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/internal.h"
  43 #include "libavutil/mem.h"
  44
  45 typedef struct pthread_t {
  46     void *handle;
  47     void *(*func)(void* arg);
  48     void *arg;
  49     void *ret;
  50 } pthread_t;
  51
  52 /* the conditional variable api for windows 6.0+ uses critical sections and
  53  * not mutexes */
  54 typedef CRITICAL_SECTION pthread_mutex_t;
  55
  56 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
  57  * conditional variables on kernels 6.0+.
  58  * MinGW does not currently have this typedef. */
  59 typedef struct pthread_cond_t {
  60     void *ptr;
  61 } pthread_cond_t;
  62
  63 /* function pointers to conditional variable API on windows 6.0+ kernels */
  64 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  65 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  66 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  67 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  68                                 DWORD milliseconds);
  69
  70 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  71 {
  72     pthread_t *h = arg;
  73     h->ret = h->func(h->arg);
  74     return 0;
  75 }
  76
  77 static int pthread_create(pthread_t *thread, const void *unused_attr,
  78                           void *(*start_routine)(void*), void *arg)
  79 {
  80     thread->func   = start_routine;
  81     thread->arg    = arg;
  82     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  83                                            0, NULL);
  84     return !thread->handle;
  85 }
  86
  87 static void pthread_join(pthread_t thread, void **value_ptr)
  88 {
  89     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  90     if (ret != WAIT_OBJECT_0)
  91         return;
  92     if (value_ptr)
  93         *value_ptr = thread.ret;
  94     CloseHandle(thread.handle);
  95 }
  96
  97 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
  98 {
  99     InitializeCriticalSection(m);
 100     return 0;
 101 }
 102 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 103 {
 104     DeleteCriticalSection(m);
 105     return 0;
 106 }
 107 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 108 {
 109     EnterCriticalSection(m);
 110     return 0;
 111 }
 112 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 113 {
 114     LeaveCriticalSection(m);
 115     return 0;
 116 }
 117
 118 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 119  * variable and api */
 120 typedef struct  win32_cond_t {
 121     pthread_mutex_t mtx_broadcast;
 122     pthread_mutex_t mtx_waiter_count;
 123     volatile int waiter_count;
 124     HANDLE semaphore;
 125     HANDLE waiters_done;
 126     volatile int is_broadcast;
 127 } win32_cond_t;
 128
 129 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 130 {
 131     win32_cond_t *win32_cond = NULL;
 132     if (cond_init) {
 133         cond_init(cond);
 134         return;
 135     }
 136
 137     /* non native condition variables */
 138     win32_cond = av_mallocz(sizeof(win32_cond_t));
 139     if (!win32_cond)
 140         return;
 141     cond->ptr = win32_cond;
 142     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 143     if (!win32_cond->semaphore)
 144         return;
 145     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 146     if (!win32_cond->waiters_done)
 147         return;
 148
 149     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 150     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 151 }
 152
 153 static void pthread_cond_destroy(pthread_cond_t *cond)
 154 {
 155     win32_cond_t *win32_cond = cond->ptr;
 156     /* native condition variables do not destroy */
 157     if (cond_init)
 158         return;
 159
 160     /* non native condition variables */
 161     CloseHandle(win32_cond->semaphore);
 162     CloseHandle(win32_cond->waiters_done);
 163     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 164     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 165     av_freep(&win32_cond);
 166     cond->ptr = NULL;
 167 }
 168
 169 static void pthread_cond_broadcast(pthread_cond_t *cond)
 170 {
 171     win32_cond_t *win32_cond = cond->ptr;
 172     int have_waiter;
 173
 174     if (cond_broadcast) {
 175         cond_broadcast(cond);
 176         return;
 177     }
 178
 179     /* non native condition variables */
 180     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 181     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 182     have_waiter = 0;
 183
 184     if (win32_cond->waiter_count) {
 185         win32_cond->is_broadcast = 1;
 186         have_waiter = 1;
 187     }
 188
 189     if (have_waiter) {
 190         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 191         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 192         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 193         ResetEvent(win32_cond->waiters_done);
 194         win32_cond->is_broadcast = 0;
 195     } else
 196         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 197     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 198 }
 199
 200 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 201 {
 202     win32_cond_t *win32_cond = cond->ptr;
 203     int last_waiter;
 204     if (cond_wait) {
 205         cond_wait(cond, mutex, INFINITE);
 206         return 0;
 207     }
 208
 209     /* non native condition variables */
 210     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 211     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 212     win32_cond->waiter_count++;
 213     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 214     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 215
 216     // unlock the external mutex
 217     pthread_mutex_unlock(mutex);
 218     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 219
 220     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 221     win32_cond->waiter_count--;
 222     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 223     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 224
 225     if (last_waiter)
 226         SetEvent(win32_cond->waiters_done);
 227
 228     // lock the external mutex
 229     return pthread_mutex_lock(mutex);
 230 }
 231
 232 static void pthread_cond_signal(pthread_cond_t *cond)
 233 {
 234     win32_cond_t *win32_cond = cond->ptr;
 235     int have_waiter;
 236     if (cond_signal) {
 237         cond_signal(cond);
 238         return;
 239     }
 240
 241     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 242
 243     /* non-native condition variables */
 244     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 245     have_waiter = win32_cond->waiter_count;
 246     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 247
 248     if (have_waiter) {
 249         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 250         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 251         ResetEvent(win32_cond->waiters_done);
 252     }
 253
 254     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 255 }
 256
 257 static void w32thread_init(void)
 258 {
 259     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 260     /* if one is available, then they should all be available */
 261     cond_init      =
 262         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 263     cond_broadcast =
 264         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 265     cond_signal    =
 266         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 267     cond_wait      =
 268         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 269 }
 270
 271 #endif /* AVCODEC_W32PTHREADS_H */