This is xnu-8019. See this file in:
/*
 * Copyright (c) 2001-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include "IOPMPowerStateQueue.h"

#define super IOEventSource
OSDefineMetaClassAndStructors( IOPMPowerStateQueue, IOEventSource )

IOPMPowerStateQueue * IOPMPowerStateQueue::PMPowerStateQueue(
	OSObject * inOwner, Action inAction )
{
	IOPMPowerStateQueue * me = new IOPMPowerStateQueue;

	if (me && !me->init(inOwner, inAction)) {
		me->release();
		return NULL;
	}

	return me;
}

bool
IOPMPowerStateQueue::init( OSObject * inOwner, Action inAction )
{
	if (!inAction || !(super::init(inOwner, inAction))) {
		return false;
	}

	queue_init( &queueHead );

	queueLock = IOLockAlloc();
	if (!queueLock) {
		return false;
	}

	return true;
}

bool
IOPMPowerStateQueue::submitPowerEvent(
	uint32_t eventType,
	void *   arg0,
	uint64_t arg1 )
{
	PowerEventEntry * entry;

	entry = IOMallocType(PowerEventEntry);

	entry->eventType = eventType;
	entry->arg0 = arg0;
	entry->arg1 = arg1;

	IOLockLock(queueLock);
	queue_enter(&queueHead, entry, PowerEventEntry *, chain);
	IOLockUnlock(queueLock);
	signalWorkAvailable();

	return true;
}

bool
IOPMPowerStateQueue::checkForWork( void )
{
	IOPMPowerStateQueueAction queueAction = (IOPMPowerStateQueueAction) action;
	PowerEventEntry * entry;

	IOLockLock(queueLock);
	while (!queue_empty(&queueHead)) {
		queue_remove_first(&queueHead, entry, PowerEventEntry *, chain);
		IOLockUnlock(queueLock);

		(*queueAction)(owner, entry->eventType, entry->arg0, entry->arg1);
		IOFreeType(entry, PowerEventEntry);

		IOLockLock(queueLock);
	}
	IOLockUnlock(queueLock);

	return false;
}