NAME

Danga::Socket - Event loop and event-driven async socket base class

SYNOPSIS

  package My::Socket
  use Danga::Socket;
  use base ('Danga::Socket');
  use fields ('my_attribute');

  sub new {
     my My::Socket $self = shift;
     $self = fields::new($self) unless ref $self;
     $self->SUPER::new( @_ );

     $self->{my_attribute} = 1234;
     return $self;
  }

  sub event_err { ... }
  sub event_hup { ... }
  sub event_write { ... }
  sub event_read { ... }
  sub close { ... }

  $my_sock->tcp_cork($bool);

  # write returns 1 if all writes have gone through, or 0 if there
  # are writes in queue
  $my_sock->write($scalar);
  $my_sock->write($scalarref);
  $my_sock->write(sub { ... });  # run when previous data written
  $my_sock->write(undef);        # kick-starts

  # read max $bytecount bytes, or undef on connection closed
  $scalar_ref = $my_sock->read($bytecount);

  # watch for writability.  not needed with ->write().  write()
  # will automatically turn on watch_write when you wrote too much
  # and turn it off when done
  $my_sock->watch_write($bool);

  # watch for readability
  $my_sock->watch_read($bool);

  # if you read too much and want to push some back on
  # readable queue.  (not incredibly well-tested)
  $my_sock->push_back_read($buf); # scalar or scalar ref

  Danga::Socket->AddOtherFds(..);
  Danga::Socket->SetLoopTimeout($millisecs);
  Danga::Socket->DescriptorMap();
  Danga::Socket->WatchedSockets();  # count of DescriptorMap keys
  Danga::Socket->SetPostLoopCallback($code);
  Danga::Socket->EventLoop();

DESCRIPTION

This is an abstract base class for objects backed by a socket which provides the basic framework for event-driven asynchronous IO, designed to be fast. Danga::Socket is both a base class for objects, and an event loop.

Callers subclass Danga::Socket. Danga::Socket's constructor registers itself with the Danga::Socket event loop, and invokes callbacks on the object for readability, writability, errors, and other conditions.

Because Danga::Socket uses the "fields" module, your subclasses must too.

MORE INFO

For now, see servers using Danga::Socket for guidance. For example: perlbal, mogilefsd, or ddlockd.

API

Note where "CLASS" is used below, normally you would call these methods as:

  Danga::Socket->method(...);

However using a subclass works too.

The CLASS methods are all methods for the event loop part of Danga::Socket, whereas the object methods are all used on your subclasses.

CLASS->Reset()

Reset all state

CLASS->HaveEpoll()

Returns a true value if this class will use IO::Epoll for async IO.

CLASS->WatchedSockets()

Returns the number of file descriptors which are registered with the global poll object.

CLASS->EnableProfiling()

Turns profiling on, clearing current profiling data.

CLASS->DisableProfiling()

Turns off profiling, but retains data up to this point

CLASS->ProfilingData()

Returns reference to a hash of data in format:

  ITEM => [ utime, stime, #calls ]

CLASS->ToClose()

Return the list of sockets that are awaiting close() at the end of the current event loop.

CLASS->OtherFds( [%fdmap] )

Get/set the hash of file descriptors that need processing in parallel with the registered Danga::Socket objects.

CLASS->AddOtherFds( [%fdmap] )

Add fds to the OtherFds hash for processing.

CLASS->SetLoopTimeout( $timeout )

Set the loop timeout for the event loop to some value in milliseconds.

A timeout of 0 (zero) means poll forever. A timeout of -1 means poll and return immediately.

CLASS->DebugMsg( $format, @args )

Print the debugging message specified by the sprintf-style format and args

CLASS->AddTimer( $seconds, $coderef )

Add a timer to occur $seconds from now. $seconds may be fractional, but timers are not guaranteed to fire at the exact time you ask for.

Returns a timer object which you can call $timer->cancel on if you need to.

