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/common.h"
  43 #include "libavutil/internal.h"
  44 #include "libavutil/mem.h"
  45
  46 typedef struct pthread_t {
  47     void *handle;
  48     void *(*func)(void* arg);
  49     void *arg;
  50     void *ret;
  51 } pthread_t;
  52
  53 /* the conditional variable api for windows 6.0+ uses critical sections and
  54  * not mutexes */
  55 typedef CRITICAL_SECTION pthread_mutex_t;
  56
  57 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
  58  * conditional variables on kernels 6.0+.
  59  * MinGW does not currently have this typedef. */
  60 typedef struct pthread_cond_t {
  61     void *ptr;
  62 } pthread_cond_t;
  63
  64 /* function pointers to conditional variable API on windows 6.0+ kernels */
  65 #if _WIN32_WINNT < 0x0600
  66 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  67 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  68 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  69 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  70                                 DWORD milliseconds);
  71 #else
  72 #define cond_init      InitializeConditionVariable
  73 #define cond_broadcast WakeAllConditionVariable
  74 #define cond_signal    WakeConditionVariable
  75 #define cond_wait      SleepConditionVariableCS
  76 #endif
  77
  78 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  79 {
  80     pthread_t *h = arg;
  81     h->ret = h->func(h->arg);
  82     return 0;
  83 }
  84
  85 static int pthread_create(pthread_t *thread, const void *unused_attr,
  86                           void *(*start_routine)(void*), void *arg)
  87 {
  88     thread->func   = start_routine;
  89     thread->arg    = arg;
  90     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  91                                            0, NULL);
  92     return !thread->handle;
  93 }
  94
  95 static void pthread_join(pthread_t thread, void **value_ptr)
  96 {
  97     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  98     if (ret != WAIT_OBJECT_0)
  99         return;
 100     if (value_ptr)
 101         *value_ptr = thread.ret;
 102     CloseHandle(thread.handle);
 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 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 127  * variable and api */
 128 typedef struct  win32_cond_t {
 129     pthread_mutex_t mtx_broadcast;
 130     pthread_mutex_t mtx_waiter_count;
 131     volatile int waiter_count;
 132     HANDLE semaphore;
 133     HANDLE waiters_done;
 134     volatile int is_broadcast;
 135 } win32_cond_t;
 136
 137 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 138 {
 139     win32_cond_t *win32_cond = NULL;
 140     if (cond_init) {
 141         cond_init(cond);
 142         return;
 143     }
 144
 145     /* non native condition variables */
 146     win32_cond = av_mallocz(sizeof(win32_cond_t));
 147     if (!win32_cond)
 148         return;
 149     cond->ptr = win32_cond;
 150     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 151     if (!win32_cond->semaphore)
 152         return;
 153     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 154     if (!win32_cond->waiters_done)
 155         return;
 156
 157     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 158     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 159 }
 160
 161 static void pthread_cond_destroy(pthread_cond_t *cond)
 162 {
 163     win32_cond_t *win32_cond = cond->ptr;
 164     /* native condition variables do not destroy */
 165     if (cond_init)
 166         return;
 167
 168     /* non native condition variables */
 169     CloseHandle(win32_cond->semaphore);
 170     CloseHandle(win32_cond->waiters_done);
 171     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 172     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 173     av_freep(&win32_cond);
 174     cond->ptr = NULL;
 175 }
 176
 177 static void pthread_cond_broadcast(pthread_cond_t *cond)
 178 {
 179     win32_cond_t *win32_cond = cond->ptr;
 180     int have_waiter;
 181
 182     if (cond_broadcast) {
 183         cond_broadcast(cond);
 184         return;
 185     }
 186
 187     /* non native condition variables */
 188     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 189     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 190     have_waiter = 0;
 191
 192     if (win32_cond->waiter_count) {
 193         win32_cond->is_broadcast = 1;
 194         have_waiter = 1;
 195     }
 196
 197     if (have_waiter) {
 198         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 199         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 200         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 201         ResetEvent(win32_cond->waiters_done);
 202         win32_cond->is_broadcast = 0;
 203     } else
 204         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 205     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 206 }
 207
 208 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 209 {
 210     win32_cond_t *win32_cond = cond->ptr;
 211     int last_waiter;
 212     if (cond_wait) {
 213         cond_wait(cond, mutex, INFINITE);
 214         return 0;
 215     }
 216
 217     /* non native condition variables */
 218     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 219     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 220     win32_cond->waiter_count++;
 221     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 222     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 223
 224     // unlock the external mutex
 225     pthread_mutex_unlock(mutex);
 226     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 227
 228     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 229     win32_cond->waiter_count--;
 230     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 231     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 232
 233     if (last_waiter)
 234         SetEvent(win32_cond->waiters_done);
 235
 236     // lock the external mutex
 237     return pthread_mutex_lock(mutex);
 238 }
 239
 240 static void pthread_cond_signal(pthread_cond_t *cond)
 241 {
 242     win32_cond_t *win32_cond = cond->ptr;
 243     int have_waiter;
 244     if (cond_signal) {
 245         cond_signal(cond);
 246         return;
 247     }
 248
 249     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 250
 251     /* non-native condition variables */
 252     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 253     have_waiter = win32_cond->waiter_count;
 254     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 255
 256     if (have_waiter) {
 257         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 258         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 259         ResetEvent(win32_cond->waiters_done);
 260     }
 261
 262     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 263 }
 264
 265 static void w32thread_init(void)
 266 {
 267 #if _WIN32_WINNT < 0x0600
 268     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 269     /* if one is available, then they should all be available */
 270     cond_init      =
 271         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 272     cond_broadcast =
 273         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 274     cond_signal    =
 275         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 276     cond_wait      =
 277         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 278 #endif
 279
 280 }
 281
 282 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */