POE::Wheel::SocketFactory - non-blocking socket creation and management

NAME

POE::Wheel::SocketFactory - non-blocking socket creation and management

SYNOPSIS

  use Socket; # For the constants

  # Listening Unix domain socket.
  $wheel = POE::Wheel::SocketFactory->new(
    SocketDomain => AF_UNIX,               # Sets the socket() domain
    BindAddress  => $unix_socket_address,  # Sets the bind() address
    SuccessEvent => $event_success,        # Event to emit upon accept()
    FailureEvent => $event_failure,        # Event to emit upon error
    # Optional parameters (and default values):
    SocketType   => SOCK_STREAM,           # Sets the socket() type
  );

  # Connecting Unix domain socket.
  $wheel = POE::Wheel::SocketFactory->new(
    SocketDomain  => AF_UNIX,              # Sets the socket() domain
    RemoteAddress => $unix_server_address, # Sets the connect() address
    SuccessEvent  => $event_success,       # Event to emit on connection
    FailureEvent  => $event_failure,       # Event to emit on error
    # Optional parameters (and default values):
    SocketType    => SOCK_STREAM,          # Sets the socket() type
    # Optional parameters (that have no defaults):
    BindAddress   => $unix_client_address, # Sets the bind() address
  );

  # Listening Internet domain socket.
  $wheel = POE::Wheel::SocketFactory->new(
    BindAddress    => $inet_address,       # Sets the bind() address
    BindPort       => $inet_port,          # Sets the bind() port
    SuccessEvent   => $event_success,      # Event to emit upon accept()
    FailureEvent   => $event_failure,      # Event to emit upon error
    # Optional parameters (and default values):
    SocketDomain   => AF_INET,             # Sets the socket() domain
    SocketType     => SOCK_STREAM,         # Sets the socket() type
    SocketProtocol => 'tcp',               # Sets the socket() protocol
    ListenQueue    => SOMAXCONN,           # The listen() queue length
    Reuse          => 'on',                # Lets the port be reused
  );

  # Connecting Internet domain socket.
  $wheel = POE::Wheel::SocketFactory->new(
    RemoteAddress  => $inet_address,       # Sets the connect() address
    RemotePort     => $inet_port,          # Sets the connect() port
    SuccessEvent   => $event_success,      # Event to emit on connection
    FailureEvent   => $event_failure,      # Event to emit on error
    # Optional parameters (and default values):
    SocketDomain   => AF_INET,             # Sets the socket() domain
    SocketType     => SOCK_STREAM,         # Sets the socket() type
    SocketProtocol => 'tcp',               # Sets the socket() protocol
    Reuse          => 'yes',               # Lets the port be reused
  );

  $wheel->event( ... );

  $wheel->ID();

  $wheel->pause_accept();
  $wheel->resume_accept();

DESCRIPTION

SocketFactory creates sockets. It can create connectionless sockets like UDP, or connected sockets like UNIX domain streams and TCP sockets.

The SocketFactory manages connecting and listening sockets on behalf of the session that created it. It will watch a connecting socket and fire a SuccessEvent or FailureEvent event when something happens. It will watch a listening socket and fire a SuccessEvent or FailureEvent for every connection.

PUBLIC METHODS

new LOTS_OF_THINGS: new() creates a new socket. If necessary, it registers event handlers to manage the socket. new() has parameters for just about every aspect of socket creation; thankfully they all aren't needed at once.; new() always returns a SocketFactory wheel reference, even if a socket couldn't be created.; These parameters provide information for the SocketFactory's socket() call.
event EVENT_TYPE => EVENT_NAME, ...: event() is covered in the POE::Wheel manpage.
getsockname: getsockname() behaves like the built-in function of the same name. Because the SocketFactory's underlying socket is hidden away, it's hard to do this directly.; It's useful for finding which address and/or port the SocketFactory has bound to when it's been instructed to use BindAddress => INADDR_ANY or BindPort => 0.
ID: The ID method returns a SocketFactory wheel's unique ID. This ID will be included in every event the wheel generates, and it can be used to match events with the wheels which generated them.
pause_accept
resume_accept: Listening SocketFactory instances will accept connections for as long as they exist. This may not be desirable in pre-forking servers where the main process must not handle connections.; pause_accept() temporarily stops a SocketFactory from accepting new connections. It continues to listen, however. resume_accept() ends a temporary pause, allowing a SocketFactory to accept new connections.; In a pre-forking server, the main process would pause_accept() immediately after the SocketFactory was created. As forked child processes start, they call resume_accept() to begin accepting connections.

EVENTS AND PARAMETERS

SuccessEvent

SuccessEvent defines the event that will be emitted when a socket has been established successfully. The SuccessEvent event is fired when outbound sockets have connected or whenever listening sockets accept new connections.

SuccessEvent must be the name of a state within the current session.

In all cases, ARG0 holds the new socket handle. ARG3 holds the wheel's unique ID. The parameters between them differ according to the socket's domain and whether it's listening or connecting.

For INET sockets, ARG1 and ARG2 hold the socket's remote address and port, respectively. The address is packed; use inet_ntoa() (See the Socket manpage) if a human-readable version is necessary.

For UNIX client sockets, ARG1 holds the server address. It may be undefined on systems that have trouble retrieving a UNIX socket's remote address. ARG2 is always undefined for UNIX client sockets.

According to _Perl Cookbook_, the remote address returned by accept() on UNIX sockets is undefined, so ARG1 and ARG2 are also undefined in this case.

A sample SuccessEvent handler:

  sub server_accept {
    my $accepted_handle = $_[ARG0];

    my $peer_host = inet_ntoa($_[ARG1]);
    print( "Wheel $_[ARG3] accepted a connection from ",
           "$peer_host port $peer_port\n"
         );

    # Do something with the new connection.
    &spawn_connection_session( $accepted_handle );
  }

FailureEvent

FailureEvent defines the event that will be emitted when a socket error occurs. EAGAIN does not count as an error since the SocketFactory knows what to do with it.

FailureEvent must be the name of a state within the current session.

The FailureEvent event comes with the standard error event parameters.

ARG0 contains the name of the operation that failed. ARG1 and ARG2 hold numeric and string values for $!, respectively. ARG3 contains the wheel's unique ID, which may be matched back to the wheel itself via the $wheel->ID call.

A sample ErrorEvent handler:

  sub error_state {
    my ($operation, $errnum, $errstr, $wheel_id) = @_[ARG0..ARG3];
    warn "Wheel $wheel_id generated $operation error $errnum: $errstr\n";
    delete $heap->{wheels}->{$wheel_id}; # shut down that wheel
  }

BUGS

Many (if not all) of the croak/carp/warn/die statements should fire back FailureEvent instead.

SocketFactory is only tested with UNIX streams and INET sockets using the UDP and TCP protocols. Others may or may not work, but the latest design is data driven and should be easy to extend. Patches are welcome, as are test cases for new families and protocols. Even if test cases fail, they'll make nice reference code to test additions to the SocketFactory class.

AUTHORS & COPYRIGHTS

Please see POE for more information about authors and contributors.

POE::Wheel::SocketFactory - non-blocking socket creation and management