jiajunwang commented on a change in pull request #827: Add intermediate storage for customized state URL: https://github.com/apache/helix/pull/827#discussion_r388112511
########## File path: helix-core/src/main/java/org/apache/helix/common/caches/ParticipantStateCache.java ########## @@ -0,0 +1,177 @@ +package org.apache.helix.common.caches; + +/* + * 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 com.google.common.collect.Maps; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Set; +import org.apache.helix.HelixDataAccessor; +import org.apache.helix.PropertyKey; +import org.apache.helix.common.controllers.ControlContextProvider; +import org.apache.helix.controller.LogUtil; +import org.apache.helix.model.LiveInstance; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +/** + * Represent a cache that holds a certain participant side state of for the whole cluster. + */ +public abstract class ParticipantStateCache<T> extends AbstractDataCache { + private static Logger LOG = LoggerFactory.getLogger(ParticipantStateCache.class); + protected Map<String, Map<String, Map<String, T>>> _participantStateMap; + + protected Map<PropertyKey, T> _participantStateCache = Maps.newHashMap(); + + public ParticipantStateCache(ControlContextProvider controlContextProvider) { + super(controlContextProvider); + _participantStateMap = new HashMap<>(); + } + + /** + * This refreshes the participant state cache data by re-fetching the data from zookeeper in an + * efficient way + * @param accessor + * @param liveInstanceMap map of all liveInstances in cluster + * @return + */ + public boolean refresh(HelixDataAccessor accessor, Map<String, LiveInstance> liveInstanceMap, + Boolean snapshotEnabled) { + long startTime = System.currentTimeMillis(); + + refreshParticipantStatesCacheFromZk(accessor, liveInstanceMap, snapshotEnabled); + Map<String, Map<String, Map<String, T>>> allParticipantStateMap = new HashMap<>(); + // There should be 4 levels of keys. The first one is the cluster name, the second one is the + // instance name, the third one is a customized key (could be session Id or customized state + // type), the fourth one is the resourceName + for (PropertyKey key : _participantStateCache.keySet()) { + T participantState = _participantStateCache.get(key); + String[] params = key.getParams(); + if (participantState != null && params.length >= 4) { + String instanceName = params[1]; + String customizedName = params[2]; + String resourceName = params[3]; + Map<String, Map<String, T>> instanceMap = allParticipantStateMap.get(instanceName); + if (instanceMap == null) { + instanceMap = Maps.newHashMap(); + allParticipantStateMap.put(instanceName, instanceMap); + } + Map<String, T> customizedMap = instanceMap.get(customizedName); + if (customizedMap == null) { + customizedMap = Maps.newHashMap(); + instanceMap.put(customizedName, customizedMap); + } + customizedMap.put(resourceName, participantState); + } else { + LogUtil.logError(LOG, genEventInfo(), "Invalid key found in the participant state cache" + key); + } + } + + _participantStateMap = Collections.unmodifiableMap(allParticipantStateMap); + + long endTime = System.currentTimeMillis(); + LogUtil.logInfo(LOG, genEventInfo(), + "END: participantStateCache.refresh() for cluster " + _controlContextProvider.getClusterName() + + ", started at : " + startTime + ", took " + (endTime - startTime) + " ms"); + if (LOG.isDebugEnabled()) { + LogUtil.logDebug(LOG, genEventInfo(), + String.format("Participant State refreshed : %s", _participantStateMap.toString())); + } + return true; + } + + // reload participant states that has been changed from zk to local cache. + private void refreshParticipantStatesCacheFromZk(HelixDataAccessor accessor, + Map<String, LiveInstance> liveInstanceMap, Boolean snapshotEnabled) { + + long start = System.currentTimeMillis(); + Set<PropertyKey> participantStateKeys = PopulateParticipantKeys(accessor, liveInstanceMap); + + // All new entries from zk not cached locally yet should be read from ZK. + Set<PropertyKey> reloadKeys = new HashSet<>(participantStateKeys); + reloadKeys.removeAll(_participantStateCache.keySet()); + + Set<PropertyKey> cachedKeys = new HashSet<>(_participantStateCache.keySet()); + cachedKeys.retainAll(participantStateKeys); + + Set<PropertyKey> reloadedKeys = new HashSet<>(); + Map<PropertyKey, T> newStateCache = Collections.unmodifiableMap( + refreshProperties(accessor, reloadKeys, new ArrayList<>(cachedKeys), _participantStateCache, reloadedKeys)); + + if (snapshotEnabled) { + refreshSnapshot(newStateCache, _participantStateCache, reloadedKeys); + } + + _participantStateCache = newStateCache; + + if (LOG.isDebugEnabled()) { + LogUtil.logDebug(LOG, genEventInfo(), + "# of participant state reload: " + reloadKeys.size() + ", skipped:" + (participantStateKeys.size() + - reloadKeys.size()) + ". took " + (System.currentTimeMillis() - start) + + " ms to reload new participant states for cluster: " + _controlContextProvider.getClusterName() + + "and state: " + this.getClass().getName()); + } + } + + protected abstract Set<PropertyKey> PopulateParticipantKeys(HelixDataAccessor accessor, + Map<String, LiveInstance> liveInstanceMap); + + protected abstract void refreshSnapshot(Map<PropertyKey, T> newStateCache, Map<PropertyKey, T> participantStateCache, Review comment: Since the customized state cache won't support snapshot for now, just comment on this method as OPTIONAL to be implemented. If the child class does not support snapshot, just do nothing. And we don't need the boolean to differentiate. We might want to support it later though. ---------------------------------------------------------------- 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] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
