<?php
namespace React\EventLoop;
use BadMethodCallException;
use Event;
use EventBase;
use React\EventLoop\Tick\FutureTickQueue;
use React\EventLoop\Timer\Timer;
use SplObjectStorage;
/**
* An `ext-libevent` based event loop.
*
* This uses the [`libevent` PECL extension](https://pecl.php.net/package/libevent).
* `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, the [`Factory`](#factory) will not 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.
*
* @link https://pecl.php.net/package/libevent
*/
final class ExtLibeventLoop implements LoopInterface
{
/** @internal */
const MICROSECONDS_PER_SECOND = 1000000;
private $eventBase;
private $futureTickQueue;
private $timerCallback;
private $timerEvents;
private $streamCallback;
private $readEvents = array();
private $writeEvents = array();
private $readListeners = array();
private $writeListeners = array();
private $running;
private $signals;
private $signalEvents = array();
public function __construct()
{
if (!function_exists('event_base_new')) {
throw new BadMethodCallException('Cannot create ExtLibeventLoop, ext-libevent extension missing');
}
$this->eventBase = event_base_new();
$this->futureTickQueue = new FutureTickQueue();
$this->timerEvents = new SplObjectStorage();
$this->signals = new SignalsHandler();
$this->createTimerCallback();
$this->createStreamCallback();
}
public function addReadStream($stream, $listener)
{
$key = (int) $stream;
if (isset($this->readListeners[$key])) {
return;
}
$event = event_new();
event_set($event, $stream, EV_PERSIST | EV_READ, $this->streamCallback);
event_base_set($event, $this->eventBase);
event_add($event);
$this->readEvents[$key] = $event;
$this->readListeners[$key] = $listener;
}
public function addWriteStream($stream, $listener)
{
$key = (int) $stream;
if (isset($this->writeListeners[$key])) {
return;
}
$event = event_new();
event_set($event, $stream, EV_PERSIST | EV_WRITE, $this->streamCallback);
event_base_set($event, $this->eventBase);
event_add($event);
$this->writeEvents[$key] = $event;
$this->writeListeners[$key] = $listener;
}
public function removeReadStream($stream)
{
$key = (int) $stream;
if (isset($this->readListeners[$key])) {
$event = $this->readEvents[$key];
event_del($event);
event_free($event);
unset(
$this->readEvents[$key],
$this->readListeners[$key]
);
}
}
public function removeWriteStream($stream)
{
$key = (int) $stream;
if (isset($this->writeListeners[$key])) {
$event = $this->writeEvents[$key];
event_del($event);
event_free($event);
unset(
$this->writeEvents[$key],
$this->writeListeners[$key]
);
}
}
public function addTimer($interval, $callback)
{
$timer = new Timer($interval, $callback, false);
$this->scheduleTimer($timer);
return $timer;
}
public function addPeriodicTimer($interval, $callback)
{
$timer = new Timer($interval, $callback, true);
$this->scheduleTimer($timer);
return $timer;
}
public function cancelTimer(TimerInterface $timer)
{
if ($this->timerEvents->contains($timer)) {
$event = $this->timerEvents[$timer];
event_del($event);
event_free($event);
$this->timerEvents->detach($timer);
}
}
public function futureTick($listener)
{
$this->futureTickQueue->add($listener);
}
public function addSignal($signal, $listener)
{
$this->signals->add($signal, $listener);
if (!isset($this->signalEvents[$signal])) {
$this->signalEvents[$signal] = event_new();
event_set($this->signalEvents[$signal], $signal, EV_PERSIST | EV_SIGNAL, array($this->signals, 'call'));
event_base_set($this->signalEvents[$signal], $this->eventBase);
event_add($this->signalEvents[$signal]);
}
}
public function removeSignal($signal, $listener)
{
$this->signals->remove($signal, $listener);
if (isset($this->signalEvents[$signal]) && $this->signals->count($signal) === 0) {
event_del($this->signalEvents[$signal]);
event_free($this->signalEvents[$signal]);
unset($this->signalEvents[$signal]);
}
}
public function run()
{
$this->running = true;
while ($this->running) {
$this->futureTickQueue->tick();
$flags = EVLOOP_ONCE;
if (!$this->running || !$this->futureTickQueue->isEmpty()) {
$flags |= EVLOOP_NONBLOCK;
} elseif (!$this->readEvents && !$this->writeEvents && !$this->timerEvents->count() && $this->signals->isEmpty()) {
break;
}
event_base_loop($this->eventBase, $flags);
}
}
public function stop()
{
$this->running = false;
}
/**
* Schedule a timer for execution.
*
* @param TimerInterface $timer
*/
private function scheduleTimer(TimerInterface $timer)
{
$this->timerEvents[$timer] = $event = event_timer_new();
event_timer_set($event, $this->timerCallback, $timer);
event_base_set($event, $this->eventBase);
event_add($event, $timer->getInterval() * self::MICROSECONDS_PER_SECOND);
}
/**
* Create a callback used as the target of timer events.
*
* A reference is kept to the callback for the lifetime of the loop
* to prevent "Cannot destroy active lambda function" fatal error from
* the event extension.
*/
private function createTimerCallback()
{
$that = $this;
$timers = $this->timerEvents;
$this->timerCallback = function ($_, $__, $timer) use ($timers, $that) {
call_user_func($timer->getCallback(), $timer);
// Timer already cancelled ...
if (!$timers->contains($timer)) {
return;
}
// Reschedule periodic timers ...
if ($timer->isPeriodic()) {
event_add(
$timers[$timer],
$timer->getInterval() * ExtLibeventLoop::MICROSECONDS_PER_SECOND
);
// Clean-up one shot timers ...
} else {
$that->cancelTimer($timer);
}
};
}
/**
* Create a callback used as the target of stream events.
*
* A reference is kept to the callback for the lifetime of the loop
* to prevent "Cannot destroy active lambda function" fatal error from
* the event extension.
*/
private function createStreamCallback()
{
$read =& $this->readListeners;
$write =& $this->writeListeners;
$this->streamCallback = function ($stream, $flags) use (&$read, &$write) {
$key = (int) $stream;
if (EV_READ === (EV_READ & $flags) && isset($read[$key])) {
call_user_func($read[$key], $stream);
}
if (EV_WRITE === (EV_WRITE & $flags) && isset($write[$key])) {
call_user_func($write[$key], $stream);
}
};
}
}