[zeromq-dev] Application design. Overcomplicated?

[Pieter Hintjens]

2011/4/18 Ilja Golshtein <ilejncs at yandex.ru>:

> There is zlist_push call in zctx__socket_new without any mutex or something. The consideration is if it is safe to call zsocket_new from different threads as we can see in server_worker method in asyncsrv.c. My feeling is these threads use the same zctx_t. Is it wrong?

Each thread has a separate zctx_t object, each with its own list of
open sockets. The various zctx_t objects may share the same underlying
0MQ context, if they're created as attached threads. This lets libzapi
safely shutdown automatically. The one thing that's not possible is
socket migration, though it could be added.

> In zthread.c zctx_thread_new method is mentioned, though I failed to find it. Is it renamed?

Yes, I moved the thread functions into their own zthread class, and
the methods are zthread_new (detached thread that doesn't share an
underlying 0MQ context) and zthread_fork (attached thread that shares
the same 0MQ context).

> What is there behind server_task and client_task termination? Is client_task and server_task epilogue epilogue with zctx_destroy really meaningful having in mind infinite loop above?

When using detached threads (which simulate separate processes, but
using threads) it's kind of meaningless to try to get clean process
shutdown. It doesn't make sense architecturally. In the examples I've
ensured attached threads always end cleanly, but detached threads
don't.

> What is your attitude towards libzapi in C++?

I'm hoping the new C++ binding (libzapi++?) will adopt some of the
same semantics, maybe reuse some of the code. Obviously there are
parts that aren't needed, e.g. list and hash containers. Other parts
seem worth reusing. I've started a wiki page to collect abstractions
which we could try to get spread across all language bindings:

http://www.zeromq.org/topics:binding-abstractions

> My zapi version is 2c1bd38bfd1220226c04c03a39a28e62adf4c631

I'd suggest taking the latest master, there are a few issues I fixed
while hammering libzapi in some of the examples.

When I have reports of other people using it and not finding problems,
I'll make a stable release.

Cheers
-Pieter