1 | /* $Id: semsrw-generic.cpp 8245 2008-04-21 17:24:28Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Read-Write Semaphore, Generic.
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4 | *
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5 | * This is a generic implementation for OSes which don't have
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6 | * native RW semaphores.
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7 | */
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8 |
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9 | /*
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10 | * Copyright (C) 2006-2007 Sun Microsystems, Inc.
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11 | *
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12 | * This file is part of VirtualBox Open Source Edition (OSE), as
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13 | * available from http://www.virtualbox.org. This file is free software;
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14 | * you can redistribute it and/or modify it under the terms of the GNU
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15 | * General Public License (GPL) as published by the Free Software
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16 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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17 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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18 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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19 | *
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20 | * The contents of this file may alternatively be used under the terms
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21 | * of the Common Development and Distribution License Version 1.0
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22 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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23 | * VirtualBox OSE distribution, in which case the provisions of the
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24 | * CDDL are applicable instead of those of the GPL.
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25 | *
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26 | * You may elect to license modified versions of this file under the
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27 | * terms and conditions of either the GPL or the CDDL or both.
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28 | *
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29 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
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30 | * Clara, CA 95054 USA or visit http://www.sun.com if you need
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31 | * additional information or have any questions.
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32 | */
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33 |
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34 | /** @todo fix generic RW sems. (reimplement) */
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35 | #define USE_CRIT_SECT
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36 |
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37 |
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38 | /*******************************************************************************
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39 | * Header Files *
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40 | *******************************************************************************/
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41 | #include <iprt/semaphore.h>
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42 | #include <iprt/alloc.h>
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43 | #include <iprt/time.h>
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44 | #include <iprt/asm.h>
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45 | #include <iprt/assert.h>
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46 | #include <iprt/thread.h>
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47 | #include <iprt/err.h>
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48 | #ifdef USE_CRIT_SECT
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49 | #include <iprt/critsect.h>
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50 | #endif
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51 |
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52 |
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53 |
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54 | /*******************************************************************************
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55 | * Structures and Typedefs *
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56 | *******************************************************************************/
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57 | /** Internal representation of a Read-Write semaphore for the
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58 | * Generic implementation. */
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59 | struct RTSEMRWINTERNAL
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60 | {
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61 | #ifdef USE_CRIT_SECT
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62 | /** Critical section. */
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63 | RTCRITSECT CritSect;
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64 | #else
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65 | /** Magic (RTSEMRW_MAGIC). */
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66 | uint32_t u32Magic;
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67 | /** This critical section serializes the access to and updating of the structure members. */
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68 | RTCRITSECT CritSect;
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69 | /** The current number of readers. */
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70 | uint32_t cReaders;
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71 | /** The number of readers waiting. */
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72 | uint32_t cReadersWaiting;
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73 | /** The current number of waiting writers. */
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74 | uint32_t cWritersWaiting;
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75 | /** The handle of the event object on which the waiting readers block. (manual reset). */
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76 | RTSEMEVENTMULTI EventReaders;
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77 | /** The handle of the event object on which the waiting writers block. (manual reset). */
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78 | RTSEMEVENTMULTI EventWriters;
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79 | /** The current state of the read-write lock. */
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80 | KPRF_TYPE(,RWLOCKSTATE) enmState;
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81 |
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82 | #endif
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83 | };
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84 |
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85 |
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86 | /**
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87 | * Validate a read-write semaphore handle passed to one of the interface.
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88 | *
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89 | * @returns true if valid.
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90 | * @returns false if invalid.
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91 | * @param pIntRWSem Pointer to the read-write semaphore to validate.
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92 | */
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93 | inline bool rtsemRWValid(struct RTSEMRWINTERNAL *pIntRWSem)
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94 | {
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95 | if (!VALID_PTR(pIntRWSem))
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96 | return false;
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97 |
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98 | #ifdef USE_CRIT_SECT
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99 | if (pIntRWSem->CritSect.u32Magic != RTCRITSECT_MAGIC)
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100 | return false;
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101 | #else
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102 | if (pIntRWSem->u32Check != (uint32_t)~0)
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103 | return false;
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104 | #endif
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105 | return true;
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106 | }
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107 |
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108 |
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109 | RTDECL(int) RTSemRWCreate(PRTSEMRW pRWSem)
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110 | {
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111 | int rc;
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112 |
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113 | /*
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114 | * Allocate memory.
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115 | */
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116 | struct RTSEMRWINTERNAL *pIntRWSem = (struct RTSEMRWINTERNAL *)RTMemAlloc(sizeof(struct RTSEMRWINTERNAL));
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117 | if (pIntRWSem)
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118 | {
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119 | #ifdef USE_CRIT_SECT
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120 | rc = RTCritSectInit(&pIntRWSem->CritSect);
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121 | if (RT_SUCCESS(rc))
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122 | {
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123 | *pRWSem = pIntRWSem;
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124 | return VINF_SUCCESS;
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125 | }
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126 | #else
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127 | /*
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128 | * Create the semaphores.
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129 | */
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130 | rc = RTSemEventCreate(&pIntRWSem->WriteEvent);
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131 | if (RT_SUCCESS(rc))
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132 | {
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133 | rc = RTSemEventMultiCreate(&pIntRWSem->ReadEvent);
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134 | if (RT_SUCCESS(rc))
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135 | {
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136 | rc = RTSemMutexCreate(&pIntRWSem->Mutex);
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137 | if (RT_SUCCESS(rc))
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138 | {
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139 | /*
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140 | * Signal the read semaphore and initialize other variables.
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141 | */
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142 | rc = RTSemEventMultiSignal(pIntRWSem->ReadEvent);
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143 | if (RT_SUCCESS(rc))
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144 | {
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145 | pIntRWSem->cReaders = 0;
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146 | pIntRWSem->cWriters = 0;
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147 | pIntRWSem->WROwner = NIL_RTTHREAD;
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148 | pIntRWSem->u32Check = ~0;
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149 | *pRWSem = pIntRWSem;
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150 | return VINF_SUCCESS;
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151 | }
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152 | RTSemMutexDestroy(pIntRWSem->Mutex);
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153 | }
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154 | RTSemEventMultiDestroy(pIntRWSem->ReadEvent);
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155 | }
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156 | RTSemEventDestroy(pIntRWSem->WriteEvent);
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157 | }
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158 | #endif
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159 | RTMemFree(pIntRWSem);
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160 | }
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161 | else
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162 | rc = VERR_NO_MEMORY;
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163 |
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164 | return rc;
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165 | }
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166 |
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167 |
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168 | RTDECL(int) RTSemRWDestroy(RTSEMRW RWSem)
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169 | {
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170 | /*
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171 | * Validate handle.
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172 | */
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173 | if (!rtsemRWValid(RWSem))
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174 | {
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175 | AssertMsgFailed(("Invalid handle %p!\n", RWSem));
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176 | return VERR_INVALID_HANDLE;
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177 | }
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178 |
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179 | #ifdef USE_CRIT_SECT
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180 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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181 | int rc = RTCritSectDelete(&pIntRWSem->CritSect);
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182 | if (RT_SUCCESS(rc))
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183 | RTMemFree(pIntRWSem);
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184 | return rc;
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185 | #else
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186 |
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187 | /*
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188 | * Check if busy.
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189 | */
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190 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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191 | int rc = RTSemMutexRequest(pIntRWSem->Mutex, 32);
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192 | if (RT_SUCCESS(rc))
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193 | {
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194 | if (!pIntRWSem->cReaders && !pIntRWSem->cWriters)
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195 | {
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196 | /*
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197 | * Make it invalid and unusable.
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198 | */
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199 | ASMAtomicXchgU32(&pIntRWSem->u32Check, 0);
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200 | ASMAtomicXchgU32(&pIntRWSem->cReaders, ~0);
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201 |
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202 | /*
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203 | * Do actual cleanup.
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204 | * None of these can now fail excep for the mutex which
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205 | * can be a little bit busy.
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206 | */
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207 | rc = RTSemEventMultiDestroy(pIntRWSem->ReadEvent);
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208 | AssertMsg(RT_SUCCESS(rc), ("RTSemEventMultiDestroy failed! rc=%d\n", rc)); NOREF(rc);
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209 | pIntRWSem->ReadEvent = NIL_RTSEMEVENTMULTI;
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210 |
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211 | rc = RTSemEventDestroy(pIntRWSem->WriteEvent);
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212 | AssertMsg(RT_SUCCESS(rc), ("RTSemEventDestroy failed! rc=%d\n", rc)); NOREF(rc);
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213 | pIntRWSem->WriteEvent = NIL_RTSEMEVENT;
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214 |
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215 | RTSemMutexRelease(pIntRWSem->Mutex);
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216 | for (unsigned i = 32; i > 0; i--)
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217 | {
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218 | rc = RTSemMutexDestroy(pIntRWSem->Mutex);
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219 | if (RT_SUCCESS(rc))
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220 | break;
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221 | RTThreadSleep(1);
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222 | }
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223 | AssertMsg(RT_SUCCESS(rc), ("RTSemMutexDestroy failed! rc=%d\n", rc)); NOREF(rc);
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224 | pIntRWSem->Mutex = (RTSEMMUTEX)0;
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225 |
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226 | RTMemFree(pIntRWSem);
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227 | rc = VINF_SUCCESS;
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228 | }
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229 | else
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230 | {
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231 | rc = VERR_SEM_BUSY;
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232 | RTSemMutexRelease(pIntRWSem->Mutex);
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233 | }
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234 | }
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235 | else
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236 | rc = rc == VERR_TIMEOUT ? VERR_SEM_BUSY : rc;
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237 |
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238 | return VINF_SUCCESS;
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239 | #endif
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240 | }
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241 |
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242 |
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243 | RTDECL(int) RTSemRWRequestRead(RTSEMRW RWSem, unsigned cMillies)
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244 | {
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245 | /*
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246 | * Validate handle.
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247 | */
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248 | if (!rtsemRWValid(RWSem))
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249 | {
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250 | AssertMsgFailed(("Invalid handle %p!\n", RWSem));
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251 | return VERR_INVALID_HANDLE;
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252 | }
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253 |
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254 | #ifdef USE_CRIT_SECT
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255 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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256 | return RTCritSectEnter(&pIntRWSem->CritSect);
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257 | #else
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258 |
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259 | /*
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260 | * Take mutex and check if already reader.
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261 | */
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262 | //RTTHREAD Self = RTThreadSelf();
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263 | RTTHREAD Self = (RTTHREAD)RTThreadNativeSelf();
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264 | unsigned cMilliesInitial = cMillies;
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265 | uint64_t tsStart = 0;
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266 | if (cMillies != RTSEM_INDEFINITE_WAIT)
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267 | tsStart = RTTimeNanoTS();
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268 |
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269 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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270 | int rc = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
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271 | if (RT_FAILURE(rc))
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272 | {
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273 | AssertMsgFailed(("RTSemMutexRequest failed on rwsem %p, rc=%d\n", RWSem, rc));
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274 | return rc;
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275 | }
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276 |
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277 | unsigned i = pIntRWSem->cReaders;
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278 | while (i-- > 0)
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279 | {
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280 | if (pIntRWSem->aReaders[i].Thread == Self)
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281 | {
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282 | if (pIntRWSem->aReaders[i].cNesting + 1 < (unsigned)~0)
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283 | pIntRWSem->aReaders[i].cNesting++;
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284 | else
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285 | {
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286 | AssertMsgFailed(("Too many requests for one thread!\n"));
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287 | rc = RTSemMutexRelease(pIntRWSem->Mutex);
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288 | AssertMsg(RT_SUCCESS(rc), ("RTSemMutexRelease failed rc=%d\n", rc));
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289 | return VERR_TOO_MANY_SEM_REQUESTS;
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290 | }
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291 | }
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292 | }
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293 |
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294 |
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295 | for (;;)
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296 | {
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297 | /*
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298 | * Check if the stat of the affairs allow read access.
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299 | */
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300 | if (pIntRWSem->u32Check == (uint32_t)~0)
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301 | {
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302 | if (pIntRWSem->cWriters == 0)
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303 | {
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304 | if (pIntRWSem->cReaders < ELEMENTS(pIntRWSem->aReaders))
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305 | {
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306 | /*
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307 | * Add ourselves to the list of readers and return.
