--- /dev/null
+<?php
+
+/**
+ * This class stores an arbitrary value along with its dependencies.
+ * Users should typically only use DependencyWrapper::getFromCache(), rather
+ * than instantiating one of these objects directly.
+ */
+class DependencyWrapper {
+ var $value;
+ var $deps;
+
+ /**
+ * Create an instance.
+ * @param mixed $value The user-supplied value
+ * @param mixed $deps A dependency or dependency array. All dependencies
+ * must be objects implementing CacheDependency.
+ */
+ function __construct( $value = false, $deps = array() ) {
+ $this->value = $value;
+ if ( !is_array( $deps ) ) {
+ $deps = array( $deps );
+ }
+ $this->deps = $deps;
+ }
+
+ /**
+ * Returns true if any of the dependencies have expired
+ */
+ function isExpired() {
+ foreach ( $this->deps as $dep ) {
+ if ( $dep->isExpired() ) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Initialise dependency values in preparation for storing. This must be
+ * called before serialization.
+ */
+ function initialiseDeps() {
+ foreach ( $this->deps as $dep ) {
+ $dep->loadDependencyValues();
+ }
+ }
+
+ /**
+ * Get the user-defined value
+ */
+ function getValue() {
+ return $this->value;
+ }
+
+ /**
+ * Store the wrapper to a cache
+ */
+ function storeToCache( $cache, $key, $expiry = 0 ) {
+ $this->initialiseDeps();
+ $cache->set( $key, $this, $expiry );
+ }
+
+ /**
+ * Attempt to get a value from the cache. If the value is expired or missing,
+ * it will be generated with the callback function (if present), and the newly
+ * calculated value will be stored to the cache in a wrapper.
+ *
+ * @param object $cache A cache object such as $wgMemc
+ * @param string $key The cache key
+ * @param integer $expiry The expiry timestamp or interval in seconds
+ * @param mixed $callback The callback for generating the value, or false
+ * @param array $callbackParams The function parameters for the callback
+ * @param array $deps The dependencies to store on a cache miss. Note: these
+ * are not the dependencies used on a cache hit! Cache hits use the stored
+ * dependency array.
+ *
+ * @return mixed The value, or null if it was not present in the cache and no
+ * callback was defined.
+ */
+ static function getValueFromCache( $cache, $key, $expiry = 0, $callback = false,
+ $callbackParams = array(), $deps = array() )
+ {
+ $obj = $cache->get( $key );
+ if ( $obj && !$obj->isExpired() ) {
+ $value = $obj->value;
+ } elseif ( $callback ) {
+ $value = call_user_func_array( $callback, $callbackParams );
+ # Cache the newly-generated value
+ $wrapper = new DependencyWrapper( $value, $deps );
+ $wrapper->storeToCache( $cache, $key, $expiry );
+ } else {
+ $value = null;
+ }
+ return $value;
+ }
+}
+
+abstract class CacheDependency {
+ /**
+ * Returns true if the dependency is expired, false otherwise
+ */
+ abstract function isExpired();
+
+ /**
+ * Hook to perform any expensive pre-serialize loading of dependency values.
+ */
+ function loadDependencyValues() {}
+}
+
+class FileDependency extends CacheDependency {
+ var $filename, $timestamp;
+
+ /**
+ * Create a file dependency
+ *
+ * @param string $filename The name of the file, preferably fully qualified
+ * @param mixed $timestamp The unix last modified timestamp, or false if the
+ * file does not exist. If omitted, the timestamp will be loaded from
+ * the file.
+ *
+ * A dependency on a nonexistent file will be triggered when the file is
+ * created. A dependency on an existing file will be triggered when the
+ * file is changed.
+ */
+ function __construct( $filename, $timestamp = null ) {
+ $this->filename = $filename;
+ $this->timestamp = $timestamp;
+ }
+
+ function loadDependencyValues() {
+ if ( is_null( $this->timestamp ) ) {
+ if ( !file_exists( $this->filename ) ) {
+ # Dependency on a non-existent file
+ # This is a valid concept!
