VirtualBox

source: vbox/trunk/include/VBox/com/EventQueue.h@ 103224

Last change on this file since 103224 was 98103, checked in by vboxsync, 2 years ago

Copyright year updates by scm.

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1/* $Id: EventQueue.h 98103 2023-01-17 14:15:46Z vboxsync $ */
2/** @file
3 * MS COM / XPCOM Abstraction Layer - Event queue class declaration.
4 */
5
6/*
7 * Copyright (C) 2013-2023 Oracle and/or its affiliates.
8 *
9 * This file is part of VirtualBox base platform packages, as
10 * available from https://www.virtualbox.org.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation, in version 3 of the
15 * License.
16 *
17 * This program is distributed in the hope that it will be useful, but
18 * WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, see <https://www.gnu.org/licenses>.
24 *
25 * The contents of this file may alternatively be used under the terms
26 * of the Common Development and Distribution License Version 1.0
27 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28 * in the VirtualBox distribution, in which case the provisions of the
29 * CDDL are applicable instead of those of the GPL.
30 *
31 * You may elect to license modified versions of this file under the
32 * terms and conditions of either the GPL or the CDDL or both.
33 *
34 * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35 */
36
37#ifndef VBOX_INCLUDED_com_EventQueue_h
38#define VBOX_INCLUDED_com_EventQueue_h
39#ifndef RT_WITHOUT_PRAGMA_ONCE
40# pragma once
41#endif
42
43#include <list>
44
45#include <iprt/asm.h>
46#include <iprt/critsect.h>
47
48#include <VBox/com/defs.h>
49#include <VBox/com/assert.h>
50
51
52/** @defgroup grp_com_evtqueue Event Queue Classes
53 * @ingroup grp_com
54 * @{
55 */
56
57namespace com
58{
59
60class EventQueue;
61
62/**
63 * Base class for all events. Intended to be subclassed to introduce new
64 * events and handlers for them.
65 *
66 * Subclasses usually reimplement virtual #handler() (that does nothing by
67 * default) and add new data members describing the event.
68 */
69class Event
70{
71public:
72
73 Event(void) :
74 mRefCount(0) { }
75 virtual ~Event(void) { AssertMsg(!mRefCount,
76 ("Reference count of event=%p not 0 on destruction (is %RU32)\n",
77 this, mRefCount)); }
78public:
79
80 uint32_t AddRef(void) { return ASMAtomicIncU32(&mRefCount); }
81 void Release(void)
82 {
83 Assert(mRefCount);
84 uint32_t cRefs = ASMAtomicDecU32(&mRefCount);
85 if (!cRefs)
86 delete this;
87 }
88
89protected:
90
91 /**
92 * Event handler. Called in the context of the event queue's thread.
93 * Always reimplemented by subclasses
94 *
95 * @return reserved, should be NULL.
96 */
97 virtual void *handler(void) { return NULL; }
98
99 friend class EventQueue;
100
101protected:
102
103 /** The event's reference count. */
104 uint32_t mRefCount;
105};
106
107typedef std::list< Event* > EventQueueList;
108typedef std::list< Event* >::iterator EventQueueListIterator;
109typedef std::list< Event* >::const_iterator EventQueueListIteratorConst;
110
111/**
112 * Simple event queue.
113 */
114class EventQueue
115{
116public:
117
118 EventQueue(void);
119 virtual ~EventQueue(void);
120
121public:
122
123 BOOL postEvent(Event *event);
124 int processEventQueue(RTMSINTERVAL cMsTimeout);
125 int processPendingEvents(size_t cNumEvents);
126 int interruptEventQueueProcessing();
127
128private:
129
130 /** Critical section for serializing access to this
131 * event queue. */
132 RTCRITSECT mCritSect;
133 /** Number of concurrent users. At the moment we
134 * only support one concurrent user at a time when
135 calling processEventQueue(). */
136 uint32_t mUserCnt;
137 /** Event semaphore for getting notified on new
138 * events being handled. */
139 RTSEMEVENT mSemEvent;
140 /** The actual event queue, implemented as a list. */
141 EventQueueList mEvents;
142 /** Shutdown indicator. */
143 bool mShutdown;
144};
145
146} /* namespace com */
147
148/** @} */
149
150#endif /* !VBOX_INCLUDED_com_EventQueue_h */
151
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