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308 | */
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309 | i = pIntRWSem->cReaders;
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310 | pIntRWSem->aReaders[i].Thread = Self;
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311 | pIntRWSem->aReaders[i].cNesting = 1;
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312 | ASMAtomicXchgU32(&pIntRWSem->cReaders, i + 1);
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313 |
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314 | RTSemMutexRelease(pIntRWSem->Mutex);
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315 | return VINF_SUCCESS;
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316 | }
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317 | else
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318 | {
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319 | AssertMsgFailed(("Too many readers! How come we have so many threads!?!\n"));
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320 | rc = VERR_TOO_MANY_SEM_REQUESTS;
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321 | }
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322 | }
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323 | #if 0 /* any action here shouldn't be necessary */
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324 | else
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325 | {
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326 | rc = RTSemEventMultiReset(pIntRWSem->ReadEvent);
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327 | AssertMsg(RT_SUCCESS(rc), ("RTSemEventMultiReset failed on RWSem %p, rc=%d\n", RWSem, rc));
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328 | }
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329 | #endif
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330 | }
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331 | else
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332 | rc = VERR_SEM_DESTROYED;
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333 | RTSemMutexRelease(pIntRWSem->Mutex);
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334 | if (RT_FAILURE(rc))
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335 | break;
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336 |
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337 |
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338 | /*
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339 | * Wait till it's ready for reading.
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340 | */
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341 | if (cMillies != RTSEM_INDEFINITE_WAIT)
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342 | {
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343 | int64_t tsDelta = RTTimeNanoTS() - tsStart;
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344 | if (tsDelta >= 1000000)
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345 | {
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346 | cMillies = cMilliesInitial - (unsigned)(tsDelta / 1000000);
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347 | if (cMillies > cMilliesInitial)
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348 | cMillies = cMilliesInitial ? 1 : 0;
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349 | }
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350 | }
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351 | rc = RTSemEventMultiWait(pIntRWSem->ReadEvent, cMillies);
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352 | if (RT_FAILURE(rc))
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353 | {
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354 | AssertMsg(rc == VERR_TIMEOUT, ("RTSemEventMultiWait failed on rwsem %p, rc=%d\n", RWSem, rc));
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355 | break;
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356 | }
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357 |
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358 | /*
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359 | * Get Mutex.
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360 | */
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361 | rc = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
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362 | if (RT_FAILURE(rc))
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363 | {
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364 | AssertMsgFailed(("RTSemMutexRequest failed on rwsem %p, rc=%d\n", RWSem, rc));
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365 | break;
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366 | }
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367 | }
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368 |
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369 | return rc;
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370 | #endif
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371 | }
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372 |
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373 |
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374 | RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW RWSem, unsigned cMillies)
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375 | {
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376 | return RTSemRWRequestRead(RWSem, cMillies);
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377 | }
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378 |
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379 |
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380 | RTDECL(int) RTSemRWReleaseRead(RTSEMRW RWSem)
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381 | {
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382 | /*
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383 | * Validate handle.
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384 | */
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385 | if (!rtsemRWValid(RWSem))
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386 | {
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387 | AssertMsgFailed(("Invalid handle %p!\n", RWSem));
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388 | return VERR_INVALID_HANDLE;
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389 | }
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390 |
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391 | #ifdef USE_CRIT_SECT
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392 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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393 | return RTCritSectLeave(&pIntRWSem->CritSect);
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394 | #else
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395 |
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396 | /*
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397 | * Take Mutex.
