/**
 * 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.mapreduce.filecache;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.security.PrivilegedExceptionAction;
import java.util.Random;
import java.util.concurrent.TimeUnit;

import javax.security.auth.login.LoginException;

import junit.framework.TestCase;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.DefaultTaskController;
import org.apache.hadoop.mapred.TaskController;
import org.apache.hadoop.mapred.TaskTracker;
import org.apache.hadoop.mapreduce.Cluster;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.MRConfig;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.filecache.DistributedCache;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.RawLocalFileSystem;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.mapreduce.filecache.TaskDistributedCacheManager;
import org.apache.hadoop.mapreduce.filecache.TrackerDistributedCacheManager;
import org.apache.hadoop.mapreduce.server.tasktracker.TTConfig;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.util.ReflectionUtils;
import org.mortbay.log.Log;

public class TestTrackerDistributedCacheManager extends TestCase {

  protected String TEST_ROOT_DIR =
      new File(System.getProperty("test.build.data", "/tmp"),
          TestTrackerDistributedCacheManager.class.getSimpleName())
          .getAbsolutePath();

  protected File ROOT_MAPRED_LOCAL_DIR;
  protected int numLocalDirs = 6;

  private static final int TEST_FILE_SIZE = 4 * 1024; // 4K
  private static final int LOCAL_CACHE_LIMIT = 5 * 1024; //5K
  private static final int LOCAL_CACHE_SUBDIR = 2;
  protected Configuration conf;
  protected Path firstCacheFile;
  protected Path secondCacheFile;
  private FileSystem fs;

  protected LocalDirAllocator localDirAllocator = 
    new LocalDirAllocator(MRConfig.LOCAL_DIR);
  protected TaskController taskController;

  @Override
  protected void setUp() throws IOException,InterruptedException {

    // Prepare the tests' root dir
    File TEST_ROOT = new File(TEST_ROOT_DIR);
    if (!TEST_ROOT.exists()) {
      TEST_ROOT.mkdirs();
    }

    // Prepare the tests' mapred-local-dir
    ROOT_MAPRED_LOCAL_DIR = new File(TEST_ROOT_DIR, "mapred/local");
    ROOT_MAPRED_LOCAL_DIR.mkdirs();

    String []localDirs = new String[numLocalDirs];
    for (int i = 0; i < numLocalDirs; i++) {
      File localDir = new File(ROOT_MAPRED_LOCAL_DIR, "0_" + i);
      localDirs[i] = localDir.getPath();
      localDir.mkdir();
    }

    conf = new Configuration();
    conf.setStrings(MRConfig.LOCAL_DIR, localDirs);
    conf.set(FileSystem.FS_DEFAULT_NAME_KEY, "file:///");
    fs = FileSystem.get(conf);
    Class<? extends TaskController> taskControllerClass = conf.getClass(
        TTConfig.TT_TASK_CONTROLLER, DefaultTaskController.class,
        TaskController.class);
    taskController = (TaskController) ReflectionUtils.newInstance(
        taskControllerClass, conf);

    // setup permissions for mapred local dir
    taskController.setup();

    // Create the temporary cache files to be used in the tests.
    firstCacheFile = new Path(TEST_ROOT_DIR, "firstcachefile");
    secondCacheFile = new Path(TEST_ROOT_DIR, "secondcachefile");
    createPrivateTempFile(firstCacheFile);
    createPrivateTempFile(secondCacheFile);
  }
  
  protected void refreshConf(Configuration conf) throws IOException {
    taskController.setConf(conf);
    taskController.setup();
  }

  /**
   * Whether the test can run on the machine
   * 
   * @return true if test can run on the machine, false otherwise
   */
  protected boolean canRun() {
    return true;
  }
  
  /**
   * This is the typical flow for using the DistributedCache classes.
   * 
   * @throws IOException
   * @throws LoginException
   */
  public void testManagerFlow() throws IOException, LoginException {
    if (!canRun()) {
      return;
    }

