zhangmeng916 commented on a change in pull request #1307: URL: https://github.com/apache/helix/pull/1307#discussion_r493828839
########## File path: helix-core/src/main/java/org/apache/helix/model/ClusterTrie.java ########## @@ -0,0 +1,150 @@ +package org.apache.helix.model; + +/* + * 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. + */ + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.stream.Collectors; + +import org.apache.helix.HelixException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +/** + * This is a class that uses a trie data structure to represent cluster topology. Each node + * except the terminal node represents a certain domain in the topology, and an terminal node + * represents an instance in the cluster. + */ +public class ClusterTrie { + public static final String DELIMITER = "/"; + public static final String CONNECTOR = ":"; + + private static Logger logger = LoggerFactory.getLogger(ClusterTrie.class); + private TrieNode _rootNode; + private String[] _topologyKeys; + private String _faultZoneType; + private List<String> _invalidInstances = new ArrayList<>(); + + public ClusterTrie(final List<String> liveNodes, + final Map<String, InstanceConfig> instanceConfigMap, ClusterConfig clusterConfig) { + validateInstanceConfig(liveNodes, instanceConfigMap); + validateClusterConfig(clusterConfig); + _faultZoneType = clusterConfig.getFaultZoneType(); + _rootNode = constructTrie(instanceConfigMap); + } + + + public TrieNode getRootNode() { + return _rootNode; + } + + public String[] getTopologyKeys() { + return _topologyKeys; + } + + public String getFaultZoneType() { + return _faultZoneType; + } + + public List<String> getInvalidInstances() { + return _invalidInstances; + } + + private void removeInvalidInstanceConfig(Map<String, InstanceConfig> instanceConfigMap) { + for (String instanceName : instanceConfigMap.keySet()) { + try { + Map<String, String> domainAsMap = instanceConfigMap.get(instanceName).getDomainAsMap(); + for (String key : _topologyKeys) { + String value = domainAsMap.get(key); + if (value == null || value.length() == 0) { + logger.info(String.format("Domain %s for instance %s is not set", domainAsMap.get(key), + instanceName)); + _invalidInstances.add(instanceName); + break; + } + } + } catch (IllegalArgumentException e) { + _invalidInstances.add(instanceName); + } + } + _invalidInstances.forEach(entry -> instanceConfigMap.remove(entry)); + } + + private void validateInstanceConfig(final List<String> liveNodes, + final Map<String, InstanceConfig> instanceConfigMap) { + if (instanceConfigMap == null || !instanceConfigMap.keySet().containsAll(liveNodes)) { + List<String> liveNodesCopy = new ArrayList<>(); + liveNodesCopy.addAll(liveNodes); + throw new HelixException(String.format("Config for instances %s is not found!", + instanceConfigMap == null ? liveNodes + : liveNodesCopy.removeAll(instanceConfigMap.keySet()))); + } + } + + // Note that we do not validate whether topology-aware is enabled or fault zone type is + // defined, as they do not block the construction of the trie + private void validateClusterConfig(ClusterConfig clusterConfig) { + String topologyDef = clusterConfig.getTopology(); + if (topologyDef == null) { + throw new HelixException(String.format("The topology of cluster %s is empty!", + clusterConfig.getClusterName())); + } + // A list of all keys in cluster topology, e.g., a cluster topology defined as + // /group/zone/rack/host will return ["group", "zone", "rack", "host"]. + _topologyKeys = Arrays.asList(topologyDef.trim().split(DELIMITER)).stream() + .filter(str -> !str.isEmpty()).collect(Collectors.toList()).toArray(new String[0]); + if (_topologyKeys.length == 0) { + throw new HelixException(String.format("The topology of cluster %s is not correctly defined", + clusterConfig.getClusterName())); + } + } + + /** + * Constructs a trie based on the provided instance config map. It loops through all instance + * configs and constructs the trie in a top down manner. + */ + private TrieNode constructTrie(Map<String, InstanceConfig> instanceConfigMap) { + TrieNode rootNode = new TrieNode(new HashMap<>(), "", "ROOT"); + removeInvalidInstanceConfig(instanceConfigMap); + Map<String, Map<String, String>> instanceDomainsMap = new HashMap<>(); + instanceConfigMap.entrySet().forEach( + entry -> instanceDomainsMap.put(entry.getKey(), entry.getValue().getDomainAsMap())); + + for (Map.Entry<String, Map<String, String>> entry : instanceDomainsMap.entrySet()) { + TrieNode curNode = rootNode; + String path = ""; + for (int i = 0; i < _topologyKeys.length; i++) { + String key = _topologyKeys[i] + CONNECTOR + entry.getValue().get(_topologyKeys[i]); + path = path + DELIMITER + key; + TrieNode nextNode = curNode.getChildren().get(key); + if (nextNode == null) { + nextNode = new TrieNode(new HashMap<>(), path, _topologyKeys[i]); Review comment: I understand your point. I tried a bit with removing path variable. The problem is that I will need to compose the path when I try to return the results. e.g. if the domain given is "zone":"0", I find the trie node and all its children, and when I return, I'll need to return "group:0/zone:0" as the full path, so I still need to build the string with parent information, there is no other way to know the domains above it. So the path is actually very convenient. What do you think? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
