| /** |
| * 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 |
| * <p> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p> |
| * 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.hdfs.server.protocol; |
| |
| import com.google.common.collect.ImmutableMap; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| import javax.annotation.Nonnull; |
| import javax.annotation.Nullable; |
| import java.util.Map; |
| |
| /** |
| * A class that allows a DataNode to communicate information about all |
| * its peer DataNodes that appear to be slow. |
| * |
| * The wire representation of this structure is a list of |
| * SlowPeerReportProto messages. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public final class SlowPeerReports { |
| /** |
| * A map from the DataNode's DataNodeUUID to its aggregate latency |
| * as seen by the reporting node. |
| * |
| * The exact choice of the aggregate is opaque to the NameNode but it |
| * should be chosen consistently by all DataNodes in the cluster. |
| * Examples of aggregates are 90th percentile (good) and mean (not so |
| * good). |
| * |
| * The NameNode must not attempt to interpret the aggregate latencies |
| * beyond exposing them as a diagnostic. e.g. metrics. Also, comparing |
| * latencies across reports from different DataNodes may not be not |
| * meaningful and must be avoided. |
| */ |
| @Nonnull |
| private final Map<String, Double> slowPeers; |
| |
| /** |
| * An object representing a SlowPeerReports with no entries. Should |
| * be used instead of null or creating new objects when there are |
| * no slow peers to report. |
| */ |
| public static final SlowPeerReports EMPTY_REPORT = |
| new SlowPeerReports(ImmutableMap.<String, Double>of()); |
| |
| private SlowPeerReports(Map<String, Double> slowPeers) { |
| this.slowPeers = slowPeers; |
| } |
| |
| public static SlowPeerReports create( |
| @Nullable Map<String, Double> slowPeers) { |
| if (slowPeers == null || slowPeers.isEmpty()) { |
| return EMPTY_REPORT; |
| } |
| return new SlowPeerReports(slowPeers); |
| } |
| |
| public Map<String, Double> getSlowPeers() { |
| return slowPeers; |
| } |
| |
| public boolean haveSlowPeers() { |
| return slowPeers.size() > 0; |
| } |
| |
| /** |
| * Return true if the two objects represent the same set slow peer |
| * entries. Primarily for unit testing convenience. |
| */ |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| |
| if (!(o instanceof SlowPeerReports)) { |
| return false; |
| } |
| |
| SlowPeerReports that = (SlowPeerReports) o; |
| |
| return slowPeers.equals(that.slowPeers); |
| } |
| |
| @Override |
| public int hashCode() { |
| return slowPeers.hashCode(); |
| } |
| } |