w32pthreads: use the CONDITION_VARIABLE typedef if available
[libav.git] / compat / w32pthreads.h
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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
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29#ifndef LIBAV_COMPAT_W32PTHREADS_H
30#define LIBAV_COMPAT_W32PTHREADS_H
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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
6baeadd1 42#include "libavutil/attributes.h"
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43#include "libavutil/internal.h"
44#include "libavutil/mem.h"
45
e4cbf752 46typedef struct pthread_t {
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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 */
55typedef CRITICAL_SECTION pthread_mutex_t;
56
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57/* This is the CONDITION_VARIABLE typedef for using Windows' native
58 * conditional variables on kernels 6.0+. */
59#if HAVE_CONDITION_VARIABLE_PTR
60typedef CONDITION_VARIABLE pthread_cond_t;
61#else
e4cbf752 62typedef struct pthread_cond_t {
73ea3ffc 63 void *Ptr;
27237d52 64} pthread_cond_t;
73ea3ffc 65#endif
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66
67/* function pointers to conditional variable API on windows 6.0+ kernels */
4332bf98 68#if _WIN32_WINNT < 0x0600
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69static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
70static void (WINAPI *cond_init)(pthread_cond_t *cond);
71static void (WINAPI *cond_signal)(pthread_cond_t *cond);
72static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
73 DWORD milliseconds);
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74#else
75#define cond_init InitializeConditionVariable
76#define cond_broadcast WakeAllConditionVariable
77#define cond_signal WakeConditionVariable
78#define cond_wait SleepConditionVariableCS
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79
80#define CreateEvent(a, reset, init, name) \
81 CreateEventEx(a, name, \
82 (reset ? CREATE_EVENT_MANUAL_RESET : 0) | \
83 (init ? CREATE_EVENT_INITIAL_SET : 0), \
84 EVENT_ALL_ACCESS)
85// CreateSemaphoreExA seems to be desktop-only, but as long as we don't
86// use named semaphores, it doesn't matter if we use the W version.
87#define CreateSemaphore(a, b, c, d) \
88 CreateSemaphoreExW(a, b, c, d, 0, SEMAPHORE_ALL_ACCESS)
89#define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
90#define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
4332bf98 91#endif
27237d52 92
6baeadd1 93static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
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94{
95 pthread_t *h = arg;
96 h->ret = h->func(h->arg);
97 return 0;
98}
99
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100static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
101 void *(*start_routine)(void*), void *arg)
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102{
103 thread->func = start_routine;
104 thread->arg = arg;
105 thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
106 0, NULL);
107 return !thread->handle;
108}
109
6baeadd1 110static av_unused void pthread_join(pthread_t thread, void **value_ptr)
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111{
112 DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
113 if (ret != WAIT_OBJECT_0)
114 return;
115 if (value_ptr)
116 *value_ptr = thread.ret;
117 CloseHandle(thread.handle);
118}
119
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120static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
121{
122 InitializeCriticalSection(m);
123 return 0;
124}
125static inline int pthread_mutex_destroy(pthread_mutex_t *m)
126{
127 DeleteCriticalSection(m);
128 return 0;
129}
130static inline int pthread_mutex_lock(pthread_mutex_t *m)
131{
132 EnterCriticalSection(m);
133 return 0;
134}
135static inline int pthread_mutex_unlock(pthread_mutex_t *m)
136{
137 LeaveCriticalSection(m);
138 return 0;
139}
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140
141/* for pre-Windows 6.0 platforms we need to define and use our own condition
142 * variable and api */
e4cbf752 143typedef struct win32_cond_t {
8b03d7fe 144 pthread_mutex_t mtx_broadcast;
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145 pthread_mutex_t mtx_waiter_count;
146 volatile int waiter_count;
147 HANDLE semaphore;
8b03d7fe 148 HANDLE waiters_done;
01eb9805 149 volatile int is_broadcast;
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150} win32_cond_t;
151
6baeadd1 152static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
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153{
154 win32_cond_t *win32_cond = NULL;
ef51692a 155 if (cond_init) {
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156 cond_init(cond);
157 return;
158 }
159
160 /* non native condition variables */
161 win32_cond = av_mallocz(sizeof(win32_cond_t));
162 if (!win32_cond)
163 return;
73ea3ffc 164 cond->Ptr = win32_cond;
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165 win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
166 if (!win32_cond->semaphore)
167 return;
2003a292 168 win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
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169 if (!win32_cond->waiters_done)
170 return;
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171
172 pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
