com.gemstone.gemfire.cache.wan.EventSequenceID Maven / Gradle / Ivy

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SnappyData store based off Pivotal GemFireXD
There is a newer version: 2.0-BETA
/*
 * 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.cache.wan;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.util.Arrays;

import com.gemstone.gemfire.distributed.internal.membership.InternalDistributedMember;

/**
 * This class wraps 1) DistributedMembershipID 2) ThreadID 3) SequenceID
 * attributes which are used to uniquely identify any Region Operation like
 * create, update, destroy etc. This helps in sequencing the events belonging to
 * a unique producer. As an example, the EventSequenceID can be used to track 
 * the events received by AsyncEventListener. 
 * If the event has already been seen, AsyncEventListener can 
 * choose to ignore it.
 */
public final class EventSequenceID {
  /**
   * Uniquely identifies the distributed member VM in which the Event is
   * produced
   */
  private String membershipID;

  /**
   * Unqiuely identifies the thread producing the event
   */
  private long threadID;

  /**
   * Uniquely identifies individual event produced by a given thread
   */
  private long sequenceID;

  public EventSequenceID(byte[] membershipID, long threadID, long sequenceID) {
    // convert the byte array of membershipID to a readable string
    Object mbr;
    try {
      mbr = InternalDistributedMember.readEssentialData(new DataInputStream(
          new ByteArrayInputStream(membershipID)));
    }
    catch (Exception e) {
      mbr = Arrays.toString(membershipID); // punt and use the bytes
    }
    this.membershipID = mbr.toString();
    this.threadID = threadID;
    this.sequenceID = sequenceID;
  }

  public String getMembershipID() {
    return this.membershipID;
  }

  public long getThreadID() {
    return this.threadID;
  }

  public long getSequenceID() {
    return this.sequenceID;
  }
  
  public boolean equals(Object obj) {
    if (!(obj instanceof EventSequenceID))
      return false;

    EventSequenceID obj2 = (EventSequenceID)obj;
    return (this.membershipID.equals(obj2.getMembershipID())
        && this.threadID == obj2.getThreadID() 
        && this.sequenceID == obj2.getSequenceID());
  }
  
  public int hashCode() {
    StringBuilder builder = new StringBuilder();
    builder.append(this.membershipID);
    builder.append(this.threadID);
    builder.append(this.sequenceID);
    return builder.toString().hashCode();
  }
  
  public String toString() {
    StringBuilder builder = new StringBuilder();
    builder.append("membershipID: " + membershipID);
    builder.append("; threadID: " + threadID);
    builder.append("; sequenceID: " + sequenceID);
    return builder.toString();
  }

}