    // ****** Imitate JobClient code
    // Configures a task/job with both a regular file and a "classpath" file.
    Configuration subConf = new Configuration(conf);
    String userName = getJobOwnerName();
    subConf.set(MRJobConfig.USER_NAME, userName);
    DistributedCache.addCacheFile(firstCacheFile.toUri(), subConf);
    DistributedCache.addFileToClassPath(secondCacheFile, subConf);
    TrackerDistributedCacheManager.determineTimestamps(subConf);
    TrackerDistributedCacheManager.determineCacheVisibilities(subConf);
    // ****** End of imitating JobClient code

    Path jobFile = new Path(TEST_ROOT_DIR, "job.xml");
    FileOutputStream os = new FileOutputStream(new File(jobFile.toString()));
    subConf.writeXml(os);
    os.close();

    // ****** Imitate TaskRunner code.
    TrackerDistributedCacheManager manager = 
      new TrackerDistributedCacheManager(conf, taskController);
    TaskDistributedCacheManager handle =
      manager.newTaskDistributedCacheManager(subConf);
    assertNull(null, DistributedCache.getLocalCacheFiles(subConf));
    File workDir = new File(new Path(TEST_ROOT_DIR, "workdir").toString());
    handle.setup(localDirAllocator, workDir, TaskTracker
        .getPrivateDistributedCacheDir(userName), 
        TaskTracker.getPublicDistributedCacheDir());
    // ****** End of imitating TaskRunner code

    Path[] localCacheFiles = DistributedCache.getLocalCacheFiles(subConf);
    assertNotNull(null, localCacheFiles);
    assertEquals(2, localCacheFiles.length);
    Path cachedFirstFile = localCacheFiles[0];
    Path cachedSecondFile = localCacheFiles[1];
    assertFileLengthEquals(firstCacheFile, cachedFirstFile);
    assertFalse("Paths should be different.", 
        firstCacheFile.equals(cachedFirstFile));

    assertEquals(1, handle.getClassPaths().size());
    assertEquals(cachedSecondFile.toString(), handle.getClassPaths().get(0));

    checkFilePermissions(localCacheFiles);

    // Cleanup
    handle.release();
    manager.purgeCache();
    assertFalse(pathToFile(cachedFirstFile).exists());
  }

  /**
   * This DistributedCacheManager fails in localizing firstCacheFile.
   */
  public class FakeTrackerDistributedCacheManager extends
      TrackerDistributedCacheManager {
    public FakeTrackerDistributedCacheManager(Configuration conf)
        throws IOException {
      super(conf, taskController);
    }

    @Override
    Path localizeCache(Configuration conf, URI cache, long confFileStamp,
        CacheStatus cacheStatus, boolean isArchive, boolean isPublic)
    throws IOException {
      if (cache.equals(firstCacheFile.toUri())) {
        throw new IOException("fake fail");
      }
      return super.localizeCache(conf, cache, confFileStamp, cacheStatus,
          isArchive, isPublic);
    }
  }

  public void testReferenceCount() throws IOException, LoginException,
      URISyntaxException, InterruptedException {
    if (!canRun()) {
      return;
    }
    TrackerDistributedCacheManager manager = 
      new FakeTrackerDistributedCacheManager(conf);
    Cluster cluster = new Cluster(conf);
    String userName = getJobOwnerName();
    File workDir = new File(new Path(TEST_ROOT_DIR, "workdir").toString());

    // Configures a job with a regular file
    Job job1 = Job.getInstance(cluster, conf);
    job1.setUser(userName);
    job1.addCacheFile(secondCacheFile.toUri());
    Configuration conf1 = job1.getConfiguration();
    TrackerDistributedCacheManager.determineTimestamps(conf1);
    TrackerDistributedCacheManager.determineCacheVisibilities(conf1);

