cmccabe commented on code in PR #12776: URL: https://github.com/apache/kafka/pull/12776#discussion_r1011329462
########## metadata/src/main/java/org/apache/kafka/image/publisher/SnapshotGenerator.java: ########## @@ -0,0 +1,262 @@ +/* + * 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.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.loader.LogDeltaManifest; +import org.apache.kafka.image.loader.PreVersionChangeManifest; +import org.apache.kafka.image.loader.SnapshotManifest; +import org.apache.kafka.queue.EventQueue; +import org.apache.kafka.queue.KafkaEventQueue; +import org.apache.kafka.server.fault.FaultHandler; +import org.slf4j.Logger; + +import java.util.concurrent.TimeUnit; + + +/** + * A metadata publisher that generates snapshots when appropriate. + */ +public class SnapshotGenerator implements MetadataPublisher { + public static class Builder { + private int nodeId = 0; + private Time time = Time.SYSTEM; + private Emitter emitter = null; + private FaultHandler faultHandler = (m, e) -> null; + private long minBytesSinceLastSnapshot = 100 * 1024L * 1024L; + private long minTimeSinceLastSnapshotNs = TimeUnit.DAYS.toNanos(1); + + public Builder setNodeId(int nodeId) { + this.nodeId = nodeId; + return this; + } + + public Builder setTime(Time time) { + this.time = time; + return this; + } + + public Builder setEmitter(Emitter emitter) { + this.emitter = emitter; + return this; + } + + public Builder setFaultHandler(FaultHandler faultHandler) { + this.faultHandler = faultHandler; + return this; + } + + public Builder setMinBytesSinceLastSnapshot(long minBytesSinceLastSnapshot) { + this.minBytesSinceLastSnapshot = minBytesSinceLastSnapshot; + return this; + } + + public Builder setMinTimeSinceLastSnapshotNs(long minTimeSinceLastSnapshotNs) { + this.minTimeSinceLastSnapshotNs = minTimeSinceLastSnapshotNs; + return this; + } + + public SnapshotGenerator build() { + if (emitter == null) throw new RuntimeException("You must set a snapshot emitter."); + return new SnapshotGenerator( + nodeId, + time, + emitter, + faultHandler, + minBytesSinceLastSnapshot, + minTimeSinceLastSnapshotNs + ); + } + } + + /** + * The callback which actually generates the snapshot. + */ + public interface Emitter { + void emit(MetadataImage image); + } + + /** + * The node ID. + */ + private final int nodeId; + + /** + * The clock to use. + */ + private final Time time; + + /** + * The emitter callback, which actually generates the snapshot. + */ + private final Emitter emitter; + + /** + * The slf4j logger to use. + */ + private final Logger log; + + /** + * The fault handler to use. + */ + private final FaultHandler faultHandler; + + /** + * The minimum number of bytes we will wait to see before emitting a snapshot. + */ + private final long minBytesSinceLastSnapshot; + + /** + * The minimum amount of time we will wait before emitting a snapshot, or 0 to disable + * time-based snapshotting. + */ + private final long minTimeSinceLastSnapshotNs; + + /** + * If non-null, the reason why snapshots have been disabled. + */ + private volatile String disabledReason; + + /** + * The event queue used to schedule emitting snapshots. + */ + private final EventQueue eventQueue; + + /** + * The log bytes that we have read since the last snapshot. + */ + private long bytesSinceLastSnapshot; + + /** + * The time at which we created the last snapshot. + */ + private long lastSnapshotTimeNs; + + private SnapshotGenerator( + int nodeId, + Time time, + Emitter emitter, + FaultHandler faultHandler, + long minBytesSinceLastSnapshot, + long minTimeSinceLastSnapshotNs + ) { + this.nodeId = nodeId; + this.time = time; + this.emitter = emitter; + this.faultHandler = faultHandler; + this.minBytesSinceLastSnapshot = minBytesSinceLastSnapshot; + this.minTimeSinceLastSnapshotNs = minTimeSinceLastSnapshotNs; + LogContext logContext = new LogContext("[SnapshotGenerator " + nodeId + "] "); + this.log = logContext.logger(SnapshotGenerator.class); + this.disabledReason = null; + this.eventQueue = new KafkaEventQueue(time, logContext, ""); Review Comment: fair enough. we have all the information here, so there is no reason why not (and some good reasons why to!) -- This is an automated message from the Apache Git Service. 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