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/*
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 "../include/zmq.h"
#include "fq.hpp"
#include "pipe.hpp"
#include "err.hpp"
#include "i_terminate_events.hpp"
zmq::fq_t::fq_t (i_terminate_events *sink_) :
active (0),
current (0),
more (false),
sink (sink_),
terminating (false)
{
}
zmq::fq_t::~fq_t ()
{
zmq_assert (pipes.empty ());
}
void zmq::fq_t::attach (reader_t *pipe_)
{
pipe_->set_event_sink (this);
pipes.push_back (pipe_);
pipes.swap (active, pipes.size () - 1);
active++;
// If we are already terminating, ask the pipe to terminate straight away.
if (terminating)
pipe_->terminate ();
}
void zmq::fq_t::terminated (reader_t *pipe_)
{
// TODO: This is a problem with session-initiated termination. It breaks
// message atomicity. However, for socket initiated termination it's
// just fine.
zmq_assert (!more || pipes [current] != pipe_);
// Remove the pipe from the list; adjust number of active pipes
// accordingly.
if (pipes.index (pipe_) < active) {
active--;
if (current == active)
current = 0;
}
pipes.erase (pipe_);
if (terminating && pipes.empty ())
sink->terminated ();
}
void zmq::fq_t::terminate ()
{
zmq_assert (!terminating);
terminating = true;
if (pipes.empty ()) {
sink->terminated ();
return;
}
for (pipes_t::size_type i = 0; i != pipes.size (); i++)
pipes [i]->terminate ();
}
void zmq::fq_t::activated (reader_t *pipe_)
{
// Move the pipe to the list of active pipes.
pipes.swap (pipes.index (pipe_), active);
active++;
}
int zmq::fq_t::recv (zmq_msg_t *msg_, int flags_)
{
// Deallocate old content of the message.
zmq_msg_close (msg_);
// Round-robin over the pipes to get the next message.
for (int count = active; count != 0; count--) {
// Try to fetch new message. If we've already read part of the message
// subsequent part should be immediately available.
bool fetched = pipes [current]->read (msg_);
// Check the atomicity of the message. If we've already received the
// first part of the message we should get the remaining parts
// without blocking.
zmq_assert (!(more && !fetched));
// Note that when message is not fetched, current pipe is deactivated
// and replaced by another active pipe. Thus we don't have to increase
// the 'current' pointer.
if (fetched) {
more = msg_->flags & ZMQ_MSG_MORE;
if (!more) {
current++;
if (current >= active)
current = 0;
}
return 0;
}
else {
active--;
pipes.swap (current, active);
if (current == active)
current = 0;
}
}
// No message is available. Initialise the output parameter
// to be a 0-byte message.
zmq_msg_init (msg_);
errno = EAGAIN;
return -1;
}
bool zmq::fq_t::has_in ()
{
// There are subsequent parts of the partly-read message available.
if (more)
return true;
// Note that messing with current doesn't break the fairness of fair
// queueing algorithm. If there are no messages available current will
// get back to its original value. Otherwise it'll point to the first
// pipe holding messages, skipping only pipes with no messages available.
for (int count = active; count != 0; count--) {
if (pipes [current]->check_read ())
return true;
// Deactivate the pipe.
active--;
pipes.swap (current, active);
if (current == active)
current = 0;
}
return false;
}
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