    // Task localizing for first job
    TaskDistributedCacheManager handle = manager
        .newTaskDistributedCacheManager(conf1);
    handle.setup(localDirAllocator, workDir, TaskTracker
          .getPrivateDistributedCacheDir(userName), 
          TaskTracker.getPublicDistributedCacheDir());
    handle.release();
    for (TaskDistributedCacheManager.CacheFile c : handle.getCacheFiles()) {
      assertEquals(0, manager.getReferenceCount(c.uri, conf1, c.timestamp,
          c.owner));
    }
    
    Path thirdCacheFile = new Path(TEST_ROOT_DIR, "thirdcachefile");
    createPrivateTempFile(thirdCacheFile);
    
    // Configures another job with three regular files.
    Job job2 = Job.getInstance(cluster, conf);
    job2.setUser(userName);
    // add a file that would get failed to localize
    job2.addCacheFile(firstCacheFile.toUri());
    // add a file that is already localized by different job
    job2.addCacheFile(secondCacheFile.toUri());
    // add a file that is never localized
    job2.addCacheFile(thirdCacheFile.toUri());
    Configuration conf2 = job2.getConfiguration();
    TrackerDistributedCacheManager.determineTimestamps(conf2);
    TrackerDistributedCacheManager.determineCacheVisibilities(conf2);

    // Task localizing for second job
    // localization for the "firstCacheFile" will fail.
    handle = manager.newTaskDistributedCacheManager(conf2);
    Throwable th = null;
    try {
      handle.setup(localDirAllocator, workDir, TaskTracker
          .getPrivateDistributedCacheDir(userName), 
          TaskTracker.getPublicDistributedCacheDir());
    } catch (IOException e) {
      th = e;
      Log.info("Exception during setup", e);
    }
    assertNotNull(th);
    assertTrue(th.getMessage().contains("fake fail"));
    handle.release();
    th = null;
    for (TaskDistributedCacheManager.CacheFile c : handle.getCacheFiles()) {
      try {
        assertEquals(0, manager.getReferenceCount(c.uri, conf2, c.timestamp,
            c.owner));
      } catch (IOException ie) {
        th = ie;
        Log.info("Exception getting reference count for " + c.uri, ie);
      }
    }
    assertNotNull(th);
    assertTrue(th.getMessage().contains(thirdCacheFile.getName()));
    fs.delete(thirdCacheFile, false);
  }
  
  /**
   * Tests that localization of distributed cache file happens in the desired
   * directory
   * @throws IOException
   * @throws LoginException
   */
  public void testPublicPrivateCache() 
  throws IOException, LoginException, InterruptedException {
    if (!canRun()) {
      return;
    }
    checkLocalizedPath(true);
    checkLocalizedPath(false);
  }
  
  public void testPrivateCacheForMultipleUsers() 
  throws IOException, LoginException, InterruptedException{
    if (!canRun()) {
      return;
    }
    // Try to initialize the distributed cache for the same file on the
    // HDFS, for two different users.
    // First initialize as the user running the test, then as some other user.
    // Although the same cache file is used in both, the localization
    // should happen twice.
    
    UserGroupInformation ugi = UserGroupInformation.getLoginUser();
    Path p = ugi.doAs(new PrivilegedExceptionAction<Path>() {
      public Path run() 
      throws IOException, LoginException, InterruptedException {
        return checkLocalizedPath(false);
      }
    });
    String distCacheDir = TaskTracker.getPrivateDistributedCacheDir(
        ugi.getShortUserName());
    assertTrue("Cache file didn't get localized in the expected directory. " +
        "Expected localization to happen within " + 
        ROOT_MAPRED_LOCAL_DIR + "/" + distCacheDir +
        ", but was localized at " + 
        p, p.toString().contains(distCacheDir));
    
    ugi = UserGroupInformation.createRemoteUser("fooUserInMachine");
    p = ugi.doAs(new PrivilegedExceptionAction<Path>() {
      public Path run() 
      throws IOException, LoginException, InterruptedException {
        return checkLocalizedPath(false);
      }
    });
    distCacheDir = TaskTracker.getPrivateDistributedCacheDir(
        ugi.getShortUserName());
    assertTrue("Cache file didn't get localized in the expected directory. " +
        "Expected localization to happen within " + 
        ROOT_MAPRED_LOCAL_DIR + "/" + distCacheDir +
        ", but was localized at " + 
        p, p.toString().contains(distCacheDir));
    
