Provided by: libmojolicious-perl_7.59+dfsg-1ubuntu1_all bug

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 use as a promise and/or for flow-control.  Callbacks
       will be passed along to "steps" in Mojo::IOLoop::Delay.

         # Wrap continuation-passing style APIs with promises
         my $ua = Mojo::UserAgent->new;
         sub get {
           my $promise = Mojo::IOLoop->delay;
           $ua->get(@_ => sub {
             my ($ua, $tx) = @_;
             my $err = $tx->error;
             $promise->resolve($tx) if !$err || $err->{code};
             $promise->reject($err->{message});
           });
           return $promise;
         }
         my $mojo = get('http://mojolicious.org');
         my $cpan = get('http://metacpan.org');
         Mojo::Promise->race($mojo, $cpan)->then(sub { say shift->req->url })->wait;

         # 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;

   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;
         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 $subprocess = shift;
             sleep 5;
             return '♥', 'Mojolicious';
           },
           sub {
             my ($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>.