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1 |
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2 /* Thread package. |
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3 This is intended to be usable independently from Python. |
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4 The implementation for system foobar is in a file thread_foobar.h |
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5 which is included by this file dependent on config settings. |
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6 Stuff shared by all thread_*.h files is collected here. */ |
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7 |
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8 #include "Python.h" |
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9 |
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10 |
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11 #ifndef _POSIX_THREADS |
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12 /* This means pthreads are not implemented in libc headers, hence the macro |
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13 not present in unistd.h. But they still can be implemented as an external |
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14 library (e.g. gnu pth in pthread emulation) */ |
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15 # ifdef HAVE_PTHREAD_H |
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16 # include <pthread.h> /* _POSIX_THREADS */ |
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17 # endif |
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18 #endif |
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19 |
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20 #ifndef DONT_HAVE_STDIO_H |
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21 #include <stdio.h> |
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22 #endif |
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23 |
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24 #include <stdlib.h> |
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25 |
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26 #ifdef __sgi |
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27 #ifndef HAVE_PTHREAD_H /* XXX Need to check in configure.in */ |
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28 #undef _POSIX_THREADS |
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29 #endif |
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30 #endif |
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31 |
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32 #include "pythread.h" |
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33 |
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34 #ifndef _POSIX_THREADS |
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35 |
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36 #ifdef __sgi |
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37 #define SGI_THREADS |
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38 #endif |
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39 |
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40 #ifdef HAVE_THREAD_H |
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41 #define SOLARIS_THREADS |
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42 #endif |
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43 |
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44 #if defined(sun) && !defined(SOLARIS_THREADS) |
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45 #define SUN_LWP |
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46 #endif |
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47 |
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48 /* Check if we're running on HP-UX and _SC_THREADS is defined. If so, then |
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49 enough of the Posix threads package is implimented to support python |
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50 threads. |
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51 |
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52 This is valid for HP-UX 11.23 running on an ia64 system. If needed, add |
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53 a check of __ia64 to verify that we're running on a ia64 system instead |
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54 of a pa-risc system. |
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55 */ |
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56 #ifdef __hpux |
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57 #ifdef _SC_THREADS |
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58 #define _POSIX_THREADS |
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59 #endif |
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60 #endif |
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61 |
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62 #endif /* _POSIX_THREADS */ |
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63 |
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64 |
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65 #ifdef Py_DEBUG |
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66 static int thread_debug = 0; |
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67 #define dprintf(args) (void)((thread_debug & 1) && printf args) |
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68 #define d2printf(args) ((thread_debug & 8) && printf args) |
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69 #else |
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70 #define dprintf(args) |
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71 #define d2printf(args) |
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72 #endif |
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73 |
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74 static int initialized; |
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75 |
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76 static void PyThread__init_thread(void); /* Forward */ |
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77 |
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78 void |
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79 PyThread_init_thread(void) |
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80 { |
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81 #ifdef Py_DEBUG |
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82 char *p = Py_GETENV("PYTHONTHREADDEBUG"); |
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83 |
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84 if (p) { |
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85 if (*p) |
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86 thread_debug = atoi(p); |
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87 else |
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88 thread_debug = 1; |
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89 } |
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90 #endif /* Py_DEBUG */ |
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91 if (initialized) |
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92 return; |
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93 initialized = 1; |
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94 dprintf(("PyThread_init_thread called\n")); |
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95 PyThread__init_thread(); |
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96 } |
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97 |
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98 /* Support for runtime thread stack size tuning. |
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99 A value of 0 means using the platform's default stack size |
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100 or the size specified by the THREAD_STACK_SIZE macro. */ |
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101 static size_t _pythread_stacksize = 0; |
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102 |
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103 #ifdef SGI_THREADS |
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104 #include "thread_sgi.h" |
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105 #endif |
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106 |
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107 #ifdef SOLARIS_THREADS |
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108 #include "thread_solaris.h" |
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109 #endif |
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110 |
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111 #ifdef SUN_LWP |
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112 #include "thread_lwp.h" |
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113 #endif |
