[zeromq-dev] [zmqpp] Handling of EINTR

[Pieter Hintjens]

Handling EINTR with exceptions seems messy. The right way to improve
the quality of code sent via pull requests is simply to patch it into
shape or delete it if it's offensive (upfront code reviews tend to
just introduce friction).

On Mon, Jan 13, 2014 at 6:45 PM, Lindley French <lindleyf at gmail.com> wrote:
> My zmqpp code has ended up completely littered with clauses like:
>
>             bool gotit = false;
>             try
>             {
>                 gotit = ts.receive(clientId_str,msgin);
>             }
>             catch (zmqpp::zmq_internal_exception e)
>             {
>                 if (e.zmq_error() != EINTR)
>                 {
>                     throw;
>                 }
>             }
>
> This is messy, and clearly not ideal because a class type with "internal" in
> the name shouldn't be necessary for the library user.
>
> So let's think for a minute. The purpose of EINTR is to ensure blocking
> calls can't prevent signal handling from working properly. It isn't really
> an exceptional condition, so is an  exception the appropriate way to handle
> it? (I'm of the opinion that, unlike Java, exceptions in C++ should normally
> be reserved for things going seriously wrong.)
>
> The two places this occurs are poller::poll() and socket::receive(). Both of
> these already return bool. Perhaps we can simply return false in the event
> if EINTR, instead of throwing? At the very least, this makes sense for the
> non-blocking version of receive().
>
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