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Mojo::IOLoop(3)	      User Contributed Perl Documentation      Mojo::IOLoop(3)

NAME
       Mojo::IOLoop - Minimalistic event loop

SYNOPSIS
	 use Mojo::IOLoop;

	 # Listen on port 3000
	 Mojo::IOLoop->server({port => 3000} =>	sub {
	   my ($loop, $stream) = @_;

	   $stream->on(read => sub {
	     my	($stream, $bytes) = @_;

	     # Process input chunk
	     say $bytes;

	     # Write response
	     $stream->write('HTTP/1.1 200 OK');
	   });
	 });

	 # Connect to port 3000
	 my $id	= Mojo::IOLoop->client({port =>	3000} => sub {
	   my ($loop, $err, $stream) = @_;

	   $stream->on(read => sub {
	     my	($stream, $bytes) = @_;

	     # Process input
	     say "Input: $bytes";
	   });

	   # Write request
	   $stream->write("GET / HTTP/1.1\x0d\x0a\x0d\x0a");
	 });

	 # Add a timer
	 Mojo::IOLoop->timer(5 => sub {
	   my $loop = shift;
	   $loop->remove($id);
	 });

	 # Start event loop if necessary
	 Mojo::IOLoop->start unless Mojo::IOLoop->is_running;

DESCRIPTION
       Mojo::IOLoop is a very minimalistic event loop based on Mojo::Reactor,
       it has been reduced to the absolute minimal feature set required	to
       build solid and scalable	non-blocking clients and servers.

       Depending on operating system, the default per-process and system-wide
       file descriptor limits are often	very low and need to be	tuned for
       better scalability. The "LIBEV_FLAGS" environment variable should also
       be used to select the best possible EV backend, which usually defaults
       to the not very scalable	"select".

	 LIBEV_FLAGS=1	 # select
	 LIBEV_FLAGS=2	 # poll
	 LIBEV_FLAGS=4	 # epoll (Linux)
	 LIBEV_FLAGS=8	 # kqueue (*BSD, OS X)

       The event loop will be resilient	to time	jumps if a monotonic clock is
       available through Time::HiRes. A	TLS certificate	and key	are also built
       right in, to make writing test servers as easy as possible. Also	note
       that for	convenience the	"PIPE" signal will be set to "IGNORE" when
       Mojo::IOLoop is loaded.

       For better scalability (epoll, kqueue) and to provide non-blocking name
       resolution, SOCKS5 as well as TLS support, the optional modules EV
       (4.0+), Net::DNS::Native	(0.15+), IO::Socket::Socks (0.64+) and
       IO::Socket::SSL (1.94+) will be used automatically if possible.
       Individual features can also be disabled	with the "MOJO_NO_NNR",
       "MOJO_NO_SOCKS" and "MOJO_NO_TLS" environment variables.

       See "REAL-TIME WEB" in Mojolicious::Guides::Cookbook for	more.

EVENTS
       Mojo::IOLoop inherits all events	from Mojo::EventEmitter	and can	emit
       the following new ones.

   finish
	 $loop->on(finish => sub {
	   my $loop = shift;
	   ...
	 });

       Emitted when the	event loop wants to shut down gracefully and is	just
       waiting for all existing	connections to be closed.

ATTRIBUTES
       Mojo::IOLoop implements the following attributes.

   max_accepts
	 my $max = $loop->max_accepts;
	 $loop	 = $loop->max_accepts(1000);

       The maximum number of connections this event loop is allowed to accept,
       before shutting down gracefully without interrupting existing
       connections, defaults to	0. Setting the value to	0 will allow this
       event loop to accept new	connections indefinitely. Note that up to half
       of this value can be subtracted randomly	to improve load	balancing
       between multiple	server processes, and to make sure that	not all	of
       them restart at the same	time.

   max_connections
	 my $max = $loop->max_connections;
	 $loop	 = $loop->max_connections(100);

       The maximum number of accepted connections this event loop is allowed
       to handle concurrently, before stopping to accept new incoming
       connections, defaults to	1000.

   reactor
	 my $reactor = $loop->reactor;
	 $loop	     = $loop->reactor(Mojo::Reactor->new);

       Low-level event reactor,	usually	a Mojo::Reactor::Poll or
       Mojo::Reactor::EV object	with a default subscriber to the event "error"
       in Mojo::Reactor.

