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/*
Copyright (c) 2007-2009 FastMQ Inc.
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/zs.h"
#include "fair_aggregator.hpp"
#include "err.hpp"
#include "pipe_reader.hpp"
#include "session.hpp"
// Swaps pipes at specified indices.
#define swap_pipes(i1_, i2_) \
std::swap (pipes [i1_], pipes [i2_]);\
pipes [i1_]->set_index (i1_);\
pipes [i2_]->set_index (i2_);
zs::fair_aggregator_t::fair_aggregator_t () :
session (NULL),
active (0),
current (0)
{
}
void zs::fair_aggregator_t::set_session (session_t *session_)
{
zs_assert (!session);
session = session_;
}
void zs::fair_aggregator_t::shutdown ()
{
// No need to deallocate pipes here. They'll be deallocated during the
// shutdown of the dispatcher.
delete this;
}
void zs::fair_aggregator_t::terminate ()
{
// Pipe unregisters itself during the call to terminate, so the pipes
// list shinks by one in each iteration.
while (!pipes.empty ())
pipes [0]->terminate ();
delete this;
}
zs::fair_aggregator_t::~fair_aggregator_t ()
{
}
void zs::fair_aggregator_t::attach_pipe (pipe_reader_t *pipe_)
{
// Associate new pipe with the mux object.
pipe_->set_mux (this);
pipes.push_back (pipe_);
active++;
if (pipes.size () > active)
swap_pipes (pipes.size () - 1, active - 1);
if (active == 1)
session->revive ();
}
void zs::fair_aggregator_t::detach_pipe (pipe_reader_t *pipe_)
{
// Move the pipe from the list of active pipes to the list of idle pipes.
deactivate (pipe_);
// Move the pipe to the end of the idle list and remove it.
swap_pipes (pipe_->get_index (), pipes.size () - 1);
pipes.pop_back ();
}
bool zs::fair_aggregator_t::empty ()
{
return pipes.empty ();
}
bool zs::fair_aggregator_t::recv (zs_msg *msg_)
{
// Deallocate old content of the message.
zs_msg_close (msg_);
// O(1) fair queueing. Round-robin over the active pipes to get
// next message.
for (pipes_t::size_type i = active; i != 0; i--) {
// Update current.
current = (current + 1) % active;
// Try to read from current.
if (pipes [current]->read (msg_))
return true;
}
// No message is available. Initialise the output parameter
// to be a 0-byte message.
zs_msg_init (msg_);
return false;
}
void zs::fair_aggregator_t::deactivate (pipe_reader_t *pipe_)
{
int index = pipe_->get_index ();
// Suspend an active pipe.
swap_pipes (index, active - 1);
active--;
// If the deactiveted pipe is the current one, shift the current one pipe
// backwards so that the pipe that replaced the deactiveted one will be
// processed immediately rather than skipped.
if (index == (int) current) {
index--;
if (index == -1)
index = active - 1;
current = index;
}
}
void zs::fair_aggregator_t::reactivate (pipe_reader_t *pipe_)
{
// Revive an idle pipe.
swap_pipes (pipe_->get_index (), active);
active++;
if (active == 1)
session->revive ();
}
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