git.sesse.net Git - ffmpeg/blob - compat/w32pthreads.h

   1 /*
   2  * Copyright (C) 2010-2011 x264 project
   3  *
   4  * Authors: Steven Walters <kemuri9@gmail.com>
   5  *          Pegasys Inc. <http://www.pegasys-inc.com>
   6  *
   7  * This file is part of Libav.
   8  *
   9  * Libav is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * Libav is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /**
  25  * @file
  26  * w32threads to pthreads wrapper
  27  */
  28
  29 #ifndef LIBAV_COMPAT_W32PTHREADS_H
  30 #define LIBAV_COMPAT_W32PTHREADS_H
  31
  32 /* Build up a pthread-like API using underlying Windows API. Have only static
  33  * methods so as to not conflict with a potentially linked in pthread-win32
  34  * library.
  35  * As most functions here are used without checking return values,
  36  * only implement return values as necessary. */
  37
  38 #define WIN32_LEAN_AND_MEAN
  39 #include <windows.h>
  40 #include <process.h>
  41
  42 #if _WIN32_WINNT < 0x0600 && defined(__MINGW32__)
  43 #undef MemoryBarrier
  44 #define MemoryBarrier __sync_synchronize
  45 #endif
  46
  47 #include "libavutil/attributes.h"
  48 #include "libavutil/internal.h"
  49 #include "libavutil/mem.h"
  50
  51 typedef struct pthread_t {
  52     void *handle;
  53     void *(*func)(void* arg);
  54     void *arg;
  55     void *ret;
  56 } pthread_t;
  57
  58 /* the conditional variable api for windows 6.0+ uses critical sections and
  59  * not mutexes */
  60 typedef CRITICAL_SECTION pthread_mutex_t;
  61
  62 /* This is the CONDITION_VARIABLE typedef for using Windows' native
  63  * conditional variables on kernels 6.0+. */
  64 #if HAVE_CONDITION_VARIABLE_PTR
  65 typedef CONDITION_VARIABLE pthread_cond_t;
  66 #else
  67 typedef struct pthread_cond_t {
  68     void *Ptr;
  69 } pthread_cond_t;
  70 #endif
  71
  72 #if _WIN32_WINNT >= 0x0600
  73 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  74 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  75 #endif
  76
  77 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  78 {
  79     pthread_t *h = arg;
  80     h->ret = h->func(h->arg);
  81     return 0;
  82 }
  83
  84 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
  85                                     void *(*start_routine)(void*), void *arg)
  86 {
  87     thread->func   = start_routine;
  88     thread->arg    = arg;
  89     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  90                                            0, NULL);
  91     return !thread->handle;
  92 }
  93
  94 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
  95 {
  96     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  97     if (ret != WAIT_OBJECT_0)
  98         return;
  99     if (value_ptr)
 100         *value_ptr = thread.ret;
 101     CloseHandle(thread.handle);
 102 }
 103
 104 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 105 {
 106     InitializeCriticalSection(m);
 107     return 0;
 108 }
 109 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 110 {
 111     DeleteCriticalSection(m);
 112     return 0;
 113 }
 114 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 115 {
 116     EnterCriticalSection(m);
 117     return 0;
 118 }
 119 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 120 {
 121     LeaveCriticalSection(m);
 122     return 0;
 123 }
 124
 125 #if _WIN32_WINNT >= 0x0600
 126
 127 typedef INIT_ONCE pthread_once_t;
 128 #define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
 129
 130 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
 131 {
 132     BOOL pending = FALSE;
 133     InitOnceBeginInitialize(once_control, 0, &pending, NULL);
 134     if (pending)
 135         init_routine();
 136     InitOnceComplete(once_control, 0, NULL);
 137     return 0;
 138 }
 139
 140 static inline void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 141 {
 142     InitializeConditionVariable(cond);
 143 }
 144
 145 /* native condition variables do not destroy */
 146 static inline void pthread_cond_destroy(pthread_cond_t *cond)
 147 {
 148     return;
 149 }
 150
 151 static inline void pthread_cond_broadcast(pthread_cond_t *cond)
 152 {
 153     WakeAllConditionVariable(cond);
 154 }
 155
 156 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 157 {
 158     SleepConditionVariableCS(cond, mutex, INFINITE);
 159     return 0;
 160 }
 161
 162 static inline void pthread_cond_signal(pthread_cond_t *cond)
 163 {
 164     WakeConditionVariable(cond);
 165 }
 166
 167 #else // _WIN32_WINNT < 0x0600
 168
 169 /* atomic init state of dynamically loaded functions */
 170 static LONG w32thread_init_state = 0;
 171 static av_unused void w32thread_init(void);
 172
 173 /* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
 174  * compatible to the one used in the native API */
 175
 176 typedef union pthread_once_t  {
 177     void * Ptr;    ///< For the Windows 6.0+ native functions
 178     LONG state;    ///< For the pre-Windows 6.0 compat code
 179 } pthread_once_t;
 180
 181 #define PTHREAD_ONCE_INIT {0}
 182
 183 /* function pointers to init once API on windows 6.0+ kernels */
 184 static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
 185 static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
 186
 187 /* pre-Windows 6.0 compat using a spin-lock */
 188 static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
 189 {
 190     switch (InterlockedCompareExchange(state, 1, 0)) {
 191     /* Initial run */
 192     case 0:
 193         init_routine();
 194         InterlockedExchange(state, 2);
 195         break;
 196     /* Another thread is running init */
 197     case 1:
 198         while (1) {
 199             MemoryBarrier();
 200             if (*state == 2)
 201                 break;
 202             Sleep(0);
 203         }
 204         break;
 205     /* Initialization complete */
 206     case 2:
 207         break;
 208     }
 209 }
 210
 211 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
 212 {
 213     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
 214
 215     /* Use native functions on Windows 6.0+ */
 216     if (initonce_begin && initonce_complete) {
 217         BOOL pending = FALSE;
 218         initonce_begin(once_control, 0, &pending, NULL);
 219         if (pending)
 220             init_routine();
 221         initonce_complete(once_control, 0, NULL);
 222         return 0;