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114 |
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115 #ifdef HAVE_PTH |
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116 #include "thread_pth.h" |
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117 #undef _POSIX_THREADS |
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118 #endif |
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119 |
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120 #ifdef _POSIX_THREADS |
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121 #include "thread_pthread.h" |
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122 #endif |
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123 |
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124 #ifdef C_THREADS |
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125 #include "thread_cthread.h" |
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126 #endif |
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127 |
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128 #ifdef NT_THREADS |
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129 #include "thread_nt.h" |
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130 #endif |
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131 |
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132 #ifdef OS2_THREADS |
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133 #include "thread_os2.h" |
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134 #endif |
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135 |
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136 #ifdef BEOS_THREADS |
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137 #include "thread_beos.h" |
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138 #endif |
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139 |
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140 #ifdef WINCE_THREADS |
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141 #include "thread_wince.h" |
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142 #endif |
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143 |
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144 #ifdef PLAN9_THREADS |
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145 #include "thread_plan9.h" |
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146 #endif |
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147 |
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148 #ifdef ATHEOS_THREADS |
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149 #include "thread_atheos.h" |
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150 #endif |
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151 |
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152 /* |
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153 #ifdef FOOBAR_THREADS |
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154 #include "thread_foobar.h" |
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155 #endif |
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156 */ |
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157 |
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158 /* return the current thread stack size */ |
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159 size_t |
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160 PyThread_get_stacksize(void) |
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161 { |
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162 return _pythread_stacksize; |
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163 } |
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164 |
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165 /* Only platforms defining a THREAD_SET_STACKSIZE() macro |
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166 in thread_<platform>.h support changing the stack size. |
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167 Return 0 if stack size is valid, |
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168 -1 if stack size value is invalid, |
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169 -2 if setting stack size is not supported. */ |
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170 int |
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171 PyThread_set_stacksize(size_t size) |
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172 { |
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173 #if defined(THREAD_SET_STACKSIZE) |
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174 return THREAD_SET_STACKSIZE(size); |
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175 #else |
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176 return -2; |
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177 #endif |
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178 } |
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179 |
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180 #ifndef Py_HAVE_NATIVE_TLS |
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181 /* If the platform has not supplied a platform specific |
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182 TLS implementation, provide our own. |
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183 |
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184 This code stolen from "thread_sgi.h", where it was the only |
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185 implementation of an existing Python TLS API. |
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186 */ |
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187 /* ------------------------------------------------------------------------ |
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188 Per-thread data ("key") support. |
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189 |
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190 Use PyThread_create_key() to create a new key. This is typically shared |
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191 across threads. |
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192 |
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193 Use PyThread_set_key_value(thekey, value) to associate void* value with |
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194 thekey in the current thread. Each thread has a distinct mapping of thekey |
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195 to a void* value. Caution: if the current thread already has a mapping |
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196 for thekey, value is ignored. |
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197 |
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198 Use PyThread_get_key_value(thekey) to retrieve the void* value associated |
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199 with thekey in the current thread. This returns NULL if no value is |
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200 associated with thekey in the current thread. |
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201 |
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202 Use PyThread_delete_key_value(thekey) to forget the current thread's associated |
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203 value for thekey. PyThread_delete_key(thekey) forgets the values associated |
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204 with thekey across *all* threads. |
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205 |
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206 While some of these functions have error-return values, none set any |
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207 Python exception. |
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208 |
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209 None of the functions does memory management on behalf of the void* values. |
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210 You need to allocate and deallocate them yourself. If the void* values |
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211 happen to be PyObject*, these functions don't do refcount operations on |
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212 them either. |
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213 |
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214 The GIL does not need to be held when calling these functions; they supply |
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215 their own locking. This isn't true of PyThread_create_key(), though (see |
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216 next paragraph). |
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217 |
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218 There's a hidden assumption that PyThread_create_key() will be called before |
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219 any of the other functions are called. There's also a hidden assumption |
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220 that calls to PyThread_create_key() are serialized externally. |
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221 ------------------------------------------------------------------------ */ |
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222 |
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223 /* A singly-linked list of struct key objects remembers all the key->value |
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224 * associations. File static keyhead heads the list. keymutex is used |
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225 * to enforce exclusion internally. |
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226 */ |
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227 struct key { |
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228 /* Next record in the list, or NULL if this is the last record. */ |
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229 struct key *next; |
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230 |
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231 /* The thread id, according to PyThread_get_thread_ident(). */ |
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232 long id; |
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233 |
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234 /* The key and its associated value. */ |
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235 int key; |
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236 void *value; |
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237 }; |
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238 |
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239 static struct key *keyhead = NULL; |
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240 static PyThread_type_lock keymutex = NULL; |
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241 static int nkeys = 0; /* PyThread_create_key() hands out nkeys+1 next */ |
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242 |
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243 /* Internal helper. |
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244 * If the current thread has a mapping for key, the appropriate struct key* |
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245 * is returned. NB: value is ignored in this case! |
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246 * If there is no mapping for key in the current thread, then: |
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247 * If value is NULL, NULL is returned. |
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248 * Else a mapping of key to value is created for the current thread, |
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249 * and a pointer to a new struct key* is returned; except that if |
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250 * malloc() can't find room for a new struct key*, NULL is returned. |
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251 * So when value==NULL, this acts like a pure lookup routine, and when |
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252 * value!=NULL, this acts like dict.setdefault(), returning an existing |
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253 * mapping if one exists, else creating a new mapping. |
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254 * |
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255 * Caution: this used to be too clever, trying to hold keymutex only |
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256 * around the "p->next = keyhead; keyhead = p" pair. That allowed |
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257 * another thread to mutate the list, via key deletion, concurrent with |
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258 * find_key() crawling over the list. Hilarity ensued. For example, when |
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259 * the for-loop here does "p = p->next", p could end up pointing at a |
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260 * record that PyThread_delete_key_value() was concurrently free()'ing. |
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261 * That could lead to anything, from failing to find a key that exists, to |
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262 * segfaults. Now we lock the whole routine. |
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263 */ |
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264 static struct key * |
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265 find_key(int key, void *value) |
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266 { |
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267 struct key *p, *prev_p; |
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268 long id = PyThread_get_thread_ident(); |
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269 |
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270 if (!keymutex) |
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271 return NULL; |
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272 PyThread_acquire_lock(keymutex, 1); |
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273 prev_p = NULL; |
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274 for (p = keyhead; p != NULL; p = p->next) { |
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275 if (p->id == id && p->key == key) |
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276 goto Done; |
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277 /* Sanity check. These states should never happen but if |
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278 * they do we must abort. Otherwise we'll end up spinning in |
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279 * in a tight loop with the lock held. A similar check is done |
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280 * in pystate.c tstate_delete_common(). */ |
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281 if (p == prev_p) |
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282 Py_FatalError("tls find_key: small circular list(!)"); |
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283 prev_p = p; |
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284 if (p->next == keyhead) |
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285 Py_FatalError("tls find_key: circular list(!)"); |
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286 } |
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287 if (value == NULL) { |
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288 assert(p == NULL); |
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289 goto Done; |
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290 } |
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291 p = (struct key *)malloc(sizeof(struct key)); |
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292 if (p != NULL) { |
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293 p->id = id; |
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294 p->key = key; |
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295 p->value = value; |
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296 p->next = keyhead; |
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297 keyhead = p; |
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298 } |
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299 Done: |
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300 PyThread_release_lock(keymutex); |
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301 return p; |
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302 } |
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303 |
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304 /* Return a new key. This must be called before any other functions in |
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305 * this family, and callers must arrange to serialize calls to this |
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306 * function. No violations are detected. |
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307 */ |
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308 int |
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309 PyThread_create_key(void) |
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310 { |
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311 /* All parts of this function are wrong if it's called by multiple |
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312 * threads simultaneously. |
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313 */ |
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314 if (keymutex == NULL) |
