IO::Async::Channel(3) User Contributed Perl DocumentationIO::Async::Channel(3)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>
perl v5.18.2 2014-05-14 IO::Async::Channel(3)
