[PATCH v4 1/2] POSIX Asynchronous I/O support: aio files

[Corinna Vinschen]

Hi Mark,

there's just one problem left:

On Jul 20 01:44, Mark Geisert wrote:
> This is the core of the AIO implementation: aio.cc and aio.h.  The
> latter is used within the Cygwin DLL by aio.cc and the fhandler* modules,
> as well as by user programs wanting the AIO functionality.
> ---
>  winsup/cygwin/aio.cc        | 1006 +++++++++++++++++++++++++++++++++++
>  winsup/cygwin/include/aio.h |   82 +++
>  2 files changed, 1088 insertions(+)
>  create mode 100644 winsup/cygwin/aio.cc
>  create mode 100644 winsup/cygwin/include/aio.h
> 
> diff --git a/winsup/cygwin/aio.cc b/winsup/cygwin/aio.cc
> new file mode 100644
> index 000000000..0244edf60
> --- /dev/null
> +++ b/winsup/cygwin/aio.cc
> [...]
> +static int
> +aiosuspend (const struct aiocb *const aiolist[],
> +         int nent, const struct timespec *timeout)
> +{
> +  /* Returns lowest list index of completed aios, else 'nent' if all completed.
> +   * If none completed on entry, wait for interval specified by 'timeout'.
> +   */
> +  int       res;
> +  sigset_t  sigmask;
> +  siginfo_t si;
> +  ULONGLONG ticks = 0;
> +  ULONGLONG time0, time1;
> +  struct timespec to = {0};
> +
> +  if (timeout)
> +    {
> +      to = *timeout;
> +      if (to.tv_sec < 0 || to.tv_nsec < 0 || to.tv_nsec > NSPERSEC)
> +        {
> +          set_errno (EINVAL);
> +          return -1;
> +        }
> +      ticks = (NS100PERSEC * to.tv_sec) +
> +              ((to.tv_nsec + (NSPERSEC/NS100PERSEC) - 1) /
> +                             (NSPERSEC/NS100PERSEC));
> +    }
> +
> +retry:
> +  sigemptyset (&sigmask);
> +  int aiocount = 0;
> +  for (int i = 0; i < nent; ++i)
> +    if (aiolist[i] && aiolist[i]->aio_liocb)
> +      {
> +        if (aiolist[i]->aio_errno == EINPROGRESS ||
> +            aiolist[i]->aio_errno == ENOBUFS ||
> +            aiolist[i]->aio_errno == EBUSY)
> +          {
> +            ++aiocount;
> +            if (aiolist[i]->aio_sigevent.sigev_notify == SIGEV_SIGNAL ||
> +                aiolist[i]->aio_sigevent.sigev_notify == SIGEV_THREAD)
> +              sigaddset (&sigmask, aiolist[i]->aio_sigevent.sigev_signo);
> +          }
> +        else
> +          return i;
> +      }
> +
> +  if (aiocount == 0)
> +    return nent;
> +
> +  if (timeout && ticks == 0)
> +    {
> +      set_errno (EAGAIN);
> +      return -1;
> +    }
> +
> +  QueryUnbiasedInterruptTime (&time0);

Nice idea to use QueryUnbiasedInterruptTime.  The problem here is just
that QueryUnbiasedInterruptTime has been introduced with Windows 7, but
we still support Windows Vista :}

We could just drop Vista support (is anybody actually using it?) but
there's an alternative: Include hires.h and use ntod, a global ns
counter object using Windows performance counters under the hood:

  #include "hires.h"

  time0 = ntod.nsecs ();  /* ns, *not* 100ns */
  ...

With that single change I think your patch series can go in.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
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