/**
    * Copyright 2007 The Apache Software Foundation
    *
    * 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.regionserver.wal;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.EOFException;
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.io.WritableComparable;
  
  /**
   * A Key for an entry in the change log.
   *
   * The log intermingles edits to many tables and rows, so each log entry
   * identifies the appropriate table and row.  Within a table and row, they're
   * also sorted.
   *
   * <p>Some Transactional edits (START, COMMIT, ABORT) will not have an
   * associated row.
   */
  public class HLogKey implements WritableComparable<HLogKey> {
    private byte [] regionName;
    private byte [] tablename;
    private long logSeqNum;
    // Time at which this edit was written.
    private long writeTime;
  
    private byte clusterId;
    private int scope;
  
    /** Writable Consructor -- Do not use. */
    public HLogKey() {
      this(null, null, 0L, HConstants.LATEST_TIMESTAMP);
    }
  
    /**
     * Create the log key!
     * We maintain the tablename mainly for debugging purposes.
     * A regionName is always a sub-table object.
     *
     * @param regionName  - name of region
     * @param tablename   - name of table
     * @param logSeqNum   - log sequence number
     * @param now Time at which this edit was written.
     */
    public HLogKey(final byte [] regionName, final byte [] tablename,
        long logSeqNum, final long now) {
      this.regionName = regionName;
      this.tablename = tablename;
      this.logSeqNum = logSeqNum;
      this.writeTime = now;
      this.clusterId = HConstants.DEFAULT_CLUSTER_ID;
      this.scope = HConstants.REPLICATION_SCOPE_LOCAL;
    }
  
    //////////////////////////////////////////////////////////////////////////////
    // A bunch of accessors
    //////////////////////////////////////////////////////////////////////////////
  
    /** @return region name */
    public byte [] getRegionName() {
      return regionName;
    }
  
    /** @return table name */
    public byte [] getTablename() {
      return tablename;
    }
  
    /** @return log sequence number */
    public long getLogSeqNum() {
      return logSeqNum;
    }
  
    void setLogSeqNum(long logSeqNum) {
      this.logSeqNum = logSeqNum;
    }
  
    /**
    * @return the write time
    */
   public long getWriteTime() {
     return this.writeTime;
   }
 
   /**
    * Get the id of the original cluster
    * @return
    */
   public byte getClusterId() {
     return clusterId;
   }
 
   /**
    * Set the cluster id of this key
    * @param clusterId
    */
   public void setClusterId(byte clusterId) {
     this.clusterId = clusterId;
   }
 
   /**
    * Get the replication scope of this key
    * @return replication scope
    */
   public int getScope() {
     return this.scope;
   }
 
   /**
    * Set the replication scope of this key
    * @param scope The new scope
    */
   public void setScope(int scope) {
     this.scope = scope;
   }
 
   @Override
   public String toString() {
     return Bytes.toString(tablename) + "/" + Bytes.toString(regionName) + "/" +
       logSeqNum;
   }
 
   @Override
   public boolean equals(Object obj) {
     if (this == obj) {
       return true;
     }
     if (obj == null || getClass() != obj.getClass()) {
       return false;
     }
     return compareTo((HLogKey)obj) == 0;
   }
 
   @Override
   public int hashCode() {
     int result = Bytes.hashCode(this.regionName);
     result ^= this.logSeqNum;
     result ^= this.writeTime;
     result ^= this.clusterId;
     result ^= this.scope;
     return result;
   }
 
   public int compareTo(HLogKey o) {
     int result = Bytes.compareTo(this.regionName, o.regionName);
     if (result == 0) {
       if (this.logSeqNum < o.logSeqNum) {
         result = -1;
       } else if (this.logSeqNum > o.logSeqNum) {
         result = 1;
       }
       if (result == 0) {
         if (this.writeTime < o.writeTime) {
           result = -1;
         } else if (this.writeTime > o.writeTime) {
           return 1;
         }
       }
     }
     return result;
   }
 
   public void write(DataOutput out) throws IOException {
     Bytes.writeByteArray(out, this.regionName);
     Bytes.writeByteArray(out, this.tablename);
     out.writeLong(this.logSeqNum);
     out.writeLong(this.writeTime);
     out.writeByte(this.clusterId);
     out.writeInt(this.scope);
   }
 
   public void readFields(DataInput in) throws IOException {
     this.regionName = Bytes.readByteArray(in);
     this.tablename = Bytes.readByteArray(in);
     this.logSeqNum = in.readLong();
     this.writeTime = in.readLong();
     try {
       this.clusterId = in.readByte();
       this.scope = in.readInt();
     } catch(EOFException e) {
       // Means it's an old key, just continue
     }
   }
 
 }