/*
 * 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.geode.cache;

import java.util.List;

/**
 * <p>
 * An event that describes the culmination of an entire transaction. It either describes the work
 * done by a committed transaction or the work abandoned by an explicit rollback or failed commit.
 * The actual work is represented by an ordered list of {@link EntryEvent} instances.
 *
 * <p>
 * A <code>TransactionListener</code> receives an instance of this class allowing exploration of the
 * resultant operations. The resultant operation is the final result of, potentially, a sequence of
 * operations on a key such that earlier operations might be masked. For example, multiple put
 * operations using the same key will result in only one {@link EntryEvent} for that key.
 *
 * <p>
 * An instance of TransactionEvent for the same transaction on the originating VM may differ from a
 * recipient VM. The amount of variation will depend on the variation of the state of Entries on
 * each VM. One reason for why this might occur is the different Expiration/Eviction settings of the
 * similar Regions on different VMs.
 *
 * <p>
 * The event lists are ordered according to the chronological order of the indiviual operations.
 *
 * <p>
 * The {@link EntryEvent} instances always return <code>null</code> as their
 * {@link CacheEvent#getCallbackArgument callback argument}.
 *
 *
 * @see TransactionListener
 * @see EntryEvent
 * @since GemFire 4.0
 */
public interface TransactionEvent {

  /**
   * Gets the <code>TransactionId</code> associated this TransactionEvent.
   *
   * @return the <code>TransactionId</code> associated this TransactionEvent
   */
  TransactionId getTransactionId();

  /**
   * Returns an ordered list of every {@link CacheEvent} for this transaction. The event order is
   * consistent with the order in which the operations were performed during the transaction.
   *
   * @return an unmodifiable <code>List</code> of all the {@link CacheEvent} instances; one for each
   *         operation performed by this transaction.
   * @since GemFire 5.0
   */
  List<CacheEvent<?, ?>> getEvents();

  /**
   * Gets the Cache for this transaction event
   *
   * @return <code>Cache</code>
   */
  Cache getCache();

}
