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ctx.cpp

/*
    Copyright (c) 2007-2010 iMatix Corporation

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the Lesser GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    Lesser GNU General Public License for more details.

    You should have received a copy of the Lesser GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <new>
#include <string.h>

#include "../include/zmq.h"

#include "ctx.hpp"
#include "socket_base.hpp"
#include "app_thread.hpp"
#include "io_thread.hpp"
#include "platform.hpp"
#include "err.hpp"
#include "pipe.hpp"

#if defined ZMQ_HAVE_WINDOWS
#include "windows.h"
#endif

zmq::ctx_t::ctx_t (uint32_t io_threads_) :
    sockets (0),
    terminated (false)
{
#ifdef ZMQ_HAVE_WINDOWS
    //  Intialise Windows sockets. Note that WSAStartup can be called multiple
    //  times given that WSACleanup will be called for each WSAStartup.
    WORD version_requested = MAKEWORD (2, 2);
    WSADATA wsa_data;
    int rc = WSAStartup (version_requested, &wsa_data);
    zmq_assert (rc == 0);
    zmq_assert (LOBYTE (wsa_data.wVersion) == 2 &&
        HIBYTE (wsa_data.wVersion) == 2);
#endif

    //  Initialise the array of signalers.
    signalers_count = max_app_threads + io_threads_;
    signalers = (signaler_t**) malloc (sizeof (signaler_t*) * signalers_count);
    zmq_assert (signalers);
    memset (signalers, 0, sizeof (signaler_t*) * signalers_count);

    //  Create I/O thread objects and launch them.
    for (uint32_t i = 0; i != io_threads_; i++) {
        io_thread_t *io_thread = new (std::nothrow) io_thread_t (this, i);
        zmq_assert (io_thread);
        io_threads.push_back (io_thread);
        signalers [i] = io_thread->get_signaler ();
        io_thread->start ();
    }
}

int zmq::ctx_t::term ()
{
    //  First send stop command to application threads so that any
    //  blocking calls are interrupted.
    for (app_threads_t::size_type i = 0; i != app_threads.size (); i++)
        app_threads [i].app_thread->stop ();

    //  Then mark context as terminated.
    term_sync.lock ();
    zmq_assert (!terminated);
    terminated = true;
    bool destroy = (sockets == 0);
    term_sync.unlock ();
    
    //  If there are no sockets open, destroy the context immediately.
    if (destroy)
        delete this;

    return 0;
}

zmq::ctx_t::~ctx_t ()
{
    //  Ask I/O threads to terminate. If stop signal wasn't sent to I/O
    //  thread subsequent invocation of destructor would hang-up.
    for (io_threads_t::size_type i = 0; i != io_threads.size (); i++)
        io_threads [i]->stop ();

    //  Wait till I/O threads actually terminate.
    for (io_threads_t::size_type i = 0; i != io_threads.size (); i++)
        delete io_threads [i];

    //  Close all application theads, sockets, io_objects etc.
    for (app_threads_t::size_type i = 0; i != app_threads.size (); i++)
        delete app_threads [i].app_thread;

    //  Deallocate all the orphaned pipes.
    while (!pipes.empty ())
        delete *pipes.begin ();

    //  Deallocate the array of pointers to signalers. No special work is
    //  needed as signalers themselves were deallocated with their
    //  corresponding (app_/io_) thread objects.
    free (signalers);
    
#ifdef ZMQ_HAVE_WINDOWS
    //  On Windows, uninitialise socket layer.
    int rc = WSACleanup ();
    wsa_assert (rc != SOCKET_ERROR);
#endif
}

zmq::socket_base_t *zmq::ctx_t::create_socket (int type_)
{
    app_threads_sync.lock ();

    //  Find whether the calling thread has app_thread_t object associated
    //  already. At the same time find an unused app_thread_t so that it can
    //  be used if there's no associated object for the calling thread.
    //  Check whether thread ID is already assigned. If so, return it.
    app_threads_t::size_type unused = app_threads.size ();
    app_threads_t::size_type current;
    for (current = 0; current != app_threads.size (); current++) {
        if (app_threads [current].associated &&
              thread_t::equal (thread_t::id (), app_threads [current].tid))
            break;
        if (!app_threads [current].associated)
            unused = current;
    }

    //  If no app_thread_t is associated with the calling thread,
    //  associate it with one of the unused app_thread_t objects.
    if (current == app_threads.size ()) {

        //  If all the existing app_threads are already used, create one more.
        if (unused == app_threads.size ()) {

            //  If max_app_threads limit was reached, return error.
            if (app_threads.size () == max_app_threads) {
                app_threads_sync.unlock ();
                errno = EMTHREAD;
                return NULL;
            }

