/**
 * 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;

import static org.junit.Assert.*;

import java.io.File;
import java.io.IOException;
import java.util.Collection;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.spy;

public class TestNNStorageFailures {

  public static final Log LOG = LogFactory.getLog(TestNNStorageFailures.class);

  private int editsPerformed = 0;
  private MiniDFSCluster cluster;
  private FileSystem fs;

  @Before
  public void setUpMiniCluster() throws IOException {
    Configuration conf = new Configuration();
    File baseDir = MiniDFSCluster.getBaseDirectory(conf);
    File editDir1 = new File(baseDir, "edit1");
    File editDir2 = new File(baseDir, "edit2");
    conf.set("dfs.name.edits.dir",
        editDir1.getPath() + "," + editDir2.getPath());

    cluster = new MiniDFSCluster(conf, 0, true, null);
    cluster.waitActive();
    fs = cluster.getFileSystem();
  }

  @After
  public void shutDownMiniCluster() throws IOException {
    if (fs != null)
      fs.close();
    if (cluster != null)
      cluster.shutdown();
  }

  /**
   * Do a mutative metadata operation on the file system.
   * 
   * @return true if the operation was successful, false otherwise.
   */
  private boolean doAnEdit() throws IOException {
    return fs.mkdirs(new Path("/tmp", Integer.toString(editsPerformed++)));
  }

  // check if exception is thrown when all image dirs fail
  @Test
  public void testAllImageDirsFailOnRoll() throws IOException {
    assertTrue(doAnEdit());
    Collection<File> namedirs = cluster.getNameDirs();
    for (File f : namedirs) {
      LOG.info("Changing permissions for directory " + f);
      f.setExecutable(false);
    }
    try {
      cluster.getNameNode().getNamesystem().rollEditLog();
      fail("Should get an exception here");
    } catch (IOException e) {
      LOG.info(e);
      assertTrue(e.toString()
          .contains("No image locations are available"));
      // image dirs are not writable
      assertEquals(2, NameNode.getNameNodeMetrics().imagesFailed.get());
      // journals are separate, and accessible
      assertEquals(0, NameNode.getNameNodeMetrics().journalsFailed.get());
    } finally {
      for (File f : namedirs) {
        LOG.info("Changing permissions for directory " + f);
        f.setExecutable(true);
      }
    }
  }
  
  // check if image directories are restored at two consecutive SN, 
  // when one fails
  @Test
  public void testImageDirsRemainValidOnInodeMismatch() throws IOException {
    for (int i = 0; i < 10; i++) {
      assertTrue(doAnEdit());
    }

    // replace root dir with a spy
    FSDirectory spyDir = spy(cluster.getNameNode().getNamesystem().dir);
    long originalCount = spyDir.totalInodes();
    cluster.getNameNode().getNamesystem().dir = spyDir;

    doReturn(new Long(originalCount + 1)).when(spyDir).totalInodes();
    // save namespace should fail, but not evict image directories
    try {
      cluster.getNameNode().getNamesystem().saveNamespace(true, false);
      fail("Should get an exception here");
    } catch (IOException e) {
      LOG.info(e);
    }
    doReturn(new Long(originalCount)).when(spyDir).totalInodes();
    cluster.getNameNode().getNamesystem().saveNamespace(true, false);
    assertTrue(cluster.getNameNode().getNamesystem().getFSImage().storage.removedStorageDirs
        .isEmpty());
    assertEquals(0, NameNode.getNameNodeMetrics().imagesFailed.get());
    assertEquals(0, NameNode.getNameNodeMetrics().journalsFailed.get());
  }
}