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 FFmpeg.
   8  *
   9  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 FFMPEG_COMPAT_W32PTHREADS_H
  30 #define FFMPEG_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 #include "libavutil/attributes.h"
  43 #include "libavutil/common.h"
  44 #include "libavutil/internal.h"
  45 #include "libavutil/mem.h"
  46
  47 typedef struct pthread_t {
  48     void *handle;
  49     void *(*func)(void* arg);
  50     void *arg;
  51     void *ret;
  52 } pthread_t;
  53
  54 /* the conditional variable api for windows 6.0+ uses critical sections and
  55  * not mutexes */
  56 typedef CRITICAL_SECTION pthread_mutex_t;
  57
  58 /* This is the CONDITION_VARIABLE typedef for using Windows' native
  59  * conditional variables on kernels 6.0+. */
  60 #if HAVE_CONDITION_VARIABLE_PTR
  61 typedef CONDITION_VARIABLE pthread_cond_t;
  62 #else
  63 typedef struct pthread_cond_t {
  64     void *Ptr;
  65 } pthread_cond_t;
  66 #endif
  67
  68 #if _WIN32_WINNT >= 0x0600
  69 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  70 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  71 #endif
  72
  73 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  74 {
  75     pthread_t *h = arg;
  76     h->ret = h->func(h->arg);
  77     return 0;
  78 }
  79
  80 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
  81                                     void *(*start_routine)(void*), void *arg)
  82 {
  83     thread->func   = start_routine;
  84     thread->arg    = arg;
  85     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  86                                            0, NULL);
  87     return !thread->handle;
  88 }
  89
  90 static av_unused int pthread_join(pthread_t thread, void **value_ptr)
  91 {
  92     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  93     if (ret != WAIT_OBJECT_0) {
  94         if (ret == WAIT_ABANDONED)
  95             return EINVAL;
  96         else
  97             return EDEADLK;
  98     }
  99     if (value_ptr)
 100         *value_ptr = thread.ret;
 101     CloseHandle(thread.handle);
 102     return 0;
 103 }
 104
 105 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 106 {
 107     InitializeCriticalSection(m);
 108     return 0;
 109 }
 110 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 111 {
 112     DeleteCriticalSection(m);
 113     return 0;
 114 }
 115 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 116 {
 117     EnterCriticalSection(m);
 118     return 0;
 119 }
 120 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 121 {
 122     LeaveCriticalSection(m);
 123     return 0;
 124 }
 125
 126 #if _WIN32_WINNT >= 0x0600
 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 int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 141 {
 142     InitializeConditionVariable(cond);
 143     return 0;
 144 }
 145
 146 /* native condition variables do not destroy */
 147 static inline int pthread_cond_destroy(pthread_cond_t *cond)
 148 {
 149     return 0;
 150 }
 151
 152 static inline int pthread_cond_broadcast(pthread_cond_t *cond)
 153 {
 154     WakeAllConditionVariable(cond);
 155     return 0;
 156 }
 157
 158 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 159 {
 160     SleepConditionVariableCS(cond, mutex, INFINITE);
 161     return 0;
 162 }
 163
 164 static inline int pthread_cond_signal(pthread_cond_t *cond)
 165 {
 166     WakeConditionVariable(cond);
 167     return 0;
 168 }
 169
 170 #else // _WIN32_WINNT < 0x0600
 171
 172 /* atomic init state of dynamically loaded functions */
 173 static LONG w32thread_init_state = 0;
 174 static av_unused void w32thread_init(void);
 175
 176 /* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
 177  * compatible to the one used in the native API */
 178
 179 typedef union pthread_once_t  {
 180     void * Ptr;    ///< For the Windows 6.0+ native functions
 181     LONG state;    ///< For the pre-Windows 6.0 compat code
 182 } pthread_once_t;
 183
 184 #define PTHREAD_ONCE_INIT {0}
 185
 186 /* function pointers to init once API on windows 6.0+ kernels */
 187 static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
 188 static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
 189
 190 /* pre-Windows 6.0 compat using a spin-lock */
 191 static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
 192 {
 193     switch (InterlockedCompareExchange(state, 1, 0)) {
 194     /* Initial run */
 195     case 0:
 196         init_routine();
 197         InterlockedExchange(state, 2);
 198         break;
 199     /* Another thread is running init */
 200     case 1:
 201         while (1) {
 202             MemoryBarrier();
 203             if (*state == 2)
 204                 break;
 205             Sleep(0);
 206         }
 207         break;
 208     /* Initialization complete */
 209     case 2:
 210         break;
 211     }
 212 }
 213
 214 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
 215 {
 216     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
 217
 218     /* Use native functions on Windows 6.0+ */
 219     if (initonce_begin && initonce_complete) {
 220         BOOL pending = FALSE;
 221         initonce_begin(once_control, 0, &pending, NULL);
 222         if (pending)
 223             init_routine();
 224         initonce_complete(once_control, 0, NULL);
 225         return 0;
 226     }
 227
 228     w32thread_once_fallback(&once_control->state, init_routine);
 229     return 0;
 230 }
 231
 232 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 233  * variable and api */
 234
 235 typedef struct  win32_cond_t {
 236     pthread_mutex_t mtx_broadcast;
 237     pthread_mutex_t mtx_waiter_count;
 238     volatile int waiter_count;
 239     HANDLE semaphore;
 240     HANDLE waiters_done;
 241     volatile int is_broadcast;
