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 int 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 0;
 143     }
 144
 145     /* non native condition variables */
 146     win32_cond = av_mallocz(sizeof(win32_cond_t));
 147     if (!win32_cond)
 148         return ENOMEM;
 149     cond->ptr = win32_cond;
 150     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 151     if (!win32_cond->semaphore)
 152         return ENOMEM;
 153     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 154     if (!win32_cond->waiters_done)
 155         return ENOMEM;
 156
 157     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 158     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 159     return 0;
 160 }
 161
 162 static void pthread_cond_destroy(pthread_cond_t *cond)
 163 {
 164     win32_cond_t *win32_cond = cond->ptr;
 165     /* native condition variables do not destroy */
 166     if (cond_init)
 167         return;
 168
 169     /* non native condition variables */
 170     CloseHandle(win32_cond->semaphore);
 171     CloseHandle(win32_cond->waiters_done);
 172     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 173     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 174     av_freep(&win32_cond);
 175     cond->ptr = NULL;
 176 }
 177
 178 static void pthread_cond_broadcast(pthread_cond_t *cond)
 179 {
 180     win32_cond_t *win32_cond = cond->ptr;
 181     int have_waiter;
 182
 183     if (cond_broadcast) {
 184         cond_broadcast(cond);
 185         return;
 186     }
 187
 188     /* non native condition variables */
 189     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 190     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 191     have_waiter = 0;
 192
 193     if (win32_cond->waiter_count) {
 194         win32_cond->is_broadcast = 1;
 195         have_waiter = 1;
 196     }
 197
 198     if (have_waiter) {
 199         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 200         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 201         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 202         ResetEvent(win32_cond->waiters_done);
 203         win32_cond->is_broadcast = 0;
 204     } else
 205         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 206     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 207 }
 208
 209 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 210 {
 211     win32_cond_t *win32_cond = cond->ptr;
 212     int last_waiter;
 213     if (cond_wait) {
 214         cond_wait(cond, mutex, INFINITE);
 215         return 0;
 216     }
 217
 218     /* non native condition variables */
 219     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 220     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 221     win32_cond->waiter_count++;
 222     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 223     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 224
 225     // unlock the external mutex
 226     pthread_mutex_unlock(mutex);
 227     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 228
 229     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 230     win32_cond->waiter_count--;
 231     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 232     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 233
 234     if (last_waiter)
 235         SetEvent(win32_cond->waiters_done);
 236
 237     // lock the external mutex
 238     return pthread_mutex_lock(mutex);
 239 }
 240
 241 static void pthread_cond_signal(pthread_cond_t *cond)
 242 {
 243     win32_cond_t *win32_cond = cond->ptr;
 244     int have_waiter;
 245     if (cond_signal) {
 246         cond_signal(cond);
 247         return;
 248     }
 249
 250     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 251
 252     /* non-native condition variables */
 253     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 254     have_waiter = win32_cond->waiter_count;
 255     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 256
 257     if (have_waiter) {
 258         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 259         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 260         ResetEvent(win32_cond->waiters_done);
 261     }
 262
 263     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 264 }
 265
 266 static void w32thread_init(void)
 267 {
 268 #if _WIN32_WINNT < 0x0600
 269     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 270     /* if one is available, then they should all be available */
 271     cond_init      =
 272         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 273     cond_broadcast =
 274         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 275     cond_signal    =
 276         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 277     cond_wait      =
 278         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 279 #endif
 280
 281 }
 282
 283 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */