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/**
 * 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.zookeeper;

import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.RpcController;

import java.io.EOFException;
import java.io.IOException;
import java.net.ConnectException;
import java.net.NoRouteToHostException;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.NotAllMetaRegionsOnlineException;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.client.ClusterConnection;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.HConnection;
import org.apache.hadoop.hbase.client.RegionReplicaUtil;
import org.apache.hadoop.hbase.client.RetriesExhaustedException;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.ipc.FailedServerException;
import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
import org.apache.hadoop.hbase.master.RegionState;
import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.MetaRegionServer;
import org.apache.hadoop.hbase.regionserver.RegionServerStoppedException;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.zookeeper.KeeperException;

/**
 * Utility class to perform operation (get/wait for/verify/set/delete) on znode in ZooKeeper
 * which keeps hbase:meta region server location.
 *
 * Stateless class with a bunch of static methods. Doesn't manage resources passed in
 * (e.g. HConnection, ZooKeeperWatcher etc).
 *
 * Meta region location is set by RegionServerServices.
 * This class doesn't use ZK watchers, rather accesses ZK directly.
 *
 * This class it stateless. The only reason it's not made a non-instantiable util class
 * with a collection of static methods is that it'd be rather hard to mock properly in tests.
 *
 * TODO: rewrite using RPC calls to master to find out about hbase:meta.
 */
@InterfaceAudience.Private
public class MetaTableLocator {
  private static final Log LOG = LogFactory.getLog(MetaTableLocator.class);

  // only needed to allow non-timeout infinite waits to stop when cluster shuts down
  private volatile boolean stopped = false;

  /**
   * Checks if the meta region location is available.
   * @return true if meta region location is available, false if not
   */
  public boolean isLocationAvailable(ZooKeeperWatcher zkw) {
    return getMetaRegionLocation(zkw) != null;
  }

  /**
   * @param zkw ZooKeeper watcher to be used
   * @return meta table regions and their locations.
   */
  public List> getMetaRegionsAndLocations(ZooKeeperWatcher zkw) {
    return getMetaRegionsAndLocations(zkw, HRegionInfo.DEFAULT_REPLICA_ID);
  }

  /**
   * 
   * @param zkw
   * @param replicaId
   * @return meta table regions and their locations.
   */
  public List> getMetaRegionsAndLocations(ZooKeeperWatcher zkw,
      int replicaId) {
    ServerName serverName = getMetaRegionLocation(zkw, replicaId);
    List> list = new ArrayList>();
    list.add(new Pair(RegionReplicaUtil.getRegionInfoForReplica(
        HRegionInfo.FIRST_META_REGIONINFO, replicaId), serverName));
    return list;
  }

  /**
   * @param zkw ZooKeeper watcher to be used
   * @return List of meta regions
   */
  public List getMetaRegions(ZooKeeperWatcher zkw) {
    return getMetaRegions(zkw, HRegionInfo.DEFAULT_REPLICA_ID);
  }

  /**
   * 
   * @param zkw
   * @param replicaId
   * @return List of meta regions
   */
  public List getMetaRegions(ZooKeeperWatcher zkw, int replicaId) {
    List> result;
    result = getMetaRegionsAndLocations(zkw, replicaId);
    return getListOfHRegionInfos(result);
  }

  private List getListOfHRegionInfos(
      final List> pairs) {
    if (pairs == null || pairs.isEmpty()) return null;
    List result = new ArrayList(pairs.size());
    for (Pair pair: pairs) {
      result.add(pair.getFirst());
    }
    return result;
  }

  /**
   * Gets the meta region location, if available.  Does not block.
   * @param zkw zookeeper connection to use
   * @return server name or null if we failed to get the data.
   */
  public ServerName getMetaRegionLocation(final ZooKeeperWatcher zkw) {
    try {
      RegionState state = getMetaRegionState(zkw);
      return state.isOpened() ? state.getServerName() : null;
    } catch (KeeperException ke) {
      return null;
    }
  }

