aboutsummaryrefslogtreecommitdiffstats
path: root/compat/w32pthreads.h
blob: c327962735828e80fe7f57894c79721f6c85d042 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
/*
 * Copyright (C) 2010-2011 x264 project
 *
 * Authors: Steven Walters <kemuri9@gmail.com>
 *          Pegasys Inc. <http://www.pegasys-inc.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * w32threads to pthreads wrapper
 */

#ifndef FFMPEG_COMPAT_W32PTHREADS_H
#define FFMPEG_COMPAT_W32PTHREADS_H

/* Build up a pthread-like API using underlying Windows API. Have only static
 * methods so as to not conflict with a potentially linked in pthread-win32
 * library.
 * As most functions here are used without checking return values,
 * only implement return values as necessary. */

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <process.h>

#if _WIN32_WINNT < 0x0600 && defined(__MINGW32__)
#undef MemoryBarrier
#define MemoryBarrier __sync_synchronize
#endif

#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"

typedef struct pthread_t {
    void *handle;
    void *(*func)(void* arg);
    void *arg;
    void *ret;
} pthread_t;

/* the conditional variable api for windows 6.0+ uses critical sections and
 * not mutexes */
typedef CRITICAL_SECTION pthread_mutex_t;

/* This is the CONDITION_VARIABLE typedef for using Windows' native
 * conditional variables on kernels 6.0+. */
#if HAVE_CONDITION_VARIABLE_PTR
typedef CONDITION_VARIABLE pthread_cond_t;
#else
typedef struct pthread_cond_t {
    void *Ptr;
} pthread_cond_t;
#endif

#if _WIN32_WINNT >= 0x0600
#define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
#define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
#endif

static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
{
    pthread_t *h = arg;
    h->ret = h->func(h->arg);
    return 0;
}

static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
                                    void *(*start_routine)(void*), void *arg)
{
    thread->func   = start_routine;
    thread->arg    = arg;
#if HAVE_WINRT
    thread->handle = (void*)CreateThread(NULL, 0, win32thread_worker, thread,
                                           0, NULL);
#else
    thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
                                           0, NULL);
#endif
    return !thread->handle;
}

static av_unused int pthread_join(pthread_t thread, void **value_ptr)
{
    DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
    if (ret != WAIT_OBJECT_0) {
        if (ret == WAIT_ABANDONED)
            return EINVAL;
        else
            return EDEADLK;
    }
    if (value_ptr)
        *value_ptr = thread.ret;
    CloseHandle(thread.handle);
    return 0;
}

static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
{
    InitializeCriticalSection(m);
    return 0;
}
static inline int pthread_mutex_destroy(pthread_mutex_t *m)
{
    DeleteCriticalSection(m);
    return 0;
}
static inline int pthread_mutex_lock(pthread_mutex_t *m)
{
    EnterCriticalSection(m);
    return 0;
}
static inline int pthread_mutex_unlock(pthread_mutex_t *m)
{
    LeaveCriticalSection(m);
    return 0;
}

#if _WIN32_WINNT >= 0x0600
typedef INIT_ONCE pthread_once_t;
#define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT

static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
{
    BOOL pending = FALSE;
    InitOnceBeginInitialize(once_control, 0, &pending, NULL);
    if (pending)
        init_routine();
    InitOnceComplete(once_control, 0, NULL);
    return 0;
}

static inline int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
{
    InitializeConditionVariable(cond);
    return 0;
}

/* native condition variables do not destroy */
static inline int pthread_cond_destroy(pthread_cond_t *cond)
{
    return 0;
}

static inline int pthread_cond_broadcast(pthread_cond_t *cond)
{
    WakeAllConditionVariable(cond);
    return 0;
}

static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
    SleepConditionVariableCS(cond, mutex, INFINITE);
    return 0;
}

static inline int pthread_cond_signal(pthread_cond_t *cond)
{
    WakeConditionVariable(cond);
    return 0;
}

#else // _WIN32_WINNT < 0x0600

/* atomic init state of dynamically loaded functions */
static LONG w32thread_init_state = 0;
static av_unused void w32thread_init(void);

/* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
 * compatible to the one used in the native API */

typedef union pthread_once_t  {
    void * Ptr;    ///< For the Windows 6.0+ native functions
    LONG state;    ///< For the pre-Windows 6.0 compat code
} pthread_once_t;

#define PTHREAD_ONCE_INIT {0}

/* function pointers to init once API on windows 6.0+ kernels */
static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);

/* pre-Windows 6.0 compat using a spin-lock */
static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
{
    switch (InterlockedCompareExchange(state, 1, 0)) {
    /* Initial run */
    case 0:
        init_routine();
        InterlockedExchange(state, 2);
        break;
    /* Another thread is running init */
    case 1:
        while (1) {
            MemoryBarrier();
            if (*state == 2)
                break;
            Sleep(0);
        }
        break;
    /* Initialization complete */
    case 2:
        break;
    }
}

static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
{
    w32thread_once_fallback(&w32thread_init_state, w32thread_init);

