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