            //  Create the new application thread proxy object.
            app_thread_info_t info;
            memset (&info, 0, sizeof (info));
            info.associated = false;
            info.app_thread = new (std::nothrow) app_thread_t (this,
                io_threads.size () + app_threads.size ());
            zmq_assert (info.app_thread);
            signalers [io_threads.size () + app_threads.size ()] =
                info.app_thread->get_signaler ();
            app_threads.push_back (info);
        }

        //  Incidentally, this works both when there is an unused app_thread
        //  and when a new one is created.
        current = unused;

        //  Associate the selected app_thread with the OS thread.
        app_threads [current].associated = true;
        app_threads [current].tid = thread_t::id ();
    }

    app_thread_t *thread = app_threads [current].app_thread;
    app_threads_sync.unlock ();

    socket_base_t *s = thread->create_socket (type_);
    if (!s)
        return NULL;

    term_sync.lock ();
    sockets++;
    term_sync.unlock ();

    return s;
}

void zmq::ctx_t::destroy_socket ()
{
    //  If zmq_term was already called and there are no more sockets,
    //  terminate the whole 0MQ infrastructure.
    term_sync.lock ();
    zmq_assert (sockets > 0);
    sockets--;
    bool destroy = (sockets == 0 && terminated);
    term_sync.unlock ();

    if (destroy)
       delete this;
}

void zmq::ctx_t::no_sockets (app_thread_t *thread_)
{
    app_threads_sync.lock ();
    app_threads_t::size_type i;
    for (i = 0; i != app_threads.size (); i++)
        if (app_threads [i].app_thread == thread_) {
            app_threads [i].associated = false;
            break;
        }
    zmq_assert (i != app_threads.size ());
    app_threads_sync.unlock ();
}

void zmq::ctx_t::send_command (uint32_t destination_,
    const command_t &command_)
{
    signalers [destination_]->send (command_);
}

bool zmq::ctx_t::recv_command (uint32_t thread_slot_,
    command_t *command_, bool block_)
{
    return signalers [thread_slot_]->recv (command_, block_);
}

zmq::io_thread_t *zmq::ctx_t::choose_io_thread (uint64_t affinity_)
{
    //  Find the I/O thread with minimum load.
    zmq_assert (io_threads.size () > 0);
    int min_load = -1;
    io_threads_t::size_type result = 0;
    for (io_threads_t::size_type i = 0; i != io_threads.size (); i++) {
        if (!affinity_ || (affinity_ & (uint64_t (1) << i))) {
            int load = io_threads [i]->get_load ();
            if (min_load == -1 || load < min_load) {
                min_load = load;
                result = i;
            }
        }
    }
    zmq_assert (min_load != -1);
    return io_threads [result];
}

void zmq::ctx_t::register_pipe (class pipe_t *pipe_)
{
    pipes_sync.lock ();
    bool inserted = pipes.insert (pipe_).second;
    zmq_assert (inserted);
    pipes_sync.unlock ();
}

void zmq::ctx_t::unregister_pipe (class pipe_t *pipe_)
{
    pipes_sync.lock ();
    pipes_t::size_type erased = pipes.erase (pipe_);
    zmq_assert (erased == 1);
    pipes_sync.unlock ();
}

int zmq::ctx_t::register_endpoint (const char *addr_,
    socket_base_t *socket_)
{
    endpoints_sync.lock ();

    bool inserted = endpoints.insert (std::make_pair (std::string (addr_),
        socket_)).second;
    if (!inserted) {
        errno = EADDRINUSE;
        endpoints_sync.unlock ();
        return -1;
    }

    endpoints_sync.unlock ();
    return 0;
}

void zmq::ctx_t::unregister_endpoints (socket_base_t *socket_)
{
    endpoints_sync.lock ();

    endpoints_t::iterator it = endpoints.begin ();
    while (it != endpoints.end ()) {
        if (it->second == socket_) {
            endpoints_t::iterator to_erase = it;
            it++;
            endpoints.erase (to_erase);
            continue;
        }
        it++;
    }
        
    endpoints_sync.unlock ();
}

zmq::socket_base_t *zmq::ctx_t::find_endpoint (const char *addr_)
{
     endpoints_sync.lock ();

     endpoints_t::iterator it = endpoints.find (addr_);
     if (it == endpoints.end ()) {
         endpoints_sync.unlock ();
         errno = ECONNREFUSED;
         return NULL;
     }
     socket_base_t *endpoint = it->second;

     //  Increment the command sequence number of the peer so that it won't
     //  get deallocated until "bind" command is issued by the caller.
     //  The subsequent 'bind' has to be called with inc_seqnum parameter
     //  set to false, so that the seqnum isn't incremented twice.
     endpoint->inc_seqnum ();

     endpoints_sync.unlock ();
     return endpoint;
}


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