Threaded Downloads with Curl

function_threading.php

<?php
function thread_download($file, $filename)
{
	$url		= $file;
	$headers	= get_headers($url,1);
	//print_r($headers);
	$bytes		= $headers['Content-Length'][1];
	//echo $bytes . "|";
	for($i=0;$i<$bytes-1;$i+=204800)
	{
		if($i+204800-1<=$bytes-1)
		{
			$ch[count($ch)] = $i . '-' . ($i+204800-1);
		}
		else
		{
			$ch[count($ch)] = $i . '-' . ($bytes-1);
		}
	}
	//print_r($ch);
	//die();
	
	//create the multiple cURL handle
	$mh = curl_multi_init();
	foreach($ch as $name=>$range)
	{
		$fp[$name] = fopen($filename . '.part' . $name, 'w'); 
		// create both cURL resources
		$ch[$name] = curl_init();
		
		// set URL and other appropriate options
		curl_setopt($ch[$name], CURLOPT_URL, $headers['Location']);
		//curl_setopt($ch[$name], CURLOPT_FOLLOWLOCATION, true);
		curl_setopt($ch[$name], CURLOPT_MAXREDIRS, 10);
		curl_setopt($ch[$name], CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7");
		curl_setopt($ch[$name], CURLOPT_HEADER, false);
		curl_setopt($ch[$name], CURLOPT_RETURNTRANSFER, true);
		curl_setopt($ch[$name], CURLOPT_RANGE, $range);
		curl_setopt($ch[$name], CURLOPT_FILE, $fp[$name]);
		
		curl_multi_add_handle($mh,$ch[$name]);
	}
	
	$running=null;
	//execute the handles
	do {
		curl_multi_exec($mh,$running);
	} while ($running > 0);
	//close the handles
	foreach($ch as $name=>$range)
	{
		curl_multi_remove_handle($mh,$ch[$name]);
		fclose($fp[$name]); 
	}
	curl_multi_close($mh);
	//-------------------------------------------------------------
	unlink($filename);
	$fp = fopen($filename, 'a');
	foreach($ch as $name=>$url)
	{
		$contents	= file_get_contents($filename . '.part' . $name);
		unlink($filename . '.part' . $name);
		fwrite($fp, $contents);
	}
	fclose($fp);
	return true;
}
?>