CLASS->DescriptorMap()

Get the hash of Danga::Socket objects keyed by the file descriptor (fileno) they are wrapping.

Returns a hash in list context or a hashref in scalar context.

CLASS->EventLoop()

Start processing IO events. In most daemon programs this never exits. See PostLoopCallback below for how to exit the loop.

CLASS->SetPostLoopCallback( CODEREF )

Sets post loop callback function. Pass a subref and it will be called every time the event loop finishes.

Return 1 (or any true value) from the sub to make the loop continue, 0 or false and it will exit.

The callback function will be passed two parameters: \%DescriptorMap, \%OtherFds.

OBJECT METHODS

CLASS->new( $socket )

Create a new Danga::Socket subclass object for the given socket which will react to events on it during the EventLoop.

This is normally (always?) called from your subclass via:

  $class->SUPER::new($socket);

$obj->tcp_cork( $boolean )

Turn TCP_CORK on or off depending on the value of boolean.

$obj->steal_socket()

Basically returns our socket and makes it so that we don't try to close it, but we do remove it from epoll handlers. THIS CLOSES $self. It is the same thing as calling close, except it gives you the socket to use.

$obj->close( [$reason] )

Close the socket. The reason argument will be used in debugging messages.

$obj->sock()

Returns the underlying IO::Handle for the object.

$obj->set_writer_func( CODEREF )

Sets a function to use instead of syswrite() when writing data to the socket.

$obj->write( $data )

Write the specified data to the underlying handle. data may be scalar, scalar ref, code ref (to run when there), or undef just to kick-start. Returns 1 if writes all went through, or 0 if there are writes in queue. If it returns 1, caller should stop waiting for 'writable' events)

$obj->push_back_read( $buf )

Push back buf (a scalar or scalarref) into the read stream. Useful if you read more than you need to and want to return this data on the next "read".

$obj->read( $bytecount )

Read at most bytecount bytes from the underlying handle; returns scalar ref on read, or undef on connection closed.

(VIRTUAL) $obj->event_read()

Readable event handler. Concrete deriviatives of Danga::Socket should provide an implementation of this. The default implementation will die if called.

(VIRTUAL) $obj->event_err()

Error event handler. Concrete deriviatives of Danga::Socket should provide an implementation of this. The default implementation will die if called.

(VIRTUAL) $obj->event_hup()

'Hangup' event handler. Concrete deriviatives of Danga::Socket should provide an implementation of this. The default implementation will die if called.

$obj->event_write()

Writable event handler. Concrete deriviatives of Danga::Socket may wish to provide an implementation of this. The default implementation calls write() with an undef.

$obj->watch_read( $boolean )

Turn 'readable' event notification on or off.

$obj->watch_write( $boolean )

Turn 'writable' event notification on or off.

$obj->dump_error( $message )

Prints to STDERR a backtrace with information about this socket and what lead up to the dump_error call.

$obj->debugmsg( $format, @args )

Print the debugging message specified by the sprintf-style format and args.

$obj->peer_ip_string()

Returns the string describing the peer's IP

$obj->peer_addr_string()

Returns the string describing the peer for the socket which underlies this object in form "ip:port"

$obj->local_ip_string()

Returns the string describing the local IP

$obj->local_addr_string()

Returns the string describing the local end of the socket which underlies this object in form "ip:port"

$obj->as_string()

Returns a string describing this socket.

AUTHORS

Brad Fitzpatrick <brad@danga.com> - author

Michael Granger <ged@danga.com> - docs, testing

Mark Smith <junior@danga.com> - contributor, heavy user, testing

Matt Sergeant <matt@sergeant.org> - kqueue support, docs, timers, other bits

BUGS

Not documented enough (but isn't that true of every project?).

tcp_cork only works on Linux for now. No BSD push/nopush support.

LICENSE

License is granted to use and distribute this module under the same terms as Perl itself.

cpanm Danga::Socket

perl -MCPAN -e shell
install Danga::Socket