From: Kunal Mehta <legoktm@gmail.com>
Date: Sun, 26 Jul 2015 23:07:59 +0000 (-0700)
Subject: Don't let LinkCache grow indefinitely
X-Git-Tag: 1.31.0-rc.0~10634^2
X-Git-Url: https://git.heureux-cyclage.org/?a=commitdiff_plain;h=32d1017e7d779effabb719f513b3cd346bfa814b;p=lhc%2Fweb%2Fwiklou.git

Don't let LinkCache grow indefinitely

Especially in long running maintenance scripts, this can be problematic.

LinkCache is now LRU-based, and will store a maximum of 10,000 good titles,
and 10,000 bad ones.

LinkCache::getGoodLinks() and getBadLinks() are deprecated since they
problematic to support in this implementation and are unused.

Bug: T106998
Change-Id: I1328149d65a5e75a5d6e10cb2686a099562a1847
---

diff --git a/includes/cache/LinkCache.php b/includes/cache/LinkCache.php
index e8cc5e5b67..56c92569ec 100644
--- a/includes/cache/LinkCache.php
+++ b/includes/cache/LinkCache.php
@@ -29,18 +29,34 @@
 class LinkCache {
 	// Increment $mClassVer whenever old serialized versions of this class
 	// becomes incompatible with the new version.
-	private $mClassVer = 4;
+	private $mClassVer = 5;
 
-	private $mGoodLinks = array();
-	private $mGoodLinkFields = array();
-	private $mBadLinks = array();
+	/**
+	 * @var MapCacheLRU
+	 */
+	private $mGoodLinks;
+	/**
+	 * @var MapCacheLRU
+	 */
+	private $mBadLinks;
 	private $mForUpdate = false;
 
+	/**
+	 * How many Titles to store. There are two caches, so the amount actually
+	 * stored in memory can be up to twice this.
+	 */
+	const MAX_SIZE = 10000;
+
 	/**
 	 * @var LinkCache
 	 */
 	protected static $instance;
 
+	public function __construct() {
+		$this->mGoodLinks = new MapCacheLRU( self::MAX_SIZE );
+		$this->mBadLinks = new MapCacheLRU( self::MAX_SIZE );
+	}
+
 	/**
 	 * Get an instance of this class.
 	 *
@@ -90,8 +106,9 @@ class LinkCache {
 	 * @return int
 	 */
 	public function getGoodLinkID( $title ) {
-		if ( array_key_exists( $title, $this->mGoodLinks ) ) {
-			return $this->mGoodLinks[$title];
+		if ( $this->mGoodLinks->has( $title ) ) {
+			$info = $this->mGoodLinks->get( $title );
+			return $info['id'];
 		} else {
 			return 0;
 		}
@@ -106,8 +123,9 @@ class LinkCache {
 	 */
 	public function getGoodLinkFieldObj( $title, $field ) {
 		$dbkey = $title->getPrefixedDBkey();
-		if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
-			return $this->mGoodLinkFields[$dbkey][$field];
+		if ( $this->mGoodLinks->has( $dbkey ) ) {
+			$info = $this->mGoodLinks->get( $dbkey );
+			return $info[$field];
 		} else {
 			return null;
 		}
@@ -118,7 +136,8 @@ class LinkCache {
 	 * @return bool
 	 */
 	public function isBadLink( $title ) {
-		return array_key_exists( $title, $this->mBadLinks );
+		// We need to use get here since has will not call ping.
+		return $this->mBadLinks->get( $title ) !== null;
 	}
 
 	/**
@@ -135,13 +154,13 @@ class LinkCache {
 		$revision = 0, $model = null
 	) {
 		$dbkey = $title->getPrefixedDBkey();
-		$this->mGoodLinks[$dbkey] = (int)$id;
-		$this->mGoodLinkFields[$dbkey] = array(
+		$this->mGoodLinks->set( $dbkey, array(
+			'id' => (int)$id,
 			'length' => (int)$len,
 			'redirect' => (int)$redir,
 			'revision' => (int)$revision,
 			'model' => $model ? (string)$model : null,
-		);
+		) );
 	}
 
 	/**
@@ -153,13 +172,13 @@ class LinkCache {
 	 */
 	public function addGoodLinkObjFromRow( $title, $row ) {
 		$dbkey = $title->getPrefixedDBkey();
-		$this->mGoodLinks[$dbkey] = intval( $row->page_id );
-		$this->mGoodLinkFields[$dbkey] = array(
+		$this->mGoodLinks->set( $dbkey, array(
+			'id' => intval( $row->page_id ),
 			'length' => intval( $row->page_len ),
 			'redirect' => intval( $row->page_is_redirect ),
 			'revision' => intval( $row->page_latest ),
 			'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
-		);
+		) );
 	}
 
 	/**
@@ -168,12 +187,12 @@ class LinkCache {
 	public function addBadLinkObj( $title ) {
 		$dbkey = $title->getPrefixedDBkey();
 		if ( !$this->isBadLink( $dbkey ) ) {
-			$this->mBadLinks[$dbkey] = 1;
+			$this->mBadLinks->set( $dbkey, 1 );
 		}
 	}
 
 	public function clearBadLink( $title ) {
-		unset( $this->mBadLinks[$title] );
+		$this->mBadLinks->clear( array( $title ) );
 	}
 
 	/**
@@ -181,17 +200,33 @@ class LinkCache {
 	 */
 	public function clearLink( $title ) {
 		$dbkey = $title->getPrefixedDBkey();
-		unset( $this->mBadLinks[$dbkey] );
-		unset( $this->mGoodLinks[$dbkey] );
-		unset( $this->mGoodLinkFields[$dbkey] );
+		$this->mBadLinks->clear( array( $dbkey ) );
+		$this->mGoodLinks->clear( array( $dbkey ) );
 	}
 
+
+	/**
+	 * @deprecated since 1.26
+	 * @return array
+	 */
 	public function getGoodLinks() {
-		return $this->mGoodLinks;
+		wfDeprecated( __METHOD__, '1.26' );
+		$links = array();
+		foreach ( $this->mGoodLinks->getAllKeys() as $key ) {
+			$info = $this->mGoodLinks->get( $key );
+			$links[$key] = $info['id'];
+		}
+
+		return $links;
 	}
 
+	/**
+	 * @deprecated since 1.26
+	 * @return array
+	 */
 	public function getBadLinks() {
-		return array_keys( $this->mBadLinks );
+		wfDeprecated( __METHOD__, '1.26' );
+		return $this->mBadLinks->getAllKeys();
 	}
 
 	/**
@@ -262,8 +297,7 @@ class LinkCache {
 	 * Clears cache
 	 */
 	public function clear() {
-		$this->mGoodLinks = array();
-		$this->mGoodLinkFields = array();
-		$this->mBadLinks = array();
+		$this->mGoodLinks->clear();
+		$this->mBadLinks->clear();
 	}
 }