    /* Use native functions on Windows 6.0+ */
    if (initonce_begin && initonce_complete) {
        BOOL pending = FALSE;
        initonce_begin(once_control, 0, &pending, NULL);
        if (pending)
            init_routine();
        initonce_complete(once_control, 0, NULL);
        return 0;
    }

    w32thread_once_fallback(&once_control->state, init_routine);
    return 0;
}

/* for pre-Windows 6.0 platforms we need to define and use our own condition
 * variable and api */

typedef struct  win32_cond_t {
    pthread_mutex_t mtx_broadcast;
    pthread_mutex_t mtx_waiter_count;
    volatile int waiter_count;
    HANDLE semaphore;
    HANDLE waiters_done;
    volatile int is_broadcast;
} win32_cond_t;

/* function pointers to conditional variable API on windows 6.0+ kernels */
static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
static void (WINAPI *cond_init)(pthread_cond_t *cond);
static void (WINAPI *cond_signal)(pthread_cond_t *cond);
static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
                                DWORD milliseconds);

static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
{
    win32_cond_t *win32_cond = NULL;

    w32thread_once_fallback(&w32thread_init_state, w32thread_init);

    if (cond_init) {
        cond_init(cond);
        return 0;
    }

    /* non native condition variables */
    win32_cond = av_mallocz(sizeof(win32_cond_t));
    if (!win32_cond)
        return ENOMEM;
    cond->Ptr = win32_cond;
    win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
    if (!win32_cond->semaphore)
        return ENOMEM;
    win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
    if (!win32_cond->waiters_done)
        return ENOMEM;

    pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
    pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
    return 0;
}

static av_unused int pthread_cond_destroy(pthread_cond_t *cond)
{
    win32_cond_t *win32_cond = cond->Ptr;
    /* native condition variables do not destroy */
    if (cond_init)
        return 0;

    /* non native condition variables */
    CloseHandle(win32_cond->semaphore);
    CloseHandle(win32_cond->waiters_done);
    pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
    pthread_mutex_destroy(&win32_cond->mtx_broadcast);
    av_freep(&win32_cond);
    cond->Ptr = NULL;
    return 0;
}

static av_unused int pthread_cond_broadcast(pthread_cond_t *cond)
{
    win32_cond_t *win32_cond = cond->Ptr;
    int have_waiter;

    if (cond_broadcast) {
        cond_broadcast(cond);
        return 0;
    }

    /* non native condition variables */
    pthread_mutex_lock(&win32_cond->mtx_broadcast);
    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
    have_waiter = 0;

    if (win32_cond->waiter_count) {
        win32_cond->is_broadcast = 1;
        have_waiter = 1;
    }

    if (have_waiter) {
        ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
        ResetEvent(win32_cond->waiters_done);
        win32_cond->is_broadcast = 0;
    } else
        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
    return 0;
}

static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
    win32_cond_t *win32_cond = cond->Ptr;
    int last_waiter;
    if (cond_wait) {
        cond_wait(cond, mutex, INFINITE);
        return 0;
    }

    /* non native condition variables */
    pthread_mutex_lock(&win32_cond->mtx_broadcast);
    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
    win32_cond->waiter_count++;
    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
    pthread_mutex_unlock(&win32_cond->mtx_broadcast);

    // unlock the external mutex
    pthread_mutex_unlock(mutex);
    WaitForSingleObject(win32_cond->semaphore, INFINITE);

    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
    win32_cond->waiter_count--;
    last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

    if (last_waiter)
        SetEvent(win32_cond->waiters_done);

    // lock the external mutex
    return pthread_mutex_lock(mutex);
}

static av_unused int pthread_cond_signal(pthread_cond_t *cond)
{
    win32_cond_t *win32_cond = cond->Ptr;
    int have_waiter;
    if (cond_signal) {
        cond_signal(cond);
        return 0;
    }

    pthread_mutex_lock(&win32_cond->mtx_broadcast);

    /* non-native condition variables */
    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
    have_waiter = win32_cond->waiter_count;
    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

    if (have_waiter) {
        ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
        ResetEvent(win32_cond->waiters_done);
    }

    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
    return 0;
}
#endif

static av_unused void w32thread_init(void)
{
#if _WIN32_WINNT < 0x0600
    HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
    /* if one is available, then they should all be available */
    cond_init      =
        (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
    cond_broadcast =
        (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
    cond_signal    =
        (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
    cond_wait      =
        (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
    initonce_begin =
        (void*)GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
    initonce_complete =
        (void*)GetProcAddress(kernel_dll, "InitOnceComplete");
#endif

}

#endif /* FFMPEG_COMPAT_W32PTHREADS_H */