git.sesse.net Git - ffmpeg/blob - libavcodec/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 AVCODEC_W32PTHREADS_H
  30 #define AVCODEC_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 {
  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 {
  61     void *ptr;
  62 } pthread_cond_t;
  63
  64 /* function pointers to conditional variable API on windows 6.0+ kernels */
  65 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  66 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  67 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  68 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  69                                 DWORD milliseconds);
  70
  71 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  72 {
  73     pthread_t *h = arg;
  74     h->ret = h->func(h->arg);
  75     return 0;
  76 }
  77
  78 static int pthread_create(pthread_t *thread, const void *unused_attr,
  79                           void *(*start_routine)(void*), void *arg)
  80 {
  81     thread->func   = start_routine;
  82     thread->arg    = arg;
  83     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  84                                            0, NULL);
  85     return !thread->handle;
  86 }
  87
  88 static void pthread_join(pthread_t thread, void **value_ptr)
  89 {
  90     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  91     if (ret != WAIT_OBJECT_0)
  92         return;
  93     if (value_ptr)
  94         *value_ptr = thread.ret;
  95     CloseHandle(thread.handle);
  96 }
  97
  98 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
  99 {
 100     InitializeCriticalSection(m);
 101     return 0;
 102 }
 103 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 104 {
 105     DeleteCriticalSection(m);
 106     return 0;
 107 }
 108 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 109 {
 110     EnterCriticalSection(m);
 111     return 0;
 112 }
 113 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 114 {
 115     LeaveCriticalSection(m);
 116     return 0;
 117 }
 118
 119 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 120  * variable and api */
 121 typedef struct {
 122     pthread_mutex_t mtx_broadcast;
 123     pthread_mutex_t mtx_waiter_count;
 124     volatile int waiter_count;
 125     HANDLE semaphore;
 126     HANDLE waiters_done;
 127     volatile int is_broadcast;
 128 } win32_cond_t;
 129
 130 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 131 {
 132     win32_cond_t *win32_cond = NULL;
 133     if (cond_init) {
 134         cond_init(cond);
 135         return;
 136     }
 137
 138     /* non native condition variables */
 139     win32_cond = av_mallocz(sizeof(win32_cond_t));
 140     if (!win32_cond)
 141         return;
 142     cond->ptr = win32_cond;
 143     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 144     if (!win32_cond->semaphore)
 145         return;
 146     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 147     if (!win32_cond->waiters_done)
 148         return;
 149
 150     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 151     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 152 }
 153
 154 static void pthread_cond_destroy(pthread_cond_t *cond)
 155 {
 156     win32_cond_t *win32_cond = cond->ptr;
 157     /* native condition variables do not destroy */
 158     if (cond_init)
 159         return;
 160
 161     /* non native condition variables */
 162     CloseHandle(win32_cond->semaphore);
 163     CloseHandle(win32_cond->waiters_done);
 164     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 165     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 166     av_freep(&win32_cond);
 167     cond->ptr = NULL;
 168 }
 169
 170 static void pthread_cond_broadcast(pthread_cond_t *cond)
 171 {
 172     win32_cond_t *win32_cond = cond->ptr;
 173     int have_waiter;
 174
 175     if (cond_broadcast) {
 176         cond_broadcast(cond);
 177         return;
 178     }
 179
 180     /* non native condition variables */
 181     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 182     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 183     have_waiter = 0;
 184
 185     if (win32_cond->waiter_count) {
 186         win32_cond->is_broadcast = 1;
 187         have_waiter = 1;
 188     }
 189
 190     if (have_waiter) {
 191         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 192         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 193         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 194         ResetEvent(win32_cond->waiters_done);
 195         win32_cond->is_broadcast = 0;
 196     } else
 197         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 198     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 199 }
 200
 201 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 202 {
 203     win32_cond_t *win32_cond = cond->ptr;
 204     int last_waiter;
 205     if (cond_wait) {
 206         cond_wait(cond, mutex, INFINITE);
 207         return 0;
 208     }
 209
 210     /* non native condition variables */
 211     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 212     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 213     win32_cond->waiter_count++;
 214     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 215     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 216
 217     // unlock the external mutex
 218     pthread_mutex_unlock(mutex);
 219     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 220
 221     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 222     win32_cond->waiter_count--;
 223     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 224     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 225
 226     if (last_waiter)
 227         SetEvent(win32_cond->waiters_done);
 228
 229     // lock the external mutex
 230     return pthread_mutex_lock(mutex);
 231 }
 232
 233 static void pthread_cond_signal(pthread_cond_t *cond)
 234 {
 235     win32_cond_t *win32_cond = cond->ptr;
 236     int have_waiter;
 237     if (cond_signal) {
 238         cond_signal(cond);
 239         return;
 240     }
 241
 242     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 243
 244     /* non-native condition variables */
 245     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 246     have_waiter = win32_cond->waiter_count;
 247     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 248
 249     if (have_waiter) {
 250         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 251         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 252         ResetEvent(win32_cond->waiters_done);
 253     }
 254
 255     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 256 }
 257
 258 static void w32thread_init(void)
 259 {
 260     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 261     /* if one is available, then they should all be available */
 262     cond_init      =
 263         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 264     cond_broadcast =
 265         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 266     cond_signal    =
 267         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 268     cond_wait      =
 269         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 270 }
 271
 272 #endif /* AVCODEC_W32PTHREADS_H */