Sid Gifari File Manager Pro v10.0.3

✏️ Editing: README.md Read Only

# EventLoop

[![CI status](https://github.com/reactphp/event-loop/actions/workflows/ci.yml/badge.svg)](https://github.com/reactphp/event-loop/actions)
[![installs on Packagist](https://img.shields.io/packagist/dt/react/event-loop?color=blue&label=installs%20on%20Packagist)](https://packagist.org/packages/react/event-loop)

[ReactPHP](https://reactphp.org/)'s core reactor event loop that libraries can use for evented I/O.

In order for async based libraries to be interoperable, they need to use the
same event loop. This component provides a common `LoopInterface` that any
library can target. This allows them to be used in the same loop, with one
single [`run()`](#run) call that is controlled by the user.

**Table of contents**

* [Quickstart example](#quickstart-example)
* [Usage](#usage)
    * [Loop](#loop)
        * [Loop methods](#loop-methods)
        * [Loop autorun](#loop-autorun)
        * [get()](#get)
    * [~~Factory~~](#factory)
        * [~~create()~~](#create)
    * [Loop implementations](#loop-implementations)
        * [StreamSelectLoop](#streamselectloop)
        * [ExtEventLoop](#exteventloop)
        * [ExtEvLoop](#extevloop)
        * [ExtUvLoop](#extuvloop)
        * [~~ExtLibeventLoop~~](#extlibeventloop)
        * [~~ExtLibevLoop~~](#extlibevloop)
    * [LoopInterface](#loopinterface)
        * [run()](#run)
        * [stop()](#stop)
        * [addTimer()](#addtimer)
        * [addPeriodicTimer()](#addperiodictimer)
        * [cancelTimer()](#canceltimer)
        * [futureTick()](#futuretick)
        * [addSignal()](#addsignal)
        * [removeSignal()](#removesignal)
        * [addReadStream()](#addreadstream)
        * [addWriteStream()](#addwritestream)
        * [removeReadStream()](#removereadstream)
        * [removeWriteStream()](#removewritestream)
* [Install](#install)
* [Tests](#tests)
* [License](#license)
* [More](#more)

## Quickstart example

Here is an async HTTP server built with just the event loop.

```php
<?php

use React\EventLoop\Loop;

require __DIR__ . '/vendor/autoload.php';

$server = stream_socket_server('tcp://127.0.0.1:8080');
stream_set_blocking($server, false);

Loop::addReadStream($server, function ($server) {
    $conn = stream_socket_accept($server);
    $data = "HTTP/1.1 200 OK\r\nContent-Length: 3\r\n\r\nHi\n";
    Loop::addWriteStream($conn, function ($conn) use (&$data) {
        $written = fwrite($conn, $data);
        if ($written === strlen($data)) {
            fclose($conn);
            Loop::removeWriteStream($conn);
        } else {
            $data = substr($data, $written);
        }
    });
});

Loop::addPeriodicTimer(5, function () {
    $memory = memory_get_usage() / 1024;
    $formatted = number_format($memory, 3).'K';
    echo "Current memory usage: {$formatted}\n";
});
```

See also the [examples](examples).

## Usage

Typical applications would use the [`Loop` class](#loop) to use the default
event loop like this:

```php
use React\EventLoop\Loop;

$timer = Loop::addPeriodicTimer(0.1, function () {
    echo 'Tick' . PHP_EOL;
});

Loop::addTimer(1.0, function () use ($timer) {
    Loop::cancelTimer($timer);
    echo 'Done' . PHP_EOL;
});
```

As an alternative, you can also explicitly create an event loop instance at the
beginning, reuse it throughout your program and finally run it at the end of the
program like this:

```php
$loop = React\EventLoop\Loop::get(); // or deprecated React\EventLoop\Factory::create();

$timer = $loop->addPeriodicTimer(0.1, function () {
    echo 'Tick' . PHP_EOL;
});

$loop->addTimer(1.0, function () use ($loop, $timer) {
    $loop->cancelTimer($timer);
    echo 'Done' . PHP_EOL;
});

$loop->run();
```

While the former is more concise, the latter is more explicit.
In both cases, the program would perform the exact same steps.

