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1 /* Implementation of W32-specific threads compatibility routines for
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2 libgcc2. */
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3
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4 /* Copyright (C) 1999, 2000, 2002, 2004, 2008, 2009 Free Software Foundation, Inc.
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5 Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
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6 Modified and moved to separate file by Danny Smith
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7 <dannysmith@users.sourceforge.net>.
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8
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9 This file is part of GCC.
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10
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11 GCC is free software; you can redistribute it and/or modify it under
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12 the terms of the GNU General Public License as published by the Free
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13 Software Foundation; either version 3, or (at your option) any later
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14 version.
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15
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16 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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17 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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19 for more details.
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20
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21 Under Section 7 of GPL version 3, you are granted additional
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22 permissions described in the GCC Runtime Library Exception, version
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23 3.1, as published by the Free Software Foundation.
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24
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25 You should have received a copy of the GNU General Public License and
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26 a copy of the GCC Runtime Library Exception along with this program;
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27 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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28 <http://www.gnu.org/licenses/>. */
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29
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30 #include <windows.h>
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31 #ifndef __GTHREAD_HIDE_WIN32API
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32 # define __GTHREAD_HIDE_WIN32API 1
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33 #endif
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34 #undef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
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35 #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
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36 #include <gthr-win32.h>
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37
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38 /* Windows32 threads specific definitions. The windows32 threading model
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39 does not map well into pthread-inspired gcc's threading model, and so
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40 there are caveats one needs to be aware of.
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41
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42 1. The destructor supplied to __gthread_key_create is ignored for
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43 generic x86-win32 ports. This will certainly cause memory leaks
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44 due to unreclaimed eh contexts (sizeof (eh_context) is at least
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45 24 bytes for x86 currently).
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46
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47 This memory leak may be significant for long-running applications
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48 that make heavy use of C++ EH.
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49
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50 However, Mingw runtime (version 0.3 or newer) provides a mechanism
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51 to emulate pthreads key dtors; the runtime provides a special DLL,
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52 linked in if -mthreads option is specified, that runs the dtors in
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53 the reverse order of registration when each thread exits. If
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54 -mthreads option is not given, a stub is linked in instead of the
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55 DLL, which results in memory leak. Other x86-win32 ports can use
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56 the same technique of course to avoid the leak.
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57
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58 2. The error codes returned are non-POSIX like, and cast into ints.
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59 This may cause incorrect error return due to truncation values on
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60 hw where sizeof (DWORD) > sizeof (int).
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61
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62 3. We are currently using a special mutex instead of the Critical
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63 Sections, since Win9x does not support TryEnterCriticalSection
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64 (while NT does).
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65
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66 The basic framework should work well enough. In the long term, GCC
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67 needs to use Structured Exception Handling on Windows32. */
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68
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69 int
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70 __gthr_win32_once (__gthread_once_t *once, void (*func) (void))
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71 {
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72 if (once == NULL || func == NULL)
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73 return EINVAL;
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74
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75 if (! once->done)
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76 {
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77 if (InterlockedIncrement (&(once->started)) == 0)
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78 {
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79 (*func) ();
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80 once->done = TRUE;
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81 }
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82 else
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83 {
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84 /* Another thread is currently executing the code, so wait for it
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85 to finish; yield the CPU in the meantime. If performance
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86 does become an issue, the solution is to use an Event that
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87 we wait on here (and set above), but that implies a place to
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88 create the event before this routine is called. */
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89 while (! once->done)
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90 Sleep (0);
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91 }
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92 }
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93 return 0;
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94 }
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95
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96 /* Windows32 thread local keys don't support destructors; this leads to
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97 leaks, especially in threaded applications making extensive use of
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98 C++ EH. Mingw uses a thread-support DLL to work-around this problem. */
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99
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100 int
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101 __gthr_win32_key_create (__gthread_key_t *key,
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102 void (*dtor) (void *) __attribute__((unused)))
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103 {
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104 int status = 0;
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105 DWORD tls_index = TlsAlloc ();
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106 if (tls_index != 0xFFFFFFFF)
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107 {
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108 *key = tls_index;
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109 #ifdef MINGW32_SUPPORTS_MT_EH
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110 /* Mingw runtime will run the dtors in reverse order for each thread
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111 when the thread exits. */
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112 status = __mingwthr_key_dtor (*key, dtor);
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113 #endif
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114 }
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115 else
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116 status = (int) GetLastError ();
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117 return status;
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118 }
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119
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120 int
