PHP上传大文件和处理大数据

/* 以1.5M/秒的速度写入文件，防止一次过写入文件过大导致服务器出错(chy/20150327) */
$is_large_file = false;
if( strlen($xml_str)>=2097152 ){ //当文件大于2M
$is_large_file = true;

fwrite($fp, $pre, strlen($pre)); //写入头部
$start = 0;
while( $content=mb_strcut($xml_str,$start,1572864) ){
$start = $start + 1572864;
$writeResult = fwrite($fp, $content, strlen($content));
if( !$writeResult ){
unlink($filename);
break;
}
sleep(1);
unset($content);
}
unset($xml_str);
fwrite($fp, $end, strlen($end)); //写入尾部
}else{
$content = $pre.$xml_str.$end;
fwrite($fp, $content, strlen($content));
}

//aes加密
public function aesEncode_large($info) {
//.....(省略部分代码)

　　　　if(mcrypt_generic_init($cipher, $this->aesKey, $this->aesIv) != -1){
//$cipherText = mcrypt_generic($cipher, $beianInfo); //原普通的加密方式(chy/20150327)

//处理大字符串加密。temp.text主要用于文件缓存(chy/20150327)
$filename = B_ROOT."/admin/temp/temp.txt";
file_put_contents($filename,''); //将文件清空
$fp = fopen($filename, 'wb');

while( $content=mb_strcut($info,$start,104800) ){
$start = $start + 104800;
$cipherTextCut = mcrypt_generic($cipher, $content);
fwrite($fp, $cipherTextCut, strlen($cipherTextCut));
unset($cipherTextCut);
unset($content);
}

mcrypt_generic_deinit($cipher);
mcrypt_module_close($cipher);
fclose($fp);
return true;
} else {
return false;
}
}