Estimate Time to Completion

ETC.php

<?php

/**
 * This class provides the methods to calculate the estimated time to completion
 * (or ETC) for a iterated procedure, by passing the numer of iterations you will do.
 * 
 * -----------------------------------------------------------------------------
 * Example of usage:
 * $timer = new ETC(number of iterations you have);
 * 
 * ITERATION {
 *      $timer->startIterationTimer(); OR $timer->start();
 * 
 *      YOUR CODE GOES HERE
 * 
 *      $timeForThisIteration = $timer->stopIterationTimer(); OR $timer->stop(); 
 *      print $timeForThisIteration;  //in seconds
 *      print $timer->getETC();       //in H:i:s
 * }
 * 
 * print $timer->getElapsedTime(); OR $timer->elapsed();
 * -----------------------------------------------------------------------------
 * 
 * @author Davide Barlassina <[email protected]>
 */
class ETC {
    
    protected $time_start;
    protected $avgTimeForIteration;
    protected $remainingIterations;
    protected $totalIterations;
    protected $elapsed = 0;
    protected $iterationIndex = 0;

    public function __construct($totalIterations) {
        $this->totalIterations = $totalIterations;
        $this->remainingIterations = $this->totalIterations;        
    }
    
    /**
     * Starts the timer for a single iteration
     */
    public function startIterationTimer() {
        $this->time_start = microtime(true);
    }

    /**
     * Stops the timer and returns the time of execution for a single iteration
     * @return string 
     */
    public function stopIterationTimer() {
        $time = round(microtime(true) - $this->time_start, 2);
        $this->elapsed = $this->elapsed + $time;
        $this->avgTimeForIteration = $this->elapsed / ($this->iterationIndex+1);
        $this->remainingIterations = $this->totalIterations - ($this->iterationIndex+1);
        $this->iterationIndex++;
        return $time;
    }
         
    /**
     * Returns the estimated time of completion
     * @return string
     */
    public function getETC() {
        return gmdate("H:i:s", $this->remainingIterations * $this->avgTimeForIteration);
    }
    
    /**
     * Returns the total elapsed time since the first startIterationTimer()
     * @return string
     */
    public function getElapsedTime() {
        return gmdate("H:i:s", $this->elapsed);
    }
    
    /**
     * SHORTCUTS
     */
    public function start()   { return $this->startIterationTimer(); }
    public function stop()    { return $this->stopIterationTimer(); }
    public function elapsed() { return $this->getElapsedTime(); }
}