8b03d7fe 173 pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
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174}
175
6baeadd1 176static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
27237d52 177{
73ea3ffc 178 win32_cond_t *win32_cond = cond->Ptr;
27237d52 179 /* native condition variables do not destroy */
ef51692a 180 if (cond_init)
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181 return;
182
183 /* non native condition variables */
184 CloseHandle(win32_cond->semaphore);
8b03d7fe 185 CloseHandle(win32_cond->waiters_done);
27237d52 186 pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
8b03d7fe 187 pthread_mutex_destroy(&win32_cond->mtx_broadcast);
27237d52 188 av_freep(&win32_cond);
73ea3ffc 189 cond->Ptr = NULL;
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190}
191
6baeadd1 192static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
27237d52 193{
73ea3ffc 194 win32_cond_t *win32_cond = cond->Ptr;
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195 int have_waiter;
196
ef51692a 197 if (cond_broadcast) {
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198 cond_broadcast(cond);
199 return;
200 }
201
202 /* non native condition variables */
8b03d7fe 203 pthread_mutex_lock(&win32_cond->mtx_broadcast);
27237d52 204 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
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205 have_waiter = 0;
206
27237d52 207 if (win32_cond->waiter_count) {
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208 win32_cond->is_broadcast = 1;
209 have_waiter = 1;
27237d52 210 }
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211
212 if (have_waiter) {
213 ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
214 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
215 WaitForSingleObject(win32_cond->waiters_done, INFINITE);
01eb9805 216 ResetEvent(win32_cond->waiters_done);
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217 win32_cond->is_broadcast = 0;
218 } else
219 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
220 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
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221}
222
6baeadd1 223static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
27237d52 224{
73ea3ffc 225 win32_cond_t *win32_cond = cond->Ptr;
8b03d7fe 226 int last_waiter;
ef51692a 227 if (cond_wait) {
27237d52 228 cond_wait(cond, mutex, INFINITE);
91dffb4c 229 return 0;
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230 }
231
232 /* non native condition variables */
8b03d7fe 233 pthread_mutex_lock(&win32_cond->mtx_broadcast);
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234 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
235 win32_cond->waiter_count++;
236 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
2003a292 237 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
27237d52 238
8b03d7fe 239 // unlock the external mutex
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240 pthread_mutex_unlock(mutex);
241 WaitForSingleObject(win32_cond->semaphore, INFINITE);
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242
243 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
244 win32_cond->waiter_count--;
2003a292 245 last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
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246 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
247
248 if (last_waiter)
249 SetEvent(win32_cond->waiters_done);
250
251 // lock the external mutex
252 return pthread_mutex_lock(mutex);
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253}
254
6baeadd1 255static av_unused void pthread_cond_signal(pthread_cond_t *cond)
27237d52 256{
73ea3ffc 257 win32_cond_t *win32_cond = cond->Ptr;
8b03d7fe 258 int have_waiter;
ef51692a 259 if (cond_signal) {
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260 cond_signal(cond);
261 return;
262 }
263
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264 pthread_mutex_lock(&win32_cond->mtx_broadcast);
265
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266 /* non-native condition variables */
267 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
8b03d7fe 268 have_waiter = win32_cond->waiter_count;
27237d52 269 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
8b03d7fe 270
2003a292 271 if (have_waiter) {
8b03d7fe 272 ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
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273 WaitForSingleObject(win32_cond->waiters_done, INFINITE);
274 ResetEvent(win32_cond->waiters_done);
275 }
276
277 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
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278}
279
6baeadd1 280static av_unused void w32thread_init(void)
27237d52 281{
c360fb17 282#if _WIN32_WINNT < 0x0600
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283 HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
284 /* if one is available, then they should all be available */
285 cond_init =
286 (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
287 cond_broadcast =
288 (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
289 cond_signal =
290 (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
291 cond_wait =
292 (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
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293#endif
294
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295}
296
439902e0 297#endif /* LIBAV_COMPAT_W32PTHREADS_H */