alluxio-master-2.x/core/server/master/src/main/java/alluxio/master/AlluxioSecondaryMaster.java
/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.master;

import alluxio.Process;
import alluxio.ProcessUtils;
import alluxio.RuntimeConstants;
import alluxio.conf.Configuration;
import alluxio.conf.PropertyKey;
import alluxio.master.journal.JournalSystem;
import alluxio.master.journal.JournalUtils;
import alluxio.underfs.MasterUfsManager;
import alluxio.util.CommonUtils;
import alluxio.util.CommonUtils.ProcessType;
import alluxio.util.WaitForOptions;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeoutException;
import javax.annotation.concurrent.NotThreadSafe;

/**
 * The secondary Alluxio master that replays journal logs and writes checkpoints.
 */
@NotThreadSafe
public final class AlluxioSecondaryMaster implements Process {
  private static final Logger LOG = LoggerFactory.getLogger(AlluxioSecondaryMaster.class);
  private final MasterRegistry mRegistry = new MasterRegistry();
  private final JournalSystem mJournalSystem = new JournalSystem.Builder()
      .setLocation(JournalUtils.getJournalLocation()).build(ProcessType.MASTER);
  private final CountDownLatch mLatch = new CountDownLatch(1);

  private volatile boolean mRunning = false;

  /**
   * Creates a {@link AlluxioSecondaryMaster}.
   */
  AlluxioSecondaryMaster() {
    String baseDir = Configuration.getString(PropertyKey.SECONDARY_MASTER_METASTORE_DIR);
    // Create masters.
    MasterUtils.createMasters(mRegistry, CoreMasterContext.newBuilder()
        .setJournalSystem(mJournalSystem)
        .setPrimarySelector(new AlwaysStandbyPrimarySelector())
        .setSafeModeManager(new DefaultSafeModeManager())
        .setBackupManager(new BackupManager(mRegistry))
        .setBlockStoreFactory(MasterUtils.getBlockStoreFactory(baseDir))
        .setInodeStoreFactory(MasterUtils.getInodeStoreFactory(baseDir))
        .setStartTimeMs(System.currentTimeMillis())
        .setPort(Configuration.getInt(PropertyKey.MASTER_RPC_PORT))
        .setUfsManager(new MasterUfsManager())
        .build());
    // Check that journals of each service have been formatted.
    if (!mJournalSystem.isFormatted()) {
      throw new RuntimeException(
          String.format("Journal %s has not been formatted!", JournalUtils.getJournalLocation()));
    }
  }

  @Override
  public void start() throws Exception {
    mJournalSystem.start();
    mRunning = true;
    mLatch.await();
    mJournalSystem.stop();
    mRegistry.close();
    mRunning = false;
  }

  @Override
  public void stop() throws Exception {
    mLatch.countDown();
  }

  @Override
  public boolean waitForReady(int timeoutMs) {
    try {
      CommonUtils.waitFor("Secondary master to start", () -> mRunning,
          WaitForOptions.defaults().setTimeoutMs(timeoutMs));
      return true;
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      return false;
    } catch (TimeoutException e) {
      return false;
    }
  }

  @Override
  public String toString() {
    return "Alluxio secondary master";
  }

  /**
   * Starts the secondary Alluxio master.
   *
   * @param args command line arguments, should be empty
   */
  // TODO(peis): Move the non-static methods into AlluxioSecondaryMasterProcess for consistency.
  public static void main(String[] args) {
    if (args.length != 0) {
      LOG.info("java -cp {} {}", RuntimeConstants.ALLUXIO_JAR,
          AlluxioSecondaryMaster.class.getCanonicalName());
      System.exit(-1);
    }

    AlluxioSecondaryMaster master = new AlluxioSecondaryMaster();
    ProcessUtils.run(master);
  }
}
