w32pthreads: use the condition variable API directly when targeting newer versions...
[libav.git] / 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 */