From d52a559fba83f3a1720de92e22797e7447af494a Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Fri, 18 Apr 2014 17:02:19 -0700
Subject: [PATCH] Make room for preloadFileStat() call in
 FileBackend::doOperationsInternal

Change-Id: I60f71155abcf7f69423639b10ec301ac192df728
---
 includes/filebackend/FileBackendStore.php |  7 +++++++
 includes/libs/ProcessCacheLRU.php         | 24 +++++++++++++++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/includes/filebackend/FileBackendStore.php b/includes/filebackend/FileBackendStore.php
index 2fd1bf66a7..e0b5224901 100644
--- a/includes/filebackend/FileBackendStore.php
+++ b/includes/filebackend/FileBackendStore.php
@@ -1102,6 +1102,10 @@ abstract class FileBackendStore extends FileBackend {
 			$paths = array_merge( $paths, $op->storagePathsRead() );
 			$paths = array_merge( $paths, $op->storagePathsChanged() );
 		}
+
+		// Enlarge the cache to fit the stat entries of these files
+		$this->cheapCache->resize( max( 2 * count( $paths ), self::CACHE_CHEAP_SIZE ) );
+
 		// Load from the persistent container caches
 		$this->primeContainerCache( $paths );
 		// Get the latest stat info for all the files (having locked them)
@@ -1115,6 +1119,9 @@ abstract class FileBackendStore extends FileBackend {
 		$status->merge( $subStatus );
 		$status->success = $subStatus->success; // not done in merge()
 
+		// Shrink the stat cache back to normal size
+		$this->cheapCache->resize( self::CACHE_CHEAP_SIZE );
+
 		return $status;
 	}
 
diff --git a/includes/libs/ProcessCacheLRU.php b/includes/libs/ProcessCacheLRU.php
index f2d9f42aba..f988207a89 100644
--- a/includes/libs/ProcessCacheLRU.php
+++ b/includes/libs/ProcessCacheLRU.php
@@ -38,10 +38,7 @@ class ProcessCacheLRU {
 	 * @throws UnexpectedValueException When $maxCacheKeys is not an int or =< 0.
 	 */
 	public function __construct( $maxKeys ) {
-		if ( !is_int( $maxKeys ) || $maxKeys < 1 ) {
-			throw new UnexpectedValueException( __METHOD__ . " must be given an integer >= 1" );
-		}
-		$this->maxCacheKeys = $maxKeys;
+		$this->resize( $maxKeys );
 	}
 
 	/**
@@ -119,6 +116,25 @@ class ProcessCacheLRU {
 		}
 	}
 
+	/**
+	 * Resize the maximum number of cache entries, removing older entries as needed
+	 *
+	 * @param $maxKeys integer
+	 * @return void
+	 */
+	public function resize( $maxKeys ) {
+		if ( !is_int( $maxKeys ) || $maxKeys < 1 ) {
+			throw new UnexpectedValueException( __METHOD__ . " must be given an integer >= 1" );
+		}
+		$this->maxCacheKeys = $maxKeys;
+		while ( count( $this->cache ) > $this->maxCacheKeys ) {
+			reset( $this->cache );
+			$evictKey = key( $this->cache );
+			unset( $this->cache[$evictKey] );
+			unset( $this->cacheTimes[$evictKey] );
+		}
+	}
+
 	/**
 	 * Push an entry to the top of the cache
 	 *
-- 
2.20.1