Implemented group delete for cache keys in ApcEngine

lib/Cake/Cache/Cache.php

@@ -453,6 +453,22 @@ class Cache {
 		return $success;
 	}
 
+/**
+ * Delete all keys from the cache belonging to the same group.
+ *
+ * @param string $group name of the group to be cleared
+ * @param string $config name of the configuration to use. Defaults to 'default'
+ * @return boolean True if the cache group was successfully cleared, false otherwise
+ */
+	public static function clearGroup($group, $config = 'default') {
+		if (!self::isInitialized($config)) {
+			return false;
+		}
+		$success = self::$_engines[$config]->clearGroup($group);
+		self::set(null, $config);
+		return $success;
+	}
+
 /**
  * Check if Cache has initialized a working config for the given name.
  *

lib/Cake/Cache/CacheEngine.php

@@ -120,6 +120,16 @@ abstract class CacheEngine {
  */
 	abstract public function clear($check);
 
+/**
+ * Clears all values belonging to a group. Is upt to the implementing engine
+ * to decide whether actually deete the keys or just simulate it to acheive
+ * the same result.
+ *
+ * @param string $groups name of the group to be cleared
+ * @return void
+ **/
+	abstract public function clearGroup($group);
+
 /**
  * Does whatever initialization for each group is required
  * and returns the `group value` for each of them, this is

lib/Cake/Cache/Engine/ApcEngine.php

@@ -153,4 +153,16 @@ class ApcEngine extends CacheEngine {
 		}
 		return $result;
 	}
+
+/**
+ * Increments the group value to simulate deletion of all keys under a group
+ * old values will remain in sotrage until they expire.
+ *
+ * @return boolean success
+ **/
+	public function clearGroup($group) {
+		apc_inc($group, 1, $success);
+		return $success;
+	}
+
 }

lib/Cake/Test/Case/Cache/Engine/ApcEngineTest.php

@@ -236,4 +236,21 @@ class ApcEngineTest extends CakeTestCase {
 
 		$this->assertFalse(Cache::read('test_groups', 'apc_groups'));
 	}
+
+/**
+ * Test clearing a cache group
+ *
+ * @return void
+ **/
+	public function testGroupClear() {
+		Cache::config('apc_groups', array('engine' => 'Apc', 'duration' => 0, 'groups' => array('group_a', 'group_b')));
+
+		$this->assertTrue(Cache::write('test_groups', 'value', 'apc_groups'));
+		$this->assertTrue(Cache::clearGroup('group_a', 'apc_groups'));
+		$this->assertFalse(Cache::read('test_groups', 'apc_groups'));
+
+		$this->assertTrue(Cache::write('test_groups', 'value2', 'apc_groups'));
+		$this->assertTrue(Cache::clearGroup('group_b', 'apc_groups'));
+		$this->assertFalse(Cache::read('test_groups', 'apc_groups'));
+	}
 }