Java tutorial
/** * 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.hadoop.hdfs.server.namenode; import com.google.common.base.Supplier; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.commons.logging.impl.Log4JLogger; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hdfs.HdfsConfiguration; import org.apache.hadoop.metrics2.util.MBeans; import org.apache.hadoop.test.GenericTestUtils; import org.apache.log4j.Appender; import org.apache.log4j.AppenderSkeleton; import org.apache.log4j.AsyncAppender; import org.apache.log4j.spi.LoggingEvent; import org.junit.Rule; import org.junit.Test; import org.junit.rules.Timeout; import java.io.IOException; import java.util.Collections; import java.util.List; import java.util.Random; import java.util.concurrent.TimeoutException; import java.util.regex.Pattern; import static org.apache.hadoop.hdfs.DFSConfigKeys.*; import static org.junit.Assert.*; import static org.mockito.Mockito.mock; /** * Test periodic logging of NameNode metrics. */ public class TestNameNodeMetricsLogger { static final Log LOG = LogFactory.getLog(TestNameNodeMetricsLogger.class); static final Random random = new Random(System.currentTimeMillis()); @Rule public Timeout timeout = new Timeout(300000); @Test public void testMetricsLoggerOnByDefault() throws IOException { NameNode nn = makeNameNode(true); assertNotNull(nn.metricsLoggerTimer); } @Test public void testDisableMetricsLogger() throws IOException { NameNode nn = makeNameNode(false); assertNull(nn.metricsLoggerTimer); } @Test public void testMetricsLoggerIsAsync() throws IOException { makeNameNode(true); org.apache.log4j.Logger logger = ((Log4JLogger) NameNode.MetricsLog).getLogger(); @SuppressWarnings("unchecked") List<Appender> appenders = Collections.list(logger.getAllAppenders()); assertTrue(appenders.get(0) instanceof AsyncAppender); } /** * Publish a fake metric under the "Hadoop:" domain and ensure it is * logged by the metrics logger. */ @Test public void testMetricsLogOutput() throws IOException, InterruptedException, TimeoutException { TestFakeMetric metricsProvider = new TestFakeMetric(); MBeans.register(this.getClass().getSimpleName(), "DummyMetrics", metricsProvider); makeNameNode(true); // Log metrics early and often. final PatternMatchingAppender appender = new PatternMatchingAppender("^.*FakeMetric42.*$"); addAppender(NameNode.MetricsLog, appender); // Ensure that the supplied pattern was matched. GenericTestUtils.waitFor(new Supplier<Boolean>() { @Override public Boolean get() { return appender.isMatched(); } }, 1000, 60000); } /** * Create a NameNode object that listens on a randomly chosen port * number. * * @param enableMetricsLogging true if periodic metrics logging is to be * enabled, false otherwise. */ private NameNode makeNameNode(boolean enableMetricsLogging) throws IOException { Configuration conf = new HdfsConfiguration(); conf.set(FS_DEFAULT_NAME_KEY, "hdfs://localhost:" + getRandomPort()); conf.set(DFS_NAMENODE_HTTP_ADDRESS_KEY, "0.0.0.0:" + getRandomPort()); conf.setInt(DFS_NAMENODE_METRICS_LOGGER_PERIOD_SECONDS_KEY, enableMetricsLogging ? 1 : 0); // If enabled, log early and log often return new TestNameNode(conf); } private int getRandomPort() { return 10000 + random.nextInt(50000); } private void addAppender(Log log, Appender appender) { org.apache.log4j.Logger logger = ((Log4JLogger) log).getLogger(); @SuppressWarnings("unchecked") List<Appender> appenders = Collections.list(logger.getAllAppenders()); ((AsyncAppender) appenders.get(0)).addAppender(appender); } /** * A NameNode that stubs out the NameSystem for testing. */ private static class TestNameNode extends NameNode { @Override protected void loadNamesystem(Configuration conf) throws IOException { this.namesystem = mock(FSNamesystem.class); } public TestNameNode(Configuration conf) throws IOException { super(conf); } } public interface TestFakeMetricMXBean { int getFakeMetric42(); } /** * MBean for testing */ public static class TestFakeMetric implements TestFakeMetricMXBean { @Override public int getFakeMetric42() { return 0; } } /** * An appender that matches logged messages against the given * regular expression. */ public static class PatternMatchingAppender extends AppenderSkeleton { private final Pattern pattern; private volatile boolean matched; public PatternMatchingAppender(String pattern) { this.pattern = Pattern.compile(pattern); this.matched = false; } public boolean isMatched() { return matched; } @Override protected void append(LoggingEvent event) { if (pattern.matcher(event.getMessage().toString()).matches()) { matched = true; } } @Override public void close() { } @Override public boolean requiresLayout() { return false; } } }