ffmpeg/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 void pthread_join(pthread_t thread, void **value_ptr)
  91 {
  92     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  93     if (ret != WAIT_OBJECT_0)
  94         return;
  95     if (value_ptr)
  96         *value_ptr = thread.ret;
  97     CloseHandle(thread.handle);
  98 }
  99
 100 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 101 {
 102     InitializeCriticalSection(m);
 103     return 0;
 104 }
 105 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 106 {
 107     DeleteCriticalSection(m);
 108     return 0;
 109 }
 110 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 111 {
 112     EnterCriticalSection(m);
 113     return 0;
 114 }
 115 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 116 {
 117     LeaveCriticalSection(m);
 118     return 0;
 119 }
 120
 121 #if _WIN32_WINNT >= 0x0600
 122 static inline int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 123 {
 124     InitializeConditionVariable(cond);
 125     return 0;
 126 }
 127
 128 /* native condition variables do not destroy */
 129 static inline void pthread_cond_destroy(pthread_cond_t *cond)
 130 {
 131     return;
 132 }
 133
 134 static inline void pthread_cond_broadcast(pthread_cond_t *cond)
 135 {
 136     WakeAllConditionVariable(cond);
 137 }
 138
 139 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 140 {
 141     SleepConditionVariableCS(cond, mutex, INFINITE);
 142     return 0;
 143 }
 144
 145 static inline void pthread_cond_signal(pthread_cond_t *cond)
 146 {
 147     WakeConditionVariable(cond);
 148 }
 149
 150 #else // _WIN32_WINNT < 0x0600
 151 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 152  * variable and api */
 153 typedef struct  win32_cond_t {
 154     pthread_mutex_t mtx_broadcast;
 155     pthread_mutex_t mtx_waiter_count;
 156     volatile int waiter_count;
 157     HANDLE semaphore;
 158     HANDLE waiters_done;
 159     volatile int is_broadcast;
 160 } win32_cond_t;
 161
 162 /* function pointers to conditional variable API on windows 6.0+ kernels */
 163 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
 164 static void (WINAPI *cond_init)(pthread_cond_t *cond);
 165 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
 166 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
 167                                 DWORD milliseconds);
 168
 169 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 170 {
 171     win32_cond_t *win32_cond = NULL;
 172     if (cond_init) {
 173         cond_init(cond);
 174         return 0;
 175     }
 176
 177     /* non native condition variables */
 178     win32_cond = av_mallocz(sizeof(win32_cond_t));
 179     if (!win32_cond)
 180         return ENOMEM;
 181     cond->Ptr = win32_cond;
 182     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 183     if (!win32_cond->semaphore)
 184         return ENOMEM;
 185     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 186     if (!win32_cond->waiters_done)
 187         return ENOMEM;
 188
 189     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 190     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 191     return 0;
 192 }
 193
 194 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 195 {
 196     win32_cond_t *win32_cond = cond->Ptr;
 197     /* native condition variables do not destroy */
 198     if (cond_init)
 199         return;
 200
 201     /* non native condition variables */
 202     CloseHandle(win32_cond->semaphore);
 203     CloseHandle(win32_cond->waiters_done);
 204     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 205     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 206     av_freep(&win32_cond);
 207     cond->Ptr = NULL;
 208 }
 209
 210 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 211 {
 212     win32_cond_t *win32_cond = cond->Ptr;
 213     int have_waiter;
 214
 215     if (cond_broadcast) {
 216         cond_broadcast(cond);
 217         return;
 218     }
 219
 220     /* non native condition variables */
 221     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 222     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 223     have_waiter = 0;
 224
 225     if (win32_cond->waiter_count) {
 226         win32_cond->is_broadcast = 1;
 227         have_waiter = 1;
 228     }
 229
 230     if (have_waiter) {
 231         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 232         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 233         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 234         ResetEvent(win32_cond->waiters_done);
 235         win32_cond->is_broadcast = 0;
 236     } else
 237         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 238     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 239 }
 240
 241 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 242 {
 243     win32_cond_t *win32_cond = cond->Ptr;
 244     int last_waiter;
 245     if (cond_wait) {
 246         cond_wait(cond, mutex, INFINITE);
 247         return 0;
 248     }
 249
 250     /* non native condition variables */
 251     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 252     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 253     win32_cond->waiter_count++;
 254     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 255     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 256
 257     // unlock the external mutex
 258     pthread_mutex_unlock(mutex);
 259     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 260
 261     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 262     win32_cond->waiter_count--;
 263     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 264     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 265
 266     if (last_waiter)
 267         SetEvent(win32_cond->waiters_done);
 268
 269     // lock the external mutex
 270     return pthread_mutex_lock(mutex);
 271 }
 272
 273 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 274 {
 275     win32_cond_t *win32_cond = cond->Ptr;
 276     int have_waiter;
 277     if (cond_signal) {
 278         cond_signal(cond);
 279         return;
 280     }
 281
 282     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 283
 284     /* non-native condition variables */
 285     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 286     have_waiter = win32_cond->waiter_count;
 287     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 288
 289     if (have_waiter) {
 290         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 291         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 292         ResetEvent(win32_cond->waiters_done);
 293     }
 294
 295     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 296 }
 297 #endif
 298
 299 static av_unused void w32thread_init(void)
 300 {
 301 #if _WIN32_WINNT < 0x0600
 302     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 303     /* if one is available, then they should all be available */
 304     cond_init      =
 305         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 306     cond_broadcast =
 307         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 308     cond_signal    =
 309         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 310     cond_wait      =
 311         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 312 #endif
 313
 314 }
 315
 316 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */