/*
 * Copyright 2012 LinkedIn Corp.
 *
 * Licensed 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 azkaban.execapp;

import java.io.File;
import java.io.FileFilter;
import java.io.FilenameFilter;
import java.io.IOException;
import java.lang.Thread.State;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.TimeUnit;

import org.apache.commons.io.FileUtils;
import org.apache.log4j.Logger;

import azkaban.event.Event;
import azkaban.event.EventListener;
import azkaban.execapp.event.FlowWatcher;
import azkaban.execapp.event.LocalFlowWatcher;
import azkaban.execapp.event.RemoteFlowWatcher;
import azkaban.execapp.metric.NumFailedFlowMetric;
import azkaban.executor.ExecutableFlow;
import azkaban.executor.ExecutionOptions;
import azkaban.executor.ExecutorLoader;
import azkaban.executor.ExecutorManagerException;
import azkaban.jobtype.JobTypeManager;
import azkaban.jobtype.JobTypeManagerException;
import azkaban.metric.MetricReportManager;
import azkaban.project.ProjectLoader;
import azkaban.project.ProjectWhitelist;
import azkaban.project.ProjectWhitelist.WhitelistType;
import azkaban.utils.FileIOUtils;
import azkaban.utils.FileIOUtils.JobMetaData;
import azkaban.utils.FileIOUtils.LogData;
import azkaban.utils.JSONUtils;
import azkaban.utils.Pair;
import azkaban.utils.Props;
import azkaban.utils.ThreadPoolExecutingListener;
import azkaban.utils.TrackingThreadPool;

/**
 * Execution manager for the server side execution.
 *
 * When a flow is submitted to FlowRunnerManager, it is the
 * {@link Status.PREPARING} status. When a flow is about to be executed by
 * FlowRunner, its status is updated to {@link Status.RUNNING}
 *
 * Two main data structures are used in this class to maintain flows.
 *
 * runningFlows: this is used as a bookkeeping for submitted flows in
 * FlowRunnerManager. It has nothing to do with the executor service that is
 * used to execute the flows. This bookkeeping is used at the time of canceling
 * or killing a flow. The flows in this data structure is removed in the
 * handleEvent method.
 *
 * submittedFlows: this is used to keep track the execution of the flows, so it
 * has the mapping between a Future<?> and an execution id. This would allow us
 * to find out the execution ids of the flows that are in the Status.PREPARING
 * status. The entries in this map is removed once the flow execution is
 * completed.
 *
 *
 */
public class FlowRunnerManager implements EventListener,
    ThreadPoolExecutingListener {
  private static final Logger logger = Logger.getLogger(FlowRunnerManager.class);

  private static final String EXECUTOR_USE_BOUNDED_THREADPOOL_QUEUE = "executor.use.bounded.threadpool.queue";
  private static final String EXECUTOR_THREADPOOL_WORKQUEUE_SIZE = "executor.threadpool.workqueue.size";
  private static final String EXECUTOR_FLOW_THREADS = "executor.flow.threads";
  private static final String FLOW_NUM_JOB_THREADS = "flow.num.job.threads";

  // recently finished secs to clean up. 1 minute
  private static final int RECENTLY_FINISHED_TIME_TO_LIVE = 60 * 1000;

  private static final int DEFAULT_NUM_EXECUTING_FLOWS = 30;
  private static final int DEFAULT_FLOW_NUM_JOB_TREADS = 10;

  // this map is used to store the flows that have been submitted to
  // the executor service. Once a flow has been submitted, it is either
  // in the queue waiting to be executed or in executing state.
  private final Map<Future<?>, Integer> submittedFlows = new ConcurrentHashMap<>();
  private final Map<Integer, FlowRunner> runningFlows = new ConcurrentHashMap<>();
  private final Map<Integer, ExecutableFlow> recentlyFinishedFlows = new ConcurrentHashMap<>();
  private final Map<Pair<Integer, Integer>, ProjectVersion> installedProjects;

  private final TrackingThreadPool executorService;
  private final CleanerThread cleanerThread;
  private final ExecutorLoader executorLoader;
  private final ProjectLoader projectLoader;
  private final JobTypeManager jobtypeManager;

  private final Props azkabanProps;
  private final File executionDirectory;
  private final File projectDirectory;

  private final Object executionDirDeletionSync = new Object();

  private int numThreads = DEFAULT_NUM_EXECUTING_FLOWS;
  private int threadPoolQueueSize = -1;
  private int numJobThreadPerFlow = DEFAULT_FLOW_NUM_JOB_TREADS;

  private Props globalProps;

  private long lastCleanerThreadCheckTime = -1;
  private long executionDirRetention = 1 * 24 * 60 * 60 * 1000; // 1 Day

