trusty (3) IO::Async::Channel.3pm.gz

NAME

       "IO::Async::Channel" - pass values into or out from an IO::Async::Routine

DESCRIPTION

       A "IO::Async::Channel" object allows Perl values to be passed into or out of an IO::Async::Routine. It is
       intended to be used primarily with a Routine object rather than independently. For more detail and
       examples on how to use this object see also the documentation for IO::Async::Routine.

       A Channel object is shared between the main process of the program and the process running within the
       Routine. In the main process it will be used in asynchronous mode, and in the Routine process it will be
       used in synchronous mode. In asynchronous mode all methods return immediately and use "IO::Async"-style
       callback functions. In synchronous within the Routine process the methods block until they are ready and
       may be used for flow-control within the routine. Alternatively, a Channel may be shared between two
       different Routine objects, and not used directly by the controlling program.

       The channel itself represents a FIFO of Perl reference values. New values may be put into the channel by
       the "send" method in either mode. Values may be retrieved from it by the "recv" method. Values inserted
       into the Channel are snapshot by the "send" method. Any changes to referred variables will not be
       observed by the other end of the Channel after the "send" method returns.

       Since the channel uses Storable to serialise values to write over the communication filehandle only
       reference values may be passed. To pass a single scalar value, "send" a SCALAR reference to it, and
       dereference the result of "recv".

CONSTRUCTOR

   $channel = IO::Async::Channel->new
       Returns a new "IO::Async::Channel" object. This object reference itself should be shared by both sides of
       a "fork()"ed process. After "fork()" the two "setup_*" methods may be used to configure the object for
       operation on either end.

       While this object does in fact inherit from IO::Async::Notifier for implementation reasons it is not
       intended that this object be used as a Notifier. It should not be added to a Loop object directly; event
       management will be handled by its containing "IO::Async::Routine" object.

METHODS

   $channel->configure( %params )
       Similar to the standard "configure" method on "IO::Async::Notifier", this is used to change details of
       the Channel's operation.

       on_recv => CODE
           May only be set on an async mode channel. If present, will be invoked whenever a new value is
           received, rather than using the "recv" method.

            $on_recv->( $channel, $data )

       on_eof => CODE
           May only be set on an async mode channel. If present, will be invoked when the channel gets closed by
           the peer.

            $on_eof->( $channel )

   $channel->send( $data )
       Pushes the data stored in the given Perl reference into the FIFO of the Channel, where it can be received
       by the other end. When called on a synchronous mode Channel this method may block if a "write()" call on
       the underlying filehandle blocks. When called on an asynchronous mode channel this method will not block.

   $channel->send_frozen( $record )
       A variant of the "send" method; this method pushes the byte record given.  This should be the result of a
       call to "Storable::freeze()".

   $data = $channel->recv
       When called on a synchronous mode Channel this method will block until a Perl reference value is
       available from the other end and then return it. If the Channel is closed this method will return
       "undef". Since only references may be passed and all Perl references are true the truth of the result of
       this method can be used to detect that the channel is still open and has not yet been closed.

   $channel->recv( %args )
       When called on an asynchronous mode Channel this method appends a callback function to the receiver queue
       to handle the next Perl reference value that becomes available from the other end. Takes the following
       named arguments:

       on_recv => CODE
               Called when a new Perl reference value is available. Will be passed the Channel object and the
               reference data.

                $on_recv->( $channel, $data )

       on_eof => CODE
               Called if the Channel was closed before a new value was ready. Will be passed the Channel object.

                $on_eof->( $channel )

   $channel->close
       Closes the channel. Causes a pending "recv" on the other end to return undef or the queued "on_eof"
       callbacks to be invoked.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>