/**
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.metrics;

import java.io.IOException;
import java.util.Random;

import junit.framework.TestCase;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.server.namenode.BlockManager;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.HdfsConfiguration;

/**
 * Test for metrics published by the Namenode
 */
public class TestNameNodeMetrics extends TestCase {
  private static final Configuration CONF = new HdfsConfiguration();
  private static final int DFS_REPLICATION_INTERVAL = 1;
  private static final Path TEST_ROOT_DIR_PATH = 
    new Path(System.getProperty("test.build.data", "build/test/data"));
  
  // Number of datanodes in the cluster
  private static final int DATANODE_COUNT = 3; 
  static {
    CONF.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 100);
    CONF.setInt(DFSConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY, 1);
    CONF.setLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY,
        DFS_REPLICATION_INTERVAL);
    CONF.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, 
        DFS_REPLICATION_INTERVAL);
  }
  
  private MiniDFSCluster cluster;
  private FSNamesystemMetrics metrics;
  private DistributedFileSystem fs;
  private Random rand = new Random();
  private FSNamesystem namesystem;

  private static Path getTestPath(String fileName) {
    return new Path(TEST_ROOT_DIR_PATH, fileName);
  }
  
  @Override
  protected void setUp() throws Exception {
    cluster = new MiniDFSCluster(CONF, DATANODE_COUNT, true, null);
    cluster.waitActive();
    namesystem = cluster.getNamesystem();
    fs = (DistributedFileSystem) cluster.getFileSystem();
    metrics = namesystem.getFSNamesystemMetrics();
  }
  
  @Override
  protected void tearDown() throws Exception {
    cluster.shutdown();
  }
  
  /** create a file with a length of <code>fileLen</code> */
  private void createFile(Path file, long fileLen, short replicas) throws IOException {
    DFSTestUtil.createFile(fs, file, fileLen, replicas, rand.nextLong());
  }

  private void updateMetrics() throws Exception {
    // Wait for metrics update (corresponds to dfs.replication.interval
    // for some block related metrics to get updated)
    Thread.sleep(1000);
    metrics.doUpdates(null);
  }

  /** Test metrics associated with addition of a file */
  public void testFileAdd() throws Exception {
    // Add files with 100 blocks
    final Path file = getTestPath("testFileAdd");
    createFile(file, 3200, (short)3);
    final int blockCount = 32;
    int blockCapacity = namesystem.getBlockCapacity();
    updateMetrics();
    assertEquals(blockCapacity, metrics.blockCapacity.get());

    // Blocks are stored in a hashmap. Compute its capacity, which
    // doubles every time the number of entries reach the threshold.
    int threshold = (int)(blockCapacity * BlockManager.DEFAULT_MAP_LOAD_FACTOR);
    while (threshold < blockCount) {
      blockCapacity <<= 1;
    }
    updateMetrics();
    int filesTotal = file.depth() + 1; // Add 1 for root
    assertEquals(filesTotal, metrics.filesTotal.get());
    assertEquals(blockCount, metrics.blocksTotal.get());
    assertEquals(blockCapacity, metrics.blockCapacity.get());
    fs.delete(file, true);
    filesTotal--; // reduce the filecount for deleted file
    
    // Wait for more than DATANODE_COUNT replication intervals to ensure all 
    // the blocks pending deletion are sent for deletion to the datanodes.
    Thread.sleep(DFS_REPLICATION_INTERVAL * (DATANODE_COUNT + 1) * 1000);
    updateMetrics();
    assertEquals(filesTotal, metrics.filesTotal.get());
    assertEquals(0, metrics.blocksTotal.get());
    assertEquals(0, metrics.pendingDeletionBlocks.get());
  }
  
  /** Corrupt a block and ensure metrics reflects it */
  public void testCorruptBlock() throws Exception {
    // Create a file with single block with two replicas
    final Path file = getTestPath("testCorruptBlock");
    createFile(file, 100, (short)2);
    
    // Corrupt first replica of the block
    LocatedBlock block = NameNodeAdapter.getBlockLocations(
        cluster.getNameNode(), file.toString(), 0, 1).get(0);
    namesystem.markBlockAsCorrupt(block.getBlock(), block.getLocations()[0]);
    updateMetrics();
    assertEquals(1, metrics.corruptBlocks.get());
    assertEquals(1, metrics.pendingReplicationBlocks.get());
    assertEquals(1, metrics.scheduledReplicationBlocks.get());
    fs.delete(file, true);
    updateMetrics();
    assertEquals(0, metrics.corruptBlocks.get());
    assertEquals(0, metrics.pendingReplicationBlocks.get());
    assertEquals(0, metrics.scheduledReplicationBlocks.get());
  }
  
  /** Create excess blocks by reducing the replication factor for
   * for a file and ensure metrics reflects it
   */
  public void testExcessBlocks() throws Exception {
    Path file = getTestPath("testExcessBlocks");
    createFile(file, 100, (short)2);
    int totalBlocks = 1;
    namesystem.setReplication(file.toString(), (short)1);
    updateMetrics();
    assertEquals(totalBlocks, metrics.excessBlocks.get());
    fs.delete(file, true);
  }
  
  /** Test to ensure metrics reflects missing blocks */
  public void testMissingBlock() throws Exception {
    // Create a file with single block with two replicas
    Path file = getTestPath("testMissingBlocks");
    createFile(file, 100, (short)1);
    
    // Corrupt the only replica of the block to result in a missing block
    LocatedBlock block = NameNodeAdapter.getBlockLocations(
        cluster.getNameNode(), file.toString(), 0, 1).get(0);
    namesystem.markBlockAsCorrupt(block.getBlock(), block.getLocations()[0]);
    updateMetrics();
    assertEquals(1, metrics.underReplicatedBlocks.get());
    assertEquals(1, metrics.missingBlocks.get());
    fs.delete(file, true);
    updateMetrics();
    assertEquals(0, metrics.underReplicatedBlocks.get());
  }
}