/**
 * 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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.logging.LogCapturer;
import org.apache.hadoop.metrics2.util.MBeans;
import org.apache.hadoop.test.GenericTestUtils;

import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.Timeout;

import java.io.IOException;
import java.util.Collections;
import java.util.concurrent.TimeoutException;

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 Logger LOG =
      LoggerFactory.getLogger(TestNameNodeMetricsLogger.class);

  @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
  @SuppressWarnings("unchecked")
  public void testMetricsLoggerIsAsync() throws IOException {
    makeNameNode(true);
    org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger(NameNode.METRICS_LOG_NAME);
    assertTrue(Collections.list(logger.getAllAppenders()).get(0)
        instanceof org.apache.log4j.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.
    LogCapturer logCapturer =
        LogCapturer.captureLogs(LoggerFactory.getLogger(NameNode.METRICS_LOG_NAME));

    GenericTestUtils.waitFor(() -> logCapturer.getOutput().contains("FakeMetric"),
        1000, 60000);
    logCapturer.stopCapturing();
  }

  /**
   * 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:0");
    conf.set(DFS_NAMENODE_HTTP_ADDRESS_KEY, "0.0.0.0:0");
    conf.setInt(DFS_NAMENODE_METRICS_LOGGER_PERIOD_SECONDS_KEY,
        enableMetricsLogging ? 1 : 0);  // If enabled, log early and log often
    return new TestNameNode(conf);
  }

  /**
   * 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;
    }
  }

}