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<?php |
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|
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declare(strict_types=1); |
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|
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namespace Prometheus; |
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|
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use InvalidArgumentException; |
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use Prometheus\Storage\Adapter; |
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|
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class Histogram extends Collector |
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{ |
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const TYPE = 'histogram'; |
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|
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/** |
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* @var float[]|null |
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*/ |
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private $buckets; |
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|
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/** |
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* @param Adapter $adapter |
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* @param string $namespace |
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* @param string $name |
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* @param string $help |
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* @param string[] $labels |
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* @param float[]|null $buckets |
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*/ |
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public function __construct( |
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Adapter $adapter, |
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string $namespace, |
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string $name, |
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string $help, |
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array $labels = [], |
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array $buckets = null |
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) { |
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parent::__construct($adapter, $namespace, $name, $help, $labels); |
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|
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if (null === $buckets) { |
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$buckets = self::getDefaultBuckets(); |
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} |
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|
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if (0 === count($buckets)) { |
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throw new InvalidArgumentException("Histogram must have at least one bucket."); |
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} |
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|
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for ($i = 0; $i < count($buckets) - 1; $i++) { |
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if ($buckets[$i] >= $buckets[$i + 1]) { |
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throw new InvalidArgumentException( |
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"Histogram buckets must be in increasing order: " . |
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$buckets[$i] . " >= " . $buckets[$i + 1] |
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); |
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} |
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} |
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if (in_array('le', $labels, true)) { |
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throw new \InvalidArgumentException("Histogram cannot have a label named 'le'."); |
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} |
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$this->buckets = $buckets; |
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} |
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|
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/** |
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* List of default buckets suitable for typical web application latency metrics |
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* |
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* @return float[] |
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*/ |
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public static function getDefaultBuckets(): array |
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{ |
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return [ |
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0.005, |
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0.01, |
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0.025, |
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0.05, |
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0.075, |
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0.1, |
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0.25, |
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0.5, |
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0.75, |
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1.0, |
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2.5, |
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5.0, |
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7.5, |
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10.0, |
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]; |
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} |
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|
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/** |
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* @param float $start |
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* @param float $growthFactor |
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* @param int $numberOfBuckets |
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* |
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* @return float[] |
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*/ |
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public static function exponentialBuckets(float $start, float $growthFactor, int $numberOfBuckets): array |
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{ |
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if ($numberOfBuckets < 1) { |
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throw new InvalidArgumentException('Number of buckets must be a positive integer'); |
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} |
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|
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if ($start <= 0) { |
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throw new InvalidArgumentException('The starting position of a set of buckets must be a positive integer'); |
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} |
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|
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if ($growthFactor <= 1) { |
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throw new InvalidArgumentException('The growth factor must greater than 1'); |
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} |
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|
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$buckets = []; |
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|
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for ($i = 0; $i < $numberOfBuckets; $i++) { |
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$buckets[$i] = $start; |
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$start *= $growthFactor; |
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} |
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|
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return $buckets; |
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} |
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|
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/** |
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* @param double $value e.g. 123 |
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* @param string[] $labels e.g. ['status', 'opcode'] |
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*/ |
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public function observe(float $value, array $labels = []): void |
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{ |
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$this->assertLabelsAreDefinedCorrectly($labels); |
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|
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$this->storageAdapter->updateHistogram( |
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[ |
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'value' => $value, |
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'name' => $this->getName(), |
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'help' => $this->getHelp(), |
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'type' => $this->getType(), |
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'labelNames' => $this->getLabelNames(), |
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'labelValues' => $labels, |
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'buckets' => $this->buckets, |
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] |
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); |
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} |
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|
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/** |
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* @return string |
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*/ |
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public function getType(): string |
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{ |
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return self::TYPE; |
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} |
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} |
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|