  /**
   * Gets the meta region location, if available.  Does not block.
   * @param zkw
   * @param replicaId
   * @return server name
   */
  public ServerName getMetaRegionLocation(final ZooKeeperWatcher zkw, int replicaId) {
    try {
      RegionState state = getMetaRegionState(zkw, replicaId);
      return state.isOpened() ? state.getServerName() : null;
    } catch (KeeperException ke) {
      return null;
    }
  }

  /**
   * Gets the meta region location, if available, and waits for up to the
   * specified timeout if not immediately available.
   * Given the zookeeper notification could be delayed, we will try to
   * get the latest data.
   * @param zkw
   * @param timeout maximum time to wait, in millis
   * @return server name for server hosting meta region formatted as per
   * {@link ServerName}, or null if none available
   * @throws InterruptedException if interrupted while waiting
   * @throws NotAllMetaRegionsOnlineException
   */
  public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw, long timeout)
  throws InterruptedException, NotAllMetaRegionsOnlineException {
    return waitMetaRegionLocation(zkw, HRegionInfo.DEFAULT_REPLICA_ID, timeout);
  }

  /**
   * Gets the meta region location, if available, and waits for up to the
   * specified timeout if not immediately available.
   * Given the zookeeper notification could be delayed, we will try to
   * get the latest data.
   * @param zkw
   * @param replicaId
   * @param timeout maximum time to wait, in millis
   * @return server name for server hosting meta region formatted as per
   * {@link ServerName}, or null if none available
   * @throws InterruptedException
   * @throws NotAllMetaRegionsOnlineException
   */
  public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw, int replicaId, long timeout)
  throws InterruptedException, NotAllMetaRegionsOnlineException {
    try {
      if (ZKUtil.checkExists(zkw, zkw.baseZNode) == -1) {
        String errorMsg = "Check the value configured in 'zookeeper.znode.parent'. "
            + "There could be a mismatch with the one configured in the master.";
        LOG.error(errorMsg);
        throw new IllegalArgumentException(errorMsg);
      }
    } catch (KeeperException e) {
      throw new IllegalStateException("KeeperException while trying to check baseZNode:", e);
    }
    ServerName sn = blockUntilAvailable(zkw, replicaId, timeout);

    if (sn == null) {
      throw new NotAllMetaRegionsOnlineException("Timed out; " + timeout + "ms");
    }

    return sn;
  }

  /**
   * Waits indefinitely for availability of hbase:meta.  Used during
   * cluster startup.  Does not verify meta, just that something has been
   * set up in zk.
   * @see #waitMetaRegionLocation(org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher, long)
   * @throws InterruptedException if interrupted while waiting
   */
  public void waitMetaRegionLocation(ZooKeeperWatcher zkw) throws InterruptedException {
    long startTime = System.currentTimeMillis();
    while (!stopped) {
      try {
        if (waitMetaRegionLocation(zkw, 100) != null) break;
        long sleepTime = System.currentTimeMillis() - startTime;
        // +1 in case sleepTime=0
        if ((sleepTime + 1) % 10000 == 0) {
          LOG.warn("Have been waiting for meta to be assigned for " + sleepTime + "ms");
        }
      } catch (NotAllMetaRegionsOnlineException e) {
        if (LOG.isTraceEnabled()) {
          LOG.trace("hbase:meta still not available, sleeping and retrying." +
            " Reason: " + e.getMessage());
        }
      }
    }
  }

  /**
   * Verify hbase:meta is deployed and accessible.
   * @param hConnection
   * @param zkw
   * @param timeout How long to wait on zk for meta address (passed through to
   * the internal call to {@link #getMetaServerConnection}.
   * @return True if the hbase:meta location is healthy.
   * @throws java.io.IOException
   * @throws InterruptedException
   */
  public boolean verifyMetaRegionLocation(HConnection hConnection,
      ZooKeeperWatcher zkw, final long timeout)
  throws InterruptedException, IOException {
    return verifyMetaRegionLocation(hConnection, zkw, timeout, HRegionInfo.DEFAULT_REPLICA_ID);
  }

