frankvicky commented on code in PR #20089: URL: https://github.com/apache/kafka/pull/20089#discussion_r2187192871
########## coordinator-common/src/main/java/org/apache/kafka/coordinator/common/runtime/CoordinatorLoaderImpl.java: ########## @@ -0,0 +1,338 @@ +/* + * 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.coordinator.common.runtime; + +import org.apache.kafka.common.TopicPartition; +import org.apache.kafka.common.errors.NotLeaderOrFollowerException; +import org.apache.kafka.common.record.ControlRecordType; +import org.apache.kafka.common.record.FileRecords; +import org.apache.kafka.common.record.MemoryRecords; +import org.apache.kafka.common.record.MutableRecordBatch; +import org.apache.kafka.common.record.Record; +import org.apache.kafka.common.record.Records; +import org.apache.kafka.common.requests.TransactionResult; +import org.apache.kafka.common.utils.Time; +import org.apache.kafka.server.storage.log.FetchIsolation; +import org.apache.kafka.server.util.KafkaScheduler; +import org.apache.kafka.storage.internals.log.FetchDataInfo; +import org.apache.kafka.storage.internals.log.UnifiedLog; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.Optional; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ScheduledFuture; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.function.Function; + +/** + * Coordinator loader which reads records from a partition and replays them + * to a group coordinator. + * + * @param <T> The record type. + */ +public class CoordinatorLoaderImpl<T> implements CoordinatorLoader<T> { + + private static final Logger LOG = LoggerFactory.getLogger(CoordinatorLoader.class); + + private final Time time; + private final Function<TopicPartition, Optional<UnifiedLog>> partitionLogSupplier; + private final Function<TopicPartition, Optional<Long>> partitionLogEndOffsetSupplier; + private final Deserializer<T> deserializer; + private final int loadBufferSize; + + private final AtomicBoolean isRunning = new AtomicBoolean(true); + private final KafkaScheduler scheduler = new KafkaScheduler(1); + + public CoordinatorLoaderImpl( + Time time, + Function<TopicPartition, Optional<UnifiedLog>> partitionLogSupplier, + Function<TopicPartition, Optional<Long>> partitionLogEndOffsetSupplier, + Deserializer<T> deserializer, + int loadBufferSize + ) { + this.time = time; + this.partitionLogSupplier = partitionLogSupplier; + this.partitionLogEndOffsetSupplier = partitionLogEndOffsetSupplier; + this.deserializer = deserializer; + this.loadBufferSize = loadBufferSize; + this.scheduler.startup(); + } + + /** + * Loads the coordinator by reading all the records from the TopicPartition + * and applying them to the Replayable object. + * + * @param tp The TopicPartition to read from. + * @param coordinator The object to apply records to. + */ + @Override + public CompletableFuture<LoadSummary> load(TopicPartition tp, CoordinatorPlayback<T> coordinator) { + final CompletableFuture<LoadSummary> future = new CompletableFuture<>(); + long startTimeMs = time.milliseconds(); + try { + ScheduledFuture<?> result = scheduler.scheduleOnce(String.format("Load coordinator from %s", tp), + () -> doLoad(tp, coordinator, future, startTimeMs)); + if (result.isCancelled()) { + future.completeExceptionally(new RuntimeException("Coordinator loader is closed.")); + } + } catch (Exception e) { + future.completeExceptionally(e); + } + return future; + } + + private void doLoad( + TopicPartition tp, + CoordinatorPlayback<T> coordinator, + CompletableFuture<LoadSummary> future, + long startTimeMs + ) { + long schedulerQueueTimeMs = time.milliseconds() - startTimeMs; + try { + Optional<UnifiedLog> logOpt = partitionLogSupplier.apply(tp); + if (logOpt.isEmpty()) { + future.completeExceptionally(new NotLeaderOrFollowerException( + "Could not load records from " + tp + " because the log does not exist.")); + return; + } + + UnifiedLog log = logOpt.get(); + + // Buffer may not be needed if records are read from memory. + ByteBuffer buffer = ByteBuffer.allocate(0); + long currentOffset = log.logStartOffset(); + LoadStats stats = new LoadStats(); + + long previousHighWatermark = -1L; + while (shouldFetchNextBatch(currentOffset, logEndOffset(tp), stats.readAtLeastOneRecord)) { + FetchDataInfo fetchDataInfo = log.read(currentOffset, loadBufferSize, FetchIsolation.LOG_END, true); + + stats.readAtLeastOneRecord = fetchDataInfo.records.sizeInBytes() > 0; + + MemoryRecords memoryRecords = toReadableMemoryRecords(tp, fetchDataInfo.records, buffer); + + ReplayResult replayResult = processMemoryRecords(tp, log, memoryRecords, coordinator, stats, currentOffset, previousHighWatermark); + currentOffset = replayResult.nextOffset; + previousHighWatermark = replayResult.highWatermark; + } + + completeLoadFuture(tp, future, startTimeMs, schedulerQueueTimeMs, stats); + } catch (Throwable ex) { + future.completeExceptionally(ex); + } + } + + private long logEndOffset(TopicPartition tp) { + return partitionLogEndOffsetSupplier.apply(tp).orElse(-1L); + } + + /** + * Returns true if it's still valid to fetch the next batch of records. + * <p> + * This method ensures fetching continues only under safe and meaningful conditions: + * <ul> + * <li>The current offset is less than the log end offset.</li> + * <li>At least one record was read in the previous fetch. This ensures that fetching stops even if the + * current offset remains smaller than the log end offset but the log is empty. This could happen with compacted topics.</li> + * <li>The log end offset is not -1L, which ensures the partition is online and is still the leader.</li> + * <li>The loader is still running.</li> + * </ul> + */ + private boolean shouldFetchNextBatch(long currentOffset, long logEndOffset, boolean readAtLeastOneRecord) { + return currentOffset < logEndOffset && readAtLeastOneRecord && isRunning.get(); + } + + private MemoryRecords toReadableMemoryRecords(TopicPartition tp, Records records, ByteBuffer buffer) throws IOException { + if (records instanceof MemoryRecords) { + return (MemoryRecords) records; Review Comment: ```suggestion if (records instanceof MemoryRecords memoryRecords) { return memoryRecords; ``` -- This is an automated message from the Apache Git Service. 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