1 | /* $Id: EventQueue.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * Event queue class declaration.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2013-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * SPDX-License-Identifier: GPL-3.0-only
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26 | */
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27 |
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28 | /** @todo Adapt / update documentation! */
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29 |
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30 | #include "VBox/com/EventQueue.h"
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31 |
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32 | #include <iprt/asm.h>
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33 | #include <new> /* For bad_alloc. */
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34 |
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35 | #include <iprt/err.h>
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36 | #include <iprt/semaphore.h>
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37 | #include <iprt/time.h>
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38 | #include <iprt/thread.h>
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39 | #include <iprt/log.h>
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40 |
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41 | namespace com
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42 | {
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43 |
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44 | // EventQueue class
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45 | ////////////////////////////////////////////////////////////////////////////////
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46 |
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47 | EventQueue::EventQueue(void)
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48 | : mUserCnt(0),
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49 | mShutdown(false)
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50 | {
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51 | int rc = RTCritSectInit(&mCritSect);
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52 | AssertRC(rc);
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53 |
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54 | rc = RTSemEventCreate(&mSemEvent);
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55 | AssertRC(rc);
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56 | }
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57 |
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58 | EventQueue::~EventQueue(void)
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59 | {
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60 | int rc = RTCritSectDelete(&mCritSect);
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61 | AssertRC(rc);
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62 |
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63 | rc = RTSemEventDestroy(mSemEvent);
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64 | AssertRC(rc);
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65 |
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66 | EventQueueListIterator it = mEvents.begin();
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67 | while (it != mEvents.end())
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68 | {
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69 | (*it)->Release();
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70 | it = mEvents.erase(it);
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71 | }
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72 | }
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73 |
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74 | /**
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75 | * Process events pending on this event queue, and wait up to given timeout, if
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76 | * nothing is available.
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77 | *
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78 | * Must be called on same thread this event queue was created on.
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79 | *
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80 | * @param cMsTimeout The timeout specified as milliseconds. Use
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81 | * RT_INDEFINITE_WAIT to wait till an event is posted on the
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82 | * queue.
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83 | *
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84 | * @returns VBox status code
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85 | * @retval VINF_SUCCESS if one or more messages was processed.
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86 | * @retval VERR_TIMEOUT if cMsTimeout expired.
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87 | * @retval VERR_INVALID_CONTEXT if called on the wrong thread.
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88 | * @retval VERR_INTERRUPTED if interruptEventQueueProcessing was called.
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89 | * On Windows will also be returned when WM_QUIT is encountered.
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90 | * On Darwin this may also be returned when the native queue is
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91 | * stopped or destroyed/finished.
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92 | * @retval VINF_INTERRUPTED if the native system call was interrupted by a
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93 | * an asynchronous event delivery (signal) or just felt like returning
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94 | * out of bounds. On darwin it will also be returned if the queue is
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95 | * stopped.
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96 | */
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97 | int EventQueue::processEventQueue(RTMSINTERVAL cMsTimeout)
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98 | {
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99 | size_t cNumEvents;
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100 | int rc = RTCritSectEnter(&mCritSect);
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101 | if (RT_SUCCESS(rc))
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102 | {
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103 | if (mUserCnt == 0) /* No concurrent access allowed. */
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104 | {
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105 | mUserCnt++;
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106 |
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107 | cNumEvents = mEvents.size();
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108 | if (!cNumEvents)
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109 | {
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110 | int rc2 = RTCritSectLeave(&mCritSect);
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111 | AssertRC(rc2);
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112 |
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113 | rc = RTSemEventWaitNoResume(mSemEvent, cMsTimeout);
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114 |
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115 | rc2 = RTCritSectEnter(&mCritSect);
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116 | AssertRC(rc2);
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117 |
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118 | if (RT_SUCCESS(rc))
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119 | {
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120 | if (mShutdown)
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121 | rc = VERR_INTERRUPTED;
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122 | cNumEvents = mEvents.size();
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123 | }
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124 | }
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125 |
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126 | if (RT_SUCCESS(rc))
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127 | rc = processPendingEvents(cNumEvents);
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128 |
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129 | Assert(mUserCnt);
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130 | mUserCnt--;
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131 | }
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132 | else
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133 | rc = VERR_WRONG_ORDER;
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134 |
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135 | int rc2 = RTCritSectLeave(&mCritSect);
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136 | if (RT_SUCCESS(rc))
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137 | rc = rc2;
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138 | }
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139 |
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140 | Assert(rc != VERR_TIMEOUT || cMsTimeout != RT_INDEFINITE_WAIT);
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141 | return rc;
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142 | }
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143 |
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144 | /**
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145 | * Processes all pending events in the queue at the time of
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146 | * calling. Note: Does no initial locking, must be done by the
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147 | * caller!
