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
  77 #define CreateEvent(a, reset, init, name)                   \
  78     CreateEventEx(a, name,                                  \
  79                   (reset ? CREATE_EVENT_MANUAL_RESET : 0) | \
  80                   (init ? CREATE_EVENT_INITIAL_SET : 0),    \
  81                   EVENT_ALL_ACCESS)
  82 // CreateSemaphoreExA seems to be desktop-only, but as long as we don't
  83 // use named semaphores, it doesn't matter if we use the W version.
  84 #define CreateSemaphore(a, b, c, d) \
  85     CreateSemaphoreExW(a, b, c, d, 0, SEMAPHORE_ALL_ACCESS)
  86 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  87 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  88 #endif
  89
  90 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  91 {
  92     pthread_t *h = arg;
  93     h->ret = h->func(h->arg);
  94     return 0;
  95 }
  96
  97 static int pthread_create(pthread_t *thread, const void *unused_attr,
  98                           void *(*start_routine)(void*), void *arg)
  99 {
 100     thread->func   = start_routine;
 101     thread->arg    = arg;
 102     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
 103                                            0, NULL);
 104     return !thread->handle;
 105 }
 106
 107 static void pthread_join(pthread_t thread, void **value_ptr)
 108 {
 109     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
 110     if (ret != WAIT_OBJECT_0)
 111         return;
 112     if (value_ptr)
 113         *value_ptr = thread.ret;
 114     CloseHandle(thread.handle);
 115 }
 116
 117 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 118 {
 119     InitializeCriticalSection(m);
 120     return 0;
 121 }
 122 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 123 {
 124     DeleteCriticalSection(m);
 125     return 0;
 126 }
 127 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 128 {
 129     EnterCriticalSection(m);
 130     return 0;
 131 }
 132 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 133 {
 134     LeaveCriticalSection(m);
 135     return 0;
 136 }
 137
 138 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 139  * variable and api */
 140 typedef struct  win32_cond_t {
 141     pthread_mutex_t mtx_broadcast;
 142     pthread_mutex_t mtx_waiter_count;
 143     volatile int waiter_count;
 144     HANDLE semaphore;
 145     HANDLE waiters_done;
 146     volatile int is_broadcast;
 147 } win32_cond_t;
 148
 149 static int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 150 {
 151     win32_cond_t *win32_cond = NULL;
 152     if (cond_init) {
 153         cond_init(cond);
 154         return 0;
 155     }
 156
 157     /* non native condition variables */
 158     win32_cond = av_mallocz(sizeof(win32_cond_t));
 159     if (!win32_cond)
 160         return ENOMEM;
 161     cond->ptr = win32_cond;
 162     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 163     if (!win32_cond->semaphore)
 164         return ENOMEM;
 165     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 166     if (!win32_cond->waiters_done)
 167         return ENOMEM;
 168
 169     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 170     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 171     return 0;
 172 }
 173
 174 static void pthread_cond_destroy(pthread_cond_t *cond)
 175 {
 176     win32_cond_t *win32_cond = cond->ptr;
 177     /* native condition variables do not destroy */
 178     if (cond_init)
 179         return;
 180
 181     /* non native condition variables */
 182     CloseHandle(win32_cond->semaphore);
 183     CloseHandle(win32_cond->waiters_done);
 184     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 185     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 186     av_freep(&win32_cond);
 187     cond->ptr = NULL;
 188 }
 189
 190 static void pthread_cond_broadcast(pthread_cond_t *cond)
 191 {
 192     win32_cond_t *win32_cond = cond->ptr;
 193     int have_waiter;
 194
 195     if (cond_broadcast) {
 196         cond_broadcast(cond);
 197         return;
 198     }
 199
 200     /* non native condition variables */
 201     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 202     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 203     have_waiter = 0;
 204
 205     if (win32_cond->waiter_count) {
 206         win32_cond->is_broadcast = 1;
 207         have_waiter = 1;
 208     }
 209
 210     if (have_waiter) {
 211         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 212         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 213         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 214         ResetEvent(win32_cond->waiters_done);
 215         win32_cond->is_broadcast = 0;
 216     } else
 217         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 218     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 219 }
 220
 221 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 222 {
 223     win32_cond_t *win32_cond = cond->ptr;
 224     int last_waiter;
 225     if (cond_wait) {
 226         cond_wait(cond, mutex, INFINITE);
 227         return 0;
 228     }
 229
 230     /* non native condition variables */
 231     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 232     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 233     win32_cond->waiter_count++;
 234     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 235     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 236
 237     // unlock the external mutex
 238     pthread_mutex_unlock(mutex);
 239     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 240
 241     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 242     win32_cond->waiter_count--;
 243     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 244     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 245
 246     if (last_waiter)
 247         SetEvent(win32_cond->waiters_done);
 248
 249     // lock the external mutex
 250     return pthread_mutex_lock(mutex);
 251 }
 252
 253 static void pthread_cond_signal(pthread_cond_t *cond)
 254 {
 255     win32_cond_t *win32_cond = cond->ptr;
 256     int have_waiter;
 257     if (cond_signal) {
 258         cond_signal(cond);
 259         return;
 260     }
 261
 262     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 263
 264     /* non-native condition variables */
 265     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 266     have_waiter = win32_cond->waiter_count;
 267     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 268
 269     if (have_waiter) {
 270         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 271         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 272         ResetEvent(win32_cond->waiters_done);
 273     }
 274
 275     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 276 }
 277
 278 static void w32thread_init(void)
 279 {
 280 #if _WIN32_WINNT < 0x0600
 281     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 282     /* if one is available, then they should all be available */
 283     cond_init      =
 284         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 285     cond_broadcast =
 286         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 287     cond_signal    =
 288         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 289     cond_wait      =
 290         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 291 #endif
 292
 293 }
 294
 295 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */