w32pthreads.h

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/*
 * 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 COMPAT_W32PTHREADS_H
#define 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. */
 
#include <windows.h>
#include <process.h>
#include <time.h>
 
#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"
#include "libavutil/time.h"
#include "libavutil/wchar_filename.h"
 
typedef struct w32pthread_t {
    void *handle;
    void *(*func)(void* arg);
    void *arg;
    void *ret;
} *pthread_t;
 
/* use light weight mutex/condition variable API */
typedef SRWLOCK pthread_mutex_t;
typedef CONDITION_VARIABLE pthread_cond_t;
 
#define PTHREAD_MUTEX_INITIALIZER SRWLOCK_INIT
#define PTHREAD_COND_INITIALIZER CONDITION_VARIABLE_INIT
 
#define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
#define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
 
#if HAVE_WINRT
#define THREADFUNC_RETTYPE DWORD
#else
#define THREADFUNC_RETTYPE unsigned
#endif
 
av_unused static THREADFUNC_RETTYPE
__stdcall attribute_align_arg win32thread_worker(void *arg)
{
    pthread_t h = (pthread_t)arg;
    h->ret = h->func(h->arg);
    return 0;
}
 
av_unused static int pthread_create(pthread_t *thread, const void *unused_attr,
                                    void *(*start_routine)(void*), void *arg)
{
    pthread_t ret;
 
    ret = (pthread_t)av_mallocz(sizeof(*ret));
    if (!ret)
        return EAGAIN;
 
    ret->func   = start_routine;
    ret->arg    = arg;
#if HAVE_WINRT
    ret->handle = (void*)CreateThread(NULL, 0, win32thread_worker, ret,
                                      0, NULL);
#else
    ret->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, ret,
                                        0, NULL);
#endif
 
    if (!ret->handle) {
        av_free(ret);
        return EAGAIN;
    }
 
    *thread = ret;
 
    return 0;
}
 
av_unused static 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);
    av_free(thread);
    return 0;
}
 
static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
{
    InitializeSRWLock(m);
    return 0;
}
static inline int pthread_mutex_destroy(pthread_mutex_t *m)
{
    /* Unlocked SWR locks use no resources */
    return 0;
}
static inline int pthread_mutex_lock(pthread_mutex_t *m)
{
    AcquireSRWLockExclusive(m);
    return 0;
}
static inline int pthread_mutex_unlock(pthread_mutex_t *m)
{
    ReleaseSRWLockExclusive(m);
    return 0;
}
 
static inline int pthread_mutex_trylock(pthread_mutex_t *m)
{
    return TryAcquireSRWLockExclusive(m) == 0 ? EBUSY : 0;
}
 
typedef INIT_ONCE pthread_once_t;
#define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
 
av_unused static 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)
{
    SleepConditionVariableSRW(cond, mutex, INFINITE, 0);
    return 0;
}
 
static inline int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
                                         const struct timespec *abstime)
{
    int64_t abs_milli = abstime->tv_sec * 1000LL + abstime->tv_nsec / 1000000;
    DWORD t = av_clip64(abs_milli - av_gettime() / 1000, 0, UINT32_MAX);
 
    if (!SleepConditionVariableSRW(cond, mutex, t, 0)) {
        DWORD err = GetLastError();
        if (err == ERROR_TIMEOUT)
            return ETIMEDOUT;
        else
            return EINVAL;
    }
    return 0;
}
 
static inline int pthread_cond_signal(pthread_cond_t *cond)
{
    WakeConditionVariable(cond);
    return 0;
}
 
static inline int win32_thread_setname(const char *name)
{
#if !HAVE_UWP
    typedef HRESULT (WINAPI *SetThreadDescriptionFn)(HANDLE, PCWSTR);
 
    // Although SetThreadDescription lives in kernel32.dll, on Windows Server 2016,
    // Windows 10 LTSB 2016 and Windows 10 version 1607, it was only available in
    // kernelbase.dll. So, load it from there for maximum coverage.
    HMODULE kernelbase = GetModuleHandleW(L"kernelbase.dll");
    if (!kernelbase)
        return AVERROR(ENOSYS);
 
    SetThreadDescriptionFn pSetThreadDescription =
        (SetThreadDescriptionFn)GetProcAddress(kernelbase, "SetThreadDescription");
    if (!pSetThreadDescription)
        return AVERROR(ENOSYS);
 
    wchar_t *wname;
    if (utf8towchar(name, &wname) < 0)
        return AVERROR(ENOMEM);
 
    HRESULT hr = pSetThreadDescription(GetCurrentThread(), wname);
    av_free(wname);
    return SUCCEEDED(hr) ? 0 : AVERROR(EINVAL);
#else
    // UWP is not supported because we cannot use LoadLibrary/GetProcAddress to
    // detect the availability of the SetThreadDescription API. There is a small
    // gap in Windows builds 1507-1607 where it was not available. UWP allows
    // querying the availability of APIs with QueryOptionalDelayLoadedAPI, but it
    // requires /DELAYLOAD:kernel32.dll during linking, and we cannot enforce that.
    return AVERROR(ENOSYS);
#endif
}
 
#endif /* COMPAT_W32PTHREADS_H */