  /**
   * Verify hbase:meta is deployed and accessible.
   * @param hConnection
   * @param zkw
   * @param timeout How long to wait on zk for meta address (passed through to
   * @param replicaId
   * @return True if the hbase:meta location is healthy.
   * @throws InterruptedException
   * @throws IOException
   */
  public boolean verifyMetaRegionLocation(HConnection hConnection,
      ZooKeeperWatcher zkw, final long timeout, int replicaId)
  throws InterruptedException, IOException {
    AdminProtos.AdminService.BlockingInterface service = null;
    try {
      service = getMetaServerConnection(hConnection, zkw, timeout, replicaId);
    } catch (NotAllMetaRegionsOnlineException e) {
      // Pass
    } catch (ServerNotRunningYetException e) {
      // Pass -- remote server is not up so can't be carrying root
    } catch (UnknownHostException e) {
      // Pass -- server name doesn't resolve so it can't be assigned anything.
    } catch (RegionServerStoppedException e) {
      // Pass -- server name sends us to a server that is dying or already dead.
    }
    return (service != null) && verifyRegionLocation(hConnection, service,
            getMetaRegionLocation(zkw, replicaId), RegionReplicaUtil.getRegionInfoForReplica(
                HRegionInfo.FIRST_META_REGIONINFO, replicaId).getRegionName());
  }

  /**
   * Verify we can connect to hostingServer and that its carrying
   * regionName.
   * @param hostingServer Interface to the server hosting regionName
   * @param address The servername that goes with the metaServer
   * Interface.  Used logging.
   * @param regionName The regionname we are interested in.
   * @return True if we were able to verify the region located at other side of
   * the Interface.
   * @throws IOException
   */
  // TODO: We should be able to get the ServerName from the AdminProtocol
  // rather than have to pass it in.  Its made awkward by the fact that the
  // HRI is likely a proxy against remote server so the getServerName needs
  // to be fixed to go to a local method or to a cache before we can do this.
  private boolean verifyRegionLocation(final Connection connection,
      AdminService.BlockingInterface hostingServer, final ServerName address,
      final byte [] regionName)
  throws IOException {
    if (hostingServer == null) {
      LOG.info("Passed hostingServer is null");
      return false;
    }
    Throwable t;
    RpcController controller = null;
    if (connection instanceof ClusterConnection) {
      controller = ((ClusterConnection) connection).getRpcControllerFactory().newController();
    }
    try {
      // Try and get regioninfo from the hosting server.
      return ProtobufUtil.getRegionInfo(controller, hostingServer, regionName) != null;
    } catch (ConnectException e) {
      t = e;
    } catch (RetriesExhaustedException e) {
      t = e;
    } catch (RemoteException e) {
      IOException ioe = e.unwrapRemoteException();
      t = ioe;
    } catch (IOException e) {
      Throwable cause = e.getCause();
      if (cause != null && cause instanceof EOFException) {
        t = cause;
      } else if (cause != null && cause.getMessage() != null
          && cause.getMessage().contains("Connection reset")) {
        t = cause;
      } else {
        t = e;
      }
    }
    LOG.info("Failed verification of " + Bytes.toStringBinary(regionName) +
      " at address=" + address + ", exception=" + t.getMessage());
    return false;
  }

  /**
   * Gets a connection to the server hosting meta, as reported by ZooKeeper,
   * waiting up to the specified timeout for availability.
   * 