  // We want to limit the log sizes to about 20 megs
  private String jobLogChunkSize = "5MB";
  private int jobLogNumFiles = 4;

  // If true, jobs will validate proxy user against a list of valid proxy users.
  private boolean validateProxyUser = false;

  // date time of the the last flow submitted.
  private long lastFlowSubmittedDate = 0;

  // whether the current executor is active
  private volatile boolean isActive = false;

  public FlowRunnerManager(Props props, ExecutorLoader executorLoader,
      ProjectLoader projectLoader, ClassLoader parentClassLoader) throws IOException {
    azkabanProps = props;

    // JobWrappingFactory.init(props, getClass().getClassLoader());
    executionDirRetention = props.getLong("execution.dir.retention", executionDirRetention);
    logger.info("Execution dir retention set to " + executionDirRetention + " ms");

    executionDirectory = new File(props.getString("azkaban.execution.dir", "executions"));
    if (!executionDirectory.exists()) {
      executionDirectory.mkdirs();
    }
    projectDirectory = new File(props.getString("azkaban.project.dir", "projects"));
    if (!projectDirectory.exists()) {
      projectDirectory.mkdirs();
    }

    installedProjects = loadExistingProjects();

    // azkaban.temp.dir
    numThreads = props.getInt(EXECUTOR_FLOW_THREADS, DEFAULT_NUM_EXECUTING_FLOWS);
    numJobThreadPerFlow = props.getInt(FLOW_NUM_JOB_THREADS, DEFAULT_FLOW_NUM_JOB_TREADS);
    executorService = createExecutorService(numThreads);

    this.executorLoader = executorLoader;
    this.projectLoader = projectLoader;

    this.jobLogChunkSize = azkabanProps.getString("job.log.chunk.size", "5MB");
    this.jobLogNumFiles = azkabanProps.getInt("job.log.backup.index", 4);

    this.validateProxyUser = azkabanProps.getBoolean("proxy.user.lock.down", false);

    setActive(true);

    cleanerThread = new CleanerThread();
    cleanerThread.start();

    String globalPropsPath = props.getString("executor.global.properties", null);
    if (globalPropsPath != null) {
      globalProps = new Props(null, globalPropsPath);
    }

    jobtypeManager =
        new JobTypeManager(props.getString(
            AzkabanExecutorServer.JOBTYPE_PLUGIN_DIR,
            JobTypeManager.DEFAULT_JOBTYPEPLUGINDIR), globalProps,
            parentClassLoader);
  }

  private TrackingThreadPool createExecutorService(int nThreads) {
    boolean useNewThreadPool =
        azkabanProps.getBoolean(EXECUTOR_USE_BOUNDED_THREADPOOL_QUEUE, false);
    logger.info("useNewThreadPool: " + useNewThreadPool);

    if (useNewThreadPool) {
      threadPoolQueueSize =
          azkabanProps.getInt(EXECUTOR_THREADPOOL_WORKQUEUE_SIZE, nThreads);
      logger.info("workQueueSize: " + threadPoolQueueSize);

      // using a bounded queue for the work queue. The default rejection policy
      // {@ThreadPoolExecutor.AbortPolicy} is used
      TrackingThreadPool executor =
          new TrackingThreadPool(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS,
              new LinkedBlockingQueue<Runnable>(threadPoolQueueSize), this);

      return executor;
    } else {
      // the old way of using unbounded task queue.
      // if the running tasks are taking a long time or stuck, this queue
      // will be very very long.
      return new TrackingThreadPool(nThreads, nThreads, 0L,
          TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), this);
    }
  }

  private Map<Pair<Integer, Integer>, ProjectVersion> loadExistingProjects() {
    Map<Pair<Integer, Integer>, ProjectVersion> allProjects =
        new HashMap<Pair<Integer, Integer>, ProjectVersion>();
    for (File project : projectDirectory.listFiles(new FilenameFilter() {

