1 | /* $Id: AutoCaller.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */
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2 |
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3 | /** @file
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4 | *
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5 | * VirtualBox object state implementation
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6 | */
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7 |
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8 | /*
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9 | * Copyright (C) 2006-2019 Oracle Corporation
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10 | *
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11 | * This file is part of VirtualBox Open Source Edition (OSE), as
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12 | * available from http://www.virtualbox.org. This file is free software;
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13 | * you can redistribute it and/or modify it under the terms of the GNU
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14 | * General Public License (GPL) as published by the Free Software
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15 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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16 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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17 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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18 | */
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19 |
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20 | #include <iprt/semaphore.h>
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21 |
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22 | #include "VirtualBoxBase.h"
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23 | #include "AutoCaller.h"
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24 | #include "Logging.h"
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25 |
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26 |
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27 | ////////////////////////////////////////////////////////////////////////////////
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28 | //
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29 | // ObjectState methods
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30 | //
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31 | ////////////////////////////////////////////////////////////////////////////////
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32 |
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33 |
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34 | ObjectState::ObjectState() : mStateLock(LOCKCLASS_OBJECTSTATE)
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35 | {
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36 | AssertFailed();
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37 | }
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38 |
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39 | ObjectState::ObjectState(VirtualBoxBase *aObj) :
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40 | mObj(aObj), mStateLock(LOCKCLASS_OBJECTSTATE)
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41 | {
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42 | Assert(mObj);
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43 | mState = NotReady;
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44 | mStateChangeThread = NIL_RTTHREAD;
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45 | mCallers = 0;
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46 | mFailedRC = S_OK;
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47 | mpFailedEI = NULL;
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48 | mZeroCallersSem = NIL_RTSEMEVENT;
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49 | mInitUninitSem = NIL_RTSEMEVENTMULTI;
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50 | mInitUninitWaiters = 0;
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51 | }
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52 |
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53 | ObjectState::~ObjectState()
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54 | {
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55 | Assert(mInitUninitWaiters == 0);
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56 | Assert(mInitUninitSem == NIL_RTSEMEVENTMULTI);
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57 | if (mZeroCallersSem != NIL_RTSEMEVENT)
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58 | RTSemEventDestroy(mZeroCallersSem);
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59 | mCallers = 0;
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60 | mStateChangeThread = NIL_RTTHREAD;
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61 | mState = NotReady;
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62 | mFailedRC = S_OK;
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63 | if (mpFailedEI)
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64 | {
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65 | delete mpFailedEI;
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66 | mpFailedEI = NULL;
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67 | }
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68 | mObj = NULL;
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69 | }
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70 |
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71 | ObjectState::State ObjectState::getState()
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72 | {
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73 | AutoReadLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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74 | return mState;
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75 | }
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76 |
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77 | /**
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78 | * Increments the number of calls to this object by one.
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79 | *
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80 | * After this method succeeds, it is guaranteed that the object will remain
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81 | * in the Ready (or in the Limited) state at least until #releaseCaller() is
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82 | * called.
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83 | *
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84 | * This method is intended to mark the beginning of sections of code within
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85 | * methods of COM objects that depend on the readiness (Ready) state. The
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86 | * Ready state is a primary "ready to serve" state. Usually all code that
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87 | * works with component's data depends on it. On practice, this means that
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88 | * almost every public method, setter or getter of the object should add
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89 | * itself as an object's caller at the very beginning, to protect from an
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90 | * unexpected uninitialization that may happen on a different thread.
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91 | *
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92 | * Besides the Ready state denoting that the object is fully functional,
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93 | * there is a special Limited state. The Limited state means that the object
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94 | * is still functional, but its functionality is limited to some degree, so
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95 | * not all operations are possible. The @a aLimited argument to this method
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96 | * determines whether the caller represents this limited functionality or
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97 | * not.
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98 | *
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99 | * This method succeeds (and increments the number of callers) only if the
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100 | * current object's state is Ready. Otherwise, it will return E_ACCESSDENIED
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101 | * to indicate that the object is not operational. There are two exceptions
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102 | * from this rule:
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103 | * <ol>
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104 | * <li>If the @a aLimited argument is |true|, then this method will also
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105 | * succeed if the object's state is Limited (or Ready, of course).
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106 | * </li>
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107 | * <li>If this method is called from the same thread that placed
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108 | * the object to InInit or InUninit state (i.e. either from within the
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109 | * AutoInitSpan or AutoUninitSpan scope), it will succeed as well (but
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110 | * will not increase the number of callers).