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398 | */
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399 | //RTTHREAD Self = RTThreadSelf();
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400 | RTTHREAD Self = (RTTHREAD)RTThreadNativeSelf();
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401 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
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402 | int rc = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
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403 | if (RT_SUCCESS(rc))
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404 | {
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405 | unsigned i = pIntRWSem->cReaders;
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406 | while (i-- > 0)
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407 | {
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408 | if (pIntRWSem->aReaders[i].Thread == Self)
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409 | {
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410 | AssertMsg(pIntRWSem->WROwner == NIL_RTTHREAD, ("Impossible! Writers and Readers are exclusive!\n"));
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411 |
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412 | if (pIntRWSem->aReaders[i].cNesting <= 1)
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413 | {
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414 | pIntRWSem->aReaders[i] = pIntRWSem->aReaders[pIntRWSem->cReaders - 1];
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415 | ASMAtomicXchgU32(&pIntRWSem->cReaders, pIntRWSem->cReaders - 1);
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416 |
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417 | /* Kick off writers? */
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418 | if ( pIntRWSem->cWriters > 0
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419 | && pIntRWSem->cReaders == 0)
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420 | {
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421 | rc = RTSemEventSignal(pIntRWSem->WriteEvent);
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422 | AssertMsg(RT_SUCCESS(rc), ("Failed to signal writers on rwsem %p, rc=%d\n", RWSem, rc));
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423 | }
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424 | }
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425 | else
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426 | pIntRWSem->aReaders[i].cNesting--;
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427 |
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428 | RTSemMutexRelease(pIntRWSem->Mutex);
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429 | return VINF_SUCCESS;
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430 | }
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431 | }
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432 |
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433 | RTSemMutexRelease(pIntRWSem->Mutex);
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434 | rc = VERR_NOT_OWNER;
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435 | AssertMsgFailed(("Not reader of rwsem %p\n", RWSem));
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436 | }
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437 | else
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438 | AssertMsgFailed(("RTSemMutexRequest failed on rwsem %p, rc=%d\n", RWSem, rc));
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439 |
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440 | return rc;
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441 | #endif
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442 | }
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443 |
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444 |
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445 |
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446 | RTDECL(int) RTSemRWRequestWrite(RTSEMRW RWSem, unsigned cMillies)
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447 | {
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448 | /*
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449 | * Validate handle.
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450 | */
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451 | if (!rtsemRWValid(RWSem))
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452 | {
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453 | AssertMsgFailed(("Invalid handle %p!\n", RWSem));
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454 | return VERR_INVALID_HANDLE;
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455 | }
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456 |
|
---|
457 | #ifdef USE_CRIT_SECT
|
---|
458 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
|
---|
459 | return RTCritSectEnter(&pIntRWSem->CritSect);
|
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460 | #else
|
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461 |
|
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462 | /*
|
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463 | * Get Mutex.
|
---|
464 | */
|
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465 | //RTTHREAD Self = RTThreadSelf();
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466 | RTTHREAD Self = (RTTHREAD)RTThreadNativeSelf();
|
---|
467 | unsigned cMilliesInitial = cMillies;
|
---|
468 | uint64_t tsStart = 0;
|
---|
469 | if (cMillies != RTSEM_INDEFINITE_WAIT)
|
---|
470 | tsStart = RTTimeNanoTS();
|
---|
471 |
|
---|
472 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
|
---|
473 | int rc = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
|
---|
474 | if (RT_FAILURE(rc))
|
---|
475 | {
|
---|
476 | AssertMsgFailed(("RTSemMutexWait failed on rwsem %p, rc=%d\n", RWSem, rc));
|
---|
477 | return rc;
|
---|
478 | }
|
---|
479 |
|
---|
480 | /*
|
---|
481 | * Check that we're not a reader.
|
---|
482 | */
|
---|
483 | unsigned i = pIntRWSem->cReaders;
|
---|
484 | while (i-- > 0)
|
---|
485 | {
|
---|
486 | if (pIntRWSem->aReaders[i].Thread == Self)
|
---|
487 | {
|
---|
488 | AssertMsgFailed(("Deadlock - requested write access while being a reader! rwsem %p.\n", RWSem));
|
---|
489 | RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
490 | return VERR_DEADLOCK;
|
---|
491 | }
|
---|
492 | }
|
---|
493 |
|
---|
494 |
|
---|
495 | /*
|
---|
496 | * Reset the reader event semaphore and increment number of readers.
|
---|
497 | */
|
---|
498 | rc = RTSemEventMultiReset(pIntRWSem->ReadEvent);
|
---|
499 | if (RT_FAILURE(rc))
|
---|
500 | {
|
---|
501 | AssertMsgFailed(("Failed to reset readers, rwsem %p, rc=%d.\n", RWSem, rc));
|
---|
502 | RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
503 | return rc;
|
---|
504 | }
|
---|
505 | ASMAtomicXchgU32(&pIntRWSem->cWriters, pIntRWSem->cWriters + 1);
|
---|
506 |
|
---|
507 | /*
|
---|
508 | * Wait while there are other threads owning this sem.
