a1cb396d6ec1461509404d71e6f2b277cc89b1dd
[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 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
122 typedef INIT_ONCE pthread_once_t;
123 #define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
124
125 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
126 {
127     BOOL pending = FALSE;
128     InitOnceBeginInitialize(once_control, 0, &pending, NULL);
129     if (pending)
130         init_routine();
131     InitOnceComplete(once_control, 0, NULL);
132     return 0;
133 }
134
135 static inline void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
136 {
137     InitializeConditionVariable(cond);
138 }
139
140 /* native condition variables do not destroy */
141 static inline void pthread_cond_destroy(pthread_cond_t *cond)
142 {
143     return;
144 }
145
146 static inline void pthread_cond_broadcast(pthread_cond_t *cond)
147 {
148     WakeAllConditionVariable(cond);
149 }
150
151 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
152 {
153     SleepConditionVariableCS(cond, mutex, INFINITE);
154     return 0;
155 }
156
157 static inline void pthread_cond_signal(pthread_cond_t *cond)
158 {
159     WakeConditionVariable(cond);
160 }
161
162 #else // _WIN32_WINNT < 0x0600
163 /* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
164  * compatible to the one used in the native API */
165
166 typedef union pthread_once_t  {
167     void * Ptr;    ///< For the Windows 6.0+ native functions
168     LONG state;    ///< For the pre-Windows 6.0 compat code
169 } pthread_once_t;
170
171 #define PTHREAD_ONCE_INIT {0}
172
173 /* function pointers to init once API on windows 6.0+ kernels */
174 static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
175 static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
176
177 /* pre-Windows 6.0 compat using a spin-lock */
178 static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
179 {
180     switch (InterlockedCompareExchange(state, 1, 0)) {
181     /* Initial run */
182     case 0:
183         init_routine();
184         InterlockedExchange(state, 2);
185         break;
186     /* Another thread is running init */
187     case 1:
188         while (1) {
189             MemoryBarrier();
190             if (*state == 2)
191                 break;
192             Sleep(0);
193         }
194         break;
195     /* Initialization complete */
196     case 2:
197         break;
198     }
199 }
200
201 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
202 {
203     /* Use native functions on Windows 6.0+ */
204     if (initonce_begin && initonce_complete) {
205         BOOL pending = FALSE;
206         initonce_begin(once_control, 0, &pending, NULL);
207         if (pending)
208             init_routine();
209         initonce_complete(once_control, 0, NULL);
210         return 0;
211     }
212
213     w32thread_once_fallback(&once_control->state, init_routine);
214     return 0;
215 }
216
217 /* for pre-Windows 6.0 platforms we need to define and use our own condition
218  * variable and api */
219
220 typedef struct  win32_cond_t {
221     pthread_mutex_t mtx_broadcast;
222     pthread_mutex_t mtx_waiter_count;
223     volatile int waiter_count;
224     HANDLE semaphore;
225     HANDLE waiters_done;
226     volatile int is_broadcast;
227 } win32_cond_t;
228
229 /* function pointers to conditional variable API on windows 6.0+ kernels */
230 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
231 static void (WINAPI *cond_init)(pthread_cond_t *cond);
232 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
233 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
234                                 DWORD milliseconds);
235
236 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
237 {
238     win32_cond_t *win32_cond = NULL;
239     if (cond_init) {
240         cond_init(cond);
241         return;
242     }
243
244     /* non native condition variables */
245     win32_cond = av_mallocz(sizeof(win32_cond_t));
246     if (!win32_cond)
247         return;
248     cond->Ptr = win32_cond;
249     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
250     if (!win32_cond->semaphore)
251         return;
252     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
253     if (!win32_cond->waiters_done)
254         return;
255
256     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
257     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
258 }
259
260 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
261 {
262     win32_cond_t *win32_cond = cond->Ptr;
263     /* native condition variables do not destroy */
264     if (cond_init)
265         return;
266
267     /* non native condition variables */
268     CloseHandle(win32_cond->semaphore);
269     CloseHandle(win32_cond->waiters_done);
270     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
271     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
272     av_freep(&win32_cond);
273     cond->Ptr = NULL;
274 }
275
276 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
277 {
278     win32_cond_t *win32_cond = cond->Ptr;
279     int have_waiter;
280
281     if (cond_broadcast) {
282         cond_broadcast(cond);
283         return;
284     }
285
286     /* non native condition variables */
287     pthread_mutex_lock(&win32_cond->mtx_broadcast);
288     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
289     have_waiter = 0;
290
291     if (win32_cond->waiter_count) {
292         win32_cond->is_broadcast = 1;
293         have_waiter = 1;
294     }
295
296     if (have_waiter) {
297         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
298         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
299         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
300         ResetEvent(win32_cond->waiters_done);
301         win32_cond->is_broadcast = 0;
302     } else
303         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
304     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
305 }
306
307 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
308 {
309     win32_cond_t *win32_cond = cond->Ptr;
310     int last_waiter;
311     if (cond_wait) {
312         cond_wait(cond, mutex, INFINITE);
313         return 0;
314     }
315
316     /* non native condition variables */
317     pthread_mutex_lock(&win32_cond->mtx_broadcast);
318     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
319     win32_cond->waiter_count++;
320     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
321     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
322
323     // unlock the external mutex
324     pthread_mutex_unlock(mutex);
325     WaitForSingleObject(win32_cond->semaphore, INFINITE);
326
327     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
328     win32_cond->waiter_count--;
329     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
330     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
331
332     if (last_waiter)
333         SetEvent(win32_cond->waiters_done);
334
335     // lock the external mutex
336     return pthread_mutex_lock(mutex);
337 }
338
339 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
340 {
341     win32_cond_t *win32_cond = cond->Ptr;
342     int have_waiter;
343     if (cond_signal) {
344         cond_signal(cond);
345         return;
346     }
347
348     pthread_mutex_lock(&win32_cond->mtx_broadcast);
349
350     /* non-native condition variables */
351     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
352     have_waiter = win32_cond->waiter_count;
353     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
354
355     if (have_waiter) {
356         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
357         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
358         ResetEvent(win32_cond->waiters_done);
359     }
360
361     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
362 }
363 #endif
364
365 static av_unused void w32thread_init(void)
366 {
367 #if _WIN32_WINNT < 0x0600
368     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
369     /* if one is available, then they should all be available */
370     cond_init      =
371         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
372     cond_broadcast =
373         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
374     cond_signal    =
375         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
376     cond_wait      =
377         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
378     initonce_begin =
379         (void*)GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
380     initonce_complete =
381         (void*)GetProcAddress(kernel_dll, "InitOnceComplete");
382 #endif
383
384 }
385
386 #endif /* LIBAV_COMPAT_W32PTHREADS_H */