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:

Sys::Virt::Stream::RECV_STOP_AT_HOLE: If this flag is set, the "recv" function will stop reading from stream if it has reached a hole. In that case, -3 is returned and "recv_hole" should be called to get the hole size.

$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

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.