Github user revans2 commented on a diff in the pull request:
https://github.com/apache/storm/pull/2433#discussion_r173210647
--- Diff:
storm-client/src/jvm/org/apache/storm/assignments/InMemoryAssignmentBackend.java
---
@@ -0,0 +1,152 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.storm.assignments;
+
+import java.util.ArrayList;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.storm.cluster.ClusterUtils;
+import org.apache.storm.generated.Assignment;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * An assignment backend which will keep all assignments and id-info in
memory. Only used if no backend is specified internal.
+ */
+public class InMemoryAssignmentBackend implements ILocalAssignmentsBackend
{
+ private static final Logger LOG =
LoggerFactory.getLogger(InMemoryAssignmentBackend.class);
+
+ protected Map<String, Assignment> idToAssignment;
+ protected Map<String, String> idToName;
+ protected Map<String, String> nameToId;
+ private volatile boolean isSynchronized = false;
+
+ public InMemoryAssignmentBackend() {}
+
+ @Override
+ public boolean isSynchronized() {
+ return this.isSynchronized;
+ }
+
+ @Override
+ public void setSynchronized() {
+ this.isSynchronized = true;
+ }
+
+ @Override
+ public void prepare(Map conf) {
+ // do nothing for conf now
+ this.idToAssignment = new ConcurrentHashMap<>();
+ this.idToName = new ConcurrentHashMap<>();
+ this.nameToId = new ConcurrentHashMap<>();
+ }
+
+ @Override
+ public void keepOrUpdateAssignment(String stormId, Assignment
assignment) {
+ this.idToAssignment.put(stormId, assignment);
+ }
+
+ @Override
+ public Assignment getAssignment(String stormId) {
+ return this.idToAssignment.get(stormId);
+ }
+
+ @Override
+ public void removeAssignment(String stormId) {
+ this.idToAssignment.remove(stormId);
+ }
+
+ @Override
+ public List<String> assignments() {
+ if(idToAssignment == null) {
+ return new ArrayList<>();
+ }
+ List<String> ret = new ArrayList<>();
+ ret.addAll(this.idToAssignment.keySet());
+ return ret;
+ }
+
+ @Override
+ public Map<String, Assignment> assignmentsInfo() {
+ Map<String, Assignment> ret = new HashMap<>();
+ ret.putAll(this.idToAssignment);
+
+ return ret;
+ }
+
+ @Override
+ public void syncRemoteAssignments(Map<String, byte[]> remote) {
+ Map<String, Assignment> tmp = new ConcurrentHashMap<>();
--- End diff --
The issue I am seeing is that all of this appears to not be thread safe,
even with the ConcurrentHashMap.
`idToAssignment`, `idToName`, `nameToId` all are set and read in different
methods that all appear to be able to be called from different threads. As
such there is the real possibility that they state will not be consistent. If
we don't care too much about that it might be okay, but if we are going with an
eventual consistency like route for this we should at least document it.
---
