StatsD.php

<?php

/**
 * Sends statistics to the stats daemon over UDP
 *
 **/

class StatsD {

    /**
     * Log timing information
     *
     * @param string $stats The metric to in log timing info for.
     * @param float $time The ellapsed time (ms) to log
     * @param float|1 $sampleRate the rate (0-1) for sampling.
     **/
    public static function timing($stat, $time, $sampleRate=1) {
        StatsD::send(array($stat => "$time|ms"), $sampleRate);
    }

    /**
     * Increments one or more stats counters
     *
     * @param string|array $stats The metric(s) to increment.
     * @param float|1 $sampleRate the rate (0-1) for sampling.
     * @return boolean
     **/
    public static function increment($stats, $sampleRate=1) {
        StatsD::updateStats($stats, 1, $sampleRate);
    }

    /**
     * Decrements one or more stats counters.
     *
     * @param string|array $stats The metric(s) to decrement.
     * @param float|1 $sampleRate the rate (0-1) for sampling.
     * @return boolean
     **/
    public static function decrement($stats, $sampleRate=1) {
        StatsD::updateStats($stats, -1, $sampleRate);
    }

    /**
     * Updates one or more stats counters by arbitrary amounts.
     *
     * @param string|array $stats The metric(s) to update. Should be either a string or array of metrics.
     * @param int|1 $delta The amount to increment/decrement each metric by.
     * @param float|1 $sampleRate the rate (0-1) for sampling.
     * @return boolean
     **/
    public static function updateStats($stats, $delta=1, $sampleRate=1) {
        if (!is_array($stats)) { $stats = array($stats); }
        $data = array();
        foreach($stats as $stat) {
            $data[$stat] = "$delta|c";
        }

        StatsD::send($data, $sampleRate);
    }

    /*
     * Squirt the metrics over UDP
     **/
    public static function send($data, $sampleRate=1) {

        // sampling
        $sampledData = array();

        if ($sampleRate < 1) {
            foreach ($data as $stat => $value) {
                if ((mt_rand() / mt_getrandmax()) <= $sampleRate) {
                    $sampledData[$stat] = "$value|@$sampleRate";
                }
            }
        } else {
            $sampledData = $data;
        }

        if (empty($sampledData)) { return; }

        // Wrap this in a try/catch - failures in any of this should be silently ignored
        // @TODO We're using localhost/8125 here because that's what statsd.conf is set to
        // we should probably try to read statsd.conf or some other config file but convention
        // is good enough for now, esp. since we catch and fail silently.  Up to the dev to 
        // make sure statsd is running
        try {
            $fp = fsockopen("udp://localhost", 8125, $errno, $errstr);
            if (! $fp) { return; }
            foreach ($sampledData as $stat => $value) {
                fwrite($fp, "$stat:$value");
            }
            fclose($fp);
        } catch (Exception $e) {
        }
    }
}