--- /dev/null
+<?php
+/**
+ * Data caching with dependencies.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Cache
+ */
+use MediaWiki\MediaWikiServices;
+
+/**
+ * This class stores an arbitrary value along with its dependencies.
+ * Users should typically only use DependencyWrapper::getValueFromCache(),
+ * rather than instantiating one of these objects directly.
+ * @ingroup Cache
+ */
+class DependencyWrapper {
+ private $value;
+ /** @var CacheDependency[] */
+ private $deps;
+
+ /**
+ * Create an instance.
+ * @param mixed $value The user-supplied value
+ * @param CacheDependency|CacheDependency[] $deps A dependency or dependency
+ * array. All dependencies must be objects implementing CacheDependency.
+ */
+ function __construct( $value = false, $deps = [] ) {
+ $this->value = $value;
+
+ if ( !is_array( $deps ) ) {
+ $deps = [ $deps ];
+ }
+
+ $this->deps = $deps;
+ }
+
+ /**
+ * Returns true if any of the dependencies have expired
+ *
+ * @return bool
+ */
+ 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
+ * @return bool|mixed
+ */
+ function getValue() {
+ return $this->value;
+ }
+
+ /**
+ * Store the wrapper to a cache
+ *
+ * @param BagOStuff $cache
+ * @param string $key
+ * @param int $expiry
+ */
+ 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 BagOStuff $cache A cache object
+ * @param string $key The cache key
+ * @param int $expiry The expiry timestamp or interval in seconds
+ * @param bool|callable $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 = [], $deps = []
+ ) {
+ $obj = $cache->get( $key );
+
+ if ( is_object( $obj ) && $obj instanceof DependencyWrapper && !$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;
+ }
+}
+
+/**
+ * @ingroup Cache
+ */
+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() {
+ }
+}
+
+/**
+ * @ingroup Cache
+ */
+class FileDependency extends CacheDependency {
+ private $filename;
+ private $timestamp;
+
+ /**
+ * Create a file dependency
+ *
+ * @param string $filename The name of the file, preferably fully qualified
+ * @param null|bool|int $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;
+ }
+
+ /**
+ * @return array
+ */
+ function __sleep() {
+ $this->loadDependencyValues();
+
+ return [ 'filename', 'timestamp' ];
+ }
+
+ function loadDependencyValues() {
+ if ( is_null( $this->timestamp ) ) {
+ MediaWiki\suppressWarnings();
+ # Dependency on a non-existent file stores "false"
+ # This is a valid concept!
+ $this->timestamp = filemtime( $this->filename );
+ MediaWiki\restoreWarnings();
+ }
+ }
+
+ /**
+ * @return bool
+ */
+ function isExpired() {
+ MediaWiki\suppressWarnings();
+ $lastmod = filemtime( $this->filename );
+ MediaWiki\restoreWarnings();
+ if ( $lastmod === false ) {
+ if ( $this->timestamp === false ) {
+ # Still nonexistent
+ return false;
+ } else {
+ # Deleted
+ wfDebug( "Dependency triggered: {$this->filename} deleted.\n" );
+
+ return true;
+ }
+ } else {
+ if ( $lastmod > $this->timestamp ) {
+ # Modified or created
+ wfDebug( "Dependency triggered: {$this->filename} changed.\n" );
+
+ return true;
+ } else {
+ # Not modified
+ return false;
+ }
+ }
+ }
+}
+
+/**
+ * @ingroup Cache
+ */
+class GlobalDependency extends CacheDependency {
+ private $name;
+ private $value;
+
+ function __construct( $name ) {
+ $this->name = $name;
+ $this->value = $GLOBALS[$name];
+ }
+
+ /**
+ * @return bool
+ */
+ function isExpired() {
+ if ( !isset( $GLOBALS[$this->name] ) ) {
+ return true;
+ }
+
+ return $GLOBALS[$this->name] != $this->value;
+ }
+}
+
+/**
+ * @ingroup Cache
+ */
+class MainConfigDependency extends CacheDependency {
+ private $name;
+ private $value;
+
+ function __construct( $name ) {
+ $this->name = $name;
+ $this->value = $this->getConfig()->get( $this->name );
+ }
+
+ private function getConfig() {
+ return MediaWikiServices::getInstance()->getMainConfig();
+ }
+
+ /**
+ * @return bool
+ */
+ function isExpired() {
+ if ( !$this->getConfig()->has( $this->name ) ) {
+ return true;
+ }
+
+ return $this->getConfig()->get( $this->name ) != $this->value;
+ }
+}
+
+/**
+ * @ingroup Cache
+ */
+class ConstantDependency extends CacheDependency {
+ private $name;
+ private $value;
+
+ function __construct( $name ) {
+ $this->name = $name;
+ $this->value = constant( $name );
+ }
+
+ /**
+ * @return bool
+ */
+ function isExpired() {
+ return constant( $this->name ) != $this->value;
+ }
+}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff