SocketEvent.cxx 2.75 KB
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/*
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 * Copyright 2003-2020 The Music Player Daemon Project
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 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

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#include "SocketEvent.hxx"
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#include "Loop.hxx"
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#include "event/Features.h"
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#include <cassert>
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#include <utility>
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#ifdef USE_EPOLL
#include <cerrno>
#endif

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void
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SocketEvent::Open(SocketDescriptor _fd) noexcept
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{
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	assert(!fd.IsDefined());
	assert(_fd.IsDefined());
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	fd = _fd;
}

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void
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SocketEvent::Close() noexcept
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{
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	if (!fd.IsDefined())
		return;

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	if (std::exchange(scheduled_flags, 0) != 0)
		loop.AbandonFD(fd.Get());
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	fd.Close();
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}
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void
SocketEvent::Abandon() noexcept
{
	if (std::exchange(scheduled_flags, 0) != 0)
		loop.AbandonFD(fd.Get());

	fd = SocketDescriptor::Undefined();
}

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bool
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SocketEvent::Schedule(unsigned flags) noexcept
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{
	if (flags == GetScheduledFlags())
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		return true;
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	assert(IsDefined());

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	bool success;
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	if (scheduled_flags == 0)
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		success = loop.AddFD(fd.Get(), flags, *this);
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	else if (flags == 0)
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		success = loop.RemoveFD(fd.Get(), *this);
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	else
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		success = loop.ModifyFD(fd.Get(), flags, *this);

	if (success)
		scheduled_flags = flags;
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#ifdef USE_EPOLL
	else if (errno == EBADF || errno == ENOENT)
		/* the socket was probably closed by somebody else
		   (EBADF) or a new file descriptor with the same
		   number was created but not registered already
		   (ENOENT) - we can assume that there are no
		   scheduled events */
		/* note that when this happens, we're actually lucky
		   that it has failed - imagine another thread may
		   meanwhile have created something on the same file
		   descriptor number, and has registered it; the
		   epoll_ctl() call above would then have succeeded,
		   but broke the other thread's epoll registration */
		scheduled_flags = 0;
#endif
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	return success;
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}
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void
SocketEvent::ScheduleImplicit() noexcept
{
	assert(IsDefined());
	assert(scheduled_flags == 0);

	scheduled_flags = IMPLICIT_FLAGS;
	loop.AddFD(fd.Get(), scheduled_flags, *this);
}

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void
SocketEvent::Dispatch() noexcept
{
	const unsigned flags = std::exchange(ready_flags, 0) &
		(GetScheduledFlags() | IMPLICIT_FLAGS);

	if (flags != 0)
		callback(flags);
}