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.\" ========================================================================
.\"
.IX Title "IO::Async::Listener 3pm"
.TH IO::Async::Listener 3pm "2014-10-21" "perl v5.20.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
"IO::Async::Listener" \- listen on network sockets for incoming connections
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& use IO::Async::Listener;
\&
\& use IO::Async::Loop;
\& my $loop = IO::Async::Loop\->new;
\&
\& my $listener = IO::Async::Listener\->new(
\&    on_stream => sub {
\&       my ( undef, $stream ) = @_;
\&
\&       $stream\->configure(
\&          on_read => sub {
\&             my ( $self, $buffref, $eof ) = @_;
\&             $self\->write( $$buffref );
\&             $$buffref = "";
\&             return 0;
\&          },
\&       );
\&       
\&       $loop\->add( $stream );
\&    },
\& );
\&
\& $loop\->add( $listener );
\&
\& $listener\->listen(
\&    service  => "echo",
\&    socktype => \*(Aqstream\*(Aq,
\&
\&    on_resolve_error => sub { print STDERR "Cannot resolve \- $_[0]\en"; },
\&    on_listen_error  => sub { print STDERR "Cannot listen\en"; },
\& );
\&
\& $loop\->run;
.Ve
.PP
This object can also be used indirectly via an \f(CW\*(C`IO::Async::Loop\*(C'\fR:
.PP
.Vb 1
\& use IO::Async::Stream;
\&
\& use IO::Async::Loop;
\& my $loop = IO::Async::Loop\->new;
\&
\& $loop\->listen(
\&    service  => "echo",
\&    socktype => \*(Aqstream\*(Aq,
\&
\&    on_stream => sub {
\&       ...
\&    },
\&
\&    on_resolve_error => sub { print STDERR "Cannot resolve \- $_[0]\en"; },
\&    on_listen_error  => sub { print STDERR "Cannot listen\en"; },
\& );
\&
\& $loop\->run;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This subclass of IO::Async::Handle adds behaviour which watches a socket in
listening mode, to accept incoming connections on them.
.PP
A Listener can be constructed and given a existing socket in listening mode.
Alternatively, the Listener can construct a socket by calling the \f(CW\*(C`listen\*(C'\fR
method. Either a list of addresses can be provided, or a service name can be
looked up using the underlying loop's \f(CW\*(C`resolve\*(C'\fR method.
.SH "EVENTS"
.IX Header "EVENTS"
The following events are invoked, either using subclass methods or \s-1CODE\s0
references in parameters:
.ie n .SS "on_accept $clientsocket | $handle"
.el .SS "on_accept \f(CW$clientsocket\fP | \f(CW$handle\fP"
.IX Subsection "on_accept $clientsocket | $handle"
Invoked whenever a new client connects to the socket.
.PP
If neither \f(CW\*(C`handle_constructor\*(C'\fR nor \f(CW\*(C`handle_class\*(C'\fR parameters are set, this
will be invoked with the new client socket directly. If a handle constructor
or class are set, this will be invoked with the newly-constructed handle,
having the new socket already configured onto it.
.ie n .SS "on_stream $stream"
.el .SS "on_stream \f(CW$stream\fP"
.IX Subsection "on_stream $stream"
An alternative to \f(CW\*(C`on_accept\*(C'\fR, this an instance of IO::Async::Stream when
a new client connects. This is provided as a convenience for the common case
that a Stream object is required as the transport for a Protocol object.
.PP
This is now vaguely deprecated in favour of using \f(CW\*(C`on_accept\*(C'\fR with a handle
constructor or class.
.ie n .SS "on_socket $socket"
.el .SS "on_socket \f(CW$socket\fP"
.IX Subsection "on_socket $socket"
Similar to \f(CW\*(C`on_stream\*(C'\fR, but constructs an instance of IO::Async::Socket.
This is most useful for \f(CW\*(C`SOCK_DGRAM\*(C'\fR or \f(CW\*(C`SOCK_RAW\*(C'\fR sockets.
