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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * Licensed 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. See accompanying
 * LICENSE file.
 */
/**
 * 
 */
package com.gemstone.gemfire.internal.cache.persistence;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.Serializable;
import java.util.UUID;

import com.gemstone.gemfire.internal.DataSerializableFixedID;
import com.gemstone.gemfire.internal.cache.versions.VersionSource;
import com.gemstone.gemfire.internal.shared.Version;

/**
 * A Unique ID for a disk store
 * @author dsmith
 *
 * TODO - RVV - this class is java serializable because apparently it is included in some
 * Exception that is serialized with java serialization back to a client as part
 * of a put all exception. See PutAllCSDUnitTest.testPartialKeyInPR. 
 */
public final class DiskStoreID implements VersionSource,
    Serializable {

  private static final long serialVersionUID = 1L;
  
  private long mostSig;
  private long leastSig;
  
  public DiskStoreID(UUID uuid) {
    this.mostSig = uuid.getMostSignificantBits();
    this.leastSig = uuid.getLeastSignificantBits();
  }

  public DiskStoreID(long diskStoreIdHigh, long diskStoreIdLow) {
    this.mostSig = diskStoreIdHigh;
    this.leastSig = diskStoreIdLow;
  }

  /** for deserialization */
  public DiskStoreID() {
  }

  @Override
  public void toData(DataOutput out) throws IOException {
    out.writeLong(mostSig);
    out.writeLong(leastSig);
  }
  
  @Override
  public void writeEssentialData(DataOutput out) throws IOException {
    out.writeLong(mostSig);
    out.writeLong(leastSig);
  }
  
  public static DiskStoreID readEssentialData(DataInput in) throws IOException {
    long mostSig = in.readLong();
    long leastSig = in.readLong();
    return new DiskStoreID(mostSig, leastSig);
  }

  @Override
  public void fromData(DataInput in) throws IOException, ClassNotFoundException {
    mostSig = in.readLong();
    leastSig = in.readLong();
  }

  @Override
  public int compareTo(DiskStoreID tagID) {
    if(tagID == null) {
      return 1;
    }
    int result = Long.signum(mostSig - tagID.mostSig);
    if(result != 0) {
      result = Long.signum(leastSig - tagID.leastSig);
    }
    return result;
  }

  public final long getMostSignificantBits() {
    return mostSig;
  }

  public final long getLeastSignificantBits() {
    return leastSig;
  }

  public static DiskStoreID random() {
    return new DiskStoreID(UUID.randomUUID());
  }

  @Override
  public int getDSFID() {
    return DISK_STORE_ID;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + (int) (leastSig ^ (leastSig >>> 32));
    result = prime * result + (int) (mostSig ^ (mostSig >>> 32));
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    DiskStoreID other = (DiskStoreID) obj;
    if (leastSig != other.leastSig)
      return false;
    if (mostSig != other.mostSig)
      return false;
    return true;
  }

  @Override
  public String toString() {
    //return Long.toHexString(mostSig) + "-" + Long.toHexString(leastSig);
    return toUUID().toString();
  }

  public UUID toUUID() {
    return new UUID(mostSig, leastSig);
  }

  @Override
  public Version[] getSerializationVersions() {
    return null;
  }
  
  public String abbrev() {
    return Long.toHexString(mostSig).substring(8);
  }
  
  @Override
  public int getSizeInBytes() {
  
    int size = 0;
  
    // two longs 
    size += 16;
    
    return size;    
  }
}