  }
  
  private Path checkLocalizedPath(boolean visibility) 
  throws IOException, LoginException, InterruptedException {
    TrackerDistributedCacheManager manager = 
      new TrackerDistributedCacheManager(conf, taskController);
    Cluster cluster = new Cluster(conf);
    String userName = getJobOwnerName();
    File workDir = new File(TEST_ROOT_DIR, "workdir");
    Path cacheFile = new Path(TEST_ROOT_DIR, "fourthcachefile");
    if (visibility) {
      createPublicTempFile(cacheFile);
    } else {
      createPrivateTempFile(cacheFile);
    }
    
    Job job1 = Job.getInstance(cluster, conf);
    job1.setUser(userName);
    job1.addCacheFile(cacheFile.toUri());
    Configuration conf1 = job1.getConfiguration();
    TrackerDistributedCacheManager.determineTimestamps(conf1);
    TrackerDistributedCacheManager.determineCacheVisibilities(conf1);

    // Task localizing for job
    TaskDistributedCacheManager handle = manager
        .newTaskDistributedCacheManager(conf1);
    handle.setup(localDirAllocator, workDir, TaskTracker
          .getPrivateDistributedCacheDir(userName), 
          TaskTracker.getPublicDistributedCacheDir());
    TaskDistributedCacheManager.CacheFile c = handle.getCacheFiles().get(0);
    String distCacheDir;
    if (visibility) {
      distCacheDir = TaskTracker.getPublicDistributedCacheDir(); 
    } else {
      distCacheDir = TaskTracker.getPrivateDistributedCacheDir(userName);
    }
    Path localizedPath =
      manager.getLocalCache(cacheFile.toUri(), conf1, distCacheDir,
          fs.getFileStatus(cacheFile), false,
          c.timestamp, new Path(TEST_ROOT_DIR), false,
          visibility);
    assertTrue("Cache file didn't get localized in the expected directory. " +
        "Expected localization to happen within " + 
        ROOT_MAPRED_LOCAL_DIR + "/" + distCacheDir +
        ", but was localized at " + 
        localizedPath, localizedPath.toString().contains(distCacheDir));
    if (visibility) {
      checkPublicFilePermissions(new Path[]{localizedPath});
    } else {
      checkFilePermissions(new Path[]{localizedPath});
    }
    return localizedPath;
  }
  
  /**
   * Check proper permissions on the cache files
   * 
   * @param localCacheFiles
   * @throws IOException
   */
  protected void checkFilePermissions(Path[] localCacheFiles)
      throws IOException {
    // All the files should have executable permissions on them.
    for (Path p : localCacheFiles) {
      assertTrue("Cache file is not executable!", new File(p
          .toUri().getPath()).canExecute());
    }
  }

  /**
   * Check permissions on the public cache files
   * 
   * @param localCacheFiles
   * @throws IOException
   */
  private void checkPublicFilePermissions(Path[] localCacheFiles)
      throws IOException {
    checkPublicFilePermissions(fs, localCacheFiles);
  }

