Air-Quality-Web/lib/SBRL/PerformanceCounter.php

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2019-06-20 23:02:26 +00:00
<?php
namespace SBRL;
use Exception;
/**
* Records performance information.
*/
class PerformanceCounter
{
/**
* An associative array of performance information.
* It should take the form key => [float] | float.
* HACK: If the float is the only item in an array, then it hasn't been ended yet.
* @var array
*/
private $data = [];
/**
* An array of performance counters to hide when rendering.
* Useful to keep some counters around for later, but keep them hidden so as to not clutter everything up.
* @var string[]
*/
private $hidden = [];
/**
* Creates a new performance counter instea
*/
function __construct() {
// code...
}
/**
* Starts recording the time taken for a given key.
* Calling end($key) is optional
* @param string $key The key to start recording the time taken for.
*/
public function start(string $key) {
$this->data[$key] = [microtime(true)];
}
/**
* Ends recording the time taken for a given key.
* @param string $key The key to end counting for.
* @return float The time taken, in milliseconds
*/
public function end(string $key) {
if(empty($this->data[$key]))
throw new Exception("Error: We can't end counting for $key because we haven't started yet");
$this->data[$key] = (microtime(true) - $this->data[$key][0]) * 1000;
return $this->data[$key];
}
/**
* Renders the performance information as a short string.
* Suitable for sending in a HTTP header, for example.
* @return string The rendered performance information.
*/
public function render() {
$result = "";
$parts = [];
foreach($this->data as $key => $value) {
if(in_array($key, $this->hidden))
continue;
if(is_array($value))
$value = $this->end($key);
$render = round($value, 2) . "ms $key";
if($key == "total") {
$result .= "$render | ";
continue;
}
$parts[] = $render;
}
$result .= implode(", ", $parts);
return $result;
}
}