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/* $Id: EventQueue.h $ */
/** @file
* MS COM / XPCOM Abstraction Layer - Event queue class declaration.
*/
/*
* Copyright (C) 2013-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.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, in version 3 of the
* License.
*
* 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, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#ifndef VBOX_INCLUDED_com_EventQueue_h
#define VBOX_INCLUDED_com_EventQueue_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
#include <list>
#include <iprt/asm.h>
#include <iprt/critsect.h>
#include <VBox/com/defs.h>
#include <VBox/com/assert.h>
/** @defgroup grp_com_evtqueue Event Queue Classes
* @ingroup grp_com
* @{
*/
namespace com
{
class EventQueue;
/**
* Base class for all events. Intended to be subclassed to introduce new
* events and handlers for them.
*
* Subclasses usually reimplement virtual #handler() (that does nothing by
* default) and add new data members describing the event.
*/
class Event
{
public:
Event(void) :
mRefCount(0) { }
virtual ~Event(void) { AssertMsg(!mRefCount,
("Reference count of event=%p not 0 on destruction (is %RU32)\n",
this, mRefCount)); }
public:
uint32_t AddRef(void) { return ASMAtomicIncU32(&mRefCount); }
void Release(void)
{
Assert(mRefCount);
uint32_t cRefs = ASMAtomicDecU32(&mRefCount);
if (!cRefs)
delete this;
}
protected:
/**
* Event handler. Called in the context of the event queue's thread.
* Always reimplemented by subclasses
*
* @return reserved, should be NULL.
*/
virtual void *handler(void) { return NULL; }
friend class EventQueue;
protected:
/** The event's reference count. */
uint32_t mRefCount;
};
typedef std::list< Event* > EventQueueList;
typedef std::list< Event* >::iterator EventQueueListIterator;
typedef std::list< Event* >::const_iterator EventQueueListIteratorConst;
/**
* Simple event queue.
*/
class EventQueue
{
public:
EventQueue(void);
virtual ~EventQueue(void);
public:
BOOL postEvent(Event *event);
int processEventQueue(RTMSINTERVAL cMsTimeout);
int processPendingEvents(size_t cNumEvents);
int interruptEventQueueProcessing();
private:
/** Critical section for serializing access to this
* event queue. */
RTCRITSECT mCritSect;
/** Number of concurrent users. At the moment we
* only support one concurrent user at a time when
calling processEventQueue(). */
uint32_t mUserCnt;
/** Event semaphore for getting notified on new
* events being handled. */
RTSEMEVENT mSemEvent;
/** The actual event queue, implemented as a list. */
EventQueueList mEvents;
/** Shutdown indicator. */
bool mShutdown;
};
} /* namespace com */
/** @} */
#endif /* !VBOX_INCLUDED_com_EventQueue_h */
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