w32pthreads: Load dynamically loaded functions on demand
[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
164 /* atomic init state of dynamically loaded functions */
165 static LONG w32thread_init_state = 0;
166 static av_unused void w32thread_init(void);
167
168 /* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
169  * compatible to the one used in the native API */
170
171 typedef union pthread_once_t  {
172     void * Ptr;    ///< For the Windows 6.0+ native functions
173     LONG state;    ///< For the pre-Windows 6.0 compat code
174 } pthread_once_t;
175
176 #define PTHREAD_ONCE_INIT {0}
177
178 /* function pointers to init once API on windows 6.0+ kernels */
179 static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
180 static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
181
182 /* pre-Windows 6.0 compat using a spin-lock */
183 static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
184 {
185     switch (InterlockedCompareExchange(state, 1, 0)) {
186     /* Initial run */
187     case 0:
188         init_routine();
189         InterlockedExchange(state, 2);
190         break;
191     /* Another thread is running init */
192     case 1:
193         while (1) {
194             MemoryBarrier();
195             if (*state == 2)
196                 break;
197             Sleep(0);
198         }
199         break;
200     /* Initialization complete */
201     case 2:
202         break;
203     }
204 }
205
206 static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
207 {
208     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
209
210     /* Use native functions on Windows 6.0+ */
211     if (initonce_begin && initonce_complete) {
212         BOOL pending = FALSE;
213         initonce_begin(once_control, 0, &pending, NULL);
214         if (pending)
215             init_routine();
216         initonce_complete(once_control, 0, NULL);
217         return 0;
218     }
219
220     w32thread_once_fallback(&once_control->state, init_routine);
221     return 0;
222 }
223
224 /* for pre-Windows 6.0 platforms we need to define and use our own condition
225  * variable and api */
226
227 typedef struct  win32_cond_t {
228     pthread_mutex_t mtx_broadcast;
229     pthread_mutex_t mtx_waiter_count;
230     volatile int waiter_count;
231     HANDLE semaphore;
232     HANDLE waiters_done;
233     volatile int is_broadcast;
234 } win32_cond_t;
235
236 /* function pointers to conditional variable API on windows 6.0+ kernels */
237 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
238 static void (WINAPI *cond_init)(pthread_cond_t *cond);
239 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
240 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
241                                 DWORD milliseconds);
242
243 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
244 {
245     win32_cond_t *win32_cond = NULL;
246
247     w32thread_once_fallback(&w32thread_init_state, w32thread_init);
248
249     if (cond_init) {
250         cond_init(cond);
251         return;
252     }
253
254     /* non native condition variables */
255     win32_cond = av_mallocz(sizeof(win32_cond_t));
256     if (!win32_cond)
257         return;
258     cond->Ptr = win32_cond;
259     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
260     if (!win32_cond->semaphore)
261         return;
262     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
263     if (!win32_cond->waiters_done)
264         return;
265
266     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
267     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
268 }
269
270 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
271 {
272     win32_cond_t *win32_cond = cond->Ptr;
273     /* native condition variables do not destroy */
274     if (cond_init)
275         return;
276
277     /* non native condition variables */
278     CloseHandle(win32_cond->semaphore);
279     CloseHandle(win32_cond->waiters_done);
280     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
281     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
282     av_freep(&win32_cond);
283     cond->Ptr = NULL;
284 }
285
286 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
287 {
288     win32_cond_t *win32_cond = cond->Ptr;
289     int have_waiter;
290
291     if (cond_broadcast) {
292         cond_broadcast(cond);
293         return;
294     }
295
296     /* non native condition variables */
297     pthread_mutex_lock(&win32_cond->mtx_broadcast);
298     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
299     have_waiter = 0;
300
301     if (win32_cond->waiter_count) {
302         win32_cond->is_broadcast = 1;
303         have_waiter = 1;
304     }
305
306     if (have_waiter) {
307         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
308         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
309         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
310         ResetEvent(win32_cond->waiters_done);
311         win32_cond->is_broadcast = 0;
312     } else
313         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
314     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
315 }
316
317 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
318 {
319     win32_cond_t *win32_cond = cond->Ptr;
320     int last_waiter;
321     if (cond_wait) {
322         cond_wait(cond, mutex, INFINITE);
323         return 0;
324     }
325
326     /* non native condition variables */
327     pthread_mutex_lock(&win32_cond->mtx_broadcast);
328     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
329     win32_cond->waiter_count++;
330     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
331     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
332
333     // unlock the external mutex
334     pthread_mutex_unlock(mutex);
335     WaitForSingleObject(win32_cond->semaphore, INFINITE);
336
337     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
338     win32_cond->waiter_count--;
339     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
340     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
341
342     if (last_waiter)
343         SetEvent(win32_cond->waiters_done);
344
345     // lock the external mutex
346     return pthread_mutex_lock(mutex);
347 }
348
349 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
350 {
351     win32_cond_t *win32_cond = cond->Ptr;
352     int have_waiter;
353     if (cond_signal) {
354         cond_signal(cond);
355         return;
356     }
357
358     pthread_mutex_lock(&win32_cond->mtx_broadcast);
359
360     /* non-native condition variables */
361     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
362     have_waiter = win32_cond->waiter_count;
363     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
364
365     if (have_waiter) {
366         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
367         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
368         ResetEvent(win32_cond->waiters_done);
369     }
370
371     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
372 }
373 #endif
374
375 static av_unused void w32thread_init(void)
376 {
377 #if _WIN32_WINNT < 0x0600
378     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
379     /* if one is available, then they should all be available */
380     cond_init      =
381         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
382     cond_broadcast =
383         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
384     cond_signal    =
385         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
386     cond_wait      =
387         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
388     initonce_begin =
389         (void*)GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
390     initonce_complete =
391         (void*)GetProcAddress(kernel_dll, "InitOnceComplete");
392 #endif
393
394 }
395
396 #endif /* LIBAV_COMPAT_W32PTHREADS_H */