cmccabe commented on code in PR #12776: URL: https://github.com/apache/kafka/pull/12776#discussion_r1011313984
########## metadata/src/main/java/org/apache/kafka/image/loader/MetadataLoader.java: ########## @@ -0,0 +1,504 @@ +/* + * 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.MetadataVersionChange; +import org.apache.kafka.image.MetadataVersionChangeException; +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.snapshot.SnapshotReader; +import org.slf4j.Logger; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CompletableFuture; + + +/** + * 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 = null; + 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 + "] "); + } + if (faultHandler == null) throw new RuntimeException("You must set a fault handler."); + 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; Review Comment: it would be nice to keep to minimize divergence ########## metadata/src/main/java/org/apache/kafka/image/loader/MetadataLoader.java: ########## @@ -0,0 +1,504 @@ +/* + * 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.MetadataVersionChange; +import org.apache.kafka.image.MetadataVersionChangeException; +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.snapshot.SnapshotReader; +import org.slf4j.Logger; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CompletableFuture; + + +/** + * 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 = null; + 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 + "] "); + } + if (faultHandler == null) throw new RuntimeException("You must set a fault handler."); + 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; Review Comment: it would be nice to keep to minimize divergence (although I don't feel strongly) -- This is an automated message from the Apache Git Service. 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