/**
 * 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.hbase;

import java.io.Closeable;
import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ClientService;
import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.MasterService;
import org.apache.hadoop.hbase.util.Threads;

/**
 * This class defines methods that can help with managing HBase clusters
 * from unit tests and system tests. There are 3 types of cluster deployments:
 * <ul>
 * <li><b>MiniHBaseCluster:</b> each server is run in the same JVM in separate threads,
 * used by unit tests</li>
 * <li><b>DistributedHBaseCluster:</b> the cluster is pre-deployed, system and integration tests can
 * interact with the cluster. </li>
 * <li><b>ProcessBasedLocalHBaseCluster:</b> each server is deployed locally but in separate
 * JVMs. </li>
 * </ul>
 * <p>
 * HBaseCluster unifies the way tests interact with the cluster, so that the same test can
 * be run against a mini-cluster during unit test execution, or a distributed cluster having
 * tens/hundreds of nodes during execution of integration tests.
 *
 * <p>
 * HBaseCluster exposes client-side public interfaces to tests, so that tests does not assume
 * running in a particular mode. Not all the tests are suitable to be run on an actual cluster,
 * and some tests will still need to mock stuff and introspect internal state. For those use
 * cases from unit tests, or if more control is needed, you can use the subclasses directly.
 * In that sense, this class does not abstract away <strong>every</strong> interface that
 * MiniHBaseCluster or DistributedHBaseCluster provide.
 */
@InterfaceAudience.Private
public abstract class HBaseCluster implements Closeable, Configurable {
  static final Log LOG = LogFactory.getLog(HBaseCluster.class.getName());
  protected Configuration conf;

  /** the status of the cluster before we begin */
  protected ClusterStatus initialClusterStatus;

  /**
   * Construct an HBaseCluster
   * @param conf Configuration to be used for cluster
   */
  public HBaseCluster(Configuration conf) {
    setConf(conf);
  }

  @Override
  public void setConf(Configuration conf) {
    this.conf = conf;
  }

  @Override
  public Configuration getConf() {
    return conf;
  }

  /**
   * Returns a ClusterStatus for this HBase cluster.
   * @see #getInitialClusterStatus()
   */
  public abstract ClusterStatus getClusterStatus() throws IOException;

  /**
   * Returns a ClusterStatus for this HBase cluster as observed at the
   * starting of the HBaseCluster
   */
  public ClusterStatus getInitialClusterStatus() throws IOException {
    return initialClusterStatus;
  }

  /**
   * Returns an {@link MasterAdminService.BlockingInterface} to the active master
   */
  public abstract MasterService.BlockingInterface getMaster()
  throws IOException;

  /**
   * Returns an AdminProtocol interface to the regionserver
   */
  public abstract AdminService.BlockingInterface getAdminProtocol(ServerName serverName)
  throws IOException;

  /**
   * Returns a ClientProtocol interface to the regionserver
   */
  public abstract ClientService.BlockingInterface getClientProtocol(ServerName serverName)
  throws IOException;

  /**
   * Starts a new region server on the given hostname or if this is a mini/local cluster,
   * starts a region server locally.
   * @param hostname the hostname to start the regionserver on
   * @throws IOException if something goes wrong
   */
  public abstract void startRegionServer(String hostname) throws IOException;

  /**
   * Kills the region server process if this is a distributed cluster, otherwise
   * this causes the region server to exit doing basic clean up only.
   * @throws IOException if something goes wrong
   */
  public abstract void killRegionServer(ServerName serverName) throws IOException;

  /**
   * Stops the given region server, by attempting a gradual stop.
   * @return whether the operation finished with success
   * @throws IOException if something goes wrong
   */
  public abstract void stopRegionServer(ServerName serverName) throws IOException;

  /**
   * Wait for the specified region server to join the cluster
   * @return whether the operation finished with success
   * @throws IOException if something goes wrong or timeout occurs
   */
  public void waitForRegionServerToStart(String hostname, long timeout)
      throws IOException {
    long start = System.currentTimeMillis();
    while ((System.currentTimeMillis() - start) < timeout) {
      for (ServerName server : getClusterStatus().getServers()) {
        if (server.getHostname().equals(hostname)) {
          return;
        }
      }
      Threads.sleep(100);
    }
    throw new IOException("did timeout waiting for region server to start:" + hostname);
  }

