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[ffmpeg.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 FFmpeg.
8  *
9  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 FFMPEG_COMPAT_W32PTHREADS_H
30 #define FFMPEG_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/common.h"
44 #include "libavutil/internal.h"
45 #include "libavutil/mem.h"
46
47 typedef struct pthread_t {
48     void *handle;
49     void *(*func)(void* arg);
50     void *arg;
51     void *ret;
52 } pthread_t;
53
54 /* the conditional variable api for windows 6.0+ uses critical sections and
55  * not mutexes */
56 typedef CRITICAL_SECTION pthread_mutex_t;
57
58 /* This is the CONDITION_VARIABLE typedef for using Windows' native
59  * conditional variables on kernels 6.0+. */
60 #if HAVE_CONDITION_VARIABLE_PTR
61 typedef CONDITION_VARIABLE pthread_cond_t;
62 #else
63 typedef struct pthread_cond_t {
64     void *Ptr;
65 } pthread_cond_t;
66 #endif
67
68 #if _WIN32_WINNT >= 0x0600
69 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
70 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
71 #endif
72
73 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
74 {
75     pthread_t *h = arg;
76     h->ret = h->func(h->arg);
77     return 0;
78 }
79
80 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
81                                     void *(*start_routine)(void*), void *arg)
82 {
83     thread->func   = start_routine;
84     thread->arg    = arg;
85     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
86                                            0, NULL);
87     return !thread->handle;
88 }
89
90 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
91 {
92     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
93     if (ret != WAIT_OBJECT_0)
94         return;
95     if (value_ptr)
96         *value_ptr = thread.ret;
97     CloseHandle(thread.handle);
98 }
99
100 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
101 {
102     InitializeCriticalSection(m);
103     return 0;
104 }
105 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
106 {
107     DeleteCriticalSection(m);
108     return 0;
109 }
110 static inline int pthread_mutex_lock(pthread_mutex_t *m)
111 {
112     EnterCriticalSection(m);
113     return 0;
114 }
115 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
116 {
117     LeaveCriticalSection(m);
118     return 0;
119 }
120
121 #if _WIN32_WINNT >= 0x0600
122 static inline int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
123 {
124     InitializeConditionVariable(cond);
125     return 0;
126 }
127
128 /* native condition variables do not destroy */
129 static inline void pthread_cond_destroy(pthread_cond_t *cond)
130 {
131     return;
132 }
133
134 static inline void pthread_cond_broadcast(pthread_cond_t *cond)
135 {
136     WakeAllConditionVariable(cond);
137 }
138
139 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
140 {
141     SleepConditionVariableCS(cond, mutex, INFINITE);
142     return 0;
143 }
144
145 static inline void pthread_cond_signal(pthread_cond_t *cond)
146 {
147     WakeConditionVariable(cond);
148 }
149
150 #else // _WIN32_WINNT < 0x0600
151 /* for pre-Windows 6.0 platforms we need to define and use our own condition
152  * variable and api */
153 typedef struct  win32_cond_t {
154     pthread_mutex_t mtx_broadcast;
155     pthread_mutex_t mtx_waiter_count;
156     volatile int waiter_count;
157     HANDLE semaphore;
158     HANDLE waiters_done;
159     volatile int is_broadcast;
160 } win32_cond_t;
161
162 /* function pointers to conditional variable API on windows 6.0+ kernels */
163 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
164 static void (WINAPI *cond_init)(pthread_cond_t *cond);
165 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
166 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
167                                 DWORD milliseconds);
168
169 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
170 {
171     win32_cond_t *win32_cond = NULL;
172     if (cond_init) {
173         cond_init(cond);
174         return 0;
175     }
176
177     /* non native condition variables */
178     win32_cond = av_mallocz(sizeof(win32_cond_t));
179     if (!win32_cond)
180         return ENOMEM;
181     cond->Ptr = win32_cond;
182     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
183     if (!win32_cond->semaphore)
184         return ENOMEM;
185     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
186     if (!win32_cond->waiters_done)
187         return ENOMEM;
188
189     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
190     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
191     return 0;
192 }
193
194 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
195 {
196     win32_cond_t *win32_cond = cond->Ptr;
197     /* native condition variables do not destroy */
198     if (cond_init)
199         return;
200
201     /* non native condition variables */
202     CloseHandle(win32_cond->semaphore);
203     CloseHandle(win32_cond->waiters_done);
204     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
205     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
206     av_freep(&win32_cond);
207     cond->Ptr = NULL;
208 }
209
210 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
211 {
212     win32_cond_t *win32_cond = cond->Ptr;
213     int have_waiter;
214
215     if (cond_broadcast) {
216         cond_broadcast(cond);
217         return;
218     }
219
220     /* non native condition variables */
221     pthread_mutex_lock(&win32_cond->mtx_broadcast);
222     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
223     have_waiter = 0;
224
225     if (win32_cond->waiter_count) {
226         win32_cond->is_broadcast = 1;
227         have_waiter = 1;
228     }
229
230     if (have_waiter) {
231         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
232         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
233         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
234         ResetEvent(win32_cond->waiters_done);
235         win32_cond->is_broadcast = 0;
236     } else
237         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
238     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
239 }
240
241 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
242 {
243     win32_cond_t *win32_cond = cond->Ptr;
244     int last_waiter;
245     if (cond_wait) {
246         cond_wait(cond, mutex, INFINITE);
247         return 0;
248     }
249
250     /* non native condition variables */
251     pthread_mutex_lock(&win32_cond->mtx_broadcast);
252     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
253     win32_cond->waiter_count++;
254     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
255     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
256
257     // unlock the external mutex
258     pthread_mutex_unlock(mutex);
259     WaitForSingleObject(win32_cond->semaphore, INFINITE);
260
261     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
262     win32_cond->waiter_count--;
263     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
264     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
265
266     if (last_waiter)
267         SetEvent(win32_cond->waiters_done);
268
269     // lock the external mutex
270     return pthread_mutex_lock(mutex);
271 }
272
273 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
274 {
275     win32_cond_t *win32_cond = cond->Ptr;
276     int have_waiter;
277     if (cond_signal) {
278         cond_signal(cond);
279         return;
280     }
281
282     pthread_mutex_lock(&win32_cond->mtx_broadcast);
283
284     /* non-native condition variables */
285     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
286     have_waiter = win32_cond->waiter_count;
287     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
288
289     if (have_waiter) {
290         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
291         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
292         ResetEvent(win32_cond->waiters_done);
293     }
294
295     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
296 }
297 #endif
298
299 static av_unused void w32thread_init(void)
300 {
301 #if _WIN32_WINNT < 0x0600
302     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
303     /* if one is available, then they should all be available */
304     cond_init      =
305         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
306     cond_broadcast =
307         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
308     cond_signal    =
309         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
310     cond_wait      =
311         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
312 #endif
313
314 }
315
316 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */