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From: pete@violet.berkeley.edu (Pete Goodeve)
Newsgroups: comp.sys.amiga.tech
Subject: Re: PIPEs
Summary: No Way..!
Keywords: PIPE, IP-Device
Message-ID: <1990Nov2.211906.6904@agate.berkeley.edu>
Date: 2 Nov 90 21:19:06 GMT
References: <1990Oct19.044319.4851@engin.umich.edu> <1990Nov2.091542.25505@agate.berkeley.edu> <1990Nov2.173103.18889@engin.umich.edu>
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In  <1990Nov2.173103.18889@engin.umich.edu>,
Ralph Seguin (gilgalad@caen.engin.umich.edu) wrote:
>
> The major problem with any of the pipe implementations for the Amiga is
> that they build "named" temporary files.  Kinda bad, when you're trying
> to use pipes as an IPC with files larger than a megabyte.  For instance:
>
> ilbmtoppm blah.iff|ppmquant 256|ppmscale -yscale 1.4|ppmtogif >blah.gif
>
> Hmmm... Let's see, that's 3 megs worth of temp files.
>
Now exactly WHERE did you get THAT idea??!  There is no pipe on the Amiga
that I know of that works this way. (On the IBM on the other hand...!)
Both the 1.3 (Matt Dillon) pipes and Ed Puckett's directory-based version
use circular buffers of fixed size: if the buffer gets full, the writer
will block until the reader takes some out of it.  No disk storage at
all is used!

My IP-Device works a little differently in that the packet passed by the
writer acts as a temporary buffer until it is read, which minimizes byte
copying (but may cause the writer to block more readily).

                                            -- Pete --