[FFmpeg-devel] [PATCH] winrt: multithreading support

[wm4]

On Fri, 2 Oct 2015 02:58:52 +0800
Wang Bin <wbsecg1 at gmail.com> wrote:

> From b8b5ad2d65107781116666c2a03ae5cfbe727ee6 Mon Sep 17 00:00:00 2001
> From: wang-bin <wbsecg1 at gmail.com>
> Date: Tue, 29 Sep 2015 18:11:03 +0800
> Subject: [PATCH] winrt: multithreading support
> 
> _beginthreadex is for desktop only. CreateThread is available for windows store apps on windows (and phone) 8.1 and later. http://msdn.microsoft.com/en-us/library/ms682453%28VS.85%29.aspx
> ---
>  compat/w32pthreads.h | 14 ++++++++++++++
>  configure            |  4 ++++
>  libavutil/cpu.c      | 14 +++++++++++++-
>  3 files changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/compat/w32pthreads.h b/compat/w32pthreads.h
> index deb1c53..7491cab 100644
> --- a/compat/w32pthreads.h
> +++ b/compat/w32pthreads.h
> @@ -37,7 +37,16 @@
>  
>  #define WIN32_LEAN_AND_MEAN
>  #include <windows.h>
> +#ifdef WINAPI_FAMILY
> +#include <winapifamily.h>
> +#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
> +#define TARGET_OS_WINRT
> +#endif
> +#endif
> +#ifndef TARGET_OS_WINRT
>  #include <process.h>
> +#endif
> +
>  
>  #include "libavutil/attributes.h"
>  #include "libavutil/common.h"
> @@ -82,8 +91,13 @@ static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
>  {
>      thread->func   = start_routine;
>      thread->arg    = arg;
> +#ifndef TARGET_OS_WINRT
>      thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
>                                             0, NULL);
> +#else
> +    thread->handle = (void*)CreateThread(NULL, 0, win32thread_worker, thread,
> +                                           0, NULL);
> +#endif

Why can't it always use CreateThread? This looks very suspicious.

>      return !thread->handle;
>  }
>  
> diff --git a/configure b/configure
> index 361c024..08d0d5d 100755
> --- a/configure
> +++ b/configure
> @@ -5189,6 +5189,10 @@ check_type "vdpau/vdpau.h" "VdpPictureInfoHEVC"
>  if ! disabled w32threads && ! enabled pthreads; then
>      check_func_headers "windows.h process.h" _beginthreadex &&
>          enable w32threads || disable w32threads
> +    if ! enabled w32threads; then
> +        check_func_headers "windows.h" CreateThread &&
> +            enable w32threads || disable w32threads
> +    fi
>  fi
>  
>  # check for some common methods of building with pthread support
> diff --git a/libavutil/cpu.c b/libavutil/cpu.c
> index 780368d..c562e86 100644
> --- a/libavutil/cpu.c
> +++ b/libavutil/cpu.c
> @@ -30,8 +30,14 @@
>  #endif
>  #include <sched.h>
>  #endif
> -#if HAVE_GETPROCESSAFFINITYMASK
> +#if HAVE_WINDOWS_H
>  #include <windows.h>
> +#ifdef WINAPI_FAMILY
> +#include <winapifamily.h>
> +#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
> +#define TARGET_OS_WINRT
> +#endif
> +#endif
>  #endif
>  #if HAVE_SYSCTL
>  #if HAVE_SYS_PARAM_H
> @@ -253,6 +259,9 @@ int av_cpu_count(void)
>      static volatile int printed;
>  
>      int nb_cpus = 1;
> +#ifdef TARGET_OS_WINRT
> +    SYSTEM_INFO sysinfo;
> +#endif
>  #if HAVE_SCHED_GETAFFINITY && defined(CPU_COUNT)
>      cpu_set_t cpuset;
>  
> @@ -274,6 +283,9 @@ int av_cpu_count(void)
>      nb_cpus = sysconf(_SC_NPROC_ONLN);
>  #elif HAVE_SYSCONF && defined(_SC_NPROCESSORS_ONLN)
>      nb_cpus = sysconf(_SC_NPROCESSORS_ONLN);
> +#elif defined(TARGET_OS_WINRT)
> +    GetNativeSystemInfo(&sysinfo);
> +    nb_cpus = sysinfo.dwNumberOfProcessors;
>  #endif

You could avoid the first ifdef by opening a new scope.

What's the difference to GetProcessAffinityMask() (which is apparently
not available on WinRT)?

>  
>      if (!printed) {