Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

memchan(n) [osx man page]

memchan(n)																memchan(n)

__________________________________________________________________________________________________________________________________________________

NAME
memchan - Create and manipulate memory channels SYNOPSIS
package require Tcl package require memchan memchan ?-initial-size len? _________________________________________________________________ DESCRIPTION
This manpage documents both the overall package and the command memchan. The package itself provides a number of in-memory channels which can utilized to o capture stream-like information in a natural way instead of using set and append to manipulate strings o or to transfer data between interpreters, in the same thread or not. COMMAND
memchan ?-initial-size len? creates a chunk-oriented in-memory channel and returns its handle. If an initial size is specified the system will pre-allocate len bytes of buffer space for the contents. This 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. 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 memchan 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 memchan grow as necessary they are always writable. This means that a writable fileevent-handler will fire continuously. The channels are also readable if they contain more than zero bytes and the seek location is not and the end of the channel. Under these conditions a readable fileevent-handler will fire continuously. Note that writing to such a channel usually occurs at the end, thus supressing readable events. This also means that users have to take care to seek the channel to a location before the end before trying to read data back. SEE ALSO
fifo, fifo2, null, random, zero KEYWORDS
channel, chunk, i/o, in-memory channel, memchan COPYRIGHT
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net> Memory channels 2.2 memchan(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)
Man Page