PHP Cache
If your website receives a good amount of traffic everyday and your webpages are loading slow, you might want to consider implementing some sort of caching mechanism on your website to speed-up page loading time. Because as we all know that each…
If your website receives a good amount of traffic everyday and your webpages are loading slow, you might want to consider implementing some sort of caching mechanism on your website to speed-up page loading time. Because as we all know that each client-server request consists of many queries, loops, calculations, database queries etc. these all add-up to processing time, which eventually increases page loading time. The most simplest way to avoid all these is to create cache files and store them in a separate directory, which can later be served as fast loading static pages instead of regular dynamic pages.
PHP Caching #
There are several other PHP cache engines such as APC, Xcache or OPcache to boost your application performance, but they all work quite differently, to understand them you can find many tutorials dedicated to them on the web. Here I’m going to show you the most simplest way of caching PHP pages, and that is using PHP Output Buffer and Filesystem Functions, combining these two methods we can have magnificent caching system.
PHP Output buffer :— It interestingly improves performance and decreases the amount of time it takes to download, because the output is not being sent to browser in pieces but the whole HTML page as one variable. The method is insanely simple take a look at the code below :
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<?php ob_start(); // start the output buffer /* the content */ ob_get_contents(); gets the contents of the output buffer ob_end_flush(); // Send the output and turn off output buffering ?> |
When you call ob_start() on the top of the code, it turns output buffering on, which means anything after this will be stored in the buffer, instead of outputting on the browser. The content in the buffer can be retrieved using ob_get_contents(). You should call ob_end_flush() at the end of the code to send the output to the browser and turn buffering off.
PHP Filesystem :— You may be familiar with PHP file system, it is a part of the PHP core, which allow us to read and write the file system. Have a look at the following code.
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$fp = fopen('/path/to/file.txt', 'w'); //open file for writing fwrite($fp, 'I want to write this'); //write fclose($fp); //Close file pointer |
As you can see the first line of the code fopen() opens the file for writing, the mode ‘w’ places the file pointer at the beginning of the file and if file does not exist, it attempts to create one. Second line fwrite() writes the string to the opened file, and finally fclose() closes the successfully opened file at the beginning of the code.
Implementing PHP caching #
Now you should be pretty clear about PHP output buffer and filesystem, we can use these both methods to create our PHP caching system. Please have a look at the picture below, the Flowchart gives us the basic idea about our cache system.
The cycle starts when a user request the content, we just check whether the cache copy exist for the currently requested page, if it doesn’t exist we generate a new page, create cache copy and then output the result. If the cache already exist, we just have to fetch the file and send it to the user browser.
Take a look at the Full PHP cache code below, you can just copy and paste it in your PHP projects, it should work flawlessly as depicted in above Flowchart. You can play with the settings in the code, modify the cache expire time, cache file extension, ignored pages etc.
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<?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 ?> |
Read the comment lines in the code carefully, you should find it pretty much self explanatory.
- Get the currently requested URL location.
- Construct a location path for the cache file, convert URL to MD5 hash for the fixed cache file name.
- Check whether URL is in ignore list.
- Check for existing unexpired cache file, if exist, just open and output the content with gzip compression.
- Or else, we create a new cache file and output the HTML result with gzip compression.