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111 | * </li>
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112 | * </ol>
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113 | *
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114 | * Normally, calling addCaller() never blocks. However, if this method is
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115 | * called by a thread created from within the AutoInitSpan scope and this
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116 | * scope is still active (i.e. the object state is InInit), it will block
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117 | * until the AutoInitSpan destructor signals that it has finished
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118 | * initialization.
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119 | *
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120 | * When this method returns a failure, the caller must not use the object
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121 | * and should return the failed result code to its own caller.
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122 | *
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123 | * @param aLimited |true| to add a limited caller.
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124 | *
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125 | * @return S_OK on success or E_ACCESSDENIED on failure.
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126 | *
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127 | * @sa #releaseCaller()
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128 | */
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129 | HRESULT ObjectState::addCaller(bool aLimited /* = false */)
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130 | {
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131 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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132 |
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133 | HRESULT rc = E_ACCESSDENIED;
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134 |
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135 | if (mState == Ready || (aLimited && mState == Limited))
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136 | {
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137 | /* if Ready or allows Limited, increase the number of callers */
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138 | ++mCallers;
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139 | rc = S_OK;
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140 | }
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141 | else
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142 | if (mState == InInit || mState == InUninit)
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143 | {
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144 | if (mStateChangeThread == RTThreadSelf())
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145 | {
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146 | /* Called from the same thread that is doing AutoInitSpan or
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147 | * AutoUninitSpan, just succeed */
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148 | rc = S_OK;
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149 | }
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150 | else if (mState == InInit)
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151 | {
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152 | /* addCaller() is called by a "child" thread while the "parent"
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153 | * thread is still doing AutoInitSpan/AutoReinitSpan, so wait for
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154 | * the state to become either Ready/Limited or InitFailed (in
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155 | * case of init failure).
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156 | *
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157 | * Note that we increase the number of callers anyway -- to
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158 | * prevent AutoUninitSpan from early completion if we are
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159 | * still not scheduled to pick up the posted semaphore when
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160 | * uninit() is called.
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161 | */
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162 | ++mCallers;
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163 |
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164 | /* lazy semaphore creation */
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165 | if (mInitUninitSem == NIL_RTSEMEVENTMULTI)
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166 | {
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167 | RTSemEventMultiCreate(&mInitUninitSem);
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168 | Assert(mInitUninitWaiters == 0);
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169 | }
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170 |
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171 | ++mInitUninitWaiters;
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172 |
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173 | LogFlowThisFunc(("Waiting for AutoInitSpan/AutoReinitSpan to finish...\n"));
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174 |
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175 | stateLock.release();
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176 | RTSemEventMultiWait(mInitUninitSem, RT_INDEFINITE_WAIT);
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177 | stateLock.acquire();
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178 |
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179 | if (--mInitUninitWaiters == 0)
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180 | {
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181 | /* destroy the semaphore since no more necessary */
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182 | RTSemEventMultiDestroy(mInitUninitSem);
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183 | mInitUninitSem = NIL_RTSEMEVENTMULTI;
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184 | }
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185 |
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186 | if (mState == Ready || (aLimited && mState == Limited))
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187 | rc = S_OK;
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188 | else
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189 | {
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190 | Assert(mCallers != 0);
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191 | --mCallers;
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192 | if (mCallers == 0 && mState == InUninit)
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193 | {
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194 | /* inform AutoUninitSpan ctor there are no more callers */
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195 | RTSemEventSignal(mZeroCallersSem);
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196 | }
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197 | }
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198 | }
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199 | }
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200 |
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201 | if (FAILED(rc))
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202 | {
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203 | if (mState == Limited)
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204 | rc = mObj->setError(rc, "The object functionality is limited");
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205 | else if (FAILED(mFailedRC) && mFailedRC != E_ACCESSDENIED)
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206 | {
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207 | /* replay recorded error information */
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208 | if (mpFailedEI)
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209 | ErrorInfoKeeper eik(*mpFailedEI);
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210 | rc = mFailedRC;
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211 | }
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212 | else
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213 | rc = mObj->setError(rc, "The object is not ready");
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214 | }
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215 |
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216 | return rc;
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217 | }
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218 |
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219 | /**
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220 | * Decreases the number of calls to this object by one.
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221 | *
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222 | * Must be called after every #addCaller() when protecting the object
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223 | * from uninitialization is no more necessary.
