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/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 CONDITIONAL_VARIABLE typedef for using Window's native
  59  * conditional variables on kernels 6.0+.
  60  * MinGW does not currently have this typedef. */
  61 typedef struct pthread_cond_t {
  62     void *ptr;
  63 } pthread_cond_t;
  64
  65 /* function pointers to conditional variable API on windows 6.0+ kernels */
  66 #if _WIN32_WINNT < 0x0600
  67 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  68 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  69 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  70 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  71                                 DWORD milliseconds);
  72 #else
  73 #define cond_init      InitializeConditionVariable
  74 #define cond_broadcast WakeAllConditionVariable
  75 #define cond_signal    WakeConditionVariable
  76 #define cond_wait      SleepConditionVariableCS
  77
  78 #define CreateEvent(a, reset, init, name)                   \
  79     CreateEventEx(a, name,                                  \
  80                   (reset ? CREATE_EVENT_MANUAL_RESET : 0) | \
  81                   (init ? CREATE_EVENT_INITIAL_SET : 0),    \
  82                   EVENT_ALL_ACCESS)
  83 // CreateSemaphoreExA seems to be desktop-only, but as long as we don't
  84 // use named semaphores, it doesn't matter if we use the W version.
  85 #define CreateSemaphore(a, b, c, d) \
  86     CreateSemaphoreExW(a, b, c, d, 0, SEMAPHORE_ALL_ACCESS)
  87 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  88 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  89 #endif
  90
  91 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  92 {
  93     pthread_t *h = arg;
  94     h->ret = h->func(h->arg);
  95     return 0;
  96 }
  97
  98 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
  99                                     void *(*start_routine)(void*), void *arg)
 100 {
 101     thread->func   = start_routine;
 102     thread->arg    = arg;
 103     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
 104                                            0, NULL);
 105     return !thread->handle;
 106 }
 107
 108 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
 109 {
 110     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
 111     if (ret != WAIT_OBJECT_0)
 112         return;
 113     if (value_ptr)
 114         *value_ptr = thread.ret;
 115     CloseHandle(thread.handle);
 116 }
 117
 118 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 119 {
 120     InitializeCriticalSection(m);
 121     return 0;
 122 }
 123 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 124 {
 125     DeleteCriticalSection(m);
 126     return 0;
 127 }
 128 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 129 {
 130     EnterCriticalSection(m);
 131     return 0;
 132 }
 133 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 134 {
 135     LeaveCriticalSection(m);
 136     return 0;
 137 }
 138
 139 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 140  * variable and api */
 141 typedef struct  win32_cond_t {
 142     pthread_mutex_t mtx_broadcast;
 143     pthread_mutex_t mtx_waiter_count;
 144     volatile int waiter_count;
 145     HANDLE semaphore;
 146     HANDLE waiters_done;
 147     volatile int is_broadcast;
 148 } win32_cond_t;
 149
 150 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 151 {
 152     win32_cond_t *win32_cond = NULL;
 153     if (cond_init) {
 154         cond_init(cond);
 155         return 0;
 156     }
 157
 158     /* non native condition variables */
 159     win32_cond = av_mallocz(sizeof(win32_cond_t));
 160     if (!win32_cond)
 161         return ENOMEM;
 162     cond->ptr = win32_cond;
 163     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 164     if (!win32_cond->semaphore)
 165         return ENOMEM;
 166     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 167     if (!win32_cond->waiters_done)
 168         return ENOMEM;
 169
 170     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 171     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 172     return 0;
 173 }
 174
 175 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 176 {
 177     win32_cond_t *win32_cond = cond->ptr;
 178     /* native condition variables do not destroy */
 179     if (cond_init)
 180         return;
 181
 182     /* non native condition variables */
 183     CloseHandle(win32_cond->semaphore);
 184     CloseHandle(win32_cond->waiters_done);
 185     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 186     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 187     av_freep(&win32_cond);
 188     cond->ptr = NULL;
 189 }
 190
 191 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 192 {
 193     win32_cond_t *win32_cond = cond->ptr;
 194     int have_waiter;
 195
 196     if (cond_broadcast) {
 197         cond_broadcast(cond);
 198         return;
 199     }
 200
 201     /* non native condition variables */
 202     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 203     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 204     have_waiter = 0;
 205
 206     if (win32_cond->waiter_count) {
 207         win32_cond->is_broadcast = 1;
 208         have_waiter = 1;
 209     }
 210
 211     if (have_waiter) {
 212         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 213         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 214         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 215         ResetEvent(win32_cond->waiters_done);
 216         win32_cond->is_broadcast = 0;
 217     } else
 218         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 219     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 220 }
 221
 222 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 223 {
 224     win32_cond_t *win32_cond = cond->ptr;
 225     int last_waiter;
 226     if (cond_wait) {
 227         cond_wait(cond, mutex, INFINITE);
 228         return 0;
 229     }
 230
 231     /* non native condition variables */
 232     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 233     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 234     win32_cond->waiter_count++;
 235     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 236     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 237
 238     // unlock the external mutex
 239     pthread_mutex_unlock(mutex);
 240     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 241
 242     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 243     win32_cond->waiter_count--;
 244     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 245     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 246
 247     if (last_waiter)
 248         SetEvent(win32_cond->waiters_done);
 249
 250     // lock the external mutex
 251     return pthread_mutex_lock(mutex);
 252 }
 253
 254 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 255 {
 256     win32_cond_t *win32_cond = cond->ptr;
 257     int have_waiter;
 258     if (cond_signal) {
 259         cond_signal(cond);
 260         return;
 261     }
 262
 263     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 264
 265     /* non-native condition variables */
 266     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 267     have_waiter = win32_cond->waiter_count;
 268     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 269
 270     if (have_waiter) {
 271         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 272         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 273         ResetEvent(win32_cond->waiters_done);
 274     }
 275
 276     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 277 }
 278
 279 static av_unused void w32thread_init(void)
 280 {
 281 #if _WIN32_WINNT < 0x0600
 282     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 283     /* if one is available, then they should all be available */
 284     cond_init      =
 285         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 286     cond_broadcast =
 287         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 288     cond_signal    =
 289         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 290     cond_wait      =
 291         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 292 #endif
 293
 294 }
 295
 296 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */