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/*
Copyright (c) 2010-2012 250bpm s.r.o.
Copyright (c) 2007-2009 iMatix Corporation
Copyright (c) 2011 VMware, Inc.
Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
This file is part of Crossroads I/O project.
Crossroads I/O 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.
Crossroads 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 "lb.hpp"
#include "pipe.hpp"
#include "err.hpp"
#include "msg.hpp"
xs::lb_t::lb_t () :
active (0),
current (0),
more (false),
dropping (false)
{
}
xs::lb_t::~lb_t ()
{
xs_assert (pipes.empty ());
}
void xs::lb_t::attach (pipe_t *pipe_)
{
pipes.push_back (pipe_);
pipes.swap (active, pipes.size () - 1);
active++;
}
void xs::lb_t::terminated (pipe_t *pipe_)
{
pipes_t::size_type index = pipes.index (pipe_);
// If we are in the middle of multipart message and current pipe
// have disconnected, we have to drop the remainder of the message.
if (index == current && more)
dropping = true;
// Remove the pipe from the list; adjust number of active pipes
// accordingly.
if (index < active) {
active--;
if (current == active)
current = 0;
}
pipes.erase (pipe_);
}
void xs::lb_t::activated (pipe_t *pipe_)
{
// Move the pipe to the list of active pipes.
pipes.swap (pipes.index (pipe_), active);
active++;
}
int xs::lb_t::send (msg_t *msg_, int flags_)
{
// Drop the message if required. If we are at the end of the message
// switch back to non-dropping mode.
if (dropping) {
more = msg_->flags () & msg_t::more ? true : false;
if (!more)
dropping = false;
int rc = msg_->close ();
errno_assert (rc == 0);
rc = msg_->init ();
xs_assert (rc == 0);
return 0;
}
while (active > 0) {
if (pipes [current]->write (msg_)) {
more = msg_->flags () & msg_t::more ? true : false;
break;
}
xs_assert (!more);
active--;
if (current < active)
pipes.swap (current, active);
else
current = 0;
}
// If there are no pipes we cannot send the message.
if (active == 0) {
errno = EAGAIN;
return -1;
}
// If it's final part of the message we can fluch it downstream and
// continue round-robinning (load balance).
if (!more) {
pipes [current]->flush ();
current = (current + 1) % active;
}
// Detach the message from the data buffer.
int rc = msg_->init ();
errno_assert (rc == 0);
return 0;
}
bool xs::lb_t::has_out ()
{
// If one part of the message was already written we can definitely
// write the rest of the message.
if (more)
return true;
while (active > 0) {
// Check whether zero-sized message can be written to the pipe.
msg_t msg;
int rc = msg.init ();
errno_assert (rc == 0);
if (pipes [current]->check_write (&msg)) {
rc = msg.close ();
errno_assert (rc == 0);
return true;
}
rc = msg.close ();
errno_assert (rc == 0);
// Deactivate the pipe.
active--;
pipes.swap (current, active);
if (current == active)
current = 0;
}
return false;
}
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