Java tutorial
/** * 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 com.pinterest.terrapin.zookeeper; import com.google.common.collect.Lists; import com.google.common.collect.Maps; import com.pinterest.terrapin.TerrapinUtil; import org.apache.commons.io.IOUtils; import org.apache.commons.lang3.tuple.Pair; import org.apache.helix.model.ExternalView; import org.codehaus.jackson.annotate.JsonIgnore; import org.codehaus.jackson.annotate.JsonProperty; import org.codehaus.jackson.map.ObjectMapper; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.List; import java.util.Set; import java.util.Map; import java.util.TreeMap; import java.util.Collections; import java.util.zip.GZIPInputStream; import java.util.zip.GZIPOutputStream; /** * Contains a mapping from partition to list of instances serving the partition. This * is needed to reduce amount of data being transferred from zookeeper. It serializes * The state as compressed JSON. */ public class ViewInfo { private static final Logger LOG = LoggerFactory.getLogger(ViewInfo.class); private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); @JsonProperty private final String resource; @JsonProperty private Map<String, List<String>> partitionMap; public ViewInfo() { this.resource = null; this.partitionMap = null; } public ViewInfo(ExternalView externalView) { this.resource = externalView.getResourceName(); Set<String> partitionSet = externalView.getPartitionSet(); this.partitionMap = Maps.newTreeMap(); for (String partition : partitionSet) { Map<String, String> stateMap = externalView.getStateMap(partition); Pair<String, Integer> resourceAndPartitionNum = TerrapinUtil.getResourceAndPartitionNum(partition); if (resourceAndPartitionNum == null) { LOG.warn("Invalid helix partition for " + resource + " : " + partition); continue; } if (stateMap == null) { continue; } List<String> instanceList = Lists.newArrayListWithCapacity(5); for (Map.Entry<String, String> entry : stateMap.entrySet()) { if (entry.getValue().equals("ONLINE")) { instanceList.add(entry.getKey()); } } // Keep the list in alphabetical order. if (!instanceList.isEmpty()) { Collections.sort(instanceList); this.partitionMap.put( TerrapinUtil.getViewPartitionName(resource, resourceAndPartitionNum.getRight()), instanceList); } } } public static ViewInfo fromJson(byte[] json) throws Exception { ViewInfo viewInfo = OBJECT_MAPPER.readValue(json, ViewInfo.class); for (Map.Entry<String, List<String>> entry : viewInfo.partitionMap.entrySet()) { Collections.sort(entry.getValue()); } return viewInfo; } /** * Returns the set of instances for a partition. Note that this would */ public List<String> getInstancesForPartition(String partition) { if (this.partitionMap == null || !this.partitionMap.containsKey(partition)) { return Lists.newArrayListWithCapacity(0); } return partitionMap.get(partition); } public boolean hasOnlinePartitions() { return partitionMap != null && partitionMap.size() > 0; } @JsonIgnore public int getNumOnlinePartitions() { return partitionMap == null ? 0 : partitionMap.size(); } @JsonIgnore public String getResource() { return resource; } @Override public boolean equals(Object o) { if (!(o instanceof ViewInfo)) { return false; } ViewInfo viewInfo = (ViewInfo) o; if (!resource.equals(viewInfo.resource)) { return false; } return partitionMap.equals(viewInfo.partitionMap); } public byte[] toJson() throws Exception { return OBJECT_MAPPER.writeValueAsBytes(this); } public static ViewInfo fromCompressedJson(byte[] compressedJson) throws Exception { ByteArrayInputStream in = new ByteArrayInputStream(compressedJson); GZIPInputStream zipIs = new GZIPInputStream(in); ViewInfo viewInfo = fromJson(IOUtils.toByteArray(zipIs)); in.close(); zipIs.close(); return viewInfo; } public byte[] toCompressedJson() throws Exception { ByteArrayOutputStream out = new ByteArrayOutputStream(); GZIPOutputStream zipOs = new GZIPOutputStream(out); zipOs.write(this.toJson()); zipOs.close(); byte[] data = out.toByteArray(); return data; } /** * To pretty printing JSON format with simplified partition key. The returned JSON string is a * ordered object sort by partition key. This function is only used for displaying status in * the html page * @return JSON string * @throws IOException if the dumping process raises any exceptions */ public String toPrettyPrintingJson() throws IOException { Map<Integer, List<String>> simplifiedPartitionMap = new TreeMap<Integer, List<String>>(); for (Map.Entry<String, List<String>> entry : partitionMap.entrySet()) { String longPartitionName = entry.getKey(); int partitionNumber = TerrapinUtil.getViewPartitionNumber(longPartitionName); simplifiedPartitionMap.put(partitionNumber, entry.getValue()); } return OBJECT_MAPPER.defaultPrettyPrintingWriter().writeValueAsString(simplifiedPartitionMap); } /** * Check partition is online or not * @param partition partition number * @return true if partition is online, otherwise, return false */ public boolean isOnlinePartition(String partition) { return partitionMap != null && partitionMap.containsKey(partition); } }