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 CONDITION_VARIABLE typedef for using Windows' native
  58  * conditional variables on kernels 6.0+. */
  59 #if HAVE_CONDITION_VARIABLE_PTR
  60 typedef CONDITION_VARIABLE pthread_cond_t;
  61 #else
  62 typedef struct pthread_cond_t {
  63     void *Ptr;
  64 } pthread_cond_t;
  65 #endif
  66
  67 #if _WIN32_WINNT >= 0x0600
  68 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  69 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  70 #endif
  71
  72 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  73 {
  74     pthread_t *h = arg;
  75     h->ret = h->func(h->arg);
  76     return 0;
  77 }
  78
  79 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
  80                                     void *(*start_routine)(void*), void *arg)
  81 {
  82     thread->func   = start_routine;
  83     thread->arg    = arg;
  84     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  85                                            0, NULL);
  86     return !thread->handle;
  87 }
  88
  89 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
  90 {
  91     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  92     if (ret != WAIT_OBJECT_0)
  93         return;
  94     if (value_ptr)
  95         *value_ptr = thread.ret;
  96     CloseHandle(thread.handle);
  97 }
  98
  99 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 100 {
 101     InitializeCriticalSection(m);
 102     return 0;
 103 }
 104 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 105 {
 106     DeleteCriticalSection(m);
 107     return 0;
 108 }
 109 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 110 {
 111     EnterCriticalSection(m);
 112     return 0;
 113 }
 114 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 115 {
 116     LeaveCriticalSection(m);
 117     return 0;
 118 }
 119
 120 #if _WIN32_WINNT >= 0x0600
 121 static inline void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 122 {
 123     InitializeConditionVariable(cond);
 124 }
 125
 126 /* native condition variables do not destroy */
 127 static inline void pthread_cond_destroy(pthread_cond_t *cond)
 128 {
 129     return;
 130 }
 131
 132 static inline void pthread_cond_broadcast(pthread_cond_t *cond)
 133 {
 134     WakeAllConditionVariable(cond);
 135 }
 136
 137 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 138 {
 139     SleepConditionVariableCS(cond, mutex, INFINITE);
 140     return 0;
 141 }
 142
 143 static inline void pthread_cond_signal(pthread_cond_t *cond)
 144 {
 145     WakeConditionVariable(cond);
 146 }
 147
 148 #else // _WIN32_WINNT < 0x0600
 149 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 150  * variable and api */
 151 typedef struct  win32_cond_t {
 152     pthread_mutex_t mtx_broadcast;
 153     pthread_mutex_t mtx_waiter_count;
 154     volatile int waiter_count;
 155     HANDLE semaphore;
 156     HANDLE waiters_done;
 157     volatile int is_broadcast;
 158 } win32_cond_t;
 159
 160 /* function pointers to conditional variable API on windows 6.0+ kernels */
 161 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
 162 static void (WINAPI *cond_init)(pthread_cond_t *cond);
 163 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
 164 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
 165                                 DWORD milliseconds);
 166
 167 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 168 {
 169     win32_cond_t *win32_cond = NULL;
 170     if (cond_init) {
 171         cond_init(cond);
 172         return;
 173     }
 174
 175     /* non native condition variables */
 176     win32_cond = av_mallocz(sizeof(win32_cond_t));
 177     if (!win32_cond)
 178         return;
 179     cond->Ptr = win32_cond;
 180     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 181     if (!win32_cond->semaphore)
 182         return;
 183     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 184     if (!win32_cond->waiters_done)
 185         return;
 186
 187     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 188     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 189 }
 190
 191 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 192 {
 193     win32_cond_t *win32_cond = cond->Ptr;
 194     /* native condition variables do not destroy */
 195     if (cond_init)
 196         return;
 197
 198     /* non native condition variables */
 199     CloseHandle(win32_cond->semaphore);
 200     CloseHandle(win32_cond->waiters_done);
 201     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 202     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 203     av_freep(&win32_cond);
 204     cond->Ptr = NULL;
 205 }
 206
 207 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 208 {
 209     win32_cond_t *win32_cond = cond->Ptr;
 210     int have_waiter;
 211
 212     if (cond_broadcast) {
 213         cond_broadcast(cond);
 214         return;
 215     }
 216
 217     /* non native condition variables */
 218     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 219     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 220     have_waiter = 0;
 221
 222     if (win32_cond->waiter_count) {
 223         win32_cond->is_broadcast = 1;
 224         have_waiter = 1;
 225     }
 226
 227     if (have_waiter) {
 228         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 229         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 230         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 231         ResetEvent(win32_cond->waiters_done);
 232         win32_cond->is_broadcast = 0;
 233     } else
 234         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 235     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 236 }
 237
 238 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 239 {
 240     win32_cond_t *win32_cond = cond->Ptr;
 241     int last_waiter;
 242     if (cond_wait) {
 243         cond_wait(cond, mutex, INFINITE);
 244         return 0;
 245     }
 246
 247     /* non native condition variables */
 248     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 249     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 250     win32_cond->waiter_count++;
 251     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 252     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 253
 254     // unlock the external mutex
 255     pthread_mutex_unlock(mutex);
 256     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 257
 258     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 259     win32_cond->waiter_count--;
 260     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 261     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 262
 263     if (last_waiter)
 264         SetEvent(win32_cond->waiters_done);
 265
 266     // lock the external mutex
 267     return pthread_mutex_lock(mutex);
 268 }
 269
 270 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 271 {
 272     win32_cond_t *win32_cond = cond->Ptr;
 273     int have_waiter;
 274     if (cond_signal) {
 275         cond_signal(cond);
 276         return;
 277     }
 278
 279     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 280
 281     /* non-native condition variables */
 282     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 283     have_waiter = win32_cond->waiter_count;
 284     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 285
 286     if (have_waiter) {
 287         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 288         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 289         ResetEvent(win32_cond->waiters_done);
 290     }
 291
 292     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 293 }
 294 #endif
 295
 296 static av_unused void w32thread_init(void)
 297 {
 298 #if _WIN32_WINNT < 0x0600
 299     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 300     /* if one is available, then they should all be available */
 301     cond_init      =
 302         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 303     cond_broadcast =
 304         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 305     cond_signal    =
 306         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 307     cond_wait      =
 308         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 309 #endif
 310
 311 }
 312
 313 #endif /* LIBAV_COMPAT_W32PTHREADS_H */