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>