+ $this->timestamp = false;
+ } else {
+ $this->timestamp = filemtime( $this->filename );
+ }
+ }
+ }
+
+ function isExpired() {
+ if ( !file_exists( $this->filename ) ) {
+ if ( $this->timestamp === false ) {
+ # Still nonexistent
+ return false;
+ } else {
+ # Deleted
+ wfDebug( "Dependency triggered: {$this->filename} deleted.\n" );
+ return true;
+ }
+ } else {
+ $lastmod = filemtime( $this->filename );
+ if ( $lastmod > $this->timestamp ) {
+ # Modified or created
+ wfDebug( "Dependency triggered: {$this->filename} changed.\n" );
+ return true;
+ } else {
+ # Not modified
+ return false;
+ }
+ }
+ }
+}
+
+class TitleDependency extends CacheDependency {
+ var $titleObj;
+ var $ns, $dbk;
+ var $touched;
+
+ /**
+ * Construct a title dependency
+ * @param Title $title
+ */
+ function __construct( Title $title ) {
+ $this->titleObj = $title;
+ $this->ns = $title->getNamespace();
+ $this->dbk = $title->getDBkey();
+ }
+
+ function loadDependencyValues() {
+ $this->touched = $this->getTitle()->getTouched();
+ }
+
+ /**
+ * Get rid of bulky Title object for sleep
+ */
+ function __sleep() {
+ return array( 'ns', 'dbk', 'touched' );
+ }
+
+ function getTitle() {
+ if ( !isset( $this->titleObj ) ) {
+ $this->titleObj = Title::makeTitle( $this->ns, $this->dbk );
+ }
+ return $this->titleObj;
+ }
+
+ function isExpired() {
+ $touched = $this->getTitle()->getTouched();
+ if ( $this->touched === false ) {
+ if ( $touched === false ) {
+ # Still missing
+ return false;
+ } else {
+ # Created
+ return true;
+ }
+ } elseif ( $touched === false ) {
+ # Deleted
+ return true;
+ } elseif ( $touched > $this->touched ) {
+ # Updated
+ return true;
+ } else {
+ # Unmodified
+ return false;
+ }
+ }
+}
+
+class TitleListDependency extends CacheDependency {
+ var $linkBatch;
+ var $timestamps;
+
+ /**
+ * Construct a dependency on a list of titles
+ */
+ function __construct( LinkBatch $linkBatch ) {
+ $this->linkBatch = $linkBatch;
+ }
+
+ function calculateTimestamps() {
+ # Initialise values to false
+ $timestamps = array();
+ foreach ( $this->getLinkBatch()->data as $ns => $dbks ) {
+ if ( count( $dbks ) > 0 ) {
+ $timestamps[$ns] = array();
+ foreach ( $dbks as $dbk => $value ) {
+ $timestamps[$ns][$dbk] = false;
+ }
+ }
+ }
+
+ # Do the query
+ if ( count( $timestamps ) ) {
+ $dbr =& wfGetDB( DB_SLAVE );
+ $where = $this->getLinkBatch()->constructSet( 'page', $dbr );
+ $res = $dbr->select( 'page',
+ array( 'page_namespace', 'page_title', 'page_touched' ),
+ $where, __METHOD__ );
+ while ( $row = $dbr->fetchObject( $res ) ) {
+ $timestamps[$row->page_namespace][$row->page_title] = $row->page_touched;
+ }
+ }
+ return $timestamps;
+ }
+
+ function loadDependencyValues() {
+ $this->timestamps = $this->calculateTimestamps();
+ }
+
+ function __sleep() {
+ return array( 'timestamps' );
+ }
+
+ function getLinkBatch() {
+ if ( !isset( $this->linkBatch ) ){
+ $this->linkBatch = new LinkBatch;
+ $this->linkBatch->setArray( $this->timestamps );
+ }
+ return $this->linkBatch;
+ }
+
+ function isExpired() {
+ $newTimestamps = $this->calculateTimestamps();
+ foreach ( $this->timestamps as $ns => $dbks ) {
+ foreach ( $dbks as $dbk => $oldTimestamp ) {
+ $newTimestamp = $newTimestamps[$ns][$dbk];
+ if ( $oldTimestamp === false ) {
+ if ( $newTimestamp === false ) {
+ # Still missing
+ } else {
+ # Created
+ return true;
+ }
+ } elseif ( $newTimestamp === false ) {
+ # Deleted
+ return true;
+ } elseif ( $newTimestamp > $oldTimestamp ) {
+ # Updated
+ return true;
+ } else {
+ # Unmodified
+ }
+ }
+ }
+ return false;
+ }
+}
+
+class GlobalDependency extends CacheDependency {
+ var $name, $value;
+
+ function __construct( $name ) {
+ $this->name = $name;
+ $this->value = $GLOBALS[$name];
+ }
+
+ function isExpired() {
+ return $GLOBALS[$this->name] != $this->value;
+ }
+}
+
+class ConstantDependency extends CacheDependency {
+ var $name, $value;
+
+ function __construct( $name ) {
+ $this->name = $name;
+ $this->value = constant( $name );
+ }
+
+ function isExpired() {
+ return constant( $this->name ) != $this->value;
+ }
+}
+
+?>
dépôts / lhc / web / wiklou.git / commitdiff