mumrah commented on code in PR #12983: URL: https://github.com/apache/kafka/pull/12983#discussion_r1047441883
########## core/src/main/scala/kafka/server/ControllerServer.scala: ########## @@ -68,6 +69,7 @@ class ControllerServer( val lock = new ReentrantLock() val awaitShutdownCond = lock.newCondition() var status: ProcessStatus = SHUTDOWN + var loader: MetadataLoader = _ Review Comment: Is this ever assigned? Shouldn't we just use the loader defined in SharedServer? ########## metadata/src/main/java/org/apache/kafka/image/publisher/MetadataPublisher.java: ########## @@ -0,0 +1,72 @@ +/* + * 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.kafka.image.publisher; + +import org.apache.kafka.image.MetadataDelta; +import org.apache.kafka.image.MetadataImage; +import org.apache.kafka.image.loader.LogDeltaManifest; +import org.apache.kafka.image.loader.SnapshotManifest; + + +/** + * Publishes metadata deltas which we have loaded from the log and snapshots. + * + * Publishers receive a stream of callbacks from the metadata loader which keeps them notified + * of the latest cluster metadata. This interface abstracts away some of the complications of + * following the cluster metadata. For example, if the loader needs to read a snapshot, it will + * present the contents of the snapshot in the form of a delta from the previous state. + */ +public interface MetadataPublisher extends AutoCloseable { Review Comment: Is "Publisher" the right name here? It makes it sound a bit like instances of this interface will be publishing metadata, when they are actually being published _to_. What about `MetadataListener` or `MetadataConsumer` or something? ########## core/src/main/scala/kafka/server/metadata/BrokerServerMetrics.scala: ########## @@ -17,17 +17,48 @@ package kafka.server.metadata -import java.util.concurrent.atomic.AtomicLong +import kafka.metrics.KafkaMetricsGroup + +import java.util.concurrent.atomic.{AtomicLong, AtomicReference} import org.apache.kafka.common.MetricName import org.apache.kafka.common.metrics.Gauge import org.apache.kafka.common.metrics.Metrics import org.apache.kafka.common.metrics.MetricConfig +import org.apache.kafka.image.MetadataProvenance +import org.apache.kafka.image.loader.MetadataLoaderMetrics +import org.apache.kafka.server.metrics.KafkaYammerMetrics + +import java.util.concurrent.TimeUnit.NANOSECONDS -final class BrokerServerMetrics private (metrics: Metrics) extends AutoCloseable { +final class BrokerServerMetrics private ( + metrics: Metrics +) extends MetadataLoaderMetrics with KafkaMetricsGroup { Review Comment: Are the changes to BrokerMetadataListener and BrokerServerMetrics needed in this PR, or can we save them for the next one (with the BrokerServer changes)? ########## metadata/src/main/java/org/apache/kafka/image/loader/MetadataLoader.java: ########## @@ -0,0 +1,474 @@ +/* + * 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.kafka.image.loader; + +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Time; +import org.apache.kafka.image.MetadataDelta; +import org.apache.kafka.image.MetadataImage; +import org.apache.kafka.image.MetadataProvenance; +import org.apache.kafka.image.publisher.MetadataPublisher; +import org.apache.kafka.image.writer.ImageReWriter; +import org.apache.kafka.image.writer.ImageWriterOptions; +import org.apache.kafka.queue.KafkaEventQueue; +import org.apache.kafka.raft.Batch; +import org.apache.kafka.raft.BatchReader; +import org.apache.kafka.raft.LeaderAndEpoch; +import org.apache.kafka.raft.RaftClient; +import org.apache.kafka.server.common.ApiMessageAndVersion; +import org.apache.kafka.server.fault.FaultHandler; +import org.apache.kafka.server.fault.FaultHandlerException; +import org.apache.kafka.snapshot.SnapshotReader; +import org.slf4j.Logger; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CompletableFuture; + +import static java.util.concurrent.TimeUnit.NANOSECONDS; + + +/** + * The MetadataLoader follows changes provided by a RaftClient, and packages them into metadata + * deltas and images that can be consumed by publishers. + * + * The Loader maintains its own thread, which is used to make all callbacks into publishers. If a + * publisher A is installed before B, A will receive all callbacks before B. This is also true if + * A and B are installed as part of a list [A, B]. + * + * Publishers should not modify any data structures passed to them. + * + * It is possible to change the list of publishers dynamically over time. Whenever a new publisher is + * added, it receives a catch-up delta which contains the full state. Any publisher installed when