      String pattern = "[0-9]+\\.[0-9]+";

      @Override
      public boolean accept(File dir, String name) {
        return name.matches(pattern);
      }
    })) {
      if (project.isDirectory()) {
        try {
          String fileName = new File(project.getAbsolutePath()).getName();
          int projectId = Integer.parseInt(fileName.split("\\.")[0]);
          int versionNum = Integer.parseInt(fileName.split("\\.")[1]);
          ProjectVersion version =
              new ProjectVersion(projectId, versionNum, project);
          allProjects.put(new Pair<Integer, Integer>(projectId, versionNum),
              version);
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    }
    return allProjects;
  }

  public void setActive(boolean isActive) {
    this.isActive = isActive;
  }

  public long getLastFlowSubmittedTime(){
    // Note: this is not thread safe and may result in providing dirty data.
    //       we will provide this data as is for now and will revisit if there
    //       is a string justification for change.
    return lastFlowSubmittedDate;
  }

  public Props getGlobalProps() {
    return globalProps;
  }

  public void setGlobalProps(Props globalProps) {
    this.globalProps = globalProps;
  }

  private class CleanerThread extends Thread {
    // Every hour, clean execution dir.
    private static final long EXECUTION_DIR_CLEAN_INTERVAL_MS = 60 * 60 * 1000;
    // Every 5 mins clean the old project dir
    private static final long OLD_PROJECT_DIR_INTERVAL_MS = 5 * 60 * 1000;
    // Every 2 mins clean the recently finished list
    private static final long RECENTLY_FINISHED_INTERVAL_MS = 2 * 60 * 1000;

    private boolean shutdown = false;
    private long lastExecutionDirCleanTime = -1;
    private long lastOldProjectCleanTime = -1;
    private long lastRecentlyFinishedCleanTime = -1;

    public CleanerThread() {
      this.setName("FlowRunnerManager-Cleaner-Thread");
      setDaemon(true);
    }

    @SuppressWarnings("unused")
    public void shutdown() {
      shutdown = true;
      this.interrupt();
    }

    public void run() {
      while (!shutdown) {
        synchronized (this) {
          try {
            lastCleanerThreadCheckTime = System.currentTimeMillis();
            logger.info("# of executing flows: " + getNumRunningFlows());

            // Cleanup old stuff.
            long currentTime = System.currentTimeMillis();
            if (currentTime - RECENTLY_FINISHED_INTERVAL_MS > lastRecentlyFinishedCleanTime) {
              logger.info("Cleaning recently finished");
              cleanRecentlyFinished();
              lastRecentlyFinishedCleanTime = currentTime;
            }

            if (currentTime - OLD_PROJECT_DIR_INTERVAL_MS > lastOldProjectCleanTime && isActive) {
              logger.info("Cleaning old projects");
              cleanOlderProjects();
              lastOldProjectCleanTime = currentTime;
            }

            if (currentTime - EXECUTION_DIR_CLEAN_INTERVAL_MS > lastExecutionDirCleanTime) {
              logger.info("Cleaning old execution dirs");
              cleanOlderExecutionDirs();
              lastExecutionDirCleanTime = currentTime;
            }

            wait(RECENTLY_FINISHED_TIME_TO_LIVE);
          } catch (InterruptedException e) {
            logger.info("Interrupted. Probably to shut down.");
          } catch (Throwable t) {
            logger.warn(
                "Uncaught throwable, please look into why it is not caught", t);
          }
        }
      }
    }

    private void cleanOlderExecutionDirs() {
      File dir = executionDirectory;

      final long pastTimeThreshold =
          System.currentTimeMillis() - executionDirRetention;
      File[] executionDirs = dir.listFiles(path -> path.isDirectory() && path.lastModified() < pastTimeThreshold);

      for (File exDir : executionDirs) {
        try {
          int execId = Integer.valueOf(exDir.getName());
          if (runningFlows.containsKey(execId)
              || recentlyFinishedFlows.containsKey(execId)) {
            continue;
          }
        } catch (NumberFormatException e) {
          logger.error("Can't delete exec dir " + exDir.getName()
              + " it is not a number");
          continue;
        }

