gemmellr commented on a change in pull request #3851: URL: https://github.com/apache/activemq-artemis/pull/3851#discussion_r787723700
########## File path: artemis-commons/src/main/java/org/apache/activemq/artemis/utils/LazyHashProcessor.java ########## @@ -0,0 +1,63 @@ +/** + * 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.activemq.artemis.utils; + +public abstract class LazyHashProcessor implements HashProcessor { + private HashProcessor hashProcessor; + private RuntimeException supplierException; + + public HashProcessor getHashProcessor() { + if (supplierException != null) { + throw supplierException; + } + + if (hashProcessor == null) { + synchronized (this) { + if (supplierException != null) { + throw supplierException; + } + + if (hashProcessor == null) { + try { + hashProcessor = createHashProcessor(); + } catch (RuntimeException e) { + supplierException = e; + throw supplierException; + } catch (Exception e) { + supplierException = new RuntimeException(e); + throw supplierException; + } + } + } + } Review comment: This will still be non-thread-safe because the hashProcessor field isnt volatile (prior to the synchronized addition the other one would have needed to be also). https://en.wikipedia.org/wiki/Double-checked_locking#Usage_in_Java -- 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]
