kotman12 commented on code in PR #4577: URL: https://github.com/apache/solr/pull/4577#discussion_r3844580912
########## solr/solrj-zookeeper/src/java/org/apache/solr/common/cloud/SolrZookeeperEvent.java: ########## @@ -0,0 +1,62 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.solr.common.cloud; + +import java.util.concurrent.atomic.AtomicBoolean; +import org.apache.curator.framework.CuratorFramework; +import org.apache.curator.framework.state.ConnectionState; +import org.apache.curator.framework.state.ConnectionStateListener; + +public enum SolrZookeeperEvent { + // Only triggered after resume from expiration + EXPIRED_RECONNECTION { + @Override + public ConnectionStateListener of(EventAction action) { + return new ConnectionStateListener() { + private final AtomicBoolean isExpired = new AtomicBoolean(false); + + @Override + public void stateChanged(CuratorFramework client, ConnectionState newState) { + if (newState == ConnectionState.LOST) { + isExpired.set(true); + } else if (newState == ConnectionState.RECONNECTED) { + if (isExpired.compareAndSet(true, false)) { + action.trigger(); + } + } Review Comment: Curator does have useful abstractions, my experience with the `ModeledFramework` has been positive on Solr-adjacent infrastructure we have (also using curator's clever async package). However, there is nothing in curator that specifically captures reconnected _after_ session expiry (or `LOST`). You have to write it yourself. The fact that it doesn't exist by this point of zk/curator maturity kind of hints at the fact that we may be using zk in an unconventional way as we've been agreeing about, i.e. Solr relies on this specific state transition to trigger leader re-election and various clean-up routines. Thus, I don't know how easy it will be to unwind that from Solr. I worry that it may not be worth it unless we get some tangible benefit because the risks of getting it wrong are big. That being said, if someone wants to analyze what it would take to change our Zk Controller and Election context logic to be "reconnect-type-agnostic" I'd at least take a look 😄 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
