How to cache dynamic PHP page - php

Question

How to cache PHP page which has mysql query. Any example will be great and helpful.

Answer 1

I am using phpFastCache ( for shared hosting, if you don't want to touch php.ini and root to setup memcached). Check out the Example Menu. They have full detail example, and very easy.
First you set with phpFastCache::set and then get with phpFastCache::get - DONE!
Example: Reduce Database Calls
Your website have 10,000 visitors who are online, and your dynamic page have to send 10,000 same queries to database on every page load. With phpFastCache, your page only send 1 query to DB, and use the cache to serve 9,999 other visitors.
<?php
// In your config file
include("php_fast_cache.php");
phpFastCache::$storage = "auto";
// you can set it to files, apc, memcache, memcached, pdo, or wincache
// I like auto
// In your Class, Functions, PHP Pages
// try to get from Cache first.
$products = phpFastCache::get("products_page");
if($products == null) {
$products = YOUR DB QUERIES || GET_PRODUCTS_FUNCTION;
// set products in to cache in 600 seconds = 5 minutes
phpFastCache::set("products_page",$products,600);
}
OUTPUT or RETURN your $products
?>

Answer 2

My preference is to use a caching reverse proxy, like Varnish.
As far as a pure PHP solution, you could have some code at the end of your script that caches the final output, and code at the beginning that checks to see if the page is cached. If the page was found in cache, send it and exit rather than running the queries again.
<?php
function cache_file() {
// something to (hopefully) uniquely identify the resource
$cache_key = md5($_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] . $_SERVER['QUERY_STRING']);
$cache_dir = '/tmp/phpcache';
return $cache_dir . '/' . $cache_key;
}
// if we have a cache file, deliver it
if( is_file( $cache_file = cache_file() ) ) {
readfile( $cache_file );
exit;
}
// cache via output buffering, with callback
ob_start( 'cache_output' );
//
// expensive processing happens here, along with page output.
//
function cache_output( $content ) {
file_put_contents( cache_file(), $content );
return $content;
}
Obviously this needs lots of customization for your setup, including cache expiration, a $cache_key that meets your needs, and error detection so bad pages aren't cached.

Answer 3

memcache your html out and then do something like this:
$memcache = memcache_connect('localhost', 11211);
$page = $memcache->get('homepage');
if($page == ""){
$mtime = microtime();
$page = get_home();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
memcache_set($memcache, 'homepage', $page, 0, 30);
$page .= "\n<!-- Duly stored ($totaltime) -->";
}
else{
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
$page .= "\n<!-- served from memcache ($totaltime) -->";
}
die($page);

Answer 4

<?php
//settings
$cache_ext = '.html'; //file extension
$cache_time = 3600; //Cache file expires afere these seconds (1 hour = 3600 sec)
$cache_folder = 'cache/'; //folder to store Cache files
$ignore_pages = array('', '');
$dynamic_url = 'http://'.$_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] . $_SERVER['QUERY_STRING']; // requested dynamic page (full url)
$cache_file = $cache_folder.md5($dynamic_url).$cache_ext; // construct a cache file
$ignore = (in_array($dynamic_url,$ignore_pages))?true:false; //check if url is in ignore list
if (!$ignore && file_exists($cache_file) && time() - $cache_time < filemtime($cache_file)) { //check Cache exist and it's not expired.
ob_start('ob_gzhandler'); //Turn on output buffering, "ob_gzhandler" for the compressed page with gzip.
readfile($cache_file); //read Cache file
echo '<!-- cached page - '.date('l jS \of F Y h:i:s A', filemtime($cache_file)).', Page : '.$dynamic_url.' -->';
ob_end_flush(); //Flush and turn off output buffering
exit(); //no need to proceed further, exit the flow.
}
//Turn on output buffering with gzip compression.
ob_start('ob_gzhandler');
######## Your Website Content Starts Below #########
?>
<!DOCTYPE html>
<html>
<head>
<title>Page to Cache</title>
</head>
<body>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer ut tellus libero.
</body>
</html>
<?php
######## Your Website Content Ends here #########
if (!is_dir($cache_folder)) { //create a new folder if we need to
mkdir($cache_folder);
}
if(!$ignore){
$fp = fopen($cache_file, 'w'); //open file for writing
fwrite($fp, ob_get_contents()); //write contents of the output buffer in Cache file
fclose($fp); //Close file pointer
}
ob_end_flush(); //Flush and turn off output buffering
?>

Answer 5

The important thing, often overlooked when there is discussion about caching, is process synchronization to avoid thread race (see: https://en.wikipedia.org/wiki/Race_condition).
Typical caching scenario in PHP without synchronization looks like this: if you don't have resource in the cache, or resource is expired, it must be created and put into cache. First thread/process that happens to encounter such condition is trying to create resource, and during that time, other threads will also create the resource, which leads to thread race, cache slamming and performance downspike.
Problem is magnified by number of concurrent threads and workload created by resource creation task. On busy systems it may lead to serious problems.
There is very few caching systems for PHP that takes it into consideration synchronization.
One of them is php-no-slam-cache: https://github.com/tztztztz/php-no-slam-cache