1. The event loop instance is created at the beginning of the program. This is
   implicitly done the first time you call the [`Loop` class](#loop) or
   explicitly when using the deprecated [`Factory::create()` method](#create)
   (or manually instantiating any of the [loop implementations](#loop-implementations)).
2. The event loop is used directly or passed as an instance to library and
   application code. In this example, a periodic timer is registered with the
   event loop which simply outputs `Tick` every fraction of a second until another
   timer stops the periodic timer after a second.
3. The event loop is run at the end of the program. This is automatically done
   when using the [`Loop` class](#loop) or explicitly with a single [`run()`](#run)
   call at the end of the program.

As of `v1.2.0`, we highly recommend using the [`Loop` class](#loop).
The explicit loop instructions are still valid and may still be useful in some
applications, especially for a transition period towards the more concise style.

### Loop

The `Loop` class exists as a convenient global accessor for the event loop.

#### Loop methods

The `Loop` class provides all methods that exist on the [`LoopInterface`](#loopinterface)
as static methods:

* [run()](#run)
* [stop()](#stop)
* [addTimer()](#addtimer)
* [addPeriodicTimer()](#addperiodictimer)
* [cancelTimer()](#canceltimer)
* [futureTick()](#futuretick)
* [addSignal()](#addsignal)
* [removeSignal()](#removesignal)
* [addReadStream()](#addreadstream)
* [addWriteStream()](#addwritestream)
* [removeReadStream()](#removereadstream)
* [removeWriteStream()](#removewritestream)

If you're working with the event loop in your application code, it's often
easiest to directly interface with the static methods defined on the `Loop` class
like this:

```php
use React\EventLoop\Loop;

$timer = Loop::addPeriodicTimer(0.1, function () {
    echo 'Tick' . PHP_EOL;
});

Loop::addTimer(1.0, function () use ($timer) {
    Loop::cancelTimer($timer);
    echo 'Done' . PHP_EOL;
});
```

On the other hand, if you're familiar with object-oriented programming (OOP) and
dependency injection (DI), you may want to inject an event loop instance and
invoke instance methods on the `LoopInterface` like this:

```php
use React\EventLoop\Loop;
use React\EventLoop\LoopInterface;

class Greeter
{
    private $loop;

public function __construct(LoopInterface $loop)
    {
        $this->loop = $loop;
    }

public function greet(string $name)
    {
        $this->loop->addTimer(1.0, function () use ($name) {
            echo 'Hello ' . $name . '!' . PHP_EOL;
        });
    }
}

$greeter = new Greeter(Loop::get());
$greeter->greet('Alice');
$greeter->greet('Bob');
```

Each static method call will be forwarded as-is to the underlying event loop
instance by using the [`Loop::get()`](#get) call internally.
See [`LoopInterface`](#loopinterface) for more details about available methods.

#### Loop autorun

When using the `Loop` class, it will automatically execute the loop at the end of
the program. This means the following example will schedule a timer and will
automatically execute the program until the timer event fires:

```php
use React\EventLoop\Loop;

Loop::addTimer(1.0, function () {
    echo 'Hello' . PHP_EOL;
});
```

As of `v1.2.0`, we highly recommend using the `Loop` class this way and omitting any
explicit [`run()`](#run) calls. For BC reasons, the explicit [`run()`](#run)
method is still valid and may still be useful in some applications, especially
for a transition period towards the more concise style.

If you don't want the `Loop` to run automatically, you can either explicitly
[`run()`](#run) or [`stop()`](#stop) it. This can be useful if you're using
a global exception handler like this:

```php
use React\EventLoop\Loop;

Loop::addTimer(10.0, function () {
    echo 'Never happens';
});

set_exception_handler(function (Throwable $e) {
    echo 'Error: ' . $e->getMessage() . PHP_EOL;
    Loop::stop();
});

throw new RuntimeException('Demo');
```

#### get()

The `get(): LoopInterface` method can be used to
get the currently active event loop instance.

This method will always return the same event loop instance throughout the
lifetime of your application.

```php
use React\EventLoop\Loop;
use React\EventLoop\LoopInterface;

$loop = Loop::get();

assert($loop instanceof LoopInterface);
assert($loop === Loop::get());
```

This is particularly useful if you're using object-oriented programming (OOP)
and dependency injection (DI). In this case, you may want to inject an event
loop instance and invoke instance methods on the `LoopInterface` like this:

```php
use React\EventLoop\Loop;
use React\EventLoop\LoopInterface;

class Greeter
{
    private $loop;

public function __construct(LoopInterface $loop)
    {
        $this->loop = $loop;
    }

public function greet(string $name)
    {
        $this->loop->addTimer(1.0, function () use ($name) {
            echo 'Hello ' . $name . '!' . PHP_EOL;
        });
    }
}

$greeter = new Greeter(Loop::get());
$greeter->greet('Alice');
$greeter->greet('Bob');
```

See [`LoopInterface`](#loopinterface) for more details about available methods.