        synchronized (executionDirDeletionSync) {
          try {
            FileUtils.deleteDirectory(exDir);
          } catch (IOException e) {
            logger.error("Error cleaning execution dir " + exDir.getPath(), e);
          }
        }
      }
    }

    private void cleanRecentlyFinished() {
      long cleanupThreshold =
          System.currentTimeMillis() - RECENTLY_FINISHED_TIME_TO_LIVE;
      ArrayList<Integer> executionToKill = new ArrayList<Integer>();
      for (ExecutableFlow flow : recentlyFinishedFlows.values()) {
        if (flow.getEndTime() < cleanupThreshold) {
          executionToKill.add(flow.getExecutionId());
        }
      }

      for (Integer id : executionToKill) {
        logger.info("Cleaning execution " + id
            + " from recently finished flows list.");
        recentlyFinishedFlows.remove(id);
      }
    }

    private void cleanOlderProjects() {
      Map<Integer, ArrayList<ProjectVersion>> projectVersions =
          new HashMap<Integer, ArrayList<ProjectVersion>>();
      for (ProjectVersion version : installedProjects.values()) {
        ArrayList<ProjectVersion> versionList =
            projectVersions.get(version.getProjectId());
        if (versionList == null) {
          versionList = new ArrayList<ProjectVersion>();
          projectVersions.put(version.getProjectId(), versionList);
        }
        versionList.add(version);
      }

      HashSet<Pair<Integer, Integer>> activeProjectVersions =
          new HashSet<Pair<Integer, Integer>>();
      for (FlowRunner runner : runningFlows.values()) {
        ExecutableFlow flow = runner.getExecutableFlow();
        activeProjectVersions.add(new Pair<Integer, Integer>(flow
            .getProjectId(), flow.getVersion()));
      }

      for (Map.Entry<Integer, ArrayList<ProjectVersion>> entry : projectVersions
          .entrySet()) {
        // Integer projectId = entry.getKey();
        ArrayList<ProjectVersion> installedVersions = entry.getValue();

        // Keep one version of the project around.
        if (installedVersions.size() == 1) {
          continue;
        }

        Collections.sort(installedVersions);
        for (int i = 0; i < installedVersions.size() - 1; ++i) {
          ProjectVersion version = installedVersions.get(i);
          Pair<Integer, Integer> versionKey =
              new Pair<Integer, Integer>(version.getProjectId(),
                  version.getVersion());
          if (!activeProjectVersions.contains(versionKey)) {
            try {
              logger.info("Removing old unused installed project "
                  + version.getProjectId() + ":" + version.getVersion());
              version.deleteDirectory();
              installedProjects.remove(new Pair<Integer, Integer>(version
                  .getProjectId(), version.getVersion()));
            } catch (IOException e) {
              e.printStackTrace();
            }

            installedVersions.remove(versionKey);
          }
        }
      }
    }
  }

  public void submitFlow(int execId) throws ExecutorManagerException {
    // Load file and submit
    if (runningFlows.containsKey(execId)) {
      throw new ExecutorManagerException("Execution " + execId
          + " is already running.");
    }

    ExecutableFlow flow = null;
    flow = executorLoader.fetchExecutableFlow(execId);
    if (flow == null) {
      throw new ExecutorManagerException("Error loading flow with exec "
          + execId);
    }

    // Sets up the project files and execution directory.
    setupFlow(flow);

    // Setup flow runner
    FlowWatcher watcher = null;
    ExecutionOptions options = flow.getExecutionOptions();
    if (options.getPipelineExecutionId() != null) {
      Integer pipelineExecId = options.getPipelineExecutionId();
      FlowRunner runner = runningFlows.get(pipelineExecId);

      if (runner != null) {
        watcher = new LocalFlowWatcher(runner);
      } else {
        watcher = new RemoteFlowWatcher(pipelineExecId, executorLoader);
      }
    }

    int numJobThreads = numJobThreadPerFlow;
    if (options.getFlowParameters().containsKey(FLOW_NUM_JOB_THREADS)) {
      try {
        int numJobs =
            Integer.valueOf(options.getFlowParameters().get(
                FLOW_NUM_JOB_THREADS));
        if (numJobs > 0 && (numJobs <= numJobThreads || ProjectWhitelist
                .isProjectWhitelisted(flow.getProjectId(),
                    WhitelistType.NumJobPerFlow))) {
          numJobThreads = numJobs;
        }
      } catch (Exception e) {
        throw new ExecutorManagerException(
            "Failed to set the number of job threads "
                + options.getFlowParameters().get(FLOW_NUM_JOB_THREADS)
                + " for flow " + execId, e);
      }
    }