|
---|
509 | */
|
---|
510 | while ( pIntRWSem->WROwner != NIL_RTTHREAD
|
---|
511 | || pIntRWSem->cReaders > 0)
|
---|
512 | {
|
---|
513 | AssertMsg(pIntRWSem->WROwner == NIL_RTTHREAD || pIntRWSem->cWriters > 1,
|
---|
514 | ("The lock is write owned by there is only one waiter...\n"));
|
---|
515 |
|
---|
516 | /*
|
---|
517 | * Release the mutex and wait on the writer semaphore.
|
---|
518 | */
|
---|
519 | rc = RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
520 | if (RT_FAILURE(rc))
|
---|
521 | {
|
---|
522 | AssertMsgFailed(("RTSemMutexRelease failed on rwsem %p, rc=%d\n", RWSem, rc));
|
---|
523 | return VERR_SEM_DESTROYED;
|
---|
524 | }
|
---|
525 |
|
---|
526 | /*
|
---|
527 | * Wait.
|
---|
528 | */
|
---|
529 | if (cMillies != RTSEM_INDEFINITE_WAIT)
|
---|
530 | {
|
---|
531 | int64_t tsDelta = RTTimeNanoTS() - tsStart;
|
---|
532 | if (tsDelta >= 1000000)
|
---|
533 | {
|
---|
534 | cMillies = cMilliesInitial - (unsigned)(tsDelta / 1000000);
|
---|
535 | if (cMillies > cMilliesInitial)
|
---|
536 | cMillies = cMilliesInitial ? 1 : 0;
|
---|
537 | }
|
---|
538 | }
|
---|
539 | rc = RTSemEventWait(pIntRWSem->WriteEvent, cMillies);
|
---|
540 |
|
---|
541 | /*
|
---|
542 | * Check that the semaphore wasn't destroyed while we waited.
|
---|
543 | */
|
---|
544 | if ( rc == VERR_SEM_DESTROYED
|
---|
545 | || pIntRWSem->u32Check != (uint32_t)~0)
|
---|
546 | return VERR_SEM_DESTROYED;
|
---|
547 |
|
---|
548 | /*
|
---|
549 | * Attempt take the mutex.
|
---|
550 | */
|
---|
551 | int rc2 = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
|
---|
552 | if (RT_FAILURE(rc) || RT_FAILURE(rc2))
|
---|
553 | {
|
---|
554 | AssertMsg(RT_SUCCESS(rc2), ("RTSemMutexRequest failed on rwsem %p, rc=%d\n", RWSem, rc2));
|
---|
555 | if (RT_SUCCESS(rc))
|
---|
556 | rc = rc2;
|
---|
557 | else
|
---|
558 | AssertMsg(rc == VERR_TIMEOUT, ("RTSemEventWait failed on rwsem %p, rc=%d\n", RWSem, rc));
|
---|
559 |
|
---|
560 | /*
|
---|
561 | * Remove our selves from the writers queue.
|
---|
562 | */
|
---|
563 | /** @todo write an atomic dec function! (it's too late for that kind of stuff tonight) */
|
---|
564 | if (pIntRWSem->cWriters > 0)
|
---|
565 | ASMAtomicXchgU32(&pIntRWSem->cWriters, pIntRWSem->cWriters - 1);
|
---|
566 | if (!pIntRWSem->cWriters)
|
---|
567 | RTSemEventMultiSignal(pIntRWSem->ReadEvent);
|
---|
568 | if (RT_SUCCESS(rc2))
|
---|
569 | RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
570 | return rc;
|
---|
571 | }
|
---|
572 |
|
---|
573 | AssertMsg(pIntRWSem->WROwner == NIL_RTTHREAD, ("We woke up an there is owner! %#x\n", pIntRWSem->WROwner));
|
---|
574 | AssertMsg(!pIntRWSem->cReaders, ("We woke up an there are readers around!\n"));
|
---|
575 | }
|
---|
576 |
|
---|
577 | /*
|
---|
578 | * If we get here we own the mutex and we are ready to take
|
---|
579 | * the read-write ownership.
