/**
    *
    * 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;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.io.TimeRange;
  import org.apache.hadoop.hbase.util.Writables;
  import org.apache.hadoop.io.Writable;
  
  /**
   * Stores minimum and maximum timestamp values.
   * Use this class at write-time ONLY. Too much synchronization to use at read time
   * (TODO: there are two scenarios writing, once when lots of concurrency as part of memstore
   * updates but then later we can make one as part of a compaction when there is only one thread
   * involved -- consider making different version, the synchronized and the unsynchronized).
   * Use {@link TimeRange} at read time instead of this. See toTimeRange() to make TimeRange to use.
   * MemStores use this class to track minimum and maximum timestamps. The TimeRangeTracker made by
   * the MemStore is passed to the StoreFile for it to write out as part a flush in the the file
   * metadata. If no memstore involved -- i.e. a compaction -- then the StoreFile will calculate its
   * own TimeRangeTracker as it appends. The StoreFile serialized TimeRangeTracker is used
   * at read time via an instance of {@link TimeRange} to test if Cells fit the StoreFile TimeRange.
   */
  @InterfaceAudience.Private
  public class TimeRangeTracker implements Writable {
    static final long INITIAL_MIN_TIMESTAMP = Long.MAX_VALUE;
    static final long INITIAL_MAX_TIMESTAMP = -1L;
    long minimumTimestamp = INITIAL_MIN_TIMESTAMP;
    long maximumTimestamp = INITIAL_MAX_TIMESTAMP;
  
    /**
     * Default constructor.
     * Initializes TimeRange to be null
     */
    public TimeRangeTracker() {}
  
    /**
     * Copy Constructor
     * @param trt source TimeRangeTracker
     */
    public TimeRangeTracker(final TimeRangeTracker trt) {
      set(trt.getMin(), trt.getMax());
    }
  
    public TimeRangeTracker(long minimumTimestamp, long maximumTimestamp) {
      set(minimumTimestamp, maximumTimestamp);
    }
  
    private void set(final long min, final long max) {
      this.minimumTimestamp = min;
      this.maximumTimestamp = max;
    }
  
    /**
     * @param l
     * @return True if we initialized values
     */
    private boolean init(final long l) {
      if (this.minimumTimestamp != INITIAL_MIN_TIMESTAMP) return false;
      set(l, l);
      return true;
    }
  
    /**
     * Update the current TimestampRange to include the timestamp from <code>cell</code>.
     * If the Key is of type DeleteColumn or DeleteFamily, it includes the
     * entire time range from 0 to timestamp of the key.
     * @param cell the Cell to include
     */
    public void includeTimestamp(final Cell cell) {
      includeTimestamp(cell.getTimestamp());
      if (CellUtil.isDeleteColumnOrFamily(cell)) {
        includeTimestamp(0);
      }
    }
  
    /**
     * If required, update the current TimestampRange to include timestamp
    * @param timestamp the timestamp value to include
    */
   @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="MT_CORRECTNESS",
       justification="Intentional")
   void includeTimestamp(final long timestamp) {
     // Do test outside of synchronization block.  Synchronization in here can be problematic
     // when many threads writing one Store -- they can all pile up trying to add in here.
     // Happens when doing big write upload where we are hammering on one region.
     if (timestamp < this.minimumTimestamp) {
       synchronized (this) {
         if (!init(timestamp)) {
           if (timestamp < this.minimumTimestamp) {
             this.minimumTimestamp = timestamp;
           }
         }
       }
     } else if (timestamp > this.maximumTimestamp) {
       synchronized (this) {
         if (!init(timestamp)) {
           if (this.maximumTimestamp < timestamp) {
             this.maximumTimestamp =  timestamp;
           }
         }
       }
     }
   }
 
   /**
    * Check if the range has ANY overlap with TimeRange
    * @param tr TimeRange
    * @return True if there is overlap, false otherwise
    */
   public synchronized boolean includesTimeRange(final TimeRange tr) {
     return (this.minimumTimestamp < tr.getMax() && this.maximumTimestamp >= tr.getMin());
   }
 
   /**
    * @return the minimumTimestamp
    */
   public synchronized long getMin() {
     return minimumTimestamp;
   }
 
   /**
    * @return the maximumTimestamp
    */
   public synchronized long getMax() {
     return maximumTimestamp;
   }
 
   public synchronized void write(final DataOutput out) throws IOException {
     out.writeLong(minimumTimestamp);
     out.writeLong(maximumTimestamp);
   }
 
   public synchronized void readFields(final DataInput in) throws IOException {
     this.minimumTimestamp = in.readLong();
     this.maximumTimestamp = in.readLong();
   }
 
   @Override
   public synchronized String toString() {
     return "[" + minimumTimestamp + "," + maximumTimestamp + "]";
   }
 
   /**
    * @return An instance of TimeRangeTracker filled w/ the content of serialized
    * TimeRangeTracker in <code>timeRangeTrackerBytes</code>.
    * @throws IOException
    */
   public static TimeRangeTracker getTimeRangeTracker(final byte [] timeRangeTrackerBytes)
   throws IOException {
     if (timeRangeTrackerBytes == null) return null;
     TimeRangeTracker trt = new TimeRangeTracker();
     Writables.copyWritable(timeRangeTrackerBytes, trt);
     return trt;
   }
 
   /**
    * @return An instance of a TimeRange made from the serialized TimeRangeTracker passed in
    * <code>timeRangeTrackerBytes</code>.
    * @throws IOException
    */
   static TimeRange getTimeRange(final byte [] timeRangeTrackerBytes) throws IOException {
     TimeRangeTracker trt = getTimeRangeTracker(timeRangeTrackerBytes);
     return trt == null? null: trt.toTimeRange();
   }
 
   /**
    * @return Make a TimeRange from current state of <code>this</code>.
    */
   TimeRange toTimeRange() throws IOException {
     long min = getMin();
     long max = getMax();
     // Initial TimeRangeTracker timestamps are the opposite of what you want for a TimeRange. Fix!
     if (min == INITIAL_MIN_TIMESTAMP) {
       min = TimeRange.INITIAL_MIN_TIMESTAMP;
     }
     if (max == INITIAL_MAX_TIMESTAMP) {
       max = TimeRange.INITIAL_MAX_TIMESTAMP;
     }
     return new TimeRange(min, max);
   }
 }