    FlowRunner runner =
        new FlowRunner(flow, executorLoader, projectLoader, jobtypeManager, azkabanProps);
    runner.setFlowWatcher(watcher)
        .setJobLogSettings(jobLogChunkSize, jobLogNumFiles)
        .setValidateProxyUser(validateProxyUser)
        .setNumJobThreads(numJobThreads).addListener(this);

    configureFlowLevelMetrics(runner);

    // Check again.
    if (runningFlows.containsKey(execId)) {
      throw new ExecutorManagerException("Execution " + execId
          + " is already running.");
    }

    // Finally, queue the sucker.
    runningFlows.put(execId, runner);

    try {
      // The executorService already has a queue.
      // The submit method below actually returns an instance of FutureTask,
      // which implements interface RunnableFuture, which extends both
      // Runnable and Future interfaces
      Future<?> future = executorService.submit(runner);
      // keep track of this future
      submittedFlows.put(future, runner.getExecutionId());
      // update the last submitted time.
      this.lastFlowSubmittedDate = System.currentTimeMillis();
    } catch (RejectedExecutionException re) {
      throw new ExecutorManagerException(
          "Azkaban server can't execute any more flows. "
              + "The number of running flows has reached the system configured limit."
              + "Please notify Azkaban administrators");
    }
  }

  /**
   * Configure Azkaban metrics tracking for a new flowRunner instance
   *
   * @param flowRunner
   */
  private void configureFlowLevelMetrics(FlowRunner flowRunner) {
    logger.info("Configuring Azkaban metrics tracking for flow runner object");

    if (MetricReportManager.isAvailable()) {
      MetricReportManager metricManager = MetricReportManager.getInstance();
      // Adding NumFailedFlow Metric listener
      flowRunner.addListener((NumFailedFlowMetric) metricManager
          .getMetricFromName(NumFailedFlowMetric.NUM_FAILED_FLOW_METRIC_NAME));
    }

  }

  private void setupFlow(ExecutableFlow flow) throws ExecutorManagerException {
    int execId = flow.getExecutionId();
    File execPath = new File(executionDirectory, String.valueOf(execId));
    flow.setExecutionPath(execPath.getPath());
    logger
        .info("Flow " + execId + " submitted with path " + execPath.getPath());
    execPath.mkdirs();

    // We're setting up the installed projects. First time, it may take a while
    // to set up.
    Pair<Integer, Integer> projectVersionKey =
        new Pair<Integer, Integer>(flow.getProjectId(), flow.getVersion());

    // We set up project versions this way
    ProjectVersion projectVersion = null;
    synchronized (installedProjects) {
      projectVersion = installedProjects.get(projectVersionKey);
      if (projectVersion == null) {
        projectVersion =
            new ProjectVersion(flow.getProjectId(), flow.getVersion());
        installedProjects.put(projectVersionKey, projectVersion);
      }
    }

    try {
      projectVersion.setupProjectFiles(projectLoader, projectDirectory, logger);
      projectVersion.copyCreateSymlinkDirectory(execPath);
    } catch (Exception e) {
      logger.error("Error in setting up project directory "+projectDirectory+", "+e);
      if (execPath.exists()) {
        try {
          FileUtils.deleteDirectory(execPath);
        } catch (IOException e1) {
          e1.printStackTrace();
        }
      }
      throw new ExecutorManagerException(e);
    }
  }

  public void cancelFlow(int execId, String user)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);

    if (runner == null) {
      throw new ExecutorManagerException("Execution " + execId
          + " is not running.");
    }

    runner.kill(user);
  }

  public void pauseFlow(int execId, String user)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);

    if (runner == null) {
      throw new ExecutorManagerException("Execution " + execId
          + " is not running.");
    }

