Making FileEngine not greedily clear files in a directory that may belong to another cache configuration. Tests added. Fixes #754

Author: markstory

cake/libs/cache/file.php

@@ -209,7 +209,11 @@ function clear($check) {
 			$now = time();
 			$threshold = $now - $this->settings['duration'];
 		}
+		$prefixLength = strlen($this->settings['prefix']);
 		while (($entry = $dir->read()) !== false) {
+			if (substr($entry, 0, $prefixLength) !== $this->settings['prefix']) {
+				continue;
+			}
 			if ($this->_setKey($entry) === false) {
 				continue;
 			}

cake/tests/cases/libs/cache/file.test.php

@@ -273,6 +273,34 @@ function testClear() {
 		Cache::config('default', array('engine' => 'File', 'path' => CACHE));
 	}
 
+/**
+ * test that clear() doesn't wipe files not in the current engine's prefix.
+ *
+ * @return void
+ */
+	function testClearWithPrefixes() {
+		$FileOne =& new FileEngine();
+		$FileOne->init(array(
+			'prefix' => 'prefix_one_',
+			'duration' => DAY
+		));
+		$FileTwo =& new FileEngine();
+		$FileTwo->init(array(
+			'prefix' => 'prefix_two_',
+			'duration' => DAY
+		));
+
+		$data1 = $data2 = $expected = 'content to cache';
+		$FileOne->write('key_one', $data1, DAY);
+		$FileTwo->write('key_two', $data2, DAY);
+
+		$this->assertEqual($FileOne->read('key_one'), $expected);
+		$this->assertEqual($FileTwo->read('key_two'), $expected);
+
+		$FileOne->clear(false);
+		$this->assertEqual($FileTwo->read('key_two'), $expected, 'secondary config was cleared by accident.');
+	}
+
 /**
  * testKeyPath method
  *