From 519e980f934a5522674ca6fee68f7e3b5398f4ec Mon Sep 17 00:00:00 2001
From: Robin McCorkell <rmccorkell@owncloud.com>
Date: Sat, 5 Sep 2015 20:02:49 +0100
Subject: Fallback to complete Memcached flush if getAllKeys fails

Newer Memcached's do not support the underlying protocol commands that
getAllKeys() is implemented with. We should fallback to clearing
everything in that case, as causing (temporary) performance problems for
other applications on the server is better than having stale cached data.
---
 lib/private/memcache/memcached.php |  5 +++++
 tests/lib/memcache/memcached.php   | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/lib/private/memcache/memcached.php b/lib/private/memcache/memcached.php
index 042fead3347..c14470ae5ae 100644
--- a/lib/private/memcache/memcached.php
+++ b/lib/private/memcache/memcached.php
@@ -67,6 +67,11 @@ class Memcached extends Cache {
 	public function clear($prefix = '') {
 		$prefix = $this->getNamespace() . $prefix;
 		$allKeys = self::$cache->getAllKeys();
+		if ($allKeys === false) {
+			// newer Memcached doesn't like getAllKeys(), flush everything
+			self::$cache->flush();
+			return true;
+		}
 		$keys = array();
 		$prefixLength = strlen($prefix);
 		foreach ($allKeys as $key) {
diff --git a/tests/lib/memcache/memcached.php b/tests/lib/memcache/memcached.php
index 51a78996dd4..3ea9216029a 100644
--- a/tests/lib/memcache/memcached.php
+++ b/tests/lib/memcache/memcached.php
@@ -26,4 +26,27 @@ class Memcached extends Cache {
 		parent::setUp();
 		$this->instance = new \OC\Memcache\Memcached($this->getUniqueID());
 	}
+
+	public function testClear() {
+		// Memcached is sometimes broken with clear(), so we don't test it thoroughly
+		$value='ipsum lorum';
+		$this->instance->set('1_value1', $value);
+		$this->instance->set('1_value2', $value);
+		$this->instance->set('2_value1', $value);
+		$this->instance->set('3_value1', $value);
+
+		$this->assertTrue($this->instance->clear('1_'));
+
+		$this->assertFalse($this->instance->hasKey('1_value1'));
+		$this->assertFalse($this->instance->hasKey('1_value2'));
+		//$this->assertTrue($this->instance->hasKey('2_value1'));
+		//$this->assertTrue($this->instance->hasKey('3_value1'));
+
+		$this->assertTrue($this->instance->clear());
+
+		$this->assertFalse($this->instance->hasKey('1_value1'));
+		$this->assertFalse($this->instance->hasKey('1_value2'));
+		$this->assertFalse($this->instance->hasKey('2_value1'));
+		$this->assertFalse($this->instance->hasKey('3_value1'));
+	}
 }
-- 
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