| /* |
| * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.test.lib; |
| |
| import java.util.Collection; |
| import java.util.Comparator; |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentLinkedQueue; |
| import java.util.concurrent.atomic.AtomicInteger; |
| import java.util.stream.Collectors; |
| |
| /** |
| * A logger designed specifically to allow collecting ordered log messages |
| * in a multi-threaded environment without involving any kind of locking. |
| * <p> |
| * It is particularly useful in situations when one needs to assert various |
| * details about the tested thread state or the locks it hold while also wanting |
| * to produce diagnostic log messages. |
| * <p> |
| * The logger does not provide any guarantees about the completness of the |
| * logs written from different threads - it is up to the caller to make sure |
| * {@code toString()} method is called only when all the activity has ceased |
| * and the per-thread logs contain all the necessary data. |
| * |
| * @author Jaroslav Bachorik |
| **/ |
| public class LockFreeLogger { |
| private final AtomicInteger logCntr = new AtomicInteger(0); |
| private final Collection<Map<Integer, String>> allRecords = new ConcurrentLinkedQueue<>(); |
| private final ThreadLocal<Map<Integer, String>> records = ThreadLocal.withInitial(ConcurrentHashMap::new); |
| |
| public LockFreeLogger() { |
| allRecords.add(records.get()); |
| } |
| |
| /** |
| * Log a message |
| * @param format Message format |
| * @param params Message parameters |
| */ |
| public void log(String format, Object ... params) { |
| int id = logCntr.getAndIncrement(); |
| records.get().put(id, String.format(format, params)); |
| } |
| |
| /** |
| * Will generate an aggregated log of chronologically ordered messages. |
| * <p> |
| * Make sure that you call this method only when all the related threads |
| * have finished; otherwise you might get incomplete data. |
| * |
| * @return An aggregated log of chronologically ordered messages |
| */ |
| @Override |
| public String toString() { |
| return allRecords.stream() |
| .flatMap(m -> m.entrySet().stream()) |
| .sorted(Comparator.comparing(Map.Entry::getKey)) |
| .map(Map.Entry::getValue) |
| .collect(Collectors.joining()); |
| } |
| } |