surekhasaharan commented on a change in pull request #6901: Introduce published segment cache in broker URL: https://github.com/apache/incubator-druid/pull/6901#discussion_r252135015
########## File path: server/src/main/java/org/apache/druid/client/MetadataSegmentView.java ########## @@ -0,0 +1,188 @@ +/* + * 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.druid.client; + +import com.fasterxml.jackson.core.JsonProcessingException; +import com.fasterxml.jackson.core.type.TypeReference; +import com.fasterxml.jackson.databind.JavaType; +import com.fasterxml.jackson.databind.ObjectMapper; +import com.google.common.util.concurrent.ListenableFuture; +import com.google.inject.Inject; +import org.apache.druid.client.coordinator.Coordinator; +import org.apache.druid.discovery.DruidLeaderClient; +import org.apache.druid.guice.ManageLifecycle; +import org.apache.druid.java.util.common.DateTimes; +import org.apache.druid.java.util.common.StringUtils; +import org.apache.druid.java.util.common.concurrent.Execs; +import org.apache.druid.java.util.common.lifecycle.LifecycleStart; +import org.apache.druid.java.util.common.lifecycle.LifecycleStop; +import org.apache.druid.java.util.emitter.EmittingLogger; +import org.apache.druid.java.util.http.client.Request; +import org.apache.druid.server.coordinator.BytesAccumulatingResponseHandler; +import org.apache.druid.timeline.DataSegment; +import org.jboss.netty.handler.codec.http.HttpMethod; +import org.joda.time.DateTime; + +import java.io.IOException; +import java.io.InputStream; +import java.util.Iterator; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; + +@ManageLifecycle +public class MetadataSegmentView +{ + + private static final int DEFAULT_POLL_PERIOD_IN_MS = 60000; + private static final EmittingLogger log = new EmittingLogger(MetadataSegmentView.class); + + private final DruidLeaderClient coordinatorDruidLeaderClient; + private final ObjectMapper jsonMapper; + private final BytesAccumulatingResponseHandler responseHandler; + private final BrokerSegmentWatcherConfig segmentWatcherConfig; + + private final ConcurrentMap<DataSegment, DateTime> publishedSegments = new ConcurrentHashMap<>(); + private ScheduledExecutorService scheduledExec; + + @Inject + public MetadataSegmentView( + final @Coordinator DruidLeaderClient druidLeaderClient, + ObjectMapper jsonMapper, + BytesAccumulatingResponseHandler responseHandler, + final BrokerSegmentWatcherConfig segmentWatcherConfig + ) + { + this.coordinatorDruidLeaderClient = druidLeaderClient; + this.jsonMapper = jsonMapper; + this.responseHandler = responseHandler; + this.segmentWatcherConfig = segmentWatcherConfig; + } + + @LifecycleStart + public void start() + { + scheduledExec = Execs.scheduledSingleThreaded("MetadataSegmentView-Cache--%d"); + scheduledExec.scheduleWithFixedDelay( + () -> { + try { + poll(); + } + catch (JsonProcessingException e) { + log.makeAlert(e, "Problem polling Coordinator.").emit(); + } + }, + 0, + DEFAULT_POLL_PERIOD_IN_MS, + TimeUnit.MILLISECONDS + ); + } + + @LifecycleStop + public void stop() + { + scheduledExec.shutdownNow(); + scheduledExec = null; + } + + private void poll() throws JsonProcessingException + { + log.info("polling published segments from coordinator"); + //get authorized published segments from coordinator + final JsonParserIterator<DataSegment> metadataSegments = getMetadataSegments( + coordinatorDruidLeaderClient, + jsonMapper, + responseHandler, + segmentWatcherConfig.getWatchedDataSources() + ); + + final DateTime timestamp = DateTimes.nowUtc(); + while (metadataSegments.hasNext()) { + final DataSegment interned = DataSegmentInterner.intern(metadataSegments.next()); + // timestamp is used to filter deleted segments + publishedSegments.put(interned, timestamp); + } + // filter the segments from cache whose timestamp is not equal to latest timestamp stored, + // since the presence of a segment with an earlier timestamp indicates that + // "that" segment is not returned by coordinator in latest poll, so it's + // likely deleted and therefore we remove it from publishedSegments + publishedSegments.values().removeIf(v -> v != timestamp); Review comment: If I did the replacing, then I'd be allocating memory for a map containing all published segments, (possibly) filling the young gen on every poll period, I thought it would be more memory efficient by removing the segments from existing map. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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