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Clock.php
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Clock.php
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<?php
namespace React\Http\Io;
use React\EventLoop\LoopInterface;
/**
* [internal] Clock source that returns current timestamp and memoize clock for same tick
*
* This is mostly used as an internal optimization to avoid unneeded syscalls to
* get the current system time multiple times within the same loop tick. For the
* purpose of the HTTP server, the clock is assumed to not change to a
* significant degree within the same loop tick. If you need a high precision
* clock source, you may want to use `\hrtime()` instead (PHP 7.3+).
*
* The API is modelled to resemble the PSR-20 `ClockInterface` (in draft at the
* time of writing this), but uses a `float` return value for performance
* reasons instead.
*
* Note that this is an internal class only and nothing you should usually care
* about for outside use.
*
* @internal
*/
class Clock
{
/** @var LoopInterface $loop */
private $loop;
/** @var ?float */
private $now;
public function __construct(LoopInterface $loop)
{
$this->loop = $loop;
}
/** @return float */
public function now()
{
if ($this->now === null) {
$this->now = \microtime(true);
// remember clock for current loop tick only and update on next tick
$now =& $this->now;
$this->loop->futureTick(function () use (&$now) {
assert($now !== null);
$now = null;
});
}
return $this->now;
}
}