### ~~Factory~~

> Deprecated since v1.2.0, see [`Loop` class](#loop) instead.

The deprecated `Factory` class exists as a convenient way to pick the best available
[event loop implementation](#loop-implementations).

#### ~~create()~~

> Deprecated since v1.2.0, see [`Loop::get()`](#get) instead.

The deprecated `create(): LoopInterface` method can be used to
create a new event loop instance:

```php
// deprecated
$loop = React\EventLoop\Factory::create();

// new
$loop = React\EventLoop\Loop::get();
```

This method always returns an instance implementing [`LoopInterface`](#loopinterface),
the actual [event loop implementation](#loop-implementations) is an implementation detail.

This method should usually only be called once at the beginning of the program.

### Loop implementations

In addition to the [`LoopInterface`](#loopinterface), there are a number of
event loop implementations provided.

All of the event loops support these features:

* File descriptor polling
* One-off timers
* Periodic timers
* Deferred execution on future loop tick

For most consumers of this package, the underlying event loop implementation is
an implementation detail.
You should use the [`Loop` class](#loop) to automatically create a new instance.

Advanced! If you explicitly need a certain event loop implementation, you can
manually instantiate one of the following classes.
Note that you may have to install the required PHP extensions for the respective
event loop implementation first or they will throw a `BadMethodCallException` on creation.

#### StreamSelectLoop

A `stream_select()` based event loop.

This uses the [`stream_select()`](https://www.php.net/manual/en/function.stream-select.php)
function and is the only implementation that works out of the box with PHP.

This event loop works out of the box on PHP 5.3 through PHP 8+ and HHVM.
This means that no installation is required and this library works on all
platforms and supported PHP versions.
Accordingly, the [`Loop` class](#loop) and the deprecated [`Factory`](#factory)
will use this event loop by default if you do not install any of the event loop
extensions listed below.

Under the hood, it does a simple `select` system call.
This system call is limited to the maximum file descriptor number of
`FD_SETSIZE` (platform dependent, commonly 1024) and scales with `O(m)`
(`m` being the maximum file descriptor number passed).
This means that you may run into issues when handling thousands of streams
concurrently and you may want to look into using one of the alternative
event loop implementations listed below in this case.
If your use case is among the many common use cases that involve handling only
dozens or a few hundred streams at once, then this event loop implementation
performs really well.

If you want to use signal handling (see also [`addSignal()`](#addsignal) below),
this event loop implementation requires `ext-pcntl`.
This extension is only available for Unix-like platforms and does not support
Windows.
It is commonly installed as part of many PHP distributions.
If this extension is missing (or you're running on Windows), signal handling is
not supported and throws a `BadMethodCallException` instead.

This event loop is known to rely on wall-clock time to schedule future timers
when using any version before PHP 7.3, because a monotonic time source is
only available as of PHP 7.3 (`hrtime()`).
While this does not affect many common use cases, this is an important
distinction for programs that rely on a high time precision or on systems
that are subject to discontinuous time adjustments (time jumps).
This means that if you schedule a timer to trigger in 30s on PHP < 7.3 and
then adjust your system time forward by 20s, the timer may trigger in 10s.
See also [`addTimer()`](#addtimer) for more details.

#### ExtEventLoop

An `ext-event` based event loop.

This uses the [`event` PECL extension](https://pecl.php.net/package/event),
that provides an interface to `libevent` library.
`libevent` itself supports a number of system-specific backends (epoll, kqueue).

This loop is known to work with PHP 5.4 through PHP 8+.

#### ExtEvLoop

An `ext-ev` based event loop.

This loop uses the [`ev` PECL extension](https://pecl.php.net/package/ev),
that provides an interface to `libev` library.
`libev` itself supports a number of system-specific backends (epoll, kqueue).

This loop is known to work with PHP 5.4 through PHP 8+.

#### ExtUvLoop

An `ext-uv` based event loop.