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121 __gthr_win32_key_delete (__gthread_key_t key)
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122 {
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123 return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
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124 }
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125
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126 void *
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127 __gthr_win32_getspecific (__gthread_key_t key)
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128 {
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129 DWORD lasterror;
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130 void *ptr;
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131 lasterror = GetLastError();
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132 ptr = TlsGetValue(key);
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133 SetLastError( lasterror );
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134 return ptr;
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135 }
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136
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137 int
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138 __gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
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139 {
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140 if (TlsSetValue (key, CONST_CAST2(void *, const void *, ptr)) != 0)
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141 return 0;
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142 else
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143 return GetLastError ();
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144 }
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145
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146 void
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147 __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
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148 {
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149 mutex->counter = -1;
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150 mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
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151 }
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152
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153 void
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154 __gthr_win32_mutex_destroy (__gthread_mutex_t *mutex)
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155 {
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156 CloseHandle ((HANDLE) mutex->sema);
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157 }
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158
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159 int
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160 __gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
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161 {
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162 if (InterlockedIncrement (&mutex->counter) == 0 ||
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163 WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
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164 return 0;
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165 else
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166 {
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167 /* WaitForSingleObject returns WAIT_FAILED, and we can only do
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168 some best-effort cleanup here. */
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169 InterlockedDecrement (&mutex->counter);
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170 return 1;
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171 }
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172 }
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173
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174 int
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175 __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
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176 {
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177 if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
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178 return 0;
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179 else
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180 return 1;
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181 }
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182
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183 int
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184 __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
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185 {
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186 if (InterlockedDecrement (&mutex->counter) >= 0)
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187 return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
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188 else
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189 return 0;
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190 }
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191
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192 void
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193 __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
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194 {
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195 mutex->counter = -1;
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196 mutex->depth = 0;
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197 mutex->owner = 0;
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198 mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);
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199 }
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200
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201 int
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202 __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
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203 {
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204 DWORD me = GetCurrentThreadId();
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205 if (InterlockedIncrement (&mutex->counter) == 0)
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206 {
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207 mutex->depth = 1;
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208 mutex->owner = me;
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209 }
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210 else if (mutex->owner == me)
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211 {
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212 InterlockedDecrement (&mutex->counter);
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213 ++(mutex->depth);
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214 }
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215 else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
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216 {
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217 mutex->depth = 1;
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218 mutex->owner = me;
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219 }
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220 else
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221 {
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222 /* WaitForSingleObject returns WAIT_FAILED, and we can only do
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223 some best-effort cleanup here. */
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224 InterlockedDecrement (&mutex->counter);
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225 return 1;
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226 }
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227 return 0;
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228 }
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229
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230 int
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231 __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
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232 {
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233 DWORD me = GetCurrentThreadId();
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234 if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
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235 {
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236 mutex->depth = 1;
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237 mutex->owner = me;
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238 }
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239 else if (mutex->owner == me)
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240 ++(mutex->depth);
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241 else
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242 return 1;
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243
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244 return 0;
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245 }
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246
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247 int
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248 __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
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249 {
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250 --(mutex->depth);
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251 if (mutex->depth == 0)
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252 {
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253 mutex->owner = 0;
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254
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255 if (InterlockedDecrement (&mutex->counter) >= 0)
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256 return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
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257 }
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258
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259 return 0;
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260 }
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