/**
    * 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.client;
  
  import static org.apache.hadoop.hbase.HConstants.EMPTY_END_ROW;
  import static org.apache.hadoop.hbase.HConstants.EMPTY_START_ROW;
  
  import com.google.common.annotations.VisibleForTesting;
  
  import java.io.IOException;
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.List;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.ThreadLocalRandom;
  
  import org.apache.commons.logging.Log;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellComparator;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ClientService;
  import org.apache.hadoop.hbase.security.User;
  import org.apache.hadoop.hbase.security.UserProvider;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * Utility used by client connections.
   */
  @InterfaceAudience.Private
  public class ConnectionUtils {
  
    /**
     * Calculate pause time.
     * Built on {@link HConstants#RETRY_BACKOFF}.
     * @param pause
     * @param tries
     * @return How long to wait after <code>tries</code> retries
     */
    public static long getPauseTime(final long pause, final int tries) {
      int ntries = tries;
      if (ntries >= HConstants.RETRY_BACKOFF.length) {
        ntries = HConstants.RETRY_BACKOFF.length - 1;
      }
      if (ntries < 0) {
        ntries = 0;
      }
  
      long normalPause = pause * HConstants.RETRY_BACKOFF[ntries];
      // 1% possible jitter
      long jitter = (long) (normalPause * ThreadLocalRandom.current().nextFloat() * 0.01f);
      return normalPause + jitter;
    }
  
  
    /**
     * @param conn The connection for which to replace the generator.
     * @param cnm Replaces the nonce generator used, for testing.
     * @return old nonce generator.
     */
    public static NonceGenerator injectNonceGeneratorForTesting(
        ClusterConnection conn, NonceGenerator cnm) {
      return ConnectionManager.injectNonceGeneratorForTesting(conn, cnm);
    }
  
    /**
     * Changes the configuration to set the number of retries needed when using HConnection
     * internally, e.g. for  updating catalog tables, etc.
     * Call this method before we create any Connections.
     * @param c The Configuration instance to set the retries into.
     * @param log Used to log what we set in here.
     */
    public static void setServerSideHConnectionRetriesConfig(
        final Configuration c, final String sn, final Log log) {
      // TODO: Fix this. Not all connections from server side should have 10 times the retries.
      int hcRetries = c.getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER,
        HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER);
      // Go big.  Multiply by 10.  If we can't get to meta after this many retries
     // then something seriously wrong.
     int serversideMultiplier = c.getInt("hbase.client.serverside.retries.multiplier", 10);
     int retries = hcRetries * serversideMultiplier;
     c.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, retries);
     log.info(sn + " server-side HConnection retries=" + retries);
   }
 
   /**
    * Adapt a HConnection so that it can bypass the RPC layer (serialization,
    * deserialization, networking, etc..) -- i.e. short-circuit -- when talking to a local server.
    * @param conn the connection to adapt
    * @param serverName the local server name
    * @param admin the admin interface of the local server
    * @param client the client interface of the local server
    * @return an adapted/decorated HConnection
    */
   @Deprecated
   public static ClusterConnection createShortCircuitHConnection(final Connection conn,
       final ServerName serverName, final AdminService.BlockingInterface admin,
       final ClientService.BlockingInterface client) {
     return new ConnectionAdapter(conn) {
       @Override
       public AdminService.BlockingInterface getAdmin(
           ServerName sn, boolean getMaster) throws IOException {
         return serverName.equals(sn) ? admin : super.getAdmin(sn, getMaster);
       }
 
       @Override
       public ClientService.BlockingInterface getClient(
           ServerName sn) throws IOException {
         return serverName.equals(sn) ? client : super.getClient(sn);
       }
     };
   }
 
   /**
    * Creates a short-circuit connection that can bypass the RPC layer (serialization,
    * deserialization, networking, etc..) when talking to a local server.
    * @param conf the current configuration
    * @param pool the thread pool to use for batch operations
    * @param user the user the connection is for
    * @param serverName the local server name
    * @param admin the admin interface of the local server
    * @param client the client interface of the local server
    * @return a short-circuit connection.
    * @throws IOException
    */
   public static ClusterConnection createShortCircuitConnection(final Configuration conf,
     ExecutorService pool, User user, final ServerName serverName,
     final AdminService.BlockingInterface admin, final ClientService.BlockingInterface client)
     throws IOException {
     if (user == null) {
       user = UserProvider.instantiate(conf).getCurrent();
     }
     return new ConnectionManager.HConnectionImplementation(conf, false, pool, user) {
       @Override
       public AdminService.BlockingInterface getAdmin(ServerName sn, boolean getMaster)
         throws IOException {
         return serverName.equals(sn) ? admin : super.getAdmin(sn, getMaster);
       }
 
