i can tell from the code, there's no way to know if the
secondary process is running other than by attempting to connect to it,
and get a response. So, failed connection should not be a failure
condition, because we can't know if we *can* connect to the process
until we do. Process may have ended, but socket files will still be
around, and there's nothing we can do about that. So i wouldn't consider
inability to send a message a failure condition.
Just to clarify - i'm suggesting leaving this decision up to the user.
If a user expects there to be "n" processes running, but only "m"
responses were received, he could treat it as error. Another user might
simply send periodical updates/polls to secondaries, for whatever reason
(say, stats display), and won't really care if one of them just died, so
there's no error for that user.
However, all of this has nothing to do with API. If we're able to send
messages - it's not a failure. If we can't - it is. That's the part API
should be concerned about, and that's what the return value should
indicate, IMO.