  /**
   * Verify the permissions for a file localized as a public distributed
   * cache file
   * @param fs The Local FileSystem used to get the permissions
   * @param localCacheFiles The list of files whose permissions should be 
   * verified.
   * @throws IOException
   */
  public static void checkPublicFilePermissions(FileSystem fs, 
      Path[] localCacheFiles) throws IOException {
    // All the files should have read and executable permissions for others
    for (Path p : localCacheFiles) {
      FsPermission perm = fs.getFileStatus(p).getPermission();
      assertTrue("cache file is not readable / executable by owner: perm="
          + perm.getUserAction(), perm.getUserAction()
          .implies(FsAction.READ_EXECUTE));
      assertTrue("cache file is not readable / executable by group: perm="
          + perm.getGroupAction(), perm.getGroupAction()
          .implies(FsAction.READ_EXECUTE));
      assertTrue("cache file is not readable / executable by others: perm="
          + perm.getOtherAction(), perm.getOtherAction()
          .implies(FsAction.READ_EXECUTE));
    }
  }
  
  /**
   * Verify the ownership for files localized as a public distributed cache
   * file.
   * @param fs The Local FileSystem used to get the ownership
   * @param localCacheFiles THe list of files whose ownership should be
   * verified
   * @param owner The owner of the files
   * @param group The group owner of the files.
   * @throws IOException
   */
  public static void checkPublicFileOwnership(FileSystem fs,
      Path[] localCacheFiles, String owner, String group)
      throws IOException {
    for (Path p: localCacheFiles) {
      assertEquals(owner, fs.getFileStatus(p).getOwner());
      assertEquals(group, fs.getFileStatus(p).getGroup());
    }
  }
  
  protected String getJobOwnerName() throws IOException {
    return UserGroupInformation.getCurrentUser().getUserName();
  }
  
  private long getFileStamp(Path file) throws IOException {
    FileStatus fileStatus = fs.getFileStatus(file);
    return fileStatus.getModificationTime();
  }
  

  /** test delete cache */
  public void testDeleteCache() throws Exception {
    if (!canRun()) {
      return;
    }
    // This test needs MRConfig.LOCAL_DIR to be single directory
    // instead of four, because it assumes that both 
    // firstcachefile and secondcachefile will be localized on same directory 
    // so that second localization triggers deleteCache.
    // If MRConfig.LOCAL_DIR is four directories, second localization might not 
    // trigger deleteCache, if it is localized in different directory.
    Configuration conf2 = new Configuration(conf);
    conf2.set(MRConfig.LOCAL_DIR, ROOT_MAPRED_LOCAL_DIR.toString());
    conf2.setLong(TTConfig.TT_LOCAL_CACHE_SIZE, LOCAL_CACHE_LIMIT);
    conf2.setLong(TTConfig.TT_LOCAL_CACHE_SUBDIRS_LIMIT, LOCAL_CACHE_SUBDIR);
    conf2.setLong(TTConfig.TT_DISTRIBUTED_CACHE_CHECK_PERIOD, 200); // 200 ms
    refreshConf(conf2);
    TrackerDistributedCacheManager manager = 
        new TrackerDistributedCacheManager(conf2, taskController);
    manager.startCleanupThread();
    FileSystem localfs = FileSystem.getLocal(conf2);
    String userName = getJobOwnerName();
    conf2.set(MRJobConfig.USER_NAME, userName);

