Observability PHP client

observability_client.php

<?php

declare(strict_types=1);

namespace notes;

/**
 * ObservabilityClient can throw upon instantiation, but sending does not block.
 */
class ObservabilityClient
{
    private \Closure $sendMessage;

    public function __construct(string $serverAddr, int $serverPort)
    {
        $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
        if ($socket === false) {
            throw new \RuntimeException("unable to create a UDP socket");
        }

        $this->sendMessage = fn(string $payload) => socket_sendto(
            $socket,
            $payload,
            strlen($payload),
            0,
            $serverAddr,
            $serverPort,
        );
    }

    public function send(int $time, int $val, string $name, string ...$tags): void
    {
        ($this->sendMessage)($this->encodeMetric($time, $val, $name, ...$tags));
    }

    protected function encodeMetric(int $time, int $val, string $name, string ...$tags): string
    {
        $r = pack("VP", $time, $val);
        $r .= $name;

        foreach ($tags as $tag) {
            if (!strlen($tag)) {
                break;
            }
            $r .= "\x00" . $tag;
        }

        return $r;
    }
}