WARNING: Does not retry. Use an {@link org.apache.hadoop.hbase.client.HTable} instead. * @param hConnection * @param zkw * @param timeout How long to wait on meta location * @param replicaId * @return connection to server hosting meta * @throws InterruptedException * @throws NotAllMetaRegionsOnlineException if timed out waiting * @throws IOException */ private AdminService.BlockingInterface getMetaServerConnection(HConnection hConnection, ZooKeeperWatcher zkw, long timeout, int replicaId) throws InterruptedException, NotAllMetaRegionsOnlineException, IOException { return getCachedConnection(hConnection, waitMetaRegionLocation(zkw, replicaId, timeout)); } /** * @param sn ServerName to get a connection against. * @return The AdminProtocol we got when we connected to sn * May have come from cache, may not be good, may have been setup by this * invocation, or may be null. * @throws IOException */ @SuppressWarnings("deprecation") private static AdminService.BlockingInterface getCachedConnection(HConnection hConnection, ServerName sn) throws IOException { if (sn == null) { return null; } AdminService.BlockingInterface service = null; try { service = hConnection.getAdmin(sn); } catch (RetriesExhaustedException e) { if (e.getCause() != null && e.getCause() instanceof ConnectException) { // Catch this; presume it means the cached connection has gone bad. } else { throw e; } } catch (SocketTimeoutException e) { LOG.debug("Timed out connecting to " + sn); } catch (NoRouteToHostException e) { LOG.debug("Connecting to " + sn, e); } catch (SocketException e) { LOG.debug("Exception connecting to " + sn); } catch (UnknownHostException e) { LOG.debug("Unknown host exception connecting to " + sn); } catch (FailedServerException e) { if (LOG.isDebugEnabled()) { LOG.debug("Server " + sn + " is in failed server list."); } } catch (IOException ioe) { Throwable cause = ioe.getCause(); if (ioe instanceof ConnectException) { // Catch. Connect refused. } else if (cause != null && cause instanceof EOFException) { // Catch. Other end disconnected us. } else if (cause != null && cause.getMessage() != null && cause.getMessage().toLowerCase(Locale.ROOT).contains("connection reset")) { // Catch. Connection reset. } else { throw ioe; } } return service; } /** * Sets the location of hbase:meta in ZooKeeper to the * specified server address. * @param zookeeper zookeeper reference * @param serverName The server hosting hbase:meta * @param state The region transition state * @throws KeeperException unexpected zookeeper exception */ public static void setMetaLocation(ZooKeeperWatcher zookeeper, ServerName serverName, RegionState.State state) throws KeeperException { setMetaLocation(zookeeper, serverName, HRegionInfo.DEFAULT_REPLICA_ID, state); } /** * Sets the location of hbase:meta in ZooKeeper to the * specified server address. * @param zookeeper * @param serverName * @param replicaId * @param state * @throws KeeperException */ public static void setMetaLocation(ZooKeeperWatcher zookeeper, ServerName serverName, int replicaId, RegionState.State state) throws KeeperException { LOG.info("Setting hbase:meta region location in ZooKeeper as " + serverName); // Make the MetaRegionServer pb and then get its bytes and save this as // the znode content. MetaRegionServer pbrsr = MetaRegionServer.newBuilder() .setServer(ProtobufUtil.toServerName(serverName)) .setRpcVersion(HConstants.RPC_CURRENT_VERSION) .setState(state.convert()).build(); byte[] data = ProtobufUtil.prependPBMagic(pbrsr.toByteArray()); try { ZKUtil.setData(zookeeper, zookeeper.getZNodeForReplica(replicaId), data); } catch(KeeperException.NoNodeException nne) { if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { LOG.debug("META region location doesn't exist, create it"); } else { LOG.debug("META region location doesn't exist for replicaId " + replicaId + ", create it"); } ZKUtil.createAndWatch(zookeeper, zookeeper.getZNodeForReplica(replicaId), data); } } /** * Load the meta region state from the meta server ZNode. */ public static RegionState getMetaRegionState(ZooKeeperWatcher zkw) throws KeeperException { return getMetaRegionState(zkw, HRegionInfo.DEFAULT_REPLICA_ID); } /** * Load the meta region state from the meta server ZNode. * @param zkw * @param replicaId * @return regionstate * @throws KeeperException */ public static RegionState getMetaRegionState(ZooKeeperWatcher zkw, int replicaId) throws