| /* |
| * 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.samza.coordinator; |
| |
| import org.apache.samza.annotation.InterfaceStability; |
| |
| /** |
| * Coordination Primitive to maintain the list of processors in the quorum |
| * |
| * Guarantees: |
| * 1. operations are linearizable |
| * 2. registration persistence in the absence of connection errors |
| * |
| * Non-guarantees: |
| * 1. thread safe |
| * 2. concurrent access of the list of processors in the quorum |
| * 3. persistence of registration across connection errors |
| * 4. processorId as indicator of registration order |
| * |
| * Implementor responsibilities: |
| * 1. registerProcessor returns a unique processorId |
| * 2. getNumberOfProcessors by a processor should reflect at least its own registration status |
| * 3. unregisterProcessor for a null or unregistered processorId is a no-op |
| */ |
| @InterfaceStability.Evolving |
| public interface ClusterMembership { |
| /** |
| * add processor to the list of processors in the quorum |
| * @return unique id of the processor registration |
| */ |
| String registerProcessor(); |
| |
| /** |
| * @return number of processors in the list |
| */ |
| int getNumberOfProcessors(); |
| |
| /** |
| * remove processor from the list of processors in the quorum |
| * @param processorId to be removed from the list |
| */ |
| void unregisterProcessor(String processorId); |
| } |