Ensure unique prefix for cache keys

Author: svivian

qa-include/Q2A/Storage/CacheDriver.php

@@ -75,6 +75,13 @@ public function isEnabled();
 	 */
 	public function getError();
 
+	/**
+	 * Get the prefix used for all cache keys.
+	 *
+	 * @return string
+	 */
+	public function getKeyPrefix();
+
 	/**
 	 * Get current statistics for the cache.
 	 *

qa-include/Q2A/Storage/CacheFactory.php

@@ -36,6 +36,7 @@ public static function getCacheDriver()
 		if (self::$cacheDriver === null) {
 			$config = array(
 				'enabled' => (int) qa_opt('caching_enabled') === 1,
+				'keyprefix' => QA_FINAL_MYSQL_DATABASE . '.' . QA_MYSQL_TABLE_PREFIX . '.',
 				'dir' => defined('QA_CACHE_DIRECTORY') ? QA_CACHE_DIRECTORY : null,
 			);
 

qa-include/Q2A/Storage/FileCacheDriver.php

@@ -26,6 +26,7 @@
 class Q2A_Storage_FileCacheDriver implements Q2A_Storage_CacheDriver
 {
 	private $enabled = false;
+	private $keyPrefix = '';
 	private $error;
 	private $cacheDir;
 
@@ -39,6 +40,10 @@ public function __construct($config)
 			return;
 		}
 
+		if (isset($config['keyprefix'])) {
+			$this->keyPrefix = $config['keyprefix'];
+		}
+
 		if (isset($config['dir'])) {
 			$this->cacheDir = realpath($config['dir']);
 
@@ -67,14 +72,15 @@ public function get($key)
 			return null;
 		}
 
-		$file = $this->getFilename($key);
+		$fullKey = $this->keyPrefix . $key;
+		$file = $this->getFilename($fullKey);
 
 		if (is_readable($file)) {
 			$lines = file($file, FILE_IGNORE_NEW_LINES);
 			$actualKey = array_shift($lines);
 
 			// double check this is the correct data
-			if ($key === $actualKey) {
+			if ($fullKey === $actualKey) {
 				$expiry = array_shift($lines);
 
 				if (is_numeric($expiry) && time() < $expiry) {
@@ -103,13 +109,14 @@ public function set($key, $data, $ttl)
 	{
 		$success = false;
 		$ttl = (int) $ttl;
+		$fullKey = $this->keyPrefix . $key;
 
 		if ($this->enabled && $ttl > 0) {
 			$encData = serialize($data);
 			$expiry = time() + ($ttl * 60);
-			$cache = $key . "\n" . $expiry . "\n" . $encData;
+			$cache = $fullKey . "\n" . $expiry . "\n" . $encData;
 
-			$file = $this->getFilename($key);
+			$file = $this->getFilename($fullKey);
 			$dir = dirname($file);
 			if (is_dir($dir) || mkdir($dir, 0777, true)) {
 				$success = @file_put_contents($file, $cache) !== false;
@@ -127,10 +134,10 @@ public function set($key, $data, $ttl)
 	 */
 	public function delete($key)
 	{
-		if ($this->enabled) {
-			$file = $this->getFilename($key);
-			$dir = dirname($key);
+		$fullKey = $this->keyPrefix . $key;
 
+		if ($this->enabled) {
+			$file = $this->getFilename($fullKey);
 			return $this->deleteFile($file);
 		}
 
@@ -208,6 +215,16 @@ public function getError()
 		return $this->error;
 	}
 
+	/**
+	 * Get the prefix used for all cache keys.
+	 *
+	 * @return string
+	 */
+	public function getKeyPrefix()
+	{
+		return $this->keyPrefix;
+	}
+
 	/**
 	 * Get current statistics for the cache.
 	 *
@@ -255,13 +272,13 @@ private function deleteFile($file)
 
 	/**
 	 * Generates filename for cache key, of the form `1/23/123abc`
-	 * @param string $key The unique cache key.
+	 * @param string $key The unique cache key (including prefix).
 	 *
 	 * @return string
 	 */
-	private function getFilename($key)
+	private function getFilename($fullKey)
 	{
-		$filename = sha1($key);
+		$filename = sha1($fullKey);
 		return $this->cacheDir . '/' . substr($filename, 0, 1) . '/' . substr($filename, 1, 2) . '/' . $filename;
 	}
 }

qa-include/Q2A/Storage/MemcachedDriver.php

@@ -27,6 +27,7 @@ class Q2A_Storage_MemcachedDriver implements Q2A_Storage_CacheDriver
 {
 	private $memcached;
 	private $enabled = false;
+	private $keyPrefix = '';
 	private $error;
 	private $flushed = false;
 
@@ -45,10 +46,14 @@ public function __construct($config)
 			return;
 		}
 
+		if (isset($config['keyprefix'])) {
+			$this->keyPrefix = $config['keyprefix'];
+		}
+
 		if (extension_loaded('memcached')) {
 			$this->memcached = new Memcached;
 			$this->memcached->addServer(self::HOST, self::PORT);
-			if ($this->memcached->set('q2a.test', 'TEST')) {
+			if ($this->memcached->set($this->keyPrefix . 'test', 'TEST')) {
 				$this->enabled = true;
 			} else {
 				$this->setMemcachedError();
@@ -70,7 +75,7 @@ public function get($key)
 			return null;
 		}
 
-		$result = $this->memcached->get($key);
+		$result = $this->memcached->get($this->keyPrefix . $key);
 
 		if ($result === false) {
 			$this->setMemcachedError();
@@ -96,7 +101,7 @@ public function set($key, $data, $ttl)
 
 		$ttl = (int) $ttl;
 		$expiry = time() + ($ttl * 60);
-		$success = $this->memcached->set($key, $data, $expiry);
+		$success = $this->memcached->set($this->keyPrefix . $key, $data, $expiry);
 
 		if (!$success) {
 			$this->setMemcachedError();
@@ -117,7 +122,7 @@ public function delete($key)
 			return false;
 		}
 
-		$success = $this->memcached->delete($key);
+		$success = $this->memcached->delete($this->keyPrefix . $key);
 
 		if (!$success) {
 			$this->setMemcachedError();
@@ -169,6 +174,16 @@ public function getError()
 		return $this->error;
 	}
 
+	/**
+	 * Get the prefix used for all cache keys.
+	 *
+	 * @return string
+	 */
+	public function getKeyPrefix()
+	{
+		return $this->keyPrefix;
+	}
+
 	/**
 	 * Get current statistics for the cache.
 	 *

qa-include/pages/question.php

@@ -42,7 +42,7 @@
 // Get information about this question
 
 $cacheDriver = Q2A_Storage_CacheFactory::getCacheDriver();
-$cacheKey = "q2a.question:$questionid";
+$cacheKey = "question:$questionid";
 $useCache = $userid === null && $cacheDriver->isEnabled() && !qa_is_http_post() && empty($pagestate);
 $saveCache = false;
 

qa-include/qa-db.php

@@ -524,7 +524,7 @@ function qa_db_single_select($selectspec)
 	// check for cached results
 	if (isset($selectspec['caching'])) {
 		$cacheDriver = Q2A_Storage_CacheFactory::getCacheDriver();
-		$cacheKey = 'q2a.query:' . $selectspec['caching']['key'];
+		$cacheKey = 'query:' . $selectspec['caching']['key'];
 
 		if ($cacheDriver->isEnabled()) {
 			$queryData = $cacheDriver->get($cacheKey);