    // We first test the size limit
    Path localCache = manager.getLocalCache(firstCacheFile.toUri(), conf2, 
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(firstCacheFile), false,
        getFileStamp(firstCacheFile), new Path(TEST_ROOT_DIR), false, false);
    manager.releaseCache(firstCacheFile.toUri(), conf2,
        getFileStamp(firstCacheFile), 
        TrackerDistributedCacheManager.getLocalizedCacheOwner(false));
    //in above code,localized a file of size 4K and then release the cache 
    // which will cause the cache be deleted when the limit goes out. 
    // The below code localize another cache which's designed to
    //sweep away the first cache.
    manager.getLocalCache(secondCacheFile.toUri(), conf2, 
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(secondCacheFile), false, 
        getFileStamp(secondCacheFile), new Path(TEST_ROOT_DIR), false, false);
    checkCacheDeletion(localfs, localCache, "DistributedCache failed " +
        "deleting old cache when the cache store is full.");
    // Now we test the number of sub directories limit
    // Create the temporary cache files to be used in the tests.
    Path thirdCacheFile = new Path(TEST_ROOT_DIR, "thirdcachefile");
    Path fourthCacheFile = new Path(TEST_ROOT_DIR, "fourthcachefile");
    // Adding two more small files, so it triggers the number of sub directory
    // limit but does not trigger the file size limit.
    createTempFile(thirdCacheFile, 1);
    createTempFile(fourthCacheFile, 1);
    Path thirdLocalCache = manager.getLocalCache(thirdCacheFile.toUri(), conf2,
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(thirdCacheFile), false,
        getFileStamp(thirdCacheFile), new Path(TEST_ROOT_DIR), false, false);
    // Release the third cache so that it can be deleted while sweeping
    manager.releaseCache(thirdCacheFile.toUri(), conf2,
        getFileStamp(thirdCacheFile), 
        TrackerDistributedCacheManager.getLocalizedCacheOwner(false));
    // Getting the fourth cache will make the number of sub directories becomes
    // 3 which is greater than 2. So the released cache will be deleted.
    manager.getLocalCache(fourthCacheFile.toUri(), conf2, 
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(fourthCacheFile), false, 
        getFileStamp(fourthCacheFile), new Path(TEST_ROOT_DIR), false, false);
    checkCacheDeletion(localfs, thirdLocalCache,
        "DistributedCache failed deleting old" +
        " cache when the cache exceeds the number of sub directories limit.");
    // Clean up the files created in this test
    new File(thirdCacheFile.toString()).delete();
    new File(fourthCacheFile.toString()).delete();
    manager.stopCleanupThread();
  }

  /**
   * Periodically checks if a file is there, return if the file is no longer
   * there. Fails the test if a files is there for 30 seconds.
   */
  private void checkCacheDeletion(FileSystem fs, Path cache, String msg)
    throws Exception {
    // Check every 100ms to see if the cache is deleted
    boolean cacheExists = true;
    for (int i = 0; i < 300; i++) {
      if (!fs.exists(cache)) {
        cacheExists = false;
        break;
      }
      TimeUnit.MILLISECONDS.sleep(100L);
    }
    // If the cache is still there after 5 minutes, test fails.
    assertFalse(msg, cacheExists);
  }
  
  public void testFileSystemOtherThanDefault() throws Exception {
    if (!canRun()) {
      return;
    }
    TrackerDistributedCacheManager manager =
      new TrackerDistributedCacheManager(conf, taskController);
    conf.set("fs.fakefile.impl", conf.get("fs.file.impl"));
    String userName = getJobOwnerName();
    conf.set(MRJobConfig.USER_NAME, userName);
    Path fileToCache = new Path("fakefile:///"
        + firstCacheFile.toUri().getPath());
    Path result = manager.getLocalCache(fileToCache.toUri(), conf,
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(firstCacheFile), false,
        getFileStamp(firstCacheFile),
        new Path(TEST_ROOT_DIR), false, false);
    assertNotNull("DistributedCache cached file on non-default filesystem.",
        result);
  }

  static void createTempFile(Path p) throws IOException {
    createTempFile(p, TEST_FILE_SIZE);
  }
  
  static void createTempFile(Path p, int size) throws IOException {
    File f = new File(p.toString());
    FileOutputStream os = new FileOutputStream(f);
    byte[] toWrite = new byte[size];
    new Random().nextBytes(toWrite);
    os.write(toWrite);
    os.close();
    FileSystem.LOG.info("created: " + p + ", size=" + size);
  }
  
  static void createPublicTempFile(Path p) 
  throws IOException, InterruptedException {
    createTempFile(p);
    FileUtil.chmod(p.toString(), "0777",true);
  }
  
  static void createPrivateTempFile(Path p) 
  throws IOException, InterruptedException {
    createTempFile(p);
    FileUtil.chmod(p.toString(), "0770",true);
  }

