1 files changed, 132 insertions, 10 deletions

diff --git a/kohana/libraries/drivers/Cache/Memcache.php b/kohana/libraries/drivers/Cache/Memcache.php
index ef5b8440..f443b997 100644
--- a/kohana/libraries/drivers/Cache/Memcache.php
+++ b/kohana/libraries/drivers/Cache/Memcache.php
@@ -11,17 +11,28 @@
  */
 class Cache_Memcache_Driver implements Cache_Driver {
 
+	const TAGS_KEY = 'memcache_tags_array';
+
 	// Cache backend object and flags
 	protected $backend;
 	protected $flags;
 
+	// The persistent lifetime value for expirations of 0
+	protected $persistent_lifetime;
+
+	// Tags array
+	protected $tags;
+
+	// Have the tags been changed?
+	protected $tags_changed = FALSE;
+
 	public function __construct()
 	{
 		if ( ! extension_loaded('memcache'))
 			throw new Kohana_Exception('cache.extension_not_loaded', 'memcache');
 
 		$this->backend = new Memcache;
-		$this->flags = Kohana::config('cache_memcache.compression') ? MEMCACHE_COMPRESSED : 0;
+		$this->flags = Kohana::config('cache_memcache.compression') ? MEMCACHE_COMPRESSED : FALSE;
 
 		$servers = Kohana::config('cache_memcache.servers');
 
@@ -34,11 +45,44 @@ class Cache_Memcache_Driver implements Cache_Driver {
 			$this->backend->addServer($server['host'], $server['port'], (bool) $server['persistent'])
 				or Kohana::log('error', 'Cache: Connection failed: '.$server['host']);
 		}
+
+		// Set "persistent lifetime" value to one year
+		$this->persistent_lifetime = strtotime('now +1 year');
+
+		// Load tags
+		$this->tags = $this->backend->get(self::TAGS_KEY);
+
+		if ( ! is_array($this->tags))
+		{
+			// Create a new tags array
+			$this->tags = array();
+
+			// Tags have been created
+			$this->tags_changed = TRUE;
+		}
+	}
+
+	public function __destruct()
+	{
+		if ($this->tags_changed === TRUE)
+		{
+			// Save the tags
+			$this->backend->set(self::TAGS_KEY, $this->tags, $this->flags, $this->persistent_lifetime);
+		}
 	}
 
 	public function find($tag)
 	{
-		return FALSE;
+		if (isset($this->tags[$tag]) AND $results = $this->backend->get($this->tags[$tag]))
+		{
+				// Return all the found caches
+				return $results;
+		}
+		else
+		{
+			// No matching tags
+			return array();
+		}
 	}
 
 	public function get($id)
@@ -46,32 +90,110 @@ class Cache_Memcache_Driver implements Cache_Driver {
 		return (($return = $this->backend->get($id)) === FALSE) ? NULL : $return;
 	}
 
-	public function set($id, $data, $tags, $lifetime)
+	public function set($id, $data, array $tags = NULL, $lifetime)
 	{
-		count($tags) and Kohana::log('error', 'Cache: Tags are unsupported by the memcache driver');
+		if ( ! empty($tags))
+		{
+			// Tags will be changed
+			$this->tags_changed = TRUE;
+
+			foreach ($tags as $tag)
+			{
+				// Add the id to each tag
+				$this->tags[$tag][$id] = $id;
+			}
+		}
 
-		// Memcache driver expects unix timestamp
-		if ($lifetime !== 0)
+		if ($lifetime === 0)
 		{
+			// Using an expiration of zero is unreliable, as memcache may delete
+			// it without warning. @see http://php.net/memcache_set
+			$lifetime = $this->persistent_lifetime;
+		}
+		else
+		{
+			// Memcache driver expects unix timestamp
 			$lifetime += time();
 		}
 
+		// Set a new value
 		return $this->backend->set($id, $data, $this->flags, $lifetime);
 	}
 
 	public function delete($id, $tag = FALSE)
 	{
+		// Tags will be changed
+		$this->tags_changed = TRUE;
+
 		if ($id === TRUE)
-			return $this->backend->flush();
+		{
+			if ($status = $this->backend->flush())
+			{
+				// Remove all tags, all items have been deleted
+				$this->tags = array();
 
-		if ($tag == FALSE)
-			return $this->backend->delete($id);
+				// We must sleep after flushing, or overwriting will not work!
+				// @see http://php.net/manual/en/function.memcache-flush.php#81420
+				sleep(1);
+			}
 
-		return TRUE;
+			return $status;
+		}
+		elseif ($tag === TRUE)
+		{
+			if (isset($this->tags[$id]))
+			{
+				foreach ($this->tags[$id] as $_id)
+				{
+					// Delete each id in the tag
+					$this->backend->delete($_id);
+				}
+
+				// Delete the tag
+				unset($this->tags[$id]);
+			}
+
+			return TRUE;
+		}
+		else
+		{
+			foreach ($this->tags as $tag => $_ids)
+			{
+				if (isset($this->tags[$tag][$id]))
+				{
+					// Remove the id from the tags
+					unset($this->tags[$tag][$id]);
+				}
+			}
+
+			return $this->backend->delete($id);
+		}
 	}
 
 	public function delete_expired()
 	{
+		// Tags will be changed
+		$this->tags_changed = TRUE;
+
+		foreach ($this->tags as $tag => $_ids)
+		{
+			foreach ($_ids as $id)
+			{
+				if ( ! $this->backend->get($id))
+				{
+					// This id has disappeared, delete it from the tags
+					unset($this->tags[$tag][$id]);
+				}
+			}
+
+			if (empty($this->tags[$tag]))
+			{
+				// The tag no longer has any valid ids
+				unset($this->tags[$tag]);
+			}
+		}
+
+		// Memcache handles garbage collection internally
 		return TRUE;
 	}