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224 | */
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225 | void ObjectState::releaseCaller()
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226 | {
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227 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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228 |
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229 | if (mState == Ready || mState == Limited)
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230 | {
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231 | /* if Ready or Limited, decrease the number of callers */
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232 | AssertMsgReturn(mCallers != 0, ("mCallers is ZERO!"), (void) 0);
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233 | --mCallers;
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234 |
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235 | return;
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236 | }
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237 |
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238 | if (mState == InInit || mState == InUninit)
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239 | {
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240 | if (mStateChangeThread == RTThreadSelf())
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241 | {
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242 | /* Called from the same thread that is doing AutoInitSpan or
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243 | * AutoUninitSpan: just succeed */
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244 | return;
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245 | }
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246 |
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247 | if (mState == InUninit)
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248 | {
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249 | /* the caller is being released after AutoUninitSpan has begun */
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250 | AssertMsgReturn(mCallers != 0, ("mCallers is ZERO!"), (void) 0);
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251 | --mCallers;
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252 |
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253 | if (mCallers == 0)
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254 | /* inform the Auto*UninitSpan ctor there are no more callers */
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255 | RTSemEventSignal(mZeroCallersSem);
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256 |
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257 | return;
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258 | }
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259 | }
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260 |
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261 | AssertMsgFailed(("mState = %d!", mState));
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262 | }
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263 |
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264 | bool ObjectState::autoInitSpanConstructor(ObjectState::State aExpectedState)
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265 | {
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266 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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267 |
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268 | mFailedRC = S_OK;
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269 | if (mpFailedEI)
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270 | {
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271 | delete mpFailedEI;
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272 | mpFailedEI = NULL;
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273 | }
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274 |
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275 | if (mState == aExpectedState)
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276 | {
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277 | setState(InInit);
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278 | return true;
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279 | }
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280 | else
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281 | return false;
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282 | }
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283 |
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284 | void ObjectState::autoInitSpanDestructor(State aNewState, HRESULT aFailedRC, com::ErrorInfo *apFailedEI)
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285 | {
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286 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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287 |
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288 | Assert(mState == InInit);
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289 |
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290 | if (mCallers > 0 && mInitUninitWaiters > 0)
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291 | {
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292 | /* We have some pending addCaller() calls on other threads (created
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293 | * during InInit), signal that InInit is finished and they may go on. */
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294 | RTSemEventMultiSignal(mInitUninitSem);
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295 | }
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296 |
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297 | if (aNewState == InitFailed)
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298 | {
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299 | mFailedRC = aFailedRC;
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300 | /* apFailedEI may be NULL, when there is no explicit setFailed() call,
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301 | * which also implies that aFailedRC is S_OK. This case is used by
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302 | * objects (the majority) which don't want delayed error signalling. */
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303 | mpFailedEI = apFailedEI;
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304 | }
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305 | else
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306 | {
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307 | Assert(SUCCEEDED(aFailedRC));
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308 | Assert(apFailedEI == NULL);
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309 | Assert(mpFailedEI == NULL);
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310 | }
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311 |
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312 | setState(aNewState);
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313 | }
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314 |
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315 | ObjectState::State ObjectState::autoUninitSpanConstructor(bool fTry)
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316 | {
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317 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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318 |
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319 | Assert(mState != InInit);
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320 |
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321 | if (mState == NotReady)
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322 | {
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323 | /* do nothing if already uninitialized */
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324 | return mState;
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325 | }
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326 | else if (mState == InUninit)
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327 | {
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328 | /* Another thread has already started uninitialization, wait for its
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329 | * completion. This is necessary to make sure that when this method
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330 | * returns, the object state is well-defined (NotReady). */
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331 |
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332 | if (fTry)
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333 | return Ready;
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334 |
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335 | /* lazy semaphore creation */
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336 | if (mInitUninitSem == NIL_RTSEMEVENTMULTI)
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337 | {
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338 | RTSemEventMultiCreate(&mInitUninitSem);
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339 | Assert(mInitUninitWaiters == 0);
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340 | }
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341 | ++mInitUninitWaiters;
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342 |
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343 | LogFlowFunc(("{%p}: Waiting for AutoUninitSpan to finish...\n", mObj));
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344 |
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345 | stateLock.release();
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346 | RTSemEventMultiWait(mInitUninitSem, RT_INDEFINITE_WAIT);
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347 | stateLock.acquire();
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348 |
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349 | if (--mInitUninitWaiters == 0)
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350 | {