the + * loader is closed will itself be closed. + */ +public class MetadataLoader implements RaftClient.Listener<ApiMessageAndVersion>, AutoCloseable { + public static class Builder { + private int nodeId = -1; + private Time time = Time.SYSTEM; + private LogContext logContext = null; + private String threadNamePrefix = ""; + private FaultHandler faultHandler = (m, e) -> new FaultHandlerException(m, e); + private MetadataLoaderMetrics metrics = new MetadataLoaderMetrics() { + private volatile long lastAppliedOffset = -1L; + + @Override + public void updateBatchProcessingTime(long elapsedNs) { } + + @Override + public void updateBatchSize(int size) { } + + @Override + public void updateLastAppliedImageProvenance(MetadataProvenance provenance) { + this.lastAppliedOffset = provenance.offset(); + } + + @Override + public long lastAppliedOffset() { + return lastAppliedOffset; + } + + @Override + public void close() throws Exception { } + }; + + public Builder setNodeId(int nodeId) { + this.nodeId = nodeId; + return this; + } + + public Builder setTime(Time time) { + this.time = time; + return this; + } + + public Builder setThreadNamePrefix(String threadNamePrefix) { + this.threadNamePrefix = threadNamePrefix; + return this; + } + + public Builder setFaultHandler(FaultHandler faultHandler) { + this.faultHandler = faultHandler; + return this; + } + + public Builder setMetadataLoaderMetrics(MetadataLoaderMetrics metrics) { + this.metrics = metrics; + return this; + } + + public MetadataLoader build() { + if (logContext == null) { + logContext = new LogContext("[MetadataLoader " + nodeId + "] "); + } + return new MetadataLoader( + time, + logContext, + threadNamePrefix, + faultHandler, + metrics); + } + } + + /** + * The log4j logger for this loader. + */ + private final Logger log; + + /** + * The clock used by this loader. + */ + private final Time time; + + /** + * The fault handler to use if metadata loading fails. + */ + private final FaultHandler faultHandler; + + /** + * Callbacks for updating metrics. + */ + private final MetadataLoaderMetrics metrics; + + /** + * The publishers which should receive cluster metadata updates. + */ + private final List<MetadataPublisher> publishers; + + /** + * The current leader and epoch. + */ + private LeaderAndEpoch currentLeaderAndEpoch = LeaderAndEpoch.UNKNOWN; + + /** + * The current metadata image. Accessed only from the event queue thread. + */ + private MetadataImage image; + + /** + * The event queue which runs this loader. + */ + private final KafkaEventQueue eventQueue; + + private MetadataLoader( + Time time, + LogContext logContext, + String threadNamePrefix, + FaultHandler faultHandler, + MetadataLoaderMetrics metrics + ) { + this.log = logContext.logger(MetadataLoader.class); + this.time = time; + this.faultHandler = faultHandler; + this.metrics = metrics; + this.publishers = new ArrayList<>(); + this.image = MetadataImage.EMPTY; + this.eventQueue = new KafkaEventQueue(time, logContext, threadNamePrefix); + } + + @Override + public void handleCommit(BatchReader<ApiMessageAndVersion> reader) { + eventQueue.append(() -> { + try { + MetadataDelta delta = new MetadataDelta.Builder(). + setImage(image). + build(); + LogDeltaManifest manifest = loadLogDelta(delta, reader); + if (log.isDebugEnabled()) { + log.debug("Generated a metadata delta between {} and {} from {} batch(es) " + + "in {} us.", image.offset(), manifest.provenance().offset(), + manifest.numBatches(), NANOSECONDS.toMicros(manifest.elapsedNs())); + } + try { + image = delta.apply(manifest.provenance()); + } catch (Throwable e) { + faultHandler.handleFault("Error generating new metadata image from " + + "metadata delta between offset " + image.offset() + + " and " + manifest.provenance().offset(), e); + return; + } + log.debug("Publishing new image with provenance {}.", image.provenance()); + for (MetadataPublisher publisher : publishers) { + try { + publisher.publishLogDelta(delta, image, manifest); + } catch (Throwable e) { + faultHandler.handleFault("Unhandled error publishing the new metadata " + + "image ending at " + manifest.provenance().offset() + + " with publisher " + publisher.name(), e); + } + } + metrics.updateLastAppliedImageProvenance(image.provenance()); + } catch (Throwable e) { + // This is a general catch-all block where we don't expect to end up; + // failure-prone operations should have individual try/catch blocks around them. + faultHandler.handleFault("Unhandled fault in MetadataLoader#handleCommit. " + + "Last image offset was " + image.offset(), e); + } finally { + reader.close(); + } + }); + } + + /** + * Load