<?php
declare(strict_types=1);
namespace Sabre\Event\Loop;
/**
* A simple eventloop implementation.
*
* This eventloop supports:
* * nextTick
* * setTimeout for delayed functions
* * setInterval for repeating functions
* * stream events using stream_select
*
* @copyright Copyright (C) fruux GmbH (https://fruux.com/)
* @author Evert Pot (http://evertpot.com/)
* @license http://sabre.io/license/ Modified BSD License
*/
class Loop
{
/**
* Executes a function after x seconds.
*/
public function setTimeout(callable $cb, float $timeout)
{
$triggerTime = microtime(true) + ($timeout);
if (!$this->timers) {
// Special case when the timers array was empty.
$this->timers[] = [$triggerTime, $cb];
return;
}
// We need to insert these values in the timers array, but the timers
// array must be in reverse-order of trigger times.
//
// So here we search the array for the insertion point.
$index = count($this->timers) - 1;
while (true) {
if ($triggerTime < $this->timers[$index][0]) {
array_splice(
$this->timers,
$index + 1,
0,
[[$triggerTime, $cb]]
);
break;
} elseif (0 === $index) {
array_unshift($this->timers, [$triggerTime, $cb]);
break;
}
--$index;
}
}
/**
* Executes a function every x seconds.
*
* The value this function returns can be used to stop the interval with
* clearInterval.
*/
public function setInterval(callable $cb, float $timeout): array
{
$keepGoing = true;
$f = null;
$f = function () use ($cb, &$f, $timeout, &$keepGoing) {
if ($keepGoing) {
$cb();
$this->setTimeout($f, $timeout);
}
};
$this->setTimeout($f, $timeout);
// Really the only thing that matters is returning the $keepGoing
// boolean value.
//
// We need to pack it in an array to allow returning by reference.
// Because I'm worried people will be confused by using a boolean as a
// sort of identifier, I added an extra string.
return ['I\'m an implementation detail', &$keepGoing];
}
/**
* Stops a running interval.
*/
public function clearInterval(array $intervalId)
{
$intervalId[1] = false;
}
/**
* Runs a function immediately at the next iteration of the loop.
*/
public function nextTick(callable $cb)
{
$this->nextTick[] = $cb;
}
/**
* Adds a read stream.
*
* The callback will be called as soon as there is something to read from
* the stream.
*
* You MUST call removeReadStream after you are done with the stream, to
* prevent the eventloop from never stopping.
*
* @param resource $stream
*/
public function addReadStream($stream, callable $cb)
{
$this->readStreams[(int) $stream] = $stream;
$this->readCallbacks[(int) $stream] = $cb;
}
/**
* Adds a write stream.
*
* The callback will be called as soon as the system reports it's ready to
* receive writes on the stream.
*
* You MUST call removeWriteStream after you are done with the stream, to
* prevent the eventloop from never stopping.
*
* @param resource $stream
*/
public function addWriteStream($stream, callable $cb)
{
$this->writeStreams[(int) $stream] = $stream;
$this->writeCallbacks[(int) $stream] = $cb;
}
/**
* Stop watching a stream for reads.
*
* @param resource $stream
*/
public function removeReadStream($stream)
{
unset(
$this->readStreams[(int) $stream],
$this->readCallbacks[(int) $stream]
);
}
/**
* Stop watching a stream for writes.
*
* @param resource $stream
*/
public function removeWriteStream($stream)
{
unset(
$this->writeStreams[(int) $stream],
$this->writeCallbacks[(int) $stream]
);
}
/**
* Runs the loop.
*
* This function will run continuously, until there's no more events to
* handle.
*/
public function run()
{
$this->running = true;
do {
$hasEvents = $this->tick(true);
} while ($this->running && $hasEvents);
$this->running = false;
}
/**
* Executes all pending events.
*
* If $block is turned true, this function will block until any event is
* triggered.
*
* If there are now timeouts, nextTick callbacks or events in the loop at
* all, this function will exit immediately.
*
* This function will return true if there are _any_ events left in the
* loop after the tick.
*/
public function tick(bool $block = false): bool
{
$this->runNextTicks();
$nextTimeout = $this->runTimers();
// Calculating how long runStreams should at most wait.
if (!$block) {
// Don't wait
$streamWait = 0;
} elseif ($this->nextTick) {
// There's a pending 'nextTick'. Don't wait.
$streamWait = 0;
} elseif (is_numeric($nextTimeout)) {
// Wait until the next Timeout should trigger.
$streamWait = $nextTimeout;
} else {
// Wait indefinitely
$streamWait = null;
}
$this->runStreams($streamWait);
return $this->readStreams || $this->writeStreams || $this->nextTick || $this->timers;
}
/**
* Stops a running eventloop.
*/
public function stop()
{
$this->running = false;
}
/**
* Executes all 'nextTick' callbacks.
*
* return void
*/
protected function runNextTicks()
{
$nextTick = $this->nextTick;
$this->nextTick = [];
foreach ($nextTick as $cb) {
$cb();
}
}
/**
* Runs all pending timers.
*
* After running the timer callbacks, this function returns the number of
* seconds until the next timer should be executed.
*
* If there's no more pending timers, this function returns null.
*
* @return float|null
*/
protected function runTimers()
{
$now = microtime(true);
while (($timer = array_pop($this->timers)) && $timer[0] < $now) {
$timer[1]();
}
// Add the last timer back to the array.
if ($timer) {
$this->timers[] = $timer;
return max(0, $timer[0] - microtime(true));
}
}
/**
* Runs all pending stream events.
*
* If $timeout is 0, it will return immediately. If $timeout is null, it
* will wait indefinitely.
*
* @param float|null timeout
*/
protected function runStreams($timeout)
{
if ($this->readStreams || $this->writeStreams) {
$read = $this->readStreams;
$write = $this->writeStreams;
$except = null;
if (stream_select($read, $write, $except, (null === $timeout) ? null : 0, $timeout ? (int) ($timeout * 1000000) : 0)) {
// See PHP Bug https://bugs.php.net/bug.php?id=62452
// Fixed in PHP7
foreach ($read as $readStream) {
$readCb = $this->readCallbacks[(int) $readStream];
$readCb();
}
foreach ($write as $writeStream) {
$writeCb = $this->writeCallbacks[(int) $writeStream];
$writeCb();
}
}
} elseif ($this->running && ($this->nextTick || $this->timers)) {
usleep(null !== $timeout ? intval($timeout * 1000000) : 200000);
}
}
/**
* Is the main loop active.
*
* @var bool
*/
protected $running = false;
/**
* A list of timers, added by setTimeout.
*
* @var array
*/
protected $timers = [];
/**
* A list of 'nextTick' callbacks.
*
* @var callable[]
*/
protected $nextTick = [];
/**
* List of readable streams for stream_select, indexed by stream id.
*
* @var resource[]
*/
protected $readStreams = [];
/**
* List of writable streams for stream_select, indexed by stream id.
*
* @var resource[]
*/
protected $writeStreams = [];
/**
* List of read callbacks, indexed by stream id.
*
* @var callable[]
*/
protected $readCallbacks = [];
/**
* List of write callbacks, indexed by stream id.
*
* @var callable[]
*/
protected $writeCallbacks = [];
}
