README

This module seamlessly and robustly caches page content, allowing subsequent requests to bypass server heavy operations such as database access.

Credits and Authors

• Damian Mooyman - https://github.com/tractorcow/silverstripe-dynamiccache

Requirements

• SilverStripe 3.1.7 or above
• PHP 5.4

How it works

When a page is requested by a visitor the module will attempt to return any cached content / custom headers for that request before the database connection is initiated. If a cached copy exists and can be returned, this can save a huge amount of processing overhead.

If a cached copy does not exist, then the page will process normally, but the result will then be saved for later page requests.

This differs from StaticPublisher or StaticExporter in that there is no administration caching. The caching is done incrementally on a per-page request basis rather than up front. This distributes the caching task across several requests, adding only a trivial overhead to non-cached requests, but saving a huge amount of time at the administration level.

Whenever a page is published the entire cache is cleared for the sake of robustness.

This module will allow individual pages to opt-out of caching by specifying certain headers, and will ignore caching on ajax pages or direct requests to controllers (including form submissions) by checking for any url-segments that start with an uppercase letter.

Installation Instructions

• Either extract the module into the dynamiccache folder, or install using composer

composer require "tractorcow/silverstripe-dynamiccache" "4.2.*"

• Edit your .htaccess (or web.config, etc) to redirect requests to the dynamiccache/cache-main.php file instead of the framework/main.php file

RewriteRule .* dynamiccache/cache-main.php?url=%1&%{QUERY_STRING} [L]

Configuration options

Configuration can be done by the normal Silverstripe built in configuration system. See dynamiccache.yml for the list of configurable options.

• enabled - (boolean) Global override. Turn to false to turn caching off.
• optInHeader - (null|string) If a header should be used to opt in to caching, set the regular expression here which will match the specified header.
• optOutHeader - (null|string) If a header should be used to explicitly disable caching for a cache, set the regular expression here which will be used to match the specified header. E.g. '/^X-DynamicCache-OptOut/'
• optInResponseCodes - (null|array) Status codes that should be cached
• optOutResponseCodes - (null|array) Status codes that should not be cached
• responseHeader - (null|string) Header prefix to use for reporting cache results
• optInURL - (null|string) If caching should be limited only to specified urls set the regular expression here which will be used to match those urls
• optOutURL - (null|string) If caching should be disabled for specified urls set the regular expression here which will be used to match those urls E.g. '/(^/admin)|(/[A-Z])/'
• segmentHostname - (boolean) Determine if caching should be separated for different hostnames. Important if running off a system that serves different content for different hostname, but still uses the same backend, such as the subsites module
• enableAjax - (boolean) Determine if caching should be enabled during ajax
• cacheDir - (string) Directory where file-based caches are stored (either absolute, or relative to TEMP_FOLDER). Allows usage of %BASE_PATH% and %ASSETS_PATH% placeholders. Please ensure that the folder is either located outside of the webroot, or appropriately secured.
• cacheDuration - (null|integer) Duration of the page cache, in seconds (default is 1 hour).
• cacheHeaders - (null|string) Determines which headers should also be cached. X-Include-CSS and other relevant headers can be essential in instructing the front end to include specific resource files. E.g. '/^X-/i'
• cacheBackend - (null|string) If you wish to override the cache configuration, then change this to another backend, and initialise a new SS_Cache backend in your _config file

Cache Clearing

By default the cache will be cleared whenever a SiteTree or SiteConfig object is updated or deleted, including publishing or unpublishing. This will flush the entire cache at once.

In order to prompt additional cache flushing, it may be necessary to clear this cache in other circumstances.

If this should be done when an object is changed, you should add the DynamicCacheDataObjectExtension extension to that type.

If this should be done in response to a conditional, or non-dataobject related action, then you can explicitly flush the cache with the below code:

DynamicCache::inst()->clear();

Additionally, if you are logged in (or are in dev mode) the cache can be flushed by adding the 'cache=flush' query parameter. E.g.

http://www.app.com/?cache=flush

Customising Cache Behaviour

If you extend DynamicCache you can hook into two additional methods. A helper extension class DynamicCacheExtension can be used here to get started.

The below example will allow the cache to be bypassed if a certain session value is set, and segments the cache between mobile / non-mobile users (assuming silverstripe/mobile module is installed).

	class CacheCustomisation extends DynamicCacheExtension {
		public function updateEnabled(&$enabled) {
			// Disable caching for this request if a user is logged in
			if (Member::currentUserID()) $enabled = false;

			// Disable caching for this request if in dev mode
			elseif (Director::isDev()) $enabled = false;

			// Disable caching for this request if we have a message to display
			// or the request shouldn't be cached for other reasons
			elseif (Session::get('StatusMessage') || Session::get('Uncachable')) $enabled = false;
		}

		public function updateCacheKeyFragments(array &$fragments) {
			// For any url segment cache between mobile and desktop devices.
			$fragments[] = MobileBrowserDetector::is_mobile() ? 'mobile' : 'desktop';
		}
	}

License

Copyright (c) 2013, Damian Mooyman All rights reserved.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• The name of Damian Mooyman may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.