 242 } win32_cond_t;
 243
 244 /* function pointers to conditional variable API on windows 6.0+ kernels */
 245 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
 246 static void (WINAPI *cond_init)(pthread_cond_t *cond);
 247 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
 248 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
 249                                 DWORD milliseconds);
 250
 251 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 252 {
 253     win32_cond_t *win32_cond = NULL;
 254
 255     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
 256
 257     if (cond_init) {
 258         cond_init(cond);
 259         return 0;
 260     }
 261
 262     /* non native condition variables */
 263     win32_cond = av_mallocz(sizeof(win32_cond_t));
 264     if (!win32_cond)
 265         return ENOMEM;
 266     cond->Ptr = win32_cond;
 267     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 268     if (!win32_cond->semaphore)
 269         return ENOMEM;
 270     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 271     if (!win32_cond->waiters_done)
 272         return ENOMEM;
 273
 274     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 275     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 276     return 0;
 277 }
 278
 279 static av_unused int pthread_cond_destroy(pthread_cond_t *cond)
 280 {
 281     win32_cond_t *win32_cond = cond->Ptr;
 282     /* native condition variables do not destroy */
 283     if (cond_init)
 284         return 0;
 285
 286     /* non native condition variables */
 287     CloseHandle(win32_cond->semaphore);
 288     CloseHandle(win32_cond->waiters_done);
 289     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 290     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 291     av_freep(&win32_cond);
 292     cond->Ptr = NULL;
 293     return 0;
 294 }
 295
 296 static av_unused int pthread_cond_broadcast(pthread_cond_t *cond)
 297 {
 298     win32_cond_t *win32_cond = cond->Ptr;
 299     int have_waiter;
 300
 301     if (cond_broadcast) {
 302         cond_broadcast(cond);
 303         return 0;
 304     }
 305
 306     /* non native condition variables */
 307     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 308     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 309     have_waiter = 0;
 310
 311     if (win32_cond->waiter_count) {
 312         win32_cond->is_broadcast = 1;
 313         have_waiter = 1;
 314     }
 315
 316     if (have_waiter) {
 317         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 318         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 319         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 320         ResetEvent(win32_cond->waiters_done);
 321         win32_cond->is_broadcast = 0;
 322     } else
 323         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 324     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 325     return 0;
 326 }
 327
 328 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 329 {
 330     win32_cond_t *win32_cond = cond->Ptr;
 331     int last_waiter;
 332     if (cond_wait) {
 333         cond_wait(cond, mutex, INFINITE);
 334         return 0;
 335     }
 336
 337     /* non native condition variables */
 338     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 339     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 340     win32_cond->waiter_count++;
 341     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 342     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 343
 344     // unlock the external mutex
 345     pthread_mutex_unlock(mutex);
 346     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 347
 348     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 349     win32_cond->waiter_count--;
 350     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 351     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 352
 353     if (last_waiter)
 354         SetEvent(win32_cond->waiters_done);
 355
 356     // lock the external mutex
 357     return pthread_mutex_lock(mutex);
 358 }
 359
 360 static av_unused int pthread_cond_signal(pthread_cond_t *cond)
 361 {
 362     win32_cond_t *win32_cond = cond->Ptr;
 363     int have_waiter;
 364     if (cond_signal) {
 365         cond_signal(cond);
 366         return 0;
 367     }
 368
 369     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 370
 371     /* non-native condition variables */
 372     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 373     have_waiter = win32_cond->waiter_count;
 374     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 375
 376     if (have_waiter) {
 377         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 378         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 379         ResetEvent(win32_cond->waiters_done);
 380     }
 381
 382     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 383     return 0;
 384 }
 385 #endif
 386
 387 static av_unused void w32thread_init(void)
 388 {
 389 #if _WIN32_WINNT < 0x0600
 390     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 391     /* if one is available, then they should all be available */
 392     cond_init      =
 393         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 394     cond_broadcast =
 395         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 396     cond_signal    =
 397         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 398     cond_wait      =
 399         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 400     initonce_begin =
 401         (void*)GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
 402     initonce_complete =
 403         (void*)GetProcAddress(kernel_dll, "InitOnceComplete");
 404 #endif
 405
 406 }
 407
 408 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */