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

       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"