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 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 LIBAV_COMPAT_W32PTHREADS_H
  30 #define LIBAV_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/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 av_unused 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 av_unused 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 av_unused 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 av_unused void 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;
 155     }
 156
 157     /* non native condition variables */
 158     win32_cond = av_mallocz(sizeof(win32_cond_t));
 159     if (!win32_cond)
 160         return;
 161     cond->ptr = win32_cond;
 162     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 163     if (!win32_cond->semaphore)
 164         return;
 165     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 166     if (!win32_cond->waiters_done)
 167         return;
 168
 169     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 170     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 171 }
 172
 173 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 174 {
 175     win32_cond_t *win32_cond = cond->ptr;
 176     /* native condition variables do not destroy */
 177     if (cond_init)
 178         return;
 179
 180     /* non native condition variables */
 181     CloseHandle(win32_cond->semaphore);
 182     CloseHandle(win32_cond->waiters_done);
 183     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 184     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 185     av_freep(&win32_cond);
 186     cond->ptr = NULL;
 187 }
 188
 189 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 190 {
 191     win32_cond_t *win32_cond = cond->ptr;
 192     int have_waiter;
 193
 194     if (cond_broadcast) {
 195         cond_broadcast(cond);
 196         return;
 197     }
 198
 199     /* non native condition variables */
 200     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 201     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 202     have_waiter = 0;
 203
 204     if (win32_cond->waiter_count) {
 205         win32_cond->is_broadcast = 1;
 206         have_waiter = 1;
 207     }
 208
 209     if (have_waiter) {
 210         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 211         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 212         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 213         ResetEvent(win32_cond->waiters_done);
 214         win32_cond->is_broadcast = 0;
 215     } else
 216         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 217     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 218 }
 219
 220 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 221 {
 222     win32_cond_t *win32_cond = cond->ptr;
 223     int last_waiter;
 224     if (cond_wait) {
 225         cond_wait(cond, mutex, INFINITE);
 226         return 0;
 227     }
 228
 229     /* non native condition variables */
 230     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 231     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 232     win32_cond->waiter_count++;
 233     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 234     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 235
 236     // unlock the external mutex
 237     pthread_mutex_unlock(mutex);
 238     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 239
 240     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 241     win32_cond->waiter_count--;
 242     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 243     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 244
 245     if (last_waiter)
 246         SetEvent(win32_cond->waiters_done);
 247
 248     // lock the external mutex
 249     return pthread_mutex_lock(mutex);
 250 }
 251
 252 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 253 {
 254     win32_cond_t *win32_cond = cond->ptr;
 255     int have_waiter;
 256     if (cond_signal) {
 257         cond_signal(cond);
 258         return;
 259     }
 260
 261     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 262
 263     /* non-native condition variables */
 264     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 265     have_waiter = win32_cond->waiter_count;
 266     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 267
 268     if (have_waiter) {
 269         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 270         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 271         ResetEvent(win32_cond->waiters_done);
 272     }
 273
 274     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 275 }
 276
 277 static av_unused void w32thread_init(void)
 278 {
 279 #if _WIN32_WINNT < 0x0600
 280     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 281     /* if one is available, then they should all be available */
 282     cond_init      =
 283         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 284     cond_broadcast =
 285         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 286     cond_signal    =
 287         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 288     cond_wait      =
 289         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 290 #endif
 291
 292 }
 293
 294 #endif /* LIBAV_COMPAT_W32PTHREADS_H */