 223     }
 224
 225     w32thread_once_fallback(&once_control->state, init_routine);
 226     return 0;
 227 }
 228
 229 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 230  * variable and api */
 231
 232 typedef struct  win32_cond_t {
 233     pthread_mutex_t mtx_broadcast;
 234     pthread_mutex_t mtx_waiter_count;
 235     volatile int waiter_count;
 236     HANDLE semaphore;
 237     HANDLE waiters_done;
 238     volatile int is_broadcast;
 239 } win32_cond_t;
 240
 241 /* function pointers to conditional variable API on windows 6.0+ kernels */
 242 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
 243 static void (WINAPI *cond_init)(pthread_cond_t *cond);
 244 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
 245 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
 246                                 DWORD milliseconds);
 247
 248 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 249 {
 250     win32_cond_t *win32_cond = NULL;
 251
 252     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
 253
 254     if (cond_init) {
 255         cond_init(cond);
 256         return;
 257     }
 258
 259     /* non native condition variables */
 260     win32_cond = av_mallocz(sizeof(win32_cond_t));
 261     if (!win32_cond)
 262         return;
 263     cond->Ptr = win32_cond;
 264     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 265     if (!win32_cond->semaphore)
 266         return;
 267     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 268     if (!win32_cond->waiters_done)
 269         return;
 270
 271     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 272     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 273 }
 274
 275 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 276 {
 277     win32_cond_t *win32_cond = cond->Ptr;
 278     /* native condition variables do not destroy */
 279     if (cond_init)
 280         return;
 281
 282     /* non native condition variables */
 283     CloseHandle(win32_cond->semaphore);
 284     CloseHandle(win32_cond->waiters_done);
 285     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 286     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 287     av_freep(&win32_cond);
 288     cond->Ptr = NULL;
 289 }
 290
 291 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 292 {
 293     win32_cond_t *win32_cond = cond->Ptr;
 294     int have_waiter;
 295
 296     if (cond_broadcast) {
 297         cond_broadcast(cond);
 298         return;
 299     }
 300
 301     /* non native condition variables */
 302     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 303     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 304     have_waiter = 0;
 305
 306     if (win32_cond->waiter_count) {
 307         win32_cond->is_broadcast = 1;
 308         have_waiter = 1;
 309     }
 310
 311     if (have_waiter) {
 312         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 313         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 314         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 315         ResetEvent(win32_cond->waiters_done);
 316         win32_cond->is_broadcast = 0;
 317     } else
 318         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 319     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 320 }
 321
 322 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 323 {
 324     win32_cond_t *win32_cond = cond->Ptr;
 325     int last_waiter;
 326     if (cond_wait) {
 327         cond_wait(cond, mutex, INFINITE);
 328         return 0;
 329     }
 330
 331     /* non native condition variables */
 332     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 333     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 334     win32_cond->waiter_count++;
 335     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 336     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 337
 338     // unlock the external mutex
 339     pthread_mutex_unlock(mutex);
 340     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 341
 342     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 343     win32_cond->waiter_count--;
 344     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 345     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 346
 347     if (last_waiter)
 348         SetEvent(win32_cond->waiters_done);
 349
 350     // lock the external mutex
 351     return pthread_mutex_lock(mutex);
 352 }
 353
 354 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 355 {
 356     win32_cond_t *win32_cond = cond->Ptr;
 357     int have_waiter;
 358     if (cond_signal) {
 359         cond_signal(cond);
 360         return;
 361     }
 362
 363     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 364
 365     /* non-native condition variables */
 366     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 367     have_waiter = win32_cond->waiter_count;
 368     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 369
 370     if (have_waiter) {
 371         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 372         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 373         ResetEvent(win32_cond->waiters_done);
 374     }
 375
 376     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 377 }
 378 #endif
 379
 380 static av_unused void w32thread_init(void)
 381 {
 382 #if _WIN32_WINNT < 0x0600
 383     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 384     /* if one is available, then they should all be available */
 385     cond_init      = (void (WINAPI*)(pthread_cond_t *))
 386         GetProcAddress(kernel_dll, "InitializeConditionVariable");
 387     cond_broadcast = (void (WINAPI*)(pthread_cond_t *))
 388         GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 389     cond_signal    = (void (WINAPI*)(pthread_cond_t *))
 390         GetProcAddress(kernel_dll, "WakeConditionVariable");
 391     cond_wait      = (BOOL (WINAPI*)(pthread_cond_t *, pthread_mutex_t *, DWORD))
 392         GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 393     initonce_begin = (BOOL (WINAPI*)(pthread_once_t *, DWORD, BOOL *, void **))
 394         GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
 395     initonce_complete = (BOOL (WINAPI*)(pthread_once_t *, DWORD, void *))
 396         GetProcAddress(kernel_dll, "InitOnceComplete");
 397 #endif
 398
 399 }
 400
 401 #endif /* LIBAV_COMPAT_W32PTHREADS_H */