    runner.pause(user);
  }

  public void resumeFlow(int execId, String user)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);

    if (runner == null) {
      throw new ExecutorManagerException("Execution " + execId
          + " is not running.");
    }

    runner.resume(user);
  }

  public void retryFailures(int execId, String user)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);

    if (runner == null) {
      throw new ExecutorManagerException("Execution " + execId
          + " is not running.");
    }

    runner.retryFailures(user);
  }

  public ExecutableFlow getExecutableFlow(int execId) {
    FlowRunner runner = runningFlows.get(execId);
    if (runner == null) {
      return recentlyFinishedFlows.get(execId);
    }
    return runner.getExecutableFlow();
  }

  @Override
  public void handleEvent(Event event) {
    if (event.getType() == Event.Type.FLOW_FINISHED) {

      FlowRunner flowRunner = (FlowRunner) event.getRunner();
      ExecutableFlow flow = flowRunner.getExecutableFlow();

      recentlyFinishedFlows.put(flow.getExecutionId(), flow);
      logger.info("Flow " + flow.getExecutionId()
          + " is finished. Adding it to recently finished flows list.");
      runningFlows.remove(flow.getExecutionId());
    }
  }

  public LogData readFlowLogs(int execId, int startByte, int length)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);
    if (runner == null) {
      throw new ExecutorManagerException("Running flow " + execId
          + " not found.");
    }

    File dir = runner.getExecutionDir();
    if (dir != null && dir.exists()) {
      try {
        synchronized (executionDirDeletionSync) {
          if (!dir.exists()) {
            throw new ExecutorManagerException(
                "Execution dir file doesn't exist. Probably has beend deleted");
          }

          File logFile = runner.getFlowLogFile();
          if (logFile != null && logFile.exists()) {
            return FileIOUtils.readUtf8File(logFile, startByte, length);
          } else {
            throw new ExecutorManagerException("Flow log file doesn't exist.");
          }
        }
      } catch (IOException e) {
        throw new ExecutorManagerException(e);
      }
    }

    throw new ExecutorManagerException(
        "Error reading file. Log directory doesn't exist.");
  }

  public LogData readJobLogs(int execId, String jobId, int attempt,
      int startByte, int length) throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);
    if (runner == null) {
      throw new ExecutorManagerException("Running flow " + execId
          + " not found.");
    }

    File dir = runner.getExecutionDir();
    if (dir != null && dir.exists()) {
      try {
        synchronized (executionDirDeletionSync) {
          if (!dir.exists()) {
            throw new ExecutorManagerException(
                "Execution dir file doesn't exist. Probably has beend deleted");
          }
          File logFile = runner.getJobLogFile(jobId, attempt);
          if (logFile != null && logFile.exists()) {
            return FileIOUtils.readUtf8File(logFile, startByte, length);
          } else {
            throw new ExecutorManagerException("Job log file doesn't exist.");
          }
        }
      } catch (IOException e) {
        throw new ExecutorManagerException(e);
      }
    }

    throw new ExecutorManagerException(
        "Error reading file. Log directory doesn't exist.");
  }

  public List<Object> readJobAttachments(int execId, String jobId, int attempt)
      throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);
    if (runner == null) {
      throw new ExecutorManagerException("Running flow " + execId
          + " not found.");
    }

    File dir = runner.getExecutionDir();
    if (dir == null || !dir.exists()) {
      throw new ExecutorManagerException(
          "Error reading file. Log directory doesn't exist.");
    }

    try {
      synchronized (executionDirDeletionSync) {
        if (!dir.exists()) {
          throw new ExecutorManagerException(
              "Execution dir file doesn't exist. Probably has beend deleted");
        }

        File attachmentFile = runner.getJobAttachmentFile(jobId, attempt);
        if (attachmentFile == null || !attachmentFile.exists()) {
          return null;
        }

        @SuppressWarnings("unchecked")
        List<Object> jobAttachments =
            (ArrayList<Object>) JSONUtils.parseJSONFromFile(attachmentFile);

        return jobAttachments;
      }
    } catch (IOException e) {
      throw new ExecutorManagerException(e);
    }
  }

  public JobMetaData readJobMetaData(int execId, String jobId, int attempt,
      int startByte, int length) throws ExecutorManagerException {
    FlowRunner runner = runningFlows.get(execId);
    if (runner == null) {
      throw new ExecutorManagerException("Running flow " + execId
          + " not found.");
    }

