Copy <?php
// PHP doesn't have built-in Prometheus client in base SDK
// Implementing lightweight counter/histogram manually
class MetricsCollector {
private array $counters = [];
private array $gauges = [];
private array $histograms = [];
// Counter: monotonically increasing
public function incrementCounter(string $name, float $value = 1.0, array $labels = []): void {
$key = $this->key($name, $labels);
$this->counters[$key] = ($this->counters[$key] ?? 0) + $value;
}
// Gauge: can go up or down
public function setGauge(string $name, float $value, array $labels = []): void {
$this->gauges[$this->key($name, $labels)] = $value;
}
// Histogram: tracks distribution of values
public function recordHistogram(string $name, float $value, array $buckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.5, 1.0]): void {
if (!isset($this->histograms[$name])) {
$this->histograms[$name] = ['count' => 0, 'sum' => 0, 'buckets' => []];
foreach ($buckets as $b) $this->histograms[$name]['buckets'][$b] = 0;
}
$this->histograms[$name]['count']++;
$this->histograms[$name]['sum'] += $value;
foreach ($this->histograms[$name]['buckets'] as $b => &$count) {
if ($value <= $b) $count++;
}
}
// Export in Prometheus text format
public function exposition(): string {
$lines = [];
foreach ($this->counters as $key => $val) {
$lines[] = "{$key} {$val}";
}
foreach ($this->gauges as $key => $val) {
$lines[] = "{$key} {$val}";
}
foreach ($this->histograms as $name => $data) {
$lines[] = "# TYPE {$name} histogram";
foreach ($data['buckets'] as $b => $count) {
$lines[] = "{$name}_bucket{le=\"{$b}\"} {$count}";
}
$lines[] = "{$name}_bucket{le=\"+Inf\"} {$data['count']}";
$lines[] = "{$name}_sum {$data['sum']}";
$lines[] = "{$name}_count {$data['count']}";
}
return implode("\n", $lines);
}
private function key(string $name, array $labels): string {
if (empty($labels)) return $name;
$labelStr = implode(',', array_map(fn($k, $v) => "{$k}=\"{$v}\"", array_keys($labels), $labels));
return "{$name}{{$labelStr}}";
}
}
$metrics = new MetricsCollector();
// Simulate request processing
$routes = ['/users' => 200, '/orders' => 201, '/products' => 200, '/users' => 404, '/orders' => 500];
foreach ($routes as $route => $status) {
$latency = rand(5, 250) / 1000; // 5-250ms in seconds
$metrics->incrementCounter('http_requests_total', 1, ['method' => 'GET', 'route' => $route, 'status' => $status]);
$metrics->recordHistogram('http_request_duration_seconds', $latency);
}
$metrics->setGauge('active_connections', 42);
$metrics->setGauge('memory_usage_bytes', memory_get_usage(true));
echo "=== Prometheus Exposition ===\n";
echo $metrics->exposition() . "\n"; 