This loop uses the [`uv` PECL extension](https://pecl.php.net/package/uv),
that provides an interface to `libuv` library.
`libuv` itself supports a number of system-specific backends (epoll, kqueue).

This loop is known to work with PHP 7+.

#### ~~ExtLibeventLoop~~

> Deprecated since v1.2.0, use [`ExtEventLoop`](#exteventloop) instead.

An `ext-libevent` based event loop.

This uses the [`libevent` PECL extension](https://pecl.php.net/package/libevent),
that provides an interface to `libevent` library.
`libevent` itself supports a number of system-specific backends (epoll, kqueue).

This event loop does only work with PHP 5.
An [unofficial update](https://github.com/php/pecl-event-libevent/pull/2) for
PHP 7 does exist, but it is known to cause regular crashes due to `SEGFAULT`s.
To reiterate: Using this event loop on PHP 7 is not recommended.
Accordingly, neither the [`Loop` class](#loop) nor the deprecated
[`Factory` class](#factory) will try to use this event loop on PHP 7.

This event loop is known to trigger a readable listener only if
the stream *becomes* readable (edge-triggered) and may not trigger if the
stream has already been readable from the beginning.
This also implies that a stream may not be recognized as readable when data
is still left in PHP's internal stream buffers.
As such, it's recommended to use `stream_set_read_buffer($stream, 0);`
to disable PHP's internal read buffer in this case.
See also [`addReadStream()`](#addreadstream) for more details.

#### ~~ExtLibevLoop~~

> Deprecated since v1.2.0, use [`ExtEvLoop`](#extevloop) instead.

An `ext-libev` based event loop.

This uses an [unofficial `libev` extension](https://github.com/m4rw3r/php-libev),
that provides an interface to `libev` library.
`libev` itself supports a number of system-specific backends (epoll, kqueue).

This loop does only work with PHP 5.
An update for PHP 7 is [unlikely](https://github.com/m4rw3r/php-libev/issues/8)
to happen any time soon.

### LoopInterface

#### run()

The `run(): void` method can be used to
run the event loop until there are no more tasks to perform.

For many applications, this method is the only directly visible
invocation on the event loop.
As a rule of thumb, it is usually recommended to attach everything to the
same loop instance and then run the loop once at the bottom end of the
application.

```php
$loop->run();
```

This method will keep the loop running until there are no more tasks
to perform. In other words: This method will block until the last
timer, stream and/or signal has been removed.

Likewise, it is imperative to ensure the application actually invokes
this method once. Adding listeners to the loop and missing to actually
run it will result in the application exiting without actually waiting
for any of the attached listeners.

This method MUST NOT be called while the loop is already running.
This method MAY be called more than once after it has explicitly been
[`stop()`ped](#stop) or after it automatically stopped because it
previously did no longer have anything to do.

#### stop()

The `stop(): void` method can be used to
instruct a running event loop to stop.

This method is considered advanced usage and should be used with care.
As a rule of thumb, it is usually recommended to let the loop stop
only automatically when it no longer has anything to do.

This method can be used to explicitly instruct the event loop to stop:

```php
$loop->addTimer(3.0, function () use ($loop) {
    $loop->stop();
});
```

Calling this method on a loop instance that is not currently running or
on a loop instance that has already been stopped has no effect.

#### addTimer()

The `addTimer(float $interval, callable $callback): TimerInterface` method can be used to
enqueue a callback to be invoked once after the given interval.

The second parameter MUST be a timer callback function that accepts
the timer instance as its only parameter.
If you don't use the timer instance inside your timer callback function
you MAY use a function which has no parameters at all.

The timer callback function MUST NOT throw an `Exception`.
The return value of the timer callback function will be ignored and has
no effect, so for performance reasons you're recommended to not return
any excessive data structures.

This method returns a timer instance. The same timer instance will also be 
passed into the timer callback function as described above.
You can invoke [`cancelTimer`](#canceltimer) to cancel a pending timer.
Unlike [`addPeriodicTimer()`](#addperiodictimer), this method will ensure
the callback will be invoked only once after the given interval.

```php
$loop->addTimer(0.8, function () {
    echo 'world!' . PHP_EOL;
});

$loop->addTimer(0.3, function () {
    echo 'hello ';
});
```

📁 File Manager Pro

📁 File Manager Pro