General question on the status of named pipes

General question on the status of named pipes

[Nathan Thern]

I have several scripts that use named pipes for the purpose of
processing sound files. I use them on both linux and cygwin. After the
switch to cygwin1.7 I converted most of them to the use of tempfiles.
Nevertheless, when encountering old scripts in my archives or when
trying to create efficient new scripts I find myself wishing named
pipes still worked; they are one of the more powerful unix-ish
paradigms.

What's the status/priority of getting named pipes to work in 1.7? And,
just for curiosity's sake, what was the fundamental change in 1.7 that
caused them to stop working? -- They worked great in 1.5.

Cygwin is a great tool, and I'm constantly grateful for it's existence.

regards,
NT

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Re: General question on the status of named pipes

[Eric Blake]

On 10/24/2011 06:51 AM, Nathan Thern wrote:
> I have several scripts that use named pipes for the purpose of
> processing sound files. I use them on both linux and cygwin. After the
> switch to cygwin1.7 I converted most of them to the use of tempfiles.
> Nevertheless, when encountering old scripts in my archives or when
> trying to create efficient new scripts I find myself wishing named
> pipes still worked; they are one of the more powerful unix-ish
> paradigms.
>
> What's the status/priority of getting named pipes to work in 1.7? And,
> just for curiosity's sake, what was the fundamental change in 1.7 that
> caused them to stop working? -- They worked great in 1.5.

Actually, named pipes have _never_ worked, at least according to the 
full set of POSIX rules.  It's just that some releases had code that 
limped along better than in other releases for the particular use cases 
you happened to throw at them.  cgf is working miracles to get it as far 
along as he has, but it's a very tough job to emulate POSIX fifos on top 
of windows.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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Re: General question on the status of named pipes

[Nathan Thern]

On Mon, Oct 24, 2011 at 12:55 PM, Eric Blake <eblake@redhat.com> wrote:
> Actually, named pipes have _never_ worked, at least according to the full
> set of POSIX rules.  It's just that some releases had code that limped along
> better than in other releases for the particular use cases you happened to
> throw at them.  cgf is working miracles to get it as far along as he has,
> but it's a very tough job to emulate POSIX fifos on top of windows.

Interesting. I used them successfully for a couple of years with 1.5,
IIRC. My mode of usage was usually something like:

$ mkfifo fifo1 fifo2

$ decode_audio_to_PCM audiofile | tee fifo1 > fifo2 &

$ encode_audio_to_format_1 -o newaudio1 fifo1

$ encode_audio_to_format_2 -o newaudio2 fifo2

This has two distinct advantages over tempfiles for me. I don't have
to wait for the decode to complete before I start to re-encode & I
don't need the disk space for large chunks of uncompressed audio.

NT

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Re: General question on the status of named pipes

[Christopher Faylor]

On Mon, Oct 24, 2011 at 11:55:15AM -0600, Eric Blake wrote:
>On 10/24/2011 06:51 AM, Nathan Thern wrote:
>> I have several scripts that use named pipes for the purpose of
>> processing sound files. I use them on both linux and cygwin. After the
>> switch to cygwin1.7 I converted most of them to the use of tempfiles.
>> Nevertheless, when encountering old scripts in my archives or when
>> trying to create efficient new scripts I find myself wishing named
>> pipes still worked; they are one of the more powerful unix-ish
>> paradigms.
>>
>> What's the status/priority of getting named pipes to work in 1.7? And,
>> just for curiosity's sake, what was the fundamental change in 1.7 that
>> caused them to stop working? -- They worked great in 1.5.
>
>Actually, named pipes have _never_ worked, at least according to the 
>full set of POSIX rules.  It's just that some releases had code that 
>limped along better than in other releases for the particular use cases 
>you happened to throw at them.  cgf is working miracles to get it as far 
>along as he has, but it's a very tough job to emulate POSIX fifos on top 
>of windows.

No guarantees but the most recent snapshot should work better.  There is
still at least one glaring problem that I'm aware of but it may work
better than 1.7.9.

cgf

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