  @Override
  protected void tearDown() throws IOException {
    new File(firstCacheFile.toString()).delete();
    new File(secondCacheFile.toString()).delete();
    FileUtil.fullyDelete(new File(TEST_ROOT_DIR));
  }

  protected void assertFileLengthEquals(Path a, Path b) 
      throws FileNotFoundException {
    assertEquals("File sizes mismatch.", 
       pathToFile(a).length(), pathToFile(b).length());
  }

  protected File pathToFile(Path p) {
    return new File(p.toString());
  }
  
  public static class FakeFileSystem extends RawLocalFileSystem {
    private long increment = 0;
    public FakeFileSystem() {
      super();
    }
    
    public FileStatus getFileStatus(Path p) throws IOException {
      File f = pathToFile(p);
      return new FileStatus(f.length(), f.isDirectory(), 1, 128,
      f.lastModified() + increment, makeQualified(new Path(f.getPath())));
    }
    
    void advanceClock(long millis) {
      increment += millis;
    }
  }
  
  public void testFreshness() throws Exception {
    if (!canRun()) {
      return;
    }
    Configuration myConf = new Configuration(conf);
    myConf.set(FileSystem.FS_DEFAULT_NAME_KEY, "refresh:///");
    myConf.setClass("fs.refresh.impl", FakeFileSystem.class, FileSystem.class);
    String userName = getJobOwnerName();

    TrackerDistributedCacheManager manager = 
      new TrackerDistributedCacheManager(myConf, taskController);
    // ****** Imitate JobClient code
    // Configures a task/job with both a regular file and a "classpath" file.
    Configuration subConf = new Configuration(myConf);
    subConf.set(MRJobConfig.USER_NAME, userName);
    DistributedCache.addCacheFile(firstCacheFile.toUri(), subConf);
    TrackerDistributedCacheManager.determineTimestamps(subConf);
    TrackerDistributedCacheManager.determineCacheVisibilities(subConf);
    // ****** End of imitating JobClient code

    // ****** Imitate TaskRunner code.
    TaskDistributedCacheManager handle =
      manager.newTaskDistributedCacheManager(subConf);
    assertNull(null, DistributedCache.getLocalCacheFiles(subConf));
    File workDir = new File(new Path(TEST_ROOT_DIR, "workdir").toString());
    handle.setup(localDirAllocator, workDir, TaskTracker
        .getPrivateDistributedCacheDir(userName), 
        TaskTracker.getPublicDistributedCacheDir());
    // ****** End of imitating TaskRunner code

    Path[] localCacheFiles = DistributedCache.getLocalCacheFiles(subConf);
    assertNotNull(null, localCacheFiles);
    assertEquals(1, localCacheFiles.length);
    Path cachedFirstFile = localCacheFiles[0];
    assertFileLengthEquals(firstCacheFile, cachedFirstFile);
    assertFalse("Paths should be different.", 
        firstCacheFile.equals(cachedFirstFile));
    // release
    handle.release();
    
    // change the file timestamp
    FileSystem fs = FileSystem.get(myConf);
    ((FakeFileSystem)fs).advanceClock(1);

    // running a task of the same job
    Throwable th = null;
    try {
      handle.setup(localDirAllocator, workDir, TaskTracker
          .getPrivateDistributedCacheDir(userName), TaskTracker.getPublicDistributedCacheDir());
    } catch (IOException ie) {
      th = ie;
    }
    assertNotNull("Throwable is null", th);
    assertTrue("Exception message does not match",
        th.getMessage().contains("has changed on HDFS since job started"));
    // release
    handle.release();
    
