NAME¶

Sys::Virt::Stream - Represent & manage a libvirt stream

DESCRIPTION¶

The "Sys::Virt::Stream" module represents a stream managed by the virtual machine monitor.

METHODS¶

my $st Sys::Virt::Stream->new($conn, $flags);

Creates a new data stream, ready for use with a stream based API. The optional $flags parameter can be used to configure the stream as non-blocking

$st->abort()

Abort I/O on the stream. Either this function or "finish" must be called on any stream which has been activated

$st->finish()

Complete I/O on the stream. Either this function or "abort" must be called on any stream which has been activated

$rv = $st->recv($data, $nbytes, $flags=0)

Receive up to $nbytes worth of data, copying into $data. Returns the number of bytes read, or -3 if hole is reached and $flags contains RECV_STOP_AT_HOLE, or -2 if I/O would block, or -1 on error. The $flags parameter accepts the following flags:

$rv = $st->send($data, $nbytes)

Send up to $nbytes worth of data, copying from $data. Returns the number of bytes sent, or -2 if I/O would block, or -1 on error.

$rv = $st->recv_hole($flags=0)

Determine the amount of the empty space (in bytes) to be created in a stream's target file when uploading or downloading sparsely populated files. This is the counterpart to "send_hole". The optional $flags parameter is currently unused and defaults to zero if omitted.

$st->send_hole($length, $flags=0)

Rather than transmitting empty file space, this method directs the stream target to create $length bytes of empty space. This method would be used when uploading or downloading sparsely populated files to avoid the needless copy of empty file space. The optional $flags parameter is currently unused and defaults to zero if omitted.

$st->recv_all($handler)

Receive all data available from the stream, invoking $handler to process the data. The $handler parameter must be a function which expects three arguments, the $st stream object, a scalar containing the data received and a data byte count. The function should return the number of bytes processed, or -1 upon error.

$st->send_all($handler)

Send all data produced by $handler to the stream. The $handler parameter must be a function which expects three arguments, the $st stream object, a scalar which must be filled with data and a maximum data byte count desired. The function should return the number of bytes filled, 0 on end of file, or -1 upon error

$st->sparse_recv_all($handler, $hole_handler)

Receive all data available from the sparse stream, invoking $handler to process the data. The $handler parameter must be a function which expects three arguments, the $st stream object, a scalar containing the data received and a data byte count. The function should return the number of bytes processed, or -1 upon error. The second argument $hole_handler is a function which expects two arguments: the $st stream and a scalar, number describing the size of the hole in the stream (in bytes). The $hole_handler is expected to return a non-negative number on success (usually 0) and a negative number (usually -1) otherwise.

$st->sparse_send_all($handler, $hole_handler, $skip_handler)

Send all data produced by $handler to the stream. The $handler parameter must be a function which expects three arguments, the $st stream object, a scalar which must be filled with data and a maximum data byte count desired. The function should return the number of bytes filled, 0 on end of file, or -1 upon error. The second argument $hole_handler is a function expecting just one argument $st and returning an array of two elements ($in_data, $section_len) where $in_data has zero or non-zero value if underlying file is in a hole or data section respectively. The $section_len then is the number of remaining bytes in the current section in the underlying file. Finally, the third $skip_handler is a function expecting two arguments $st and $length which moves cursor in the underlying file for $length bytes. The $skip_handler is expected to return a non-negative number on success (usually 0) and a negative number (usually -1) otherwise.

$st->add_callback($events, $coderef)

Register a callback to be invoked whenever the stream has one or more events from $events mask set. The $coderef must be a subroutine that expects 2 parameters, the original $st object and the new $events mask

$st->update_callback($events)

Change the event mask for a previously registered callback to $events

$st->remove_callback();

Remove a previously registered callback

CONSTANTS¶

Sys::Virt::Stream::NONBLOCK

Create a stream which will not block when performing I/O

Sys::Virt::Stream::EVENT_READABLE

The stream has data available for read without blocking

Sys::Virt::Stream::EVENT_WRITABLE

The stream has ability to write data without blocking

Sys::Virt::Stream::EVENT_ERROR

An error occurred on the stream

Sys::Virt::Stream::EVENT_HANGUP

The remote end of the stream closed

AUTHORS¶

Daniel P. Berrange <berrange@redhat.com>

COPYRIGHT¶

Copyright (C) 2006-2009 Red Hat Copyright (C) 2006-2007 Daniel P. Berrange

LICENSE¶

This program is free software; you can redistribute it and/or modify it under the terms of either the GNU General Public License as published by the Free Software Foundation (either version 2 of the License, or at your option any later version), or, the Artistic License, as specified in the Perl README file.

SEE ALSO¶

Sys::Virt, Sys::Virt::Error, "http://libvirt.org"