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Posted to jira@kafka.apache.org by GitBox <gi...@apache.org> on 2022/11/01 01:57:09 UTC
[GitHub] [kafka] hachikuji commented on a diff in pull request #12776: KAFKA-14327: Unify KRaft snapshot generation between broker and controller
hachikuji commented on code in PR #12776:
URL: https://github.com/apache/kafka/pull/12776#discussion_r1009809439
##########
metadata/src/test/java/org/apache/kafka/controller/ClusterControlManagerTest.java:
##########
@@ -467,36 +467,41 @@ public void testIterator(MetadataVersion metadataVersion) throws Exception {
IN_CONTROLLED_SHUTDOWN.value());
clusterControl.replay(registrationChangeRecord);
short expectedVersion = metadataVersion.registerBrokerRecordVersion();
- RecordTestUtils.assertBatchIteratorContains(Arrays.asList(
- Arrays.asList(new ApiMessageAndVersion(new RegisterBrokerRecord().
+
+ ImageWriterOptions options = new ImageWriterOptions.Builder().
+ setMetadataVersion(metadataVersion).
+ setLossHandler(__ -> { }).
+ build();
+ assertEquals(new ApiMessageAndVersion(new RegisterBrokerRecord().
setBrokerEpoch(100).setBrokerId(0).setRack(null).
setEndPoints(new BrokerEndpointCollection(Collections.singleton(
new BrokerEndpoint().setSecurityProtocol(SecurityProtocol.PLAINTEXT.id).
setPort((short) 9092).
setName("PLAINTEXT").
setHost("example.com")).iterator())).
setInControlledShutdown(metadataVersion.isInControlledShutdownStateSupported()).
- setFenced(false), expectedVersion)),
- Arrays.asList(new ApiMessageAndVersion(new RegisterBrokerRecord().
+ setFenced(false), expectedVersion),
+ clusterControl.brokerRegistrations().get(0).toRecord(options));
+ assertEquals(new ApiMessageAndVersion(new RegisterBrokerRecord().
setBrokerEpoch(100).setBrokerId(1).setRack(null).
setEndPoints(new BrokerEndpointCollection(Collections.singleton(
new BrokerEndpoint().setSecurityProtocol(SecurityProtocol.PLAINTEXT.id).
setPort((short) 9093).
setName("PLAINTEXT").
setHost("example.com")).iterator())).
- setFenced(false), expectedVersion)),
- Arrays.asList(new ApiMessageAndVersion(new RegisterBrokerRecord().
+ setFenced(false), expectedVersion),
+