some batches of records from the log. We have to do some bookkeeping here to + * translate between batch offsets and record offsets, and track the number of bytes we + * have read. Additionally, there is the chance that one of the records is a metadata + * version change which needs to be handled differently. + * + * @param delta The metadata delta we are preparing. + * @param reader The reader which yields the batches. + * @return A manifest of what was loaded. + */ + LogDeltaManifest loadLogDelta( + MetadataDelta delta, + BatchReader<ApiMessageAndVersion> reader + ) { + long startNs = time.nanoseconds(); + int numBatches = 0; + long numBytes = 0L; + long lastOffset = image.provenance().offset(); + int lastEpoch = image.provenance().epoch(); + long lastContainedLogTimeMs = image.provenance().lastContainedLogTimeMs(); + + while (reader.hasNext()) { + Batch<ApiMessageAndVersion> batch = reader.next(); + int indexWithinBatch = 0; + for (ApiMessageAndVersion record : batch.records()) { + try { + delta.replay(record.message()); + } catch (Throwable e) { + faultHandler.handleFault("Error loading metadata log record from offset " + + batch.baseOffset() + indexWithinBatch, e); + } + indexWithinBatch++; + } + metrics.updateBatchSize(batch.records().size()); + lastOffset = batch.lastOffset(); + lastEpoch = batch.epoch(); + lastContainedLogTimeMs = batch.appendTimestamp(); + numBytes += batch.sizeInBytes(); + numBatches++; + } + MetadataProvenance provenance = + new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs); + long elapsedNs = time.nanoseconds() - startNs; + metrics.updateBatchProcessingTime(elapsedNs); + return new LogDeltaManifest(provenance, + numBatches, + elapsedNs, + numBytes); + } + + @Override + public void handleSnapshot(SnapshotReader<ApiMessageAndVersion> reader) { + eventQueue.append(() -> { + try { + MetadataDelta delta = new MetadataDelta.Builder(). + setImage(image). + build(); + SnapshotManifest manifest = loadSnapshot(delta, reader); + if (log.isDebugEnabled()) { + log.debug("Generated a metadata delta from a snapshot at offset {} " + + "in {} us.", manifest.provenance().offset(), + NANOSECONDS.toMicros(manifest.elapsedNs())); + } + try { + image = delta.apply(manifest.provenance()); + } catch (Throwable e) { + faultHandler.handleFault("Error generating new metadata image from " + + "snapshot at offset " + reader.lastContainedLogOffset(), e); + return; + } + log.debug("Publishing new snapshot image with provenance {}.", image.provenance()); + for (MetadataPublisher publisher : publishers) { + try { + publisher.publishSnapshot(delta, image, manifest); + } catch (Throwable e) { + faultHandler.handleFault("Unhandled error publishing the new metadata " + + "image from snapshot at offset " + reader.lastContainedLogOffset() + + " with publisher " + publisher.name(), e); + } + } + metrics.updateLastAppliedImageProvenance(image.provenance()); + } catch (Throwable e) { + // This is a general catch-all block where we don't expect to end up; + // failure-prone operations should have individual try/catch blocks around them. + faultHandler.handleFault("Unhandled fault in MetadataLoader#handleSnapshot. " + + "Snapshot offset was " + reader.lastContainedLogOffset(), e); + } finally { + reader.close(); + } + }); + } + + /** + * Load a snapshot. This is relatively straightforward since we don't track as many things as + * we do in loadLogDelta. The main complication here is that we have to maintain an index + * of what record we are processing so that we can give useful error messages. + * + * @param delta The metadata delta we are preparing. + * @param reader The reader which yields the snapshot batches. + * @return A manifest of what was loaded. + */ + SnapshotManifest loadSnapshot( + MetadataDelta delta, + SnapshotReader<ApiMessageAndVersion> reader + ) { + long startNs = time.nanoseconds(); + int snapshotIndex = 0; + while (reader.hasNext()) { + Batch<ApiMessageAndVersion> batch = reader.next(); + for (ApiMessageAndVersion record : batch.records()) { + try { + delta.replay(record.message()); + } catch (Throwable e) { + faultHandler.handleFault("Error loading metadata log record " + snapshotIndex + + " in snapshot at offset " + reader.lastContainedLogOffset(), e); + } + snapshotIndex++; + } + } + MetadataProvenance provenance = new MetadataProvenance(reader.lastContainedLogOffset(), + reader.lastContainedLogEpoch(), + reader.lastContainedLogTimestamp()); Review Comment: nit: indentation -- This is an automated message from the Apache Git Service. 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