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148 | *
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149 | * @return IPRT status code.
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150 | */
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151 | int EventQueue::processPendingEvents(size_t cNumEvents)
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152 | {
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153 | if (!cNumEvents) /* Nothing to process? Bail out early. */
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154 | return VINF_SUCCESS;
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155 |
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156 | int rc = VINF_SUCCESS;
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157 |
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158 | EventQueueListIterator it = mEvents.begin();
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159 | for (size_t i = 0;
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160 | i < cNumEvents
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161 | && it != mEvents.end(); i++)
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162 | {
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163 | Event *pEvent = *it;
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164 | AssertPtr(pEvent);
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165 |
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166 | mEvents.erase(it);
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167 |
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168 | int rc2 = RTCritSectLeave(&mCritSect);
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169 | AssertRC(rc2);
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170 |
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171 | pEvent->handler();
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172 | pEvent->Release();
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173 |
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174 | rc2 = RTCritSectEnter(&mCritSect);
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175 | AssertRC(rc2);
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176 |
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177 | it = mEvents.begin();
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178 | if (mShutdown)
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179 | {
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180 | rc = VERR_INTERRUPTED;
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181 | break;
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182 | }
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183 | }
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184 |
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185 | return rc;
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186 | }
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187 |
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188 | /**
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189 | * Interrupt thread waiting on event queue processing.
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190 | *
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191 | * Can be called on any thread.
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192 | *
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193 | * @returns VBox status code.
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194 | */
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195 | int EventQueue::interruptEventQueueProcessing(void)
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196 | {
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197 | ASMAtomicWriteBool(&mShutdown, true);
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198 |
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199 | return RTSemEventSignal(mSemEvent);
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200 | }
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201 |
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202 | /**
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203 | * Posts an event to this event loop asynchronously.
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204 | *
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205 | * @param pEvent the event to post, must be allocated using |new|
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206 | * @return TRUE if successful and false otherwise
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207 | */
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208 | BOOL EventQueue::postEvent(Event *pEvent)
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209 | {
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210 | int rc = RTCritSectEnter(&mCritSect);
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211 | if (RT_SUCCESS(rc))
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212 | {
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213 | try
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214 | {
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215 | if (pEvent)
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216 | {
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217 | pEvent->AddRef();
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218 | mEvents.push_back(pEvent);
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219 | }
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220 | else /* No locking, since we're already in our crit sect. */
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221 | mShutdown = true;
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222 |
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223 | size_t cEvents = mEvents.size();
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224 | if (cEvents > _1K) /** @todo Make value configurable? */
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225 | {
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226 | static int s_cBitchedAboutLotEvents = 0;
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227 | if (s_cBitchedAboutLotEvents < 10)
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228 | LogRel(("Warning: Event queue received lots of events (%zu), expect delayed event handling (%d/10)\n",
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229 | cEvents, ++s_cBitchedAboutLotEvents));
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230 | }
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231 |
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232 | /* Leave critical section before signalling event. */
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233 | rc = RTCritSectLeave(&mCritSect);
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234 | if (RT_SUCCESS(rc))
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235 | {
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236 | int rc2 = RTSemEventSignal(mSemEvent);
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237 | AssertRC(rc2);
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238 | }
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239 | }
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240 | catch (std::bad_alloc &ba)
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241 | {
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242 | NOREF(ba);
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243 | rc = VERR_NO_MEMORY;
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244 | }
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245 |
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246 | if (RT_FAILURE(rc))
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247 | {
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248 | int rc2 = RTCritSectLeave(&mCritSect);
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249 | AssertRC(rc2);
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250 | }
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251 | }
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252 |
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253 | return RT_SUCCESS(rc) ? TRUE : FALSE;
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254 | }
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255 |
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256 | }
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257 | /* namespace com */
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