fifo(n) fifo(n)

NAME
       fifo - Create and manipulate u-turn fifo channels

SYNOPSIS
       package require TTccll

       package require mmeemmcchhaann

       ffiiffoo


DESCRIPTION
       ffiiffoo   creates a stream-oriented in-memory channel and returns its han-
              dle. There is no restriction on the ultimate size of  the  chan-
              nel,  it  will always grow as much as is necessary to accomodate
              the data written into it.

              In contrast to the channels generated by mmeemmcchhaann a channel  cre-
              ated  here  effectively  represents  an U-turn. All data written
              into it can be read out, but only in the same order.  This  also
              means that a fifo channel is not seekable.

              The channels created here can be transfered between interpreters
              in the same thread and between threads, but only as a whole.  It
              is  not  possible  to use them to create a bi- or unidirectional
              connection between two interpreters.

       Memory channels created by ffiiffoo provide two read-only options which can
       be queried via the standard ffccoonnffiigguurree command. These are

       -length
              The value of this option is the number of bytes currently stored
              in the queried memory channel.

       -allocated
              The value of this option is the number of bytes currently  allo-
              cated  by the queried memory channel. This number is at least as
              big as the value of -length.

       As the channels generated by ffiiffoo grow as  necessary  they  are  always
       writable.  This  means that a writable ffiilleeeevveenntt-handler will fire con-
       tinuously.

       The channels are also readable if they contain more  than  zero  bytes.
       Under  this  conditions a readable ffiilleeeevveenntt-handler will fire continu-
       ously.

NNOOTTEESS
       One possible application of memory channels created by mmeemmcchhaann or  ffiiffoo
       is  as temporay storage device to collect data coming in over a pipe or
       a socket. If part of the processing of the incoming data is to read and
       process  header  bytes or similar fifo are easier to use as they do not
       require seeking back and forth to switch between  the  assimilation  of
       headers at the beginning and writing new data at the end.

SEE ALSO
       fifo2, memchan, null

KKEEYYWWOORRDDSS
       channel, fifo, i/o, in-memory channel, memchan, stream

COPYRIGHT
       Copyright (c) 1996-2003 Andreas Kupries 



Memory channels                       2.1                              fifo(n)