.PP
This is now vaguely deprecated in favour of using \f(CW\*(C`on_accept\*(C'\fR with a handle
constructor or class.
.ie n .SS "on_accept_error $socket, $errno"
.el .SS "on_accept_error \f(CW$socket\fP, \f(CW$errno\fP"
.IX Subsection "on_accept_error $socket, $errno"
Optional. Invoked if the \f(CW\*(C`accept\*(C'\fR syscall indicates an error (other than
\&\f(CW\*(C`EAGAIN\*(C'\fR or \f(CW\*(C`EWOULDBLOCK\*(C'\fR). If not provided, failures of \f(CW\*(C`accept\*(C'\fR will
simply be ignored.
.SH "PARAMETERS"
.IX Header "PARAMETERS"
The following named parameters may be passed to \f(CW\*(C`new\*(C'\fR or \f(CW\*(C`configure\*(C'\fR:
.SS "on_accept => \s-1CODE\s0"
.IX Subsection "on_accept => CODE"
.SS "on_stream => \s-1CODE\s0"
.IX Subsection "on_stream => CODE"
.SS "on_socket => \s-1CODE\s0"
.IX Subsection "on_socket => CODE"
\&\s-1CODE\s0 reference for the event handlers. Because of the mutually-exclusive
nature of their behaviour, only one of these may be set at a time. Setting one
will remove the other two.
.SS "handle => \s-1IO\s0"
.IX Subsection "handle => IO"
The \s-1IO\s0 handle containing an existing listen-mode socket.
.SS "handle_constructor => \s-1CODE\s0"
.IX Subsection "handle_constructor => CODE"
Optional. If defined, gives a \s-1CODE\s0 reference to be invoked every time a new
client socket is accepted from the listening socket. It is passed the listener
object itself, and is expected to return a new instance of
\&\f(CW\*(C`IO::Async::Handle\*(C'\fR or a subclass, used to wrap the new client socket.
.PP
.Vb 1
\& $handle = $handle_constructor\->( $listener )
.Ve
.PP
This can also be given as a subclass method
.PP
.Vb 1
\& $handle = $listener\->handle_constructor()
.Ve
.SS "handle_class => \s-1STRING\s0"
.IX Subsection "handle_class => STRING"
Optional. If defined and \f(CW\*(C`handle_constructor\*(C'\fR isn't, then new wrapper handles
are constructed by invoking the \f(CW\*(C`new\*(C'\fR method on the given class name, passing
in no additional parameters.
.PP
.Vb 1
\& $handle = $handle_class\->new()
.Ve
.PP
This can also be given as a subclass method
.PP
.Vb 1
\& $handle = $listener\->handle_class\->new
.Ve
.SS "acceptor => STRING|CODE"
.IX Subsection "acceptor => STRING|CODE"
Optional. If defined, gives the name of a method or a \s-1CODE\s0 reference to use to
implement the actual accept behaviour. This will be invoked as:
.PP
.Vb 1
\& ( $accepted ) = $listener\->acceptor( $socket )\->get
\&
\& ( $handle ) = $listener\->acceptor( $socket, handle => $handle )\->get
.Ve
.PP
It is invoked with the listening socket as its its argument, and optionally
an \f(CW\*(C`IO::Async::Handle\*(C'\fR instance as a named parameter, and is expected to
return a \f(CW\*(C`Future\*(C'\fR that will eventually yield the newly-accepted socket or
handle instance, if such was provided.
.SH "METHODS"
.IX Header "METHODS"
The following methods documented with a trailing call to \f(CW\*(C`\->get\*(C'\fR return
Future instances.
.ie n .SS "$acceptor = $listener\->acceptor"
.el .SS "\f(CW$acceptor\fP = \f(CW$listener\fP\->acceptor"
.IX Subsection "$acceptor = $listener->acceptor"
Returns the currently-set \f(CW\*(C`acceptor\*(C'\fR method name or code reference. This may
be of interest to Loop \f(CW\*(C`listen\*(C'\fR extension methods that wish to extend or wrap
it.