KeeperException { RegionState.State state = RegionState.State.OPEN; ServerName serverName = null; try { byte[] data = ZKUtil.getData(zkw, zkw.getZNodeForReplica(replicaId)); if (data != null && data.length > 0 && ProtobufUtil.isPBMagicPrefix(data)) { try { int prefixLen = ProtobufUtil.lengthOfPBMagic(); ZooKeeperProtos.MetaRegionServer rl = ZooKeeperProtos.MetaRegionServer.PARSER.parseFrom (data, prefixLen, data.length - prefixLen); if (rl.hasState()) { state = RegionState.State.convert(rl.getState()); } HBaseProtos.ServerName sn = rl.getServer(); serverName = ServerName.valueOf( sn.getHostName(), sn.getPort(), sn.getStartCode()); } catch (InvalidProtocolBufferException e) { throw new DeserializationException("Unable to parse meta region location"); } } else { // old style of meta region location? serverName = ServerName.parseFrom(data); } } catch (DeserializationException e) { throw ZKUtil.convert(e); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } if (serverName == null) { state = RegionState.State.OFFLINE; } return new RegionState( RegionReplicaUtil.getRegionInfoForReplica(HRegionInfo.FIRST_META_REGIONINFO, replicaId), state, serverName); } /** * Deletes the location of hbase:meta in ZooKeeper. * @param zookeeper zookeeper reference * @throws KeeperException unexpected zookeeper exception */ public void deleteMetaLocation(ZooKeeperWatcher zookeeper) throws KeeperException { deleteMetaLocation(zookeeper, HRegionInfo.DEFAULT_REPLICA_ID); } public void deleteMetaLocation(ZooKeeperWatcher zookeeper, int replicaId) throws KeeperException { if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { LOG.info("Deleting hbase:meta region location in ZooKeeper"); } else { LOG.info("Deleting hbase:meta for " + replicaId + " region location in ZooKeeper"); } try { // Just delete the node. Don't need any watches. ZKUtil.deleteNode(zookeeper, zookeeper.getZNodeForReplica(replicaId)); } catch(KeeperException.NoNodeException nne) { // Has already been deleted } } /** * Wait until the primary meta region is available. Get the secondary * locations as well but don't block for those. * @param zkw * @param timeout * @param conf * @return ServerName or null if we timed out. * @throws InterruptedException */ public List blockUntilAvailable(final ZooKeeperWatcher zkw, final long timeout, Configuration conf) throws InterruptedException { int numReplicasConfigured = 1; List servers = new ArrayList(); // Make the blocking call first so that we do the wait to know // the znodes are all in place or timeout. ServerName server = blockUntilAvailable(zkw, timeout); if (server == null) return null; servers.add(server); try { List metaReplicaNodes = zkw.getMetaReplicaNodes(); numReplicasConfigured = metaReplicaNodes.size(); } catch (KeeperException e) { LOG.warn("Got ZK exception " + e); } for (int replicaId = 1; replicaId < numReplicasConfigured; replicaId++) { // return all replica locations for the meta servers.add(getMetaRegionLocation(zkw, replicaId)); } return servers; } /** * Wait until the meta region is available and is not in transition. * @param zkw zookeeper connection to use * @param timeout maximum time to wait, in millis * @return ServerName or null if we timed out. * @throws InterruptedException */ public ServerName blockUntilAvailable(final ZooKeeperWatcher zkw, final long timeout) throws InterruptedException { return blockUntilAvailable(zkw, HRegionInfo.DEFAULT_REPLICA_ID, timeout); } /** * Wait until the meta region is available and is not in transition. * @param zkw * @param replicaId * @param timeout * @return ServerName or null if we timed out. * @throws InterruptedException */ public ServerName blockUntilAvailable(final ZooKeeperWatcher zkw, int replicaId, final long timeout) throws InterruptedException { if (timeout < 0) throw new IllegalArgumentException(); if (zkw == null) throw new IllegalArgumentException(); long startTime = System.currentTimeMillis(); ServerName sn = null; while (true) { sn = getMetaRegionLocation(zkw, replicaId); if (sn != null || (System.currentTimeMillis() - startTime) > timeout - HConstants.SOCKET_RETRY_WAIT_MS) { break; } Thread.sleep(HConstants.SOCKET_RETRY_WAIT_MS); } return sn; } /** * Stop working. * Interrupts any ongoing waits. */ public void stop() { if (!stopped) { LOG.debug("Stopping MetaTableLocator"); stopped = true; } } }





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