       @Override
       public ClientService.BlockingInterface getClient(ServerName sn) throws IOException {
         return serverName.equals(sn) ? client : super.getClient(sn);
       }
     };
   }
 
   /**
    * Setup the connection class, so that it will not depend on master being online. Used for testing
    * @param conf configuration to set
    */
   @VisibleForTesting
   public static void setupMasterlessConnection(Configuration conf) {
     conf.set(HConnection.HBASE_CLIENT_CONNECTION_IMPL,
       MasterlessConnection.class.getName());
   }
 
   /**
    * Some tests shut down the master. But table availability is a master RPC which is performed on
    * region re-lookups.
    */
   static class MasterlessConnection extends ConnectionManager.HConnectionImplementation {
     MasterlessConnection(Configuration conf, boolean managed,
       ExecutorService pool, User user) throws IOException {
       super(conf, managed, pool, user);
     }
 
     @Override
     public boolean isTableDisabled(TableName tableName) throws IOException {
       // treat all tables as enabled
       return false;
     }
   }
 
   // A byte array in which all elements are the max byte, and it is used to
   // construct closest front row
   static final byte[] MAX_BYTE_ARRAY = Bytes.createMaxByteArray(9);
 
   /**
    * Create the closest row after the specified row
    */
   static byte[] createClosestRowAfter(byte[] row) {
     return Arrays.copyOf(row, row.length + 1);
   }
 
   /**
    * Create a row before the specified row and very close to the specified row.
    */
   static byte[] createCloseRowBefore(byte[] row) {
     if (row.length == 0) {
       return MAX_BYTE_ARRAY;
     }
     if (row[row.length - 1] == 0) {
       return Arrays.copyOf(row, row.length - 1);
     } else {
       byte[] nextRow = new byte[row.length + MAX_BYTE_ARRAY.length];
       System.arraycopy(row, 0, nextRow, 0, row.length - 1);
       nextRow[row.length - 1] = (byte) ((row[row.length - 1] & 0xFF) - 1);
       System.arraycopy(MAX_BYTE_ARRAY, 0, nextRow, row.length, MAX_BYTE_ARRAY.length);
       return nextRow;
     }
   }
 
   static boolean isEmptyStartRow(byte[] row) {
     return Bytes.equals(row, EMPTY_START_ROW);
   }
 
   static boolean isEmptyStopRow(byte[] row) {
     return Bytes.equals(row, EMPTY_END_ROW);
   }
 
   private static final Comparator<Cell> COMPARE_WITHOUT_ROW = new Comparator<Cell>() {
 
     @Override
     public int compare(Cell o1, Cell o2) {
       return CellComparator.compareWithoutRow(o1, o2);
     }
   };
 
   static Result filterCells(Result result, Cell keepCellsAfter) {
     if (keepCellsAfter == null) {
       // do not need to filter
       return result;
     }
     // not the same row
     if (!CellUtil.matchingRow(keepCellsAfter, result.getRow(), 0, result.getRow().length)) {
       return result;
     }
     Cell[] rawCells = result.rawCells();
     int index = Arrays.binarySearch(rawCells, keepCellsAfter, COMPARE_WITHOUT_ROW);
     if (index < 0) {
       index = -index - 1;
     } else {
       index++;
     }
     if (index == 0) {
       return result;
     }
     if (index == rawCells.length) {
       return null;
     }
     return Result.create(Arrays.copyOfRange(rawCells, index, rawCells.length), null,
       result.isStale(), result.mayHaveMoreCellsInRow());
   }
 
   static boolean noMoreResultsForScan(Scan scan, HRegionInfo info) {
     if (isEmptyStopRow(info.getEndKey())) {
       return true;
     }
     if (isEmptyStopRow(scan.getStopRow())) {
       return false;
     }
     int c = Bytes.compareTo(info.getEndKey(), scan.getStopRow());
     // 1. if our stop row is less than the endKey of the region
     // 2. if our stop row is equal to the endKey of the region and we do not include the stop row
     // for scan.
     return c > 0 || (c == 0 && !scan.includeStopRow());
   }
 
   static boolean noMoreResultsForReverseScan(Scan scan, HRegionInfo info) {
     if (isEmptyStartRow(info.getStartKey())) {
       return true;
     }
     if (isEmptyStopRow(scan.getStopRow())) {
       return false;
     }
     // no need to test the inclusive of the stop row as the start key of a region is included in
     // the region.
     return Bytes.compareTo(info.getStartKey(), scan.getStopRow()) <= 0;
   }
 
   public static ScanResultCache createScanResultCache(Scan scan, List<Result> cache) {
     if (scan.getAllowPartialResults()) {
       return new AllowPartialScanResultCache(cache);
     } else if (scan.getBatch() > 0) {
       return new BatchScanResultCache(cache, scan.getBatch());
     } else {
       return new CompleteScanResultCache(cache);
     }
   }
 }