|
---|
580 | */
|
---|
581 | ASMAtomicXchgPtr((void * volatile *)&pIntRWSem->WROwner, (void *)Self);
|
---|
582 | rc = RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
583 | AssertMsg(RT_SUCCESS(rc), ("RTSemMutexRelease failed. rc=%d\n", rc)); NOREF(rc);
|
---|
584 |
|
---|
585 | return VINF_SUCCESS;
|
---|
586 | #endif
|
---|
587 | }
|
---|
588 |
|
---|
589 |
|
---|
590 | RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW RWSem, unsigned cMillies)
|
---|
591 | {
|
---|
592 | return RTSemRWRequestWrite(RWSem, cMillies);
|
---|
593 | }
|
---|
594 |
|
---|
595 |
|
---|
596 |
|
---|
597 | RTDECL(int) RTSemRWReleaseWrite(RTSEMRW RWSem)
|
---|
598 | {
|
---|
599 | /*
|
---|
600 | * Validate handle.
|
---|
601 | */
|
---|
602 | if (!rtsemRWValid(RWSem))
|
---|
603 | {
|
---|
604 | AssertMsgFailed(("Invalid handle %p!\n", RWSem));
|
---|
605 | return VERR_INVALID_HANDLE;
|
---|
606 | }
|
---|
607 |
|
---|
608 | #ifdef USE_CRIT_SECT
|
---|
609 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
|
---|
610 | return RTCritSectLeave(&pIntRWSem->CritSect);
|
---|
611 | #else
|
---|
612 |
|
---|
613 | /*
|
---|
614 | * Check if owner.
|
---|
615 | */
|
---|
616 | //RTTHREAD Self = RTThreadSelf();
|
---|
617 | RTTHREAD Self = (RTTHREAD)RTThreadNativeSelf();
|
---|
618 | struct RTSEMRWINTERNAL *pIntRWSem = RWSem;
|
---|
619 | if (pIntRWSem->WROwner != Self)
|
---|
620 | {
|
---|
621 | AssertMsgFailed(("Not read-write owner of rwsem %p.\n", RWSem));
|
---|
622 | return VERR_NOT_OWNER;
|
---|
623 | }
|
---|
624 |
|
---|
625 | /*
|
---|
626 | * Request the mutex.
|
---|
627 | */
|
---|
628 | int rc = RTSemMutexRequest(pIntRWSem->Mutex, RTSEM_INDEFINITE_WAIT);
|
---|
629 | if (RT_FAILURE(rc))
|
---|
630 | {
|
---|
631 | AssertMsgFailed(("RTSemMutexWait failed on rwsem %p, rc=%d\n", RWSem, rc));
|
---|
632 | return rc;
|
---|
633 | }
|
---|
634 |
|
---|
635 | /*
|
---|
636 | * Release ownership and remove ourselves from the writers count.
|
---|
637 | */
|
---|
638 | ASMAtomicXchgPtr((void * volatile *)&pIntRWSem->WROwner, (void *)NIL_RTTHREAD);
|
---|
639 | Assert(pIntRWSem->cWriters > 0);
|
---|
640 | ASMAtomicXchgU32(&pIntRWSem->cWriters, pIntRWSem->cWriters - 1);
|
---|
641 |
|
---|
642 | /*
|
---|
643 | * Release the readers if no more writers.
|
---|
644 | */
|
---|
645 | if (!pIntRWSem->cWriters)
|
---|
646 | {
|
---|
647 | rc = RTSemEventMultiSignal(pIntRWSem->ReadEvent);
|
---|
648 | AssertMsg(RT_SUCCESS(rc), ("RTSemEventMultiSignal failed for rwsem %p, rc=%d.\n", RWSem, rc)); NOREF(rc);
|
---|
649 | }
|
---|
650 | rc = RTSemMutexRelease(pIntRWSem->Mutex);
|
---|
651 | AssertMsg(RT_SUCCESS(rc), ("RTSemEventMultiSignal failed for rwsem %p, rc=%d.\n", RWSem, rc)); NOREF(rc);
|
---|
652 |
|
---|
653 | return VINF_SUCCESS;
|
---|
654 | #endif
|
---|
655 | }
|
---|
656 |
|
---|