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351 | /* destroy the semaphore since no more necessary */
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352 | RTSemEventMultiDestroy(mInitUninitSem);
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353 | mInitUninitSem = NIL_RTSEMEVENTMULTI;
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354 | }
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355 |
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356 | /* the other thread set it to NotReady */
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357 | return mState;
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358 | }
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359 |
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360 | /* go to InUninit to prevent from adding new callers */
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361 | setState(InUninit);
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362 |
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363 | /* wait for already existing callers to drop to zero */
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364 | if (mCallers > 0)
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365 | {
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366 | if (fTry)
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367 | return Ready;
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368 |
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369 | /* lazy creation */
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370 | Assert(mZeroCallersSem == NIL_RTSEMEVENT);
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371 | RTSemEventCreate(&mZeroCallersSem);
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372 |
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373 | /* wait until remaining callers release the object */
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374 | LogFlowFunc(("{%p}: Waiting for callers (%d) to drop to zero...\n",
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375 | mObj, mCallers));
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376 |
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377 | stateLock.release();
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378 | RTSemEventWait(mZeroCallersSem, RT_INDEFINITE_WAIT);
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379 | }
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380 | return mState;
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381 | }
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382 |
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383 | void ObjectState::autoUninitSpanDestructor()
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384 | {
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385 | AutoWriteLock stateLock(mStateLock COMMA_LOCKVAL_SRC_POS);
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386 |
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387 | Assert(mState == InUninit);
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388 |
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389 | setState(NotReady);
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390 | }
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391 |
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392 |
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393 | void ObjectState::setState(ObjectState::State aState)
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394 | {
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395 | Assert(mState != aState);
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396 | mState = aState;
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397 | mStateChangeThread = RTThreadSelf();
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398 | }
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399 |
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400 |
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401 | ////////////////////////////////////////////////////////////////////////////////
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402 | //
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403 | // AutoInitSpan methods
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404 | //
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405 | ////////////////////////////////////////////////////////////////////////////////
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406 |
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407 | /**
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408 | * Creates a smart initialization span object that places the object to
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409 | * InInit state.
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410 | *
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411 | * Please see the AutoInitSpan class description for more info.
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412 | *
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413 | * @param aObj |this| pointer of the managed VirtualBoxBase object whose
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414 | * init() method is being called.
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415 | * @param aResult Default initialization result.
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416 | */
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417 | AutoInitSpan::AutoInitSpan(VirtualBoxBase *aObj,
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418 | Result aResult /* = Failed */)
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419 | : mObj(aObj),
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420 | mResult(aResult),
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421 | mOk(false),
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422 | mFailedRC(S_OK),
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423 | mpFailedEI(NULL)
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424 | {
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425 | Assert(mObj);
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426 | mOk = mObj->getObjectState().autoInitSpanConstructor(ObjectState::NotReady);
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427 | AssertReturnVoid(mOk);
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428 | }
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429 |
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430 | /**
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431 | * Places the managed VirtualBoxBase object to Ready/Limited state if the
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432 | * initialization succeeded or partly succeeded, or places it to InitFailed
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433 | * state and calls the object's uninit() method.
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434 | *
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435 | * Please see the AutoInitSpan class description for more info.
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436 | */
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437 | AutoInitSpan::~AutoInitSpan()
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438 | {
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439 | /* if the state was other than NotReady, do nothing */
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440 | if (!mOk)
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441 | {
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442 | Assert(SUCCEEDED(mFailedRC));
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443 | Assert(mpFailedEI == NULL);
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444 | return;
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445 | }
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446 |
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447 | ObjectState::State newState;
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448 | if (mResult == Succeeded)
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449 | newState = ObjectState::Ready;
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450 | else if (mResult == Limited)
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451 | newState = ObjectState::Limited;
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452 | else
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453 | newState = ObjectState::InitFailed;
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454 | mObj->getObjectState().autoInitSpanDestructor(newState, mFailedRC, mpFailedEI);
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455 | mFailedRC = S_OK;
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456 | mpFailedEI = NULL; /* now owned by ObjectState instance */
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457 | if (newState == ObjectState::InitFailed)
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458 | {
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459 | /* call uninit() to let the object uninit itself after failed init() */
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460 | mObj->uninit();
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461 | }
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462 | }
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463 |
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464 | // AutoReinitSpan methods
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465 | ////////////////////////////////////////////////////////////////////////////////
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466 |
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467 | /**
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468 | * Creates a smart re-initialization span object and places the object to
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469 | * InInit state.
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470 | *
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471 | * Please see the AutoInitSpan class description for more info.
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472 | *
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473 | * @param aObj |this| pointer of the managed VirtualBoxBase object whose
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474 | * re-initialization method is being called.
