I am working on a test project using the embedded PHP web server and I am testing some ideas.
I want to implement my own caching mechanism for frequently used resources (png, jpg, json, txt, etc.) in order to reduce the load on the embedded server in php.
I start the embedded server as follows:
php -S 127.0.0.1:80 -t public router.php
So, the document root on the embedded server is set to public , and it launches router.php (since I also assume to implement a simple rewrite function).
Here is the contents of my router.php file:
<?php // Register request uri $requestUri = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '/'; // Handle app resources with caching if (preg_match('/\.(?:png|jpg|jpeg|gif|xml|json|css|eot|svg|otf|ttf|woff|woff2|scss|less|txt|ico)$/', $requestUri)) { // Generate file name $fileName = __DIR__ .'/public'. $requestUri; // Parse file data $lastModified = filemtime($fileName); $etagFile = md5_file($fileName); $ifModifiedSince = (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ? $_SERVER['HTTP_IF_MODIFIED_SINCE'] : false); $etagHeader = (isset($_SERVER['HTTP_IF_NONE_MATCH']) ? trim($_SERVER['HTTP_IF_NONE_MATCH']) : false); // Set caching header header('Last-Modified: '. gmdate('D, d MYH:i:s', $lastModified) .' GMT'); header('Etag: '. $etagFile); header('Cache-Control: public'); // Check if the requested resource has changed if (@strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $lastModified || $etagHeader == $etagFile) { // File has not changed header('HTTP/1.1 304 Not Modified'); exit; } else { // Parse requested resource mime type $finfo = new finfo(FILEINFO_MIME); $mime_type = $finfo->buffer( file_get_contents($fileName, false, null, -1, 64), FILEINFO_MIME_TYPE ); // Serve requested resource header('Content-Type: '. $mime_type); header('Content-Length: '. filesize($fileName)); @readfile($fileName); $finfo = null; exit; } } // Parse requested page & action list ($page, $action) = array_pad(array_values(array_filter(explode('/', $requestUri, 3), 'strlen')), 2, 'index'); if ($page == 'index') $page = 'server'; // Test - to do rest of routing var_dump('page = '. $page); var_dump('action = '. $action); // include 'app/'. $page .'/'. $action .'.php'; ?>
I tested resource caching (png image) by visiting the following URL: http: //localhost/apple-icon-120x120.png
So, this is the first resource of the resource, so the service returns a resource with an HTTP 200 response, as expected, takes about 307ms : 
Now, if I press the F5 button to reload the page, the server will return HTTP 304 (not changed), as expected, and the request took about 5ms (excellent !!): 
If I press F5 third time, the server still returns HTTP 304 (not changed), as expected, however this time the request received approximately 306ms again (as if the resource were not cached): 
If I keep pressing F5 , the request processing time randomly alternates between 5m and approx 307ms .
Any ideas why this is so? As soon as the resource is cached, should it constantly return 304 and process the request approx 5ms ? Why is sporadic behavior?
I see that the size of the returned content is 225 bytes (when it knows the data is cached), I just can’t figure out where the bottleneck is with the request processing time. My host computer works with windows with an Intel i7 processor, 6 GB of RAM and SSDs.