.ie n .SS "$name = $listener\->sockname"
.el .SS "\f(CW$name\fP = \f(CW$listener\fP\->sockname"
.IX Subsection "$name = $listener->sockname"
Returns the \f(CW\*(C`sockname\*(C'\fR of the underlying listening socket
.ie n .SS "$family = $listener\->family"
.el .SS "\f(CW$family\fP = \f(CW$listener\fP\->family"
.IX Subsection "$family = $listener->family"
Returns the socket address family of the underlying listening socket
.ie n .SS "$socktype = $listener\->socktype"
.el .SS "\f(CW$socktype\fP = \f(CW$listener\fP\->socktype"
.IX Subsection "$socktype = $listener->socktype"
Returns the socket type of the underlying listening socket
.ie n .SS "$listener\->listen( %params )"
.el .SS "\f(CW$listener\fP\->listen( \f(CW%params\fP )"
.IX Subsection "$listener->listen( %params )"
This method sets up a listening socket and arranges for the acceptor callback
to be invoked each time a new connection is accepted on the socket.
.PP
Most parameters given to this method are passed into the \f(CW\*(C`listen\*(C'\fR method of
the IO::Async::Loop object. In addition, the following arguments are also
recognised directly:
.IP "on_listen => \s-1CODE\s0" 8
.IX Item "on_listen => CODE"
Optional. A callback that is invoked when the listening socket is ready.
Similar to that on the underlying loop method, except it is passed the
listener object itself.
.Sp
.Vb 1
\& $on_listen\->( $listener )
.Ve
.SH "EXAMPLES"
.IX Header "EXAMPLES"
.SS "Listening on \s-1UNIX\s0 Sockets"
.IX Subsection "Listening on UNIX Sockets"
The \f(CW\*(C`handle\*(C'\fR argument can be passed an existing socket already in listening
mode, making it possible to listen on other types of socket such as \s-1UNIX\s0
sockets.
.PP
.Vb 2
\& use IO::Async::Listener;
\& use IO::Socket::UNIX;
\&
\& use IO::Async::Loop;
\& my $loop = IO::Async::Loop\->new;
\&
\& my $listener = IO::Async::Listener\->new(
\&    on_stream => sub {
\&       my ( undef, $stream ) = @_;
\&
\&       $stream\->configure(
\&          on_read => sub {
\&             my ( $self, $buffref, $eof ) = @_;
\&             $self\->write( $$buffref );
\&             $$buffref = "";
\&             return 0;
\&          },
\&       );
\&       
\&       $loop\->add( $stream );
\&    },
\& );
\&
\& $loop\->add( $listener );
\&
\& my $socket = IO::Socket::UNIX\->new(
\&    Local => "echo.sock",
\&    Listen => 1,
\& ) or die "Cannot make UNIX socket \- $!\en";
\&
\& $listener\->listen(
\&    handle => $socket,
\& );
\&
\& $loop\->run;
.Ve
.SS "Passing Plain Socket Addresses"
.IX Subsection "Passing Plain Socket Addresses"
The \f(CW\*(C`addr\*(C'\fR or \f(CW\*(C`addrs\*(C'\fR parameters should contain a definition of a plain
socket address in a form that the IO::Async::OS \f(CW\*(C`extract_addrinfo\*(C'\fR
method can use.
.PP
This example shows how to listen on \s-1TCP\s0 port 8001 on address 10.0.0.1:
.PP
.Vb 9
\& $listener\->listen(
\&    addr => {
\&       family   => "inet",
\&       socktype => "stream",
\&       port     => 8001,
\&       ip       => "10.0.0.1",
\&    },
\&    ...
\& );
.Ve
.PP
This example shows another way to listen on a \s-1UNIX\s0 socket, similar to the
earlier example:
.PP
.Vb 8
\& $listener\->listen(
\&    addr => {
\&       family   => "unix",
\&       socktype => "stream",
\&       path     => "echo.sock",
\&    },
\&    ...
\& );
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
Paul Evans <leonerd@leonerd.org.uk>