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475 | */
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476 | AutoReinitSpan::AutoReinitSpan(VirtualBoxBase *aObj)
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477 | : mObj(aObj),
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478 | mSucceeded(false),
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479 | mOk(false)
|
---|
480 | {
|
---|
481 | Assert(mObj);
|
---|
482 | mOk = mObj->getObjectState().autoInitSpanConstructor(ObjectState::Limited);
|
---|
483 | AssertReturnVoid(mOk);
|
---|
484 | }
|
---|
485 |
|
---|
486 | /**
|
---|
487 | * Places the managed VirtualBoxBase object to Ready state if the
|
---|
488 | * re-initialization succeeded (i.e. #setSucceeded() has been called) or back to
|
---|
489 | * Limited state otherwise.
|
---|
490 | *
|
---|
491 | * Please see the AutoInitSpan class description for more info.
|
---|
492 | */
|
---|
493 | AutoReinitSpan::~AutoReinitSpan()
|
---|
494 | {
|
---|
495 | /* if the state was other than Limited, do nothing */
|
---|
496 | if (!mOk)
|
---|
497 | return;
|
---|
498 |
|
---|
499 | ObjectState::State newState;
|
---|
500 | if (mSucceeded)
|
---|
501 | newState = ObjectState::Ready;
|
---|
502 | else
|
---|
503 | newState = ObjectState::Limited;
|
---|
504 | mObj->getObjectState().autoInitSpanDestructor(newState, S_OK, NULL);
|
---|
505 | /* If later AutoReinitSpan can truly fail (today there is no way) then
|
---|
506 | * in this place there needs to be an mObj->uninit() call just like in
|
---|
507 | * the AutoInitSpan destructor. In that case it might make sense to
|
---|
508 | * let AutoReinitSpan inherit from AutoInitSpan, as the code can be
|
---|
509 | * made (almost) identical. */
|
---|
510 | }
|
---|
511 |
|
---|
512 | // AutoUninitSpan methods
|
---|
513 | ////////////////////////////////////////////////////////////////////////////////
|
---|
514 |
|
---|
515 | /**
|
---|
516 | * Creates a smart uninitialization span object and places this object to
|
---|
517 | * InUninit state.
|
---|
518 | *
|
---|
519 | * Please see the AutoInitSpan class description for more info.
|
---|
520 | *
|
---|
521 | * @note This method blocks the current thread execution until the number of
|
---|
522 | * callers of the managed VirtualBoxBase object drops to zero!
|
---|
523 | *
|
---|
524 | * @param aObj |this| pointer of the VirtualBoxBase object whose uninit()
|
---|
525 | * method is being called.
|
---|
526 | * @param fTry @c true if the wait for other callers should be skipped,
|
---|
527 | * requiring checking if the uninit span is actually operational.
|
---|
528 | */
|
---|
529 | AutoUninitSpan::AutoUninitSpan(VirtualBoxBase *aObj, bool fTry /* = false */)
|
---|
530 | : mObj(aObj),
|
---|
531 | mInitFailed(false),
|
---|
532 | mUninitDone(false),
|
---|
533 | mUninitFailed(false)
|
---|
534 | {
|
---|
535 | Assert(mObj);
|
---|
536 | ObjectState::State state;
|
---|
537 | state = mObj->getObjectState().autoUninitSpanConstructor(fTry);
|
---|
538 | if (state == ObjectState::InitFailed)
|
---|
539 | mInitFailed = true;
|
---|
540 | else if (state == ObjectState::NotReady)
|
---|
541 | mUninitDone = true;
|
---|
542 | else if (state == ObjectState::Ready)
|
---|
543 | mUninitFailed = true;
|
---|
544 | }
|
---|
545 |
|
---|
546 | /**
|
---|
547 | * Places the managed VirtualBoxBase object to the NotReady state.
|
---|
548 | */
|
---|
549 | AutoUninitSpan::~AutoUninitSpan()
|
---|
550 | {
|
---|
551 | /* do nothing if already uninitialized */
|
---|
552 | if (mUninitDone || mUninitFailed)
|
---|
553 | return;
|
---|
554 |
|
---|
555 | mObj->getObjectState().autoUninitSpanDestructor();
|
---|
556 | }
|
---|
557 |
|
---|
558 | /**
|
---|
559 | * Marks the uninitializion as succeeded.
|
---|
560 | *
|
---|
561 | * Same as the destructor, and makes the destructor do nothing.
|
---|
562 | */
|
---|
563 | void AutoUninitSpan::setSucceeded()
|
---|
564 | {
|
---|
565 | /* do nothing if already uninitialized */
|
---|
566 | if (mUninitDone || mUninitFailed)
|
---|
567 | return;
|
---|
568 |
|
---|
569 | mObj->getObjectState().autoUninitSpanDestructor();
|
---|
570 | mUninitDone = true;
|
---|
571 | }
|
---|