cassandra-trunk/src/java/org/apache/cassandra/diag/LastEventIdBroadcasterMBean.java
/*
 * 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.cassandra.diag;

import java.util.Map;

/**
 * Provides a list of event types and the corresponding highest event IDs. Consumers may these IDs to determine
 * if new data is available.
 *
 * <p>Example result</p>
 *
 * <table>
 *     <tr>
 *         <th>Event</th>
 *         <th>Last ID</th>
 *     </tr>
 *     <tr>
 *         <td>BootstrapEvent</td>
 *         <td>312</td>
 *     </tr>
 *     <tr>
 *         <td>CompactionEvent</td>
 *         <td>a53f9338-5f24-11e8-9c2d-fa7ae01bbebc</td>
 *     </tr>
 * </table>
 *
 * <p>Clients may either retrieve the current list of all events IDs, or make conditional requests for event IDs
 * based on the timestamp of the last update (much in the sense of e.g. HTTP's If-Modified-Since semantics).</p>
 */
public interface LastEventIdBroadcasterMBean
{
    /**
     * Retrieves a list of all event types and their highest IDs.
     */
    Map<String, Comparable> getLastEventIds();

    /**
     * Retrieves a list of all event types and their highest IDs, if updated since specified timestamp, or null.
     * @param lastUpdate timestamp to use to determine if IDs have been updated
     */
    Map<String, Comparable> getLastEventIdsIfModified(long lastUpdate);
}
