w32pthreads: use the CONDITION_VARIABLE typedef if available
[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 /* function pointers to conditional variable API on windows 6.0+ kernels */
68 #if _WIN32_WINNT < 0x0600
69 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
70 static void (WINAPI *cond_init)(pthread_cond_t *cond);
71 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
72 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
73 DWORD milliseconds);
74 #else
75 #define cond_init InitializeConditionVariable
76 #define cond_broadcast WakeAllConditionVariable
77 #define cond_signal WakeConditionVariable
78 #define cond_wait SleepConditionVariableCS
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)
91 #endif
92
93 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
94 {
95 pthread_t *h = arg;
96 h->ret = h->func(h->arg);
97 return 0;
98 }
99
100 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
101 void *(*start_routine)(void*), void *arg)
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
110 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
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
120 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
121 {
122 InitializeCriticalSection(m);
123 return 0;
124 }
125 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
126 {
127 DeleteCriticalSection(m);
128 return 0;
129 }
130 static inline int pthread_mutex_lock(pthread_mutex_t *m)
131 {
132 EnterCriticalSection(m);
133 return 0;
134 }
135 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
136 {
137 LeaveCriticalSection(m);
138 return 0;
139 }
140
141 /* for pre-Windows 6.0 platforms we need to define and use our own condition
142 * variable and api */
143 typedef struct win32_cond_t {
144 pthread_mutex_t mtx_broadcast;
145 pthread_mutex_t mtx_waiter_count;
146 volatile int waiter_count;
147 HANDLE semaphore;
148 HANDLE waiters_done;
149 volatile int is_broadcast;
150 } win32_cond_t;
151
152 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
153 {
154 win32_cond_t *win32_cond = NULL;
155 if (cond_init) {
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;
164 cond->Ptr = win32_cond;
165 win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
166 if (!win32_cond->semaphore)
167 return;
168 win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
169 if (!win32_cond->waiters_done)
170 return;
171
172 pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
173 pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
174 }
175
176 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
177 {
178 win32_cond_t *win32_cond = cond->Ptr;
179 /* native condition variables do not destroy */
180 if (cond_init)
181 return;
182
183 /* non native condition variables */
184 CloseHandle(win32_cond->semaphore);
185 CloseHandle(win32_cond->waiters_done);
186 pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
187 pthread_mutex_destroy(&win32_cond->mtx_broadcast);
188 av_freep(&win32_cond);
189 cond->Ptr = NULL;
190 }
191
192 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
193 {
194 win32_cond_t *win32_cond = cond->Ptr;
195 int have_waiter;
196
197 if (cond_broadcast) {
198 cond_broadcast(cond);
199 return;
200 }
201
202 /* non native condition variables */
203 pthread_mutex_lock(&win32_cond->mtx_broadcast);
204 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
205 have_waiter = 0;
206
207 if (win32_cond->waiter_count) {
208 win32_cond->is_broadcast = 1;
209 have_waiter = 1;
210 }
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);
216 ResetEvent(win32_cond->waiters_done);
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);
221 }
222
223 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
224 {
225 win32_cond_t *win32_cond = cond->Ptr;
226 int last_waiter;
227 if (cond_wait) {
228 cond_wait(cond, mutex, INFINITE);
229 return 0;
230 }
231
232 /* non native condition variables */
233 pthread_mutex_lock(&win32_cond->mtx_broadcast);
234 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
235 win32_cond->waiter_count++;
236 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
237 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
238
239 // unlock the external mutex
240 pthread_mutex_unlock(mutex);
241 WaitForSingleObject(win32_cond->semaphore, INFINITE);
242
243 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
244 win32_cond->waiter_count--;
245 last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
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);
253 }
254
255 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
256 {
257 win32_cond_t *win32_cond = cond->Ptr;
258 int have_waiter;
259 if (cond_signal) {
260 cond_signal(cond);
261 return;
262 }
263
264 pthread_mutex_lock(&win32_cond->mtx_broadcast);
265
266 /* non-native condition variables */
267 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
268 have_waiter = win32_cond->waiter_count;
269 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
270
271 if (have_waiter) {
272 ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
273 WaitForSingleObject(win32_cond->waiters_done, INFINITE);
274 ResetEvent(win32_cond->waiters_done);
275 }
276
277 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
278 }
279
280 static av_unused void w32thread_init(void)
281 {
282 #if _WIN32_WINNT < 0x0600
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");
293 #endif
294
295 }
296
297 #endif /* LIBAV_COMPAT_W32PTHREADS_H */