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