objectcache: Add makeLocalServerCache() method

This bypasses the indirection of global wgObjectCaches config and
ObjectCache::newFromParams static methods, which don't do anything
in practice.

This solves the ExtensionRegistry use-case where it couldn't use
the service container, which in turn opens the path for
being able to deprecate absence of Config being passed to
ObjectCache::newFromParams(), which isn't possible right now because
ExtensionRegistry depended on being able to call it without that,
and that is a hard requirement because ExtensionRegistry isn't
allowed to use the service container.

Change-Id: Ic88da279662f33d3585cb2232358d6faf590b5b3

RELEASE-NOTES-1.35

@@ -464,8 +464,11 @@ because of Phabricator reports.
   - protected $handler (not need anymore)
   - cleanupHandlersCache (not need anymore)
 * (T212738) The $wgVersion global is deprecated; instead, use MW_VERSION.
-* $wgMemc is deprecated, use
-  MediaWikiServices::getInstance()->getLocalServerObjectCache() instead.
+* $wgMemc is deprecated, use MediaWikiServices::getLocalServerObjectCache()
+  instead.
+* ObjectCache::detectLocalServerCache() is deprecated, instead use
+  MediaWikiServices::getLocalServerObjectCache() or
+  ObjectCache::makeLocalServerCache().
 * ImagePage::getImageLimitsFromOptions() is deprecated. Use static function
   MediaFileTrait::getImageLimitsFromOptions() instead.
 * A number of Parser-related methods were deprecated to simplify the API or

includes/ServiceWiring.php

@@ -467,10 +467,7 @@ return [
 	},
 
 	'LocalServerObjectCache' => function ( MediaWikiServices $services ) : BagOStuff {
-		$config = $services->getMainConfig();
-		$cacheId = ObjectCache::detectLocalServerCache();
-
-		return ObjectCache::newFromParams( $config->get( 'ObjectCaches' )[$cacheId], $config );
+		return ObjectCache::makeLocalServerCache();
 	},
 
 	'LockManagerGroupFactory' => function ( MediaWikiServices $services ) : LockManagerGroupFactory {

includes/objectcache/ObjectCache.php

@@ -291,12 +291,40 @@ class ObjectCache {
 	}
 
 	/**
-	 * Detects which local server cache library is present and returns a configuration for it
-	 * @since 1.32
+	 * Create a new BagOStuff instance for local-server caching.
 	 *
+	 * Only use this if you explicitly require the creation of
+	 * a fresh instance. Whenever possible, use or inject the object
+	 * from MediaWikiServices::getLocalServerObjectCache() instead.
+	 *
+	 * @since 1.35
+	 * @return BagOStuff
+	 */
+	public static function makeLocalServerCache() : BagOStuff {
+		$params = [ 'reportDupes' => false ];
+		if ( function_exists( 'apcu_fetch' ) ) {
+			// Make sure the APCu methods actually store anything
+			if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
+				return new APCUBagOStuff( $params );
+			}
+		} elseif ( function_exists( 'wincache_ucache_get' ) ) {
+			return new WinCacheBagOStuff( $params );
+		}
+
+		return new EmptyBagOStuff( $params );
+	}
+
+	/**
+	 * Detects which local server cache library is present and returns a configuration for it.
+	 *
+	 * @since 1.32
+	 * @deprecated since 1.35 Use MediaWikiServices::getLocalServerObjectCache() or
+	 * ObjectCache::makeLocalServerCache() instead.
 	 * @return int|string Index to cache in $wgObjectCaches
 	 */
 	public static function detectLocalServerCache() {
+		wfDeprecated( __METHOD__, '1.35' );
+
 		if ( function_exists( 'apcu_fetch' ) ) {
 			// Make sure the APCu methods actually store anything
 			if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {

includes/registration/ExtensionRegistry.php

@@ -175,19 +175,10 @@ class ExtensionRegistry {
 		$this->queued[$path] = $mtime;
 	}
 
-	private function getCache(): BagOStuff {
-		global $wgObjectCaches;
-		// We use a try/catch because we don't want to fail here
-		// if $wgObjectCaches is not configured properly for APC setup
-		try {
-			// Avoid MediaWikiServices to prevent instantiating it before extensions have loaded
-			$cacheId = ObjectCache::detectLocalServerCache();
-			return ObjectCache::newFromParams( $wgObjectCaches[$cacheId] );
-		} catch ( InvalidArgumentException $e ) {
-			// @codeCoverageIgnoreStart
-			return new EmptyBagOStuff();
-			// @codeCoverageIgnoreEnd
-		}
+	private function getCache() : BagOStuff {
+		// Can't call MediaWikiServices here, as we must not cause services
+		// to be instantiated before extensions have loaded.
+		return ObjectCache::makeLocalServerCache();
 	}
 
 	private function makeCacheKey( BagOStuff $cache, $component, ...$extra ) {