    File dir = runner.getExecutionDir();
    if (dir != null && dir.exists()) {
      try {
        synchronized (executionDirDeletionSync) {
          if (!dir.exists()) {
            throw new ExecutorManagerException(
                "Execution dir file doesn't exist. Probably has beend deleted");
          }
          File metaDataFile = runner.getJobMetaDataFile(jobId, attempt);
          if (metaDataFile != null && metaDataFile.exists()) {
            return FileIOUtils.readUtf8MetaDataFile(metaDataFile, startByte,
                length);
          } else {
            throw new ExecutorManagerException("Job log file doesn't exist.");
          }
        }
      } catch (IOException e) {
        throw new ExecutorManagerException(e);
      }
    }

    throw new ExecutorManagerException(
        "Error reading file. Log directory doesn't exist.");
  }

  public long getLastCleanerThreadCheckTime() {
    return lastCleanerThreadCheckTime;
  }

  public boolean isCleanerThreadActive() {
    return this.cleanerThread.isAlive();
  }

  public State getCleanerThreadState() {
    return this.cleanerThread.getState();
  }

  public boolean isExecutorThreadPoolShutdown() {
    return executorService.isShutdown();
  }

  public int getNumQueuedFlows() {
    return executorService.getQueue().size();
  }

  public int getNumRunningFlows() {
    return executorService.getActiveCount();
  }

  public String getRunningFlowIds() {
    // The in progress tasks are actually of type FutureTask
    Set<Runnable> inProgressTasks = executorService.getInProgressTasks();

    List<Integer> runningFlowIds =
        new ArrayList<Integer>(inProgressTasks.size());

    for (Runnable task : inProgressTasks) {
      // add casting here to ensure it matches the expected type in
      // submittedFlows
      Integer execId = submittedFlows.get((Future<?>) task);
      if (execId != null) {
        runningFlowIds.add(execId);
      } else {
        logger.warn("getRunningFlowIds: got null execId for task: " + task);
      }
    }

    Collections.sort(runningFlowIds);
    return runningFlowIds.toString();
  }

  public String getQueuedFlowIds() {
    List<Integer> flowIdList =
        new ArrayList<Integer>(executorService.getQueue().size());

    for (Runnable task : executorService.getQueue()) {
      Integer execId = submittedFlows.get(task);
      if (execId != null) {
        flowIdList.add(execId);
      } else {
        logger
            .warn("getQueuedFlowIds: got null execId for queuedTask: " + task);
      }
    }
    Collections.sort(flowIdList);
    return flowIdList.toString();
  }

  public int getMaxNumRunningFlows() {
    return numThreads;
  }

  public int getTheadPoolQueueSize() {
    return threadPoolQueueSize;
  }

  public void reloadJobTypePlugins() throws JobTypeManagerException {
    jobtypeManager.loadPlugins();
  }

  public int getTotalNumExecutedFlows() {
    return executorService.getTotalTasks();
  }

  @Override
  public void beforeExecute(Runnable r) {
  }

  @Override
  public void afterExecute(Runnable r) {
    submittedFlows.remove(r);
  }

  /**
   * This shuts down the flow runner. The call is blocking and awaits execution of all jobs.
   */
  public void shutdown() {
    logger.warn("Shutting down FlowRunnerManager...");
    executorService.shutdown();
    boolean result = false;
    while (!result) {
      logger.info("Awaiting Shutdown. # of executing flows: " + getNumRunningFlows());
      try {
        result = executorService.awaitTermination(1, TimeUnit.MINUTES);
      } catch (InterruptedException e) {
        logger.error(e);
      }
    }
    logger.warn("Shutdown FlowRunnerManager complete.");
  }

  /**
   * This attempts shuts down the flow runner immediately (unsafe).
   * This doesn't wait for jobs to finish but interrupts all threads.
   */
  public void shutdownNow() {
    logger.warn("Shutting down FlowRunnerManager now...");
    executorService.shutdownNow();
  }

}
