Tick Per Minute Class. You can add a tick at anytime, and then later calculate the average ticks per min

TPM.php

<?php
class TPM {
    public $useCtime = true; //If true, use current time for tpm calculation. If false, use last tick.
    public $purgeOlderThan = 15; //Time in minutes to purge old data

    private $ticks = array();


    //Add a tick
    public function tick(){
        $this->ticks[] = time();
    }

    //Get the Ticks per Min
    public function getTPM(){
        $this->clean();
        sort($this->ticks,SORT_NUMERIC);
        $count = count($this->ticks);
        if($count < 2) return 0;
        $lowest = $this->ticks[0];
        $highest = $this->useCtime?time():$this->ticks[$count-1];
        if($lowest == $highest) return 0;
        $min = ($highest-$lowest)/60;
        return round($count/$min,2);
    }

    private function clean(){
        $before = time()-($this->purgeOlderThan*60);
        $this->ticks = array_filter($this->ticks,create_function('$a','return $a>'.$before.';'));
    }
}
?>