From c5a0fa5bed4c5aafdf0721c1d05978576107bd85 Mon Sep 17 00:00:00 2001
From: Brian Wolff <bawolff+wn@gmail.com>
Date: Wed, 15 Mar 2017 22:51:13 +0000
Subject: [PATCH] objectcache: Never use CACHE_NONE for CACHE_ANYTHING

If $wgMainCacheType = CACHE_ACCEL, but there is no APC, then its
possible that CACHE_ANYTHING will default to CACHE_NONE because
that's what CACHE_ACCEL would do.

Possibly also T147161

Bug: T160519
Change-Id: I9ac2d071437b35a0f9cd3678e2279628f7b1931e
---
 includes/objectcache/ObjectCache.php          |  8 +-
 .../includes/objectcache/ObjectCacheTest.php  | 82 +++++++++++++++++++
 2 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 tests/phpunit/includes/objectcache/ObjectCacheTest.php

diff --git a/includes/objectcache/ObjectCache.php b/includes/objectcache/ObjectCache.php
index cf9033b88f..3370e5b9d1 100644
--- a/includes/objectcache/ObjectCache.php
+++ b/includes/objectcache/ObjectCache.php
@@ -246,8 +246,14 @@ class ObjectCache {
 		global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 		$candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
 		foreach ( $candidates as $candidate ) {
+			$cache = false;
 			if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
-				return self::getInstance( $candidate );
+				$cache = self::getInstance( $candidate );
+				// CACHE_ACCEL might default to nothing if no APCu
+				// See includes/ServiceWiring.php
+				if ( !( $cache instanceof EmptyBagOStuff ) ) {
+					return $cache;
+				}
 			}
 		}
 
diff --git a/tests/phpunit/includes/objectcache/ObjectCacheTest.php b/tests/phpunit/includes/objectcache/ObjectCacheTest.php
new file mode 100644
index 0000000000..d132183eac
--- /dev/null
+++ b/tests/phpunit/includes/objectcache/ObjectCacheTest.php
@@ -0,0 +1,82 @@
+<?php
+
+class ObjectCacheTest extends MediaWikiTestCase {
+
+	protected function setUp() {
+		// Parent calls ObjectCache::clear() among other things
+		parent::setUp();
+
+		$this->setCacheConfig();
+		$this->setMwGlobals( [
+			'wgMainCacheType' => CACHE_NONE,
+			'wgMessageCacheType' => CACHE_NONE,
+			'wgParserCacheType' => CACHE_NONE,
+		] );
+	}
+
+	private function setCacheConfig( $arr = [] ) {
+		$defaults = [
+			CACHE_NONE => [ 'class' => 'EmptyBagOStuff' ],
+			CACHE_DB => [ 'class' => 'SqlBagOStuff' ],
+			CACHE_ANYTHING => [ 'factory' => 'ObjectCache::newAnything' ],
+			// Mock ACCEL with 'hash' as being installed.
+			// This makes tests deterministic regardless of APC.
+			CACHE_ACCEL => [ 'class' => 'HashBagOStuff' ],
+			'hash' => [ 'class' => 'HashBagOStuff' ],
+		];
+		$this->setMwGlobals( 'wgObjectCaches', $arr + $defaults );
+	}
+
+	/** @covers ObjectCache::newAnything */
+	public function testNewAnythingNothing() {
+		$this->assertInstanceOf(
+			SqlBagOStuff::class,
+			ObjectCache::newAnything( [] ),
+			'No available types. Fallback to DB'
+		);
+	}
+
+	/** @covers ObjectCache::newAnything */
+	public function testNewAnythingHash() {
+		$this->setMwGlobals( [
+			'wgMainCacheType' => 'hash'
+		] );
+
+		$this->assertInstanceOf(
+			HashBagOStuff::class,
+			ObjectCache::newAnything( [] ),
+			'Use an available type (hash)'
+		);
+	}
+
+	/** @covers ObjectCache::newAnything */
+	public function testNewAnythingAccel() {
+		$this->setMwGlobals( [
+			'wgMainCacheType' => CACHE_ACCEL
+		] );
+
+		$this->assertInstanceOf(
+			HashBagOStuff::class,
+			ObjectCache::newAnything( [] ),
+			'Use an available type (CACHE_ACCEL)'
+		);
+	}
+
+	/** @covers ObjectCache::newAnything */
+	public function txestNewAnythingNoAccel() {
+		$this->setMwGlobals( [
+			'wgMainCacheType' => CACHE_ACCEL
+		] );
+
+		$this->setCacheConfig( [
+			// Mock APC not being installed (T160519, T147161)
+			CACHE_ACCEL => [ 'class' => 'EmptyBagOStuff' ]
+		] );
+
+		$this->assertInstanceOf(
+			SqlBagOStuff::class,
+			ObjectCache::newAnything( [] ),
+			'Fallback to DB if available types fall back to Empty'
+		);
+	}
+}
-- 
2.20.1