This patch, salvaged from a trainwreck accidental merge earlier, adds a
new sockopt, ZMQ_DELAY_ATTACH_ON_CONNECT which prevents a end point
being available to push messages to until it has fully connected, making
connect work more like bind. This also applies to reconnecting sockets,
which may cause message loss of in-queue messages, so it is sensible to
use this in conjunction with a low HWM and potentially an alternative
acknowledgement path.
Notes on most of the individual commits can be found the repository log.
It didn't seem straightforward to use any of the existing process calls, so I have added a new command to command_t and friends called detach. This instructs the socket_base to remove the pipe from it's pipe list. The session base stores a copy of the outpipe, and will resend the bind command on reconnection. This should allow balancing again.
This patch adds a sockopt ZMQ_DELAY_ATTACH_ON_CONNECT, which if set to 1 will attempt to preempt this behavior. It does this by extending the use of the session_base to include in the outbound as well as the inbound pipe, and only associates the pipe with the socket once it receives the connected callback via a process_attach message. This works, and a test has been added to show so, but may introduce unexpected complications. The shutdown logic in this class has become marginally more awkward because of this, requiring the session to serve as the sink for both pipes if shutdown occurs with a still-connecting pipe in place. It is also possible there could be issues around flushing the messages, but as I could not directly think how to create such an issue I have not written any code with regards to that.
The documentation has been updated to reflect the change, but please do check over the code and test and review.
I believe there was a conception that zmq_connect() and zmq_bind() will be called
only at the socket creation time and therefore don't need it.
Now it is not true anymore.
1. when we call zmq_bind()/zmq_connect() to create endpoint
we send ourselfs(through launch_child()) command to process_own(endpoint)
(and add it to own_t::owned)
in the application thread we could call zmq_unbind() / zmq_disconnect() _BEFORE_
we run process_own() in ZMQ thread and in this situation we will be unable to find it in
own_t::owned. in other words own_t::owned.find(endpoint) will not be deleted but it will be deleted from
socket_base_t::endpoints.
2. when you zmq_unbind() the lisnening TCP/IPC socket was terminated only in destructor...
so the whole ZMQ_LINGER time listening TCP/IPC socket was able to accept() new connections
but unable to handle them.
this all geting even worse since unfortunately zmq has a bug and '*_listener_t' object not terminated
untill the socket's zmq_close().
AT LEAST FOR PUSH SOCKETS.
Everything is ok for SUB sockets.
Easy to reproduce without my fix:
zmq_socket(PUSH)
zmq_bind(tcp);
// connect to it from PULL socket
zmq_unbind(tcp);
sleep(forever)
// netstat -anp | grep 'tcp listening socket'
With my fix you could see that after zmq_unbind(tcp) all previously connected tcp sessions
will not be finished untill the zmq_close(socket) regardless of ZMQ_LINGER value.
(*_listener_t terminates all owned session_base_t(connect=false) and they call pipe_t::terminate()
which in turn should call session_base_t::terminated() but this never happens)
socket. Thus, it is shared between subsequent calls
to xs_recv (and xs_send). That in turn significantly
limits the number of invocations of getimeofday (or similar)
when timeouts are used and recv/send is called in a
tight loop.
The scoket implementation for inproc transfer failed to flush
identity message. The result was that the identity message
was not delivered until after the user sent the first message.
The identity message was never delivered if the user
used the socket only to receive messages.
Previously, sockets were still "valid" after being closed and only marked
as invalid when destroyed. This meant programs could access closed sockets.
Now the socket is marked "invalid" when closed.
* Implemented new ctx API (_new, _destroy, _get, _set)
* Removed 'typesafe' macros from zmq.h
* Added support for MAX_SOCKETS (was tied into change for #337)
* Created new man pages
* Added two new files: errno.hpp and errno.cpp. They are required to use errno functionality on WM.
* zmq.cpp, msg.h: removed inclusion of errno.h because it is included in zmq.h that is also included by .cpp.
* windows.hpp: process.h is included only for desktop builds.
* thread.cpp: on CE CreateThread is used instead of __beginthreadex
* socket_base.cpp, clock.cpp: on CE include cmnintrin.h instead on intrin.h
* signaler.cpp: on Windows should use special macro around event name (for unicode builds)
* err.hpp: make it include errno.hpp (my file) instead on errno.h when building for CE
* err.cpp: use FormatMessage when building for CE (because CE does not have ANSI API functions)
* zmq.h: do not include errno.h whe building for CE
* libzmq.vcproj: add tro new files
