Add registration interface contract definition

This clarifies the contractual details of Registration interface.
Notably it clarifies that the close() method is non-blocking.

Change-Id: Ie898c4ae2baf40c6d40e83a583f5046a9c1e0d84
Signed-off-by: Robert Varga <rovarga@cisco.com>

diff --git a/concepts/src/main/java/org/opendaylight/yangtools/concepts/Registration.java b/concepts/src/main/java/org/opendaylight/yangtools/concepts/Registration.java
index 369ff5366401408dc0deaba35fc22315f1c2cee2..051200c18d09140e0d1b7c2a95b7c1e7225348e0 100644 (file)
--- a/concepts/src/main/java/org/opendaylight/yangtools/concepts/Registration.java
+++ b/concepts/src/main/java/org/opendaylight/yangtools/concepts/Registration.java
@@ -1,20 +1,34 @@
-/*\r
- * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.\r
- *\r
- * This program and the accompanying materials are made available under the\r
- * terms of the Eclipse Public License v1.0 which accompanies this distribution,\r
- * and is available at http://www.eclipse.org/legal/epl-v10.html\r
- */\r
-package org.opendaylight.yangtools.concepts;\r
-\r
-public interface Registration<T> extends AutoCloseable {\r
-\r
-    T getInstance();\r
-\r
-    /**\r
-     * Unregisters object\r
-     * \r
-     */\r
-    @Override\r
-    public void close() throws Exception;\r
-}\r
+/*
+ * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.concepts;
+
+/**
+ * Class representing a registration of an object. Such a registration is
+ * a proper resource and should be cleaned up when no longer required, so
+ * references to the object can be removed. This mechanism lies above the
+ * usual Java reference mechanism, as the entity where the object is
+ * registered may reside outside of the Java Virtual Machine.
+ */
+public interface Registration<T> extends AutoCloseable {
+    /**
+     * Return the object instance.
+     *
+     * @return Registered object.
+     */
+    T getInstance();
+
+    /**
+     * Unregisters the object. This operation is required not to invoke
+     * blocking operations. Implementations which require interaction
+     * with outside world must provide guarantees that any work is done
+     * behind the scenes and the unregistration process looks as if it
+     * has already succeeded once this method returns.
+     */
+    @Override
+    void close() throws Exception;
+}