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315 keymutex = PyThread_allocate_lock(); |
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316 return ++nkeys; |
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317 } |
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318 |
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319 /* Forget the associations for key across *all* threads. */ |
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320 void |
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321 PyThread_delete_key(int key) |
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322 { |
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323 struct key *p, **q; |
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324 |
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325 PyThread_acquire_lock(keymutex, 1); |
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326 q = &keyhead; |
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327 while ((p = *q) != NULL) { |
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328 if (p->key == key) { |
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329 *q = p->next; |
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330 free((void *)p); |
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331 /* NB This does *not* free p->value! */ |
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332 } |
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333 else |
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334 q = &p->next; |
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335 } |
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336 PyThread_release_lock(keymutex); |
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337 } |
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338 |
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339 /* Confusing: If the current thread has an association for key, |
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340 * value is ignored, and 0 is returned. Else an attempt is made to create |
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341 * an association of key to value for the current thread. 0 is returned |
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342 * if that succeeds, but -1 is returned if there's not enough memory |
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343 * to create the association. value must not be NULL. |
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344 */ |
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345 int |
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346 PyThread_set_key_value(int key, void *value) |
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347 { |
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348 struct key *p; |
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349 |
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350 assert(value != NULL); |
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351 p = find_key(key, value); |
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352 if (p == NULL) |
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353 return -1; |
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354 else |
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355 return 0; |
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356 } |
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357 |
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358 /* Retrieve the value associated with key in the current thread, or NULL |
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359 * if the current thread doesn't have an association for key. |
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360 */ |
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361 void * |
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362 PyThread_get_key_value(int key) |
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363 { |
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364 struct key *p = find_key(key, NULL); |
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365 |
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366 if (p == NULL) |
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367 return NULL; |
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368 else |
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369 return p->value; |
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370 } |
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371 |
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372 /* Forget the current thread's association for key, if any. */ |
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373 void |
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374 PyThread_delete_key_value(int key) |
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375 { |
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376 long id = PyThread_get_thread_ident(); |
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377 struct key *p, **q; |
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378 |
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379 PyThread_acquire_lock(keymutex, 1); |
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380 q = &keyhead; |
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381 while ((p = *q) != NULL) { |
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382 if (p->key == key && p->id == id) { |
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383 *q = p->next; |
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384 free((void *)p); |
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385 /* NB This does *not* free p->value! */ |
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386 break; |
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387 } |
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388 else |
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389 q = &p->next; |
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390 } |
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391 PyThread_release_lock(keymutex); |
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392 } |
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393 |
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394 /* Forget everything not associated with the current thread id. |
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395 * This function is called from PyOS_AfterFork(). It is necessary |
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396 * because other thread ids which were in use at the time of the fork |
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397 * may be reused for new threads created in the forked process. |
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398 */ |
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399 void |
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400 PyThread_ReInitTLS(void) |
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401 { |
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402 long id = PyThread_get_thread_ident(); |
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403 struct key *p, **q; |
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404 |
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405 if (!keymutex) |
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406 return; |
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407 |
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408 /* As with interpreter_lock in PyEval_ReInitThreads() |
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409 we just create a new lock without freeing the old one */ |
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410 keymutex = PyThread_allocate_lock(); |
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411 |
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412 /* Delete all keys which do not match the current thread id */ |
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413 q = &keyhead; |
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414 while ((p = *q) != NULL) { |
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415 if (p->id != id) { |
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416 *q = p->next; |
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417 free((void *)p); |
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418 /* NB This does *not* free p->value! */ |
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419 } |
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420 else |
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421 q = &p->next; |
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422 } |
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423 } |
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424 |
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425 #endif /* Py_HAVE_NATIVE_TLS */ |