    // running a task of the same job on another TaskTracker which has never
    // initialized the cache
    TrackerDistributedCacheManager manager2 = 
      new TrackerDistributedCacheManager(myConf, taskController);
    TaskDistributedCacheManager handle2 =
      manager2.newTaskDistributedCacheManager(subConf);
    File workDir2 = new File(new Path(TEST_ROOT_DIR, "workdir2").toString());
    th = null;
    try {
      handle2.setup(localDirAllocator, workDir2, TaskTracker
          .getPrivateDistributedCacheDir(userName), 
          TaskTracker.getPublicDistributedCacheDir());
    } catch (IOException ie) {
      th = ie;
    }
    assertNotNull("Throwable is null", th);
    assertTrue("Exception message does not match",
        th.getMessage().contains("has changed on HDFS since job started"));
    // release
    handle.release();
    
    // submit another job
    Configuration subConf2 = new Configuration(myConf);
    subConf2.set(MRJobConfig.USER_NAME, userName);
    DistributedCache.addCacheFile(firstCacheFile.toUri(), subConf2);
    TrackerDistributedCacheManager.determineTimestamps(subConf2);
    TrackerDistributedCacheManager.determineCacheVisibilities(subConf2);
    
    handle =
      manager.newTaskDistributedCacheManager(subConf2);
    handle.setup(localDirAllocator, workDir, TaskTracker
        .getPrivateDistributedCacheDir(userName), TaskTracker.getPublicDistributedCacheDir());
    Path[] localCacheFiles2 = DistributedCache.getLocalCacheFiles(subConf2);
    assertNotNull(null, localCacheFiles2);
    assertEquals(1, localCacheFiles2.length);
    Path cachedFirstFile2 = localCacheFiles2[0];
    assertFileLengthEquals(firstCacheFile, cachedFirstFile2);
    assertFalse("Paths should be different.", 
        firstCacheFile.equals(cachedFirstFile2));
    
    // assert that two localizations point to different paths
    assertFalse("two jobs with different timestamps did not localize" +
        " in different paths", cachedFirstFile.equals(cachedFirstFile2));
    // release
    handle.release();
  }

  /**
   * Localize a file. After localization is complete, create a file, "myFile",
   * under the directory where the file is localized and ensure that it has
   * permissions different from what is set by default. Then, localize another
   * file. Verify that "myFile" has the right permissions.
   * @throws Exception
   */
  public void testCustomPermissions() throws Exception {
    if (!canRun()) {
      return;
    }
    String userName = getJobOwnerName();
    conf.set(MRJobConfig.USER_NAME, userName);
    TrackerDistributedCacheManager manager = 
        new TrackerDistributedCacheManager(conf, taskController);
    FileSystem localfs = FileSystem.getLocal(conf);

    Path[] localCache = new Path[2];
    localCache[0] = manager.getLocalCache(firstCacheFile.toUri(), conf, 
        TaskTracker.getPrivateDistributedCacheDir(userName),
        fs.getFileStatus(firstCacheFile), false,
        getFileStamp(firstCacheFile), new Path(TEST_ROOT_DIR), false, false);
    FsPermission myPermission = new FsPermission((short)0600);
    Path myFile = new Path(localCache[0].getParent(), "myfile.txt");
    if (FileSystem.create(localfs, myFile, myPermission) == null) {
      throw new IOException("Could not create " + myFile);
    }
    try {
      localCache[1] = manager.getLocalCache(secondCacheFile.toUri(), conf, 
          TaskTracker.getPrivateDistributedCacheDir(userName),
          fs.getFileStatus(secondCacheFile), false, 
          getFileStamp(secondCacheFile), new Path(TEST_ROOT_DIR), false,
          false);
      FileStatus stat = localfs.getFileStatus(myFile);
      assertTrue(stat.getPermission().equals(myPermission));
      // validate permissions of localized files.
      checkFilePermissions(localCache);
    } finally {
      localfs.delete(myFile, false);
    }
  }

}