pkuwm commented on a change in pull request #644: Add new interface
IZkStateListener to provide session aware handleNewSession for ZkHelixManager
URL: https://github.com/apache/helix/pull/644#discussion_r355716130
##########
File path:
helix-core/src/main/java/org/apache/helix/manager/zk/client/HelixZkClient.java
##########
@@ -148,6 +187,66 @@ void asyncSetData(final String path, Object datat, final
int version,
PathBasedZkSerializer getZkSerializer();
+ /**
+ * A class that wraps a default implementation of
+ * {@link org.apache.helix.manager.zk.zookeeper.IZkStateListener}, which
means this listener
+ * runs the methods of {@link
org.apache.helix.manager.zk.zookeeper.IZkStateListener}.
+ * This is for backward compatibility and to avoid breaking the original
implementation of
+ * {@link org.I0Itec.zkclient.IZkStateListener}.
+ */
+ class I0ItecIZkStateListenerHelixImpl implements
org.I0Itec.zkclient.IZkStateListener {
+ private IZkStateListener listener;
+
+ I0ItecIZkStateListenerHelixImpl(IZkStateListener listener) {
+ this.listener = listener;
+ }
+
+ @Override
+ public void handleStateChanged(KeeperState keeperState) throws Exception {
+ listener.handleStateChanged(keeperState);
+ }
+
+ @Override
+ public void handleNewSession() throws Exception {
+ /*
+ * org.apache.helix.manager.zk.zookeeper.IZkStateListener does not have
handleNewSession(),
+ * so null is passed into handleNewSession(sessionId).
+ */
+ listener.handleNewSession(null);
Review comment:
I considered this. My thought was, if we use SESSION_NOT_SET=null,
1. we are supposed to use it anywhere related to the session id.
2. Since it is a String type, we are supposed to use like
`sessionId.equals(SESSION_NOT_SET)`, which could not check sessionId nullable.
3. And `sessionId != SESSION_NOT_SET` just doesn't look that good to me, for
a String type..
So I decided to use null and add the comments.
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