w32thread: call ResetEvent() in pthread_cond_broadcast().
[libav.git] / libavcodec / 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 AVCODEC_W32PTHREADS_H
30 #define AVCODEC_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 typedef struct {
43 void *handle;
44 void *(*func)(void* arg);
45 void *arg;
46 void *ret;
47 } pthread_t;
48
49 /* the conditional variable api for windows 6.0+ uses critical sections and
50 * not mutexes */
51 typedef CRITICAL_SECTION pthread_mutex_t;
52
53 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
54 * conditional variables on kernels 6.0+.
55 * MinGW does not currently have this typedef. */
56 typedef struct {
57 void *ptr;
58 } pthread_cond_t;
59
60 /* function pointers to conditional variable API on windows 6.0+ kernels */
61 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
62 static void (WINAPI *cond_init)(pthread_cond_t *cond);
63 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
64 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
65 DWORD milliseconds);
66
67 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
68 {
69 pthread_t *h = arg;
70 h->ret = h->func(h->arg);
71 return 0;
72 }
73
74 static int pthread_create(pthread_t *thread, const void *unused_attr,
75 void *(*start_routine)(void*), void *arg)
76 {
77 thread->func = start_routine;
78 thread->arg = arg;
79 thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
80 0, NULL);
81 return !thread->handle;
82 }
83
84 static void pthread_join(pthread_t thread, void **value_ptr)
85 {
86 DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
87 if (ret != WAIT_OBJECT_0)
88 return;
89 if (value_ptr)
90 *value_ptr = thread.ret;
91 CloseHandle(thread.handle);
92 }
93
94 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
95 {
96 InitializeCriticalSection(m);
97 return 0;
98 }
99 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
100 {
101 DeleteCriticalSection(m);
102 return 0;
103 }
104 static inline int pthread_mutex_lock(pthread_mutex_t *m)
105 {
106 EnterCriticalSection(m);
107 return 0;
108 }
109 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
110 {
111 LeaveCriticalSection(m);
112 return 0;
113 }
114
115 /* for pre-Windows 6.0 platforms we need to define and use our own condition
116 * variable and api */
117 typedef struct {
118 pthread_mutex_t mtx_broadcast;
119 pthread_mutex_t mtx_waiter_count;
120 volatile int waiter_count;
121 HANDLE semaphore;
122 HANDLE waiters_done;
123 volatile int is_broadcast;
124 } win32_cond_t;
125
126 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
127 {
128 win32_cond_t *win32_cond = NULL;
129 if (cond_init) {
130 cond_init(cond);
131 return;
132 }
133
134 /* non native condition variables */
135 win32_cond = av_mallocz(sizeof(win32_cond_t));
136 if (!win32_cond)
137 return;
138 cond->ptr = win32_cond;
139 win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
140 if (!win32_cond->semaphore)
141 return;
142 win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
143 if (!win32_cond->waiters_done)
144 return;
145
146 pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
147 pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
148 }
149
150 static void pthread_cond_destroy(pthread_cond_t *cond)
151 {
152 win32_cond_t *win32_cond = cond->ptr;
153 /* native condition variables do not destroy */
154 if (cond_init)
155 return;
156
157 /* non native condition variables */
158 CloseHandle(win32_cond->semaphore);
159 CloseHandle(win32_cond->waiters_done);
160 pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
161 pthread_mutex_destroy(&win32_cond->mtx_broadcast);
162 av_freep(&win32_cond);
163 cond->ptr = NULL;
164 }
165
166 static void pthread_cond_broadcast(pthread_cond_t *cond)
167 {
168 win32_cond_t *win32_cond = cond->ptr;
169 int have_waiter;
170
171 if (cond_broadcast) {
172 cond_broadcast(cond);
173 return;
174 }
175
176 /* non native condition variables */
177 pthread_mutex_lock(&win32_cond->mtx_broadcast);
178 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
179 have_waiter = 0;
180
181 if (win32_cond->waiter_count) {
182 win32_cond->is_broadcast = 1;
183 have_waiter = 1;
184 }
185
186 if (have_waiter) {
187 ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
188 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
189 WaitForSingleObject(win32_cond->waiters_done, INFINITE);
190 ResetEvent(win32_cond->waiters_done);
191 win32_cond->is_broadcast = 0;
192 } else
193 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
194 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
195 }
196
197 static void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
198 {
199 win32_cond_t *win32_cond = cond->ptr;
200 int last_waiter;
201 if (cond_wait) {
202 cond_wait(cond, mutex, INFINITE);
203 return;
204 }
205
206 /* non native condition variables */
207 pthread_mutex_lock(&win32_cond->mtx_broadcast);
208 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
209 win32_cond->waiter_count++;
210 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
211 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
212
213 // unlock the external mutex
214 pthread_mutex_unlock(mutex);
215 WaitForSingleObject(win32_cond->semaphore, INFINITE);
216
217 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
218 win32_cond->waiter_count--;
219 last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
220 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
221
222 if (last_waiter)
223 SetEvent(win32_cond->waiters_done);
224
225 // lock the external mutex
226 return pthread_mutex_lock(mutex);
227 }
228
229 static void pthread_cond_signal(pthread_cond_t *cond)
230 {
231 win32_cond_t *win32_cond = cond->ptr;
232 int have_waiter;
233 if (cond_signal) {
234 cond_signal(cond);
235 return;
236 }
237
238 pthread_mutex_lock(&win32_cond->mtx_broadcast);
239
240 /* non-native condition variables */
241 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
242 have_waiter = win32_cond->waiter_count;
243 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
244
245 if (have_waiter) {
246 ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
247 WaitForSingleObject(win32_cond->waiters_done, INFINITE);
248 ResetEvent(win32_cond->waiters_done);
249 }
250
251 pthread_mutex_unlock(&win32_cond->mtx_broadcast);
252 }
253
254 static void w32thread_init(void)
255 {
256 HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
257 /* if one is available, then they should all be available */
258 cond_init =
259 (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
260 cond_broadcast =
261 (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
262 cond_signal =
263 (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
264 cond_wait =
265 (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
266 }
267
268 #endif /* AVCODEC_W32PTHREADS_H */