  /**
   * Wait for the specified region server to stop the thread / process.
   * @return whether the operation finished with success
   * @throws IOException if something goes wrong or timeout occurs
   */
  public abstract void waitForRegionServerToStop(ServerName serverName, long timeout)
      throws IOException;

  /**
   * Starts a new master on the given hostname or if this is a mini/local cluster,
   * starts a master locally.
   * @param hostname the hostname to start the master on
   * @return whether the operation finished with success
   * @throws IOException if something goes wrong
   */
  public abstract void startMaster(String hostname) throws IOException;

  /**
   * Kills the master process if this is a distributed cluster, otherwise,
   * this causes master to exit doing basic clean up only.
   * @throws IOException if something goes wrong
   */
  public abstract void killMaster(ServerName serverName) throws IOException;

  /**
   * Stops the given master, by attempting a gradual stop.
   * @throws IOException if something goes wrong
   */
  public abstract void stopMaster(ServerName serverName) throws IOException;

  /**
   * Wait for the specified master to stop the thread / process.
   * @throws IOException if something goes wrong or timeout occurs
   */
  public abstract void waitForMasterToStop(ServerName serverName, long timeout)
      throws IOException;

  /**
   * Blocks until there is an active master and that master has completed
   * initialization.
   *
   * @return true if an active master becomes available.  false if there are no
   *         masters left.
   * @throws IOException if something goes wrong or timeout occurs
   */
  public boolean waitForActiveAndReadyMaster()
      throws IOException {
    return waitForActiveAndReadyMaster(Long.MAX_VALUE);
  }

  /**
   * Blocks until there is an active master and that master has completed
   * initialization.
   * @param timeout the timeout limit in ms
   * @return true if an active master becomes available.  false if there are no
   *         masters left.
   */
  public abstract boolean waitForActiveAndReadyMaster(long timeout)
      throws IOException;

  /**
   * Wait for HBase Cluster to shut down.
   */
  public abstract void waitUntilShutDown() throws IOException;

  /**
   * Shut down the HBase cluster
   */
  public abstract void shutdown() throws IOException;

  /**
   * Restores the cluster to it's initial state if this is a real cluster,
   * otherwise does nothing.
   * This is a best effort restore. If the servers are not reachable, or insufficient
   * permissions, etc. restoration might be partial.
   * @return whether restoration is complete
   */
  public boolean restoreInitialStatus() throws IOException {
    return restoreClusterStatus(getInitialClusterStatus());
  }

  /**
   * Restores the cluster to given state if this is a real cluster,
   * otherwise does nothing.
   * This is a best effort restore. If the servers are not reachable, or insufficient
   * permissions, etc. restoration might be partial.
   * @return whether restoration is complete
   */
  public boolean restoreClusterStatus(ClusterStatus desiredStatus) throws IOException {
    return true;
  }

  /**
   * Get the ServerName of region server serving the first hbase:meta region
   */
  public ServerName getServerHoldingMeta() throws IOException {
    return getServerHoldingRegion(HRegionInfo.FIRST_META_REGIONINFO.getRegionName());
  }

  /**
   * Get the ServerName of region server serving the specified region
   * @param regionName Name of the region in bytes
   * @return ServerName that hosts the region or null
   */
  public abstract ServerName getServerHoldingRegion(byte[] regionName) throws IOException;

  /**
   * @return whether we are interacting with a distributed cluster as opposed to an
   * in-process mini/local cluster.
   */
  public boolean isDistributedCluster() {
    return false;
  }

  /**
   * Closes all the resources held open for this cluster. Note that this call does not shutdown
   * the cluster.
   * @see #shutdown()
   */
  @Override
  public abstract void close() throws IOException;

  /**
   * Wait for the namenode.
   *
   * @throws InterruptedException
   */
  public void waitForNamenodeAvailable() throws InterruptedException {
  }

  public void waitForDatanodesRegistered(int nbDN) throws Exception {
  }
}