4 * Abstract special page class with scaffolding for caching the HTML output.
6 * To add HTML that should be cached, use addCachedHTML like this:
7 * $this->addCachedHTML( $callback );
9 * The callback function is only called when needed, so do all your expensive
10 * computations here. This function should returns the HTML to be cached.
11 * It should not add anything to the PageOutput object!
13 * Before the first addCachedHTML call, you should call $this->startCache();
14 * After adding the last HTML that should be cached, call $this->saveCache();
18 * @file SpecialCachedPage.php
19 * @ingroup SpecialPage
21 * @licence GNU GPL v2 or later
22 * @author Jeroen De Dauw < jeroendedauw@gmail.com >
24 abstract class SpecialCachedPage
extends SpecialPage
{
27 * The time to live for the cache, in seconds or a unix timestamp indicating the point of expiry.
32 protected $cacheExpiry = 3600;
35 * List of HTML chunks to be cached (if !hasCached) or that where cashed (of hasCached).
36 * If no cached already, then the newly computed chunks are added here,
37 * if it as cached already, chunks are removed from this list as they are needed.
42 protected $cachedChunks;
45 * Indicates if the to be cached content was already cached.
46 * Null if this information is not available yet.
51 protected $hasCached = null;
54 * If the cache is enabled or not.
59 protected $cacheEnabled = true;
62 * Sets if the cache should be enabled or not.
65 * @param boolean $cacheEnabled
67 public function setCacheEnabled( $cacheEnabled ) {
68 $this->cacheEnabled
= $cacheEnabled;
72 * Initializes the caching.
73 * Should be called before the first time anything is added via addCachedHTML.
77 * @param integer|null $cacheExpiry Sets the cache expirty, either ttl in seconds or unix timestamp.
78 * @param boolean|null $cacheEnabled Sets if the cache should be enabled or not.
80 public function startCache( $cacheExpiry = null, $cacheEnabled = null ) {
81 if ( !is_null( $cacheExpiry ) ) {
82 $this->cacheExpiry
= $cacheExpiry;
85 if ( !is_null( $cacheEnabled ) ) {
86 $this->setCacheEnabled( $cacheEnabled );
89 if ( $this->getRequest()->getText( 'action' ) === 'purge' ) {
90 $this->hasCached
= false;
97 * Returns a message that notifies the user he/she is looking at
98 * a cached version of the page, including a refresh link.
104 protected function getCachedNotice() {
105 $refreshArgs = $this->getRequest()->getQueryValues();
106 unset( $refreshArgs['title'] );
107 $refreshArgs['action'] = 'purge';
109 $refreshLink = Linker
::link(
110 $this->getTitle( $this->getTitle()->getSubpageText() ),
111 $this->msg( 'cachedspecial-refresh-now' )->escaped(),
116 if ( $this->cacheExpiry
< 86400 * 3650 ) {
117 $message = $this->msg(
118 'cachedspecial-viewing-cached-ttl',
119 $this->getLanguage()->formatDuration( $this->cacheExpiry
)
123 $message = $this->msg(
124 'cachedspecial-viewing-cached-ts'
128 return $message . ' ' . $refreshLink;
132 * Initializes the caching if not already done so.
133 * Should be called before any of the caching functionality is used.
137 protected function initCaching() {
138 if ( is_null( $this->hasCached
) ) {
139 $cachedChunks = wfGetCache( CACHE_ANYTHING
)->get( $this->getCacheKeyString() );
141 $this->hasCached
= is_array( $cachedChunks );
142 $this->cachedChunks
= $this->hasCached ?
$cachedChunks : array();
144 $this->onCacheInitialized();
149 * Gets called after the cache got initialized.
153 protected function onCacheInitialized() {
154 if ( $this->hasCached
) {
155 $this->getOutput()->setSubtitle( $this->getCachedNotice() );
160 * Add some HTML to be cached.
161 * This is done by providing a callback function that should
162 * return the HTML to be added. It will only be called if the
163 * item is not in the cache yet or when the cache has been invalidated.
167 * @param {function} $callback
169 * @param string|null $key
171 public function addCachedHTML( $callback, $args = array(), $key = null ) {
172 $this->initCaching();
174 if ( $this->cacheEnabled
&& $this->hasCached
) {
177 if ( is_null( $key ) ) {
178 $itemKey = array_keys( array_slice( $this->cachedChunks
, 0, 1 ) );
179 $itemKey = array_shift( $itemKey );
181 if ( !is_integer( $itemKey ) ) {
182 wfWarn( "Attempted to get item with non-numeric key while the next item in the queue has a key ($itemKey) in " . __METHOD__
);
184 elseif ( is_null( $itemKey ) ) {
185 wfWarn( "Attempted to get an item while the queue is empty in " . __METHOD__
);
188 $html = array_shift( $this->cachedChunks
);
192 if ( array_key_exists( $key, $this->cachedChunks
) ) {
193 $html = $this->cachedChunks
[$key];
194 unset( $this->cachedChunks
[$key] );
197 wfWarn( "There is no item with key '$key' in this->cachedChunks in " . __METHOD__
);
202 $html = call_user_func_array( $callback, $args );
204 if ( $this->cacheEnabled
) {
205 if ( is_null( $key ) ) {
206 $this->cachedChunks
[] = $html;
209 $this->cachedChunks
[$key] = $html;
214 $this->getOutput()->addHTML( $html );
218 * Saves the HTML to the cache in case it got recomputed.
219 * Should be called after the last time anything is added via addCachedHTML.
223 public function saveCache() {
224 if ( $this->cacheEnabled
&& $this->hasCached
=== false && !empty( $this->cachedChunks
) ) {
225 wfGetCache( CACHE_ANYTHING
)->set( $this->getCacheKeyString(), $this->cachedChunks
, $this->cacheExpiry
);
230 * Sets the time to live for the cache, in seconds or a unix timestamp indicating the point of expiry..
234 * @param integer $cacheExpiry
236 protected function setExpirey( $cacheExpiry ) {
237 $this->cacheExpiry
= $cacheExpiry;
241 * Returns the cache key to use to cache this page's HTML output.
242 * Is constructed from the special page name and language code.
248 protected function getCacheKeyString() {
249 return call_user_func_array( 'wfMemcKey', $this->getCacheKey() );
253 * Returns the variables used to constructed the cache key in an array.
259 protected function getCacheKey() {
262 $this->getLanguage()->getCode()