dist.cpp

/*
    Copyright (c) 2011 250bpm s.r.o.
    Copyright (c) 2011 VMware, Inc.
    Copyright (c) 2011 Other contributors as noted in the AUTHORS file

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser 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
    GNU Lesser General Public License for more details.

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

#include "dist.hpp"
#include "pipe.hpp"
#include "err.hpp"
#include "msg.hpp"
#include "likely.hpp"

zmq::dist_t::dist_t () :
    matching (0),
    active (0),
    eligible (0),
    more (false)
{
}

zmq::dist_t::~dist_t ()
{
    zmq_assert (pipes.empty ());
}

void zmq::dist_t::attach (pipe_t *pipe_)
{
    //  If we are in the middle of sending a message, we'll add new pipe
    //  into the list of eligible pipes. Otherwise we add it to the list
    //  of active pipes.
    if (more) {
        pipes.push_back (pipe_);
        pipes.swap (eligible, pipes.size () - 1);
        eligible++;
    }
    else {
        pipes.push_back (pipe_);
        pipes.swap (active, pipes.size () - 1);
        active++;
        eligible++;
    }
}

void zmq::dist_t::match (pipe_t *pipe_)
{
    //  If pipe is already matching do nothing.
    if (pipes.index (pipe_) < matching)
        return;

    //  If the pipe isn't eligible, ignore it.
    if (pipes.index (pipe_) >= eligible)
        return;

    //  Mark the pipe as matching.
    pipes.swap (pipes.index (pipe_), matching);
    matching++;    
}

void zmq::dist_t::unmatch ()
{
    matching = 0;
}

void zmq::dist_t::terminated (pipe_t *pipe_)
{
    //  Remove the pipe from the list; adjust number of matching, active and/or
    //  eligible pipes accordingly.
    if (pipes.index (pipe_) < matching)
        matching--;
    if (pipes.index (pipe_) < active)
        active--;
    if (pipes.index (pipe_) < eligible)
        eligible--;
    pipes.erase (pipe_);
}

void zmq::dist_t::activated (pipe_t *pipe_)
{
    //  Move the pipe from passive to eligible state.
    pipes.swap (pipes.index (pipe_), eligible);
    eligible++;

    //  If there's no message being sent at the moment, move it to
    //  the active state.
    if (!more) {
        pipes.swap (eligible - 1, active);
        active++;
    }
}

int zmq::dist_t::send_to_all (msg_t *msg_, int flags_)
{
    matching = active;
    return send_to_matching (msg_, flags_);
}

int zmq::dist_t::send_to_matching (msg_t *msg_, int flags_)
{
    //  Is this end of a multipart message?
    bool msg_more = msg_->flags () & msg_t::more ? true : false;

    //  Push the message to matching pipes.
    distribute (msg_, flags_);

    //  If mutlipart message is fully sent, activate all the eligible pipes.
    if (!msg_more)
        active = eligible;

    more = msg_more;

    return 0;
}

void zmq::dist_t::distribute (msg_t *msg_, int flags_)
{
    //  If there are no matching pipes available, simply drop the message.
    if (matching == 0) {
        int rc = msg_->close ();
        errno_assert (rc == 0);
        rc = msg_->init ();
        zmq_assert (rc == 0);
        return;
    }

    if (msg_->is_vsm ()) {
        for (pipes_t::size_type i = 0; i < matching; ++i)
            if(!write (pipes [i], msg_))
                --i; //  Retry last write because index will have been swapped
        int rc = msg_->close();
        errno_assert (rc == 0);
        rc = msg_->init ();
        errno_assert (rc == 0);
        return;
    }

    //  Add matching-1 references to the message. We already hold one reference,
    //  that's why -1.
    msg_->add_refs ((int) matching - 1);

    //  Push copy of the message to each matching pipe.
    int failed = 0;
    for (pipes_t::size_type i = 0; i < matching; ++i)
        if (!write (pipes [i], msg_)) {
            ++failed;
            --i; //  Retry last write because index will have been swapped
        }
    if (unlikely (failed))
        msg_->rm_refs (failed);

    //  Detach the original message from the data buffer. Note that we don't
    //  close the message. That's because we've already used all the references.
    int rc = msg_->init ();
    errno_assert (rc == 0);
}

bool zmq::dist_t::has_out ()
{
    return true;
}

bool zmq::dist_t::write (pipe_t *pipe_, msg_t *msg_)
{
    if (!pipe_->write (msg_)) {
        pipes.swap (pipes.index (pipe_), matching - 1);
        matching--;
        pipes.swap (pipes.index (pipe_), active - 1);
        active--;
        pipes.swap (active, eligible - 1);
        eligible--;
        return false;
    }
    if (!(msg_->flags () & msg_t::more))
        pipe_->flush ();
    return true;
}