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