	 # Watch if handle becomes readable or writable
	 Mojo::IOLoop->singleton->reactor->io($handle => sub {
	   my ($reactor, $writable) = @_;
	   say $writable ? 'Handle is writable'	: 'Handle is readable';
	 });

	 # Change to watching only if handle becomes writable
	 Mojo::IOLoop->singleton->reactor->watch($handle, 0, 1);

	 # Remove handle again
	 Mojo::IOLoop->singleton->reactor->remove($handle);

METHODS
       Mojo::IOLoop inherits all methods from Mojo::EventEmitter and
       implements the following	new ones.

   acceptor
	 my $server = Mojo::IOLoop->acceptor($id);
	 my $server = $loop->acceptor($id);
	 my $id	    = $loop->acceptor(Mojo::IOLoop::Server->new);

       Get Mojo::IOLoop::Server	object for id or turn object into an acceptor.

   client
	 my $id
	   = Mojo::IOLoop->client(address => '127.0.0.1', port => 3000,	sub {...});
	 my $id	= $loop->client(address	=> '127.0.0.1',	port =>	3000, sub {...});
	 my $id	= $loop->client({address => '127.0.0.1', port => 3000} => sub {...});

       Open a TCP/IP or	UNIX domain socket connection with
       Mojo::IOLoop::Client, takes the same arguments as "connect" in
       Mojo::IOLoop::Client.

	 # Connect to 127.0.0.1	on port	3000
	 Mojo::IOLoop->client({port => 3000} =>	sub {
	   my ($loop, $err, $stream) = @_;
	   ...
	 });

   delay
	 my $delay = Mojo::IOLoop->delay;
	 my $delay = $loop->delay;
	 my $delay = $loop->delay(sub {...});
	 my $delay = $loop->delay(sub {...}, sub {...});

       Build Mojo::IOLoop::Delay object	to manage callbacks and	control	the
       flow of events for this event loop, which can help you avoid deep
       nested closures that often result from continuation-passing style.
       Callbacks will be passed	along to "steps" in Mojo::IOLoop::Delay.

	 # Synchronize multiple	non-blocking operations
	 my $delay = Mojo::IOLoop->delay(sub { say 'BOOM!' });
	 for my	$i (1 .. 10) {
	   my $end = $delay->begin;
	   Mojo::IOLoop->timer($i => sub {
	     say 10 - $i;
	     $end->();
	   });
	 }
	 $delay->wait;

	 # Sequentialize multiple non-blocking operations
	 Mojo::IOLoop->delay(

	   # First step	(simple	timer)
	   sub {
	     my	$delay = shift;
	     Mojo::IOLoop->timer(2 => $delay->begin);
	     say 'Second step in 2 seconds.';
	   },

	   # Second step (concurrent timers)
	   sub {
	     my	$delay = shift;
	     Mojo::IOLoop->timer(1 => $delay->begin);
	     Mojo::IOLoop->timer(3 => $delay->begin);
	     say 'Third	step in	3 seconds.';
	   },

	   # Third step	(the end)
	   sub { say 'And done after 5 seconds total.' }
	 )->wait;

	 # Handle exceptions in	all steps
	 Mojo::IOLoop->delay(
	   sub {
	     my	$delay = shift;
	     die 'Intentional error';
	   },
	   sub {
	     my	($delay, @args)	= @_;
	     say 'Never	actually reached.';
	   }
	 )->catch(sub {
	   my ($delay, $err) = @_;
	   say "Something went wrong: $err";
	 })->wait;

   is_running
	 my $bool = Mojo::IOLoop->is_running;
	 my $bool = $loop->is_running;

       Check if	event loop is running.

	 exit unless Mojo::IOLoop->is_running;

   next_tick
	 my $undef = Mojo::IOLoop->next_tick(sub {...});
	 my $undef = $loop->next_tick(sub {...});

       Execute callback	as soon	as possible, but not before returning or other
       callbacks that have been	registered with	this method, always returns
       "undef".

	 # Perform operation on	next reactor tick
	 Mojo::IOLoop->next_tick(sub {
	   my $loop = shift;
	   ...
	 });

   one_tick
	 Mojo::IOLoop->one_tick;
	 $loop->one_tick;

       Run event loop until an event occurs.

	 # Don't block longer than 0.5 seconds
	 my $id	= Mojo::IOLoop->timer(0.5 => sub {});
	 Mojo::IOLoop->one_tick;
	 Mojo::IOLoop->remove($id);

   recurring
	 my $id	= Mojo::IOLoop->recurring(3 => sub {...});
	 my $id	= $loop->recurring(0 =>	sub {...});
	 my $id	= $loop->recurring(0.25	=> sub {...});

       Create a	new recurring timer, invoking the callback repeatedly after a
       given amount of time in seconds.

	 # Perform operation every 5 seconds
	 Mojo::IOLoop->recurring(5 => sub {
	   my $loop = shift;
	   ...
	 });

   remove
	 Mojo::IOLoop->remove($id);
	 $loop->remove($id);

       Remove anything with an id, connections will be dropped gracefully by
       allowing	them to	finish writing all data	in their write buffers.

   reset
	 Mojo::IOLoop->reset;
	 $loop->reset;

       Remove everything and stop the event loop.

   server
	 my $id	= Mojo::IOLoop->server(port => 3000, sub {...});
	 my $id	= $loop->server(port =>	3000, sub {...});
	 my $id	= $loop->server({port => 3000} => sub {...});

       Accept TCP/IP and UNIX domain socket connections	with
       Mojo::IOLoop::Server, takes the same arguments as "listen" in
       Mojo::IOLoop::Server.

	 # Listen on port 3000
	 Mojo::IOLoop->server({port => 3000} =>	sub {
	   my ($loop, $stream, $id) = @_;
	   ...
	 });

	 # Listen on random port
	 my $id	= Mojo::IOLoop->server({address	=> '127.0.0.1'}	=> sub {
	   my ($loop, $stream, $id) = @_;
	   ...
	 });
	 my $port = Mojo::IOLoop->acceptor($id)->port;

   singleton
	 my $loop = Mojo::IOLoop->singleton;

       The global Mojo::IOLoop singleton, used to access a single shared event
       loop object from	everywhere inside the process.

	 # Many	methods	also allow you to take shortcuts
	 Mojo::IOLoop->timer(2 => sub {	Mojo::IOLoop->stop });
	 Mojo::IOLoop->start;

	 # Restart active timer
	 my $id	= Mojo::IOLoop->timer(3	=> sub { say 'Timeout!'	});
	 Mojo::IOLoop->singleton->reactor->again($id);

	 # Turn	file descriptor	into handle and	watch if it becomes readable
	 my $handle = IO::Handle->new_from_fd($fd, 'r');
	 Mojo::IOLoop->singleton->reactor->io($handle => sub {
	   my ($reactor, $writable) = @_;
	   say $writable ? 'Handle is writable'	: 'Handle is readable';
	 })->watch($handle, 1, 0);

   start
	 Mojo::IOLoop->start;
	 $loop->start;

       Start the event loop, this will block until "stop" is called. Note that
       some reactors stop automatically	if there are no	events being watched
       anymore.

	 # Start event loop only if it is not running already
	 Mojo::IOLoop->start unless Mojo::IOLoop->is_running;

   stop
	 Mojo::IOLoop->stop;
	 $loop->stop;

       Stop the	event loop, this will not interrupt any	existing connections
       and the event loop can be restarted by running "start" again.

   stop_gracefully
	 Mojo::IOLoop->stop_gracefully;
	 $loop->stop_gracefully;

       Stop accepting new connections and wait for already accepted
       connections to be closed, before	stopping the event loop.

   stream
	 my $stream = Mojo::IOLoop->stream($id);
	 my $stream = $loop->stream($id);
	 my $id	    = $loop->stream(Mojo::IOLoop::Stream->new);

       Get Mojo::IOLoop::Stream	object for id or turn object into a
       connection.

	 # Increase inactivity timeout for connection to 300 seconds
	 Mojo::IOLoop->stream($id)->timeout(300);

   subprocess
	 my $subprocess	= Mojo::IOLoop->subprocess(sub {...}, sub {...});
	 my $subprocess	= $loop->subprocess(sub	{...}, sub {...});

       Build Mojo::IOLoop::Subprocess object to	perform	computationally
       expensive operations in subprocesses, without blocking the event	loop.
       Callbacks will be passed	along to "run" in Mojo::IOLoop::Subprocess.

	 # Operation that would	block the event	loop for 5 seconds
	 Mojo::IOLoop->subprocess(
	   sub {
	     my	$subprocess = shift;
	     sleep 5;
	     return 'aY', 'Mojolicious';
	   },
	   sub {
	     my	($subprocess, $err, @results) =	@_;
	     say "Subprocess error: $err" and return if	$err;
	     say "I $results[0]	$results[1]!";
	   }
	 );

   timer
	 my $id	= Mojo::IOLoop->timer(3	=> sub {...});
	 my $id	= $loop->timer(0 => sub	{...});
	 my $id	= $loop->timer(0.25 => sub {...});

       Create a	new timer, invoking the	callback after a given amount of time
       in seconds.

	 # Perform operation in	5 seconds
	 Mojo::IOLoop->timer(5 => sub {
	   my $loop = shift;
	   ...
	 });

DEBUGGING
       You can set the "MOJO_IOLOOP_DEBUG" environment variable	to get some
       advanced	diagnostics information	printed	to "STDERR".

	 MOJO_IOLOOP_DEBUG=1

SEE ALSO
       Mojolicious, Mojolicious::Guides, <http://mojolicious.org>.

perl v5.24.1			  2017-02-24		       Mojo::IOLoop(3)

NAME | SYNOPSIS | DESCRIPTION | EVENTS | ATTRIBUTES | METHODS | DEBUGGING | SEE ALSO

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