fifo2(n) [mojave man page]
fifo2(n) fifo2(n) __________________________________________________________________________________________________________________________________________________ NAME
fifo2 - Create and manipulate pipe fifo channels SYNOPSIS
package require Tcl package require memchan fifo2 _________________________________________________________________ DESCRIPTION
The command described here is only available in a not-yet released version of the package. Use the CVS to get the sources. fifo2 creates two stream-oriented in-memory channels and returns their handles as a two-element list. There is no restriction on the ulti- mate size of the channels, they will always grow as much as is necessary to accomodate the data written into them. In contrast to the channels generated by fifo a pair of channels created here is connected internally in such a way that data writ- ten into one channel can be read from the other. All data written into them is read in the same order. This also means that the two channels of the pair are not seekable. The channels created here can be transfered between interpreters in the same thread and between threads. As both channels in the pair can be transfered independently they can be used to create a bidirectional connection between two interpreters. Memory channels created by fifo2 provide two read-only options which can be queried via the standard fconfigure command. These are -rlength The value of this option is the number of bytes currently available for reading from the channel. -wlength The value of this option is the number of bytes currently written into the channel. Note that the two lengths are switched for the channels of a pair. In other words, the number of bytes written for one of the channels is the number of bytes readable from the other end. As the channels generated by fifo2 grow as necessary they are always writable. This means that a writable fileevent-handler will fire con- tinuously. The channels are also readable if they contain more than zero bytes. Under this conditions a readable fileevent-handler will fire continu- ously. SEE ALSO
fifo, memchan, null KEYWORDS
channel, fifo, i/o, in-memory channel, memchan, stream COPYRIGHT
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net> Memory channels 2.2 fifo2(n)
Check Out this Related Man Page
fifo(n) fifo(n) __________________________________________________________________________________________________________________________________________________ NAME
fifo - Create and manipulate u-turn fifo channels SYNOPSIS
package require Tcl package require memchan fifo _________________________________________________________________ DESCRIPTION
fifo creates a stream-oriented in-memory channel and returns its handle. There is no restriction on the ultimate size of the channel, it will always grow as much as is necessary to accomodate the data written into it. In contrast to the channels generated by memchan a channel created 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 fifo provide two read-only options which can be queried via the standard fconfigure 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 allocated by the queried memory channel. This number is at least as big as the value of -length. As the channels generated by fifo grow as necessary they are always writable. This means that a writable fileevent-handler will fire con- tinuously. The channels are also readable if they contain more than zero bytes. Under this conditions a readable fileevent-handler will fire continu- ously. NOTES
One possible application of memory channels created by memchan or fifo 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 KEYWORDS
channel, fifo, i/o, in-memory channel, memchan, stream COPYRIGHT
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net> Memory channels 2.1 fifo(n)