htaccess jump to cached file (htaccess & php-Cache) - php

Question

I have webpages processed by php. When they're finished processing and i get a html-file output. This file is saved in a directory called "cache".
e.g.
www.domain.tld/list.html (browser-url)
www.domain.tld/cache/list.html (cached-file)
My actual problem is, that i have no clue how I could change the htaccess-file to work out the problem.
How can I apply that the RewriteCond will check first if the "/list.html"-file exists in that folder (cache) and then (if yes): return the file and (if not) just continue to the other conditions which will in the end redirect to index.php.
But i need to keep the rule, that it have to check if the file exists anyway (without that cache-folder)
This is causing errors:
RewriteCond cache/%{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L,QSA]
How is that possible?
Some of the pages are processed for about 20-30 seconds or more. This is why I want to save them after processing and then deliver the already finished site to save time.

Answer 1

This should do what you ask:
RewriteEngine on
RewriteCond %{REQUEST_URI} ^/(.+)$
RewriteCond %{DOCUMENT_ROOT}/cache/%1 -f
RewriteRule ^ /cache/%1 [END]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^/?(.*)$ index.php?/$1 [END]
In case you receive an internal server error (http status 500) using the rule above then chances are that you operate a very old version of the apache http server. You will see a definite hint to an unsupported [END] flag in your http servers error log file in that case. You can either try to upgrade or use the older [L] flag, it probably will work the same in this situation, though that depends a bit on your setup.
This implementation will work likewise in the http servers host configuration or inside a dynamic configuration file (".htaccess" file). Obviously the rewriting module needs to be loaded inside the http server and enabled in the http host. In case you use a dynamic configuration file you need to take care that it's interpretation is enabled at all in the host configuration and that it is located in the host's DOCUMENT_ROOT folder.
And a general remark: you should always prefer to place such rules in the http servers host configuration instead of using dynamic configuration files (".htaccess"). Those dynamic configuration files add complexity, are often a cause of unexpected behavior, hard to debug and they really slow down the http server. They are only provided as a last option for situations where you do not have access to the real http servers host configuration (read: really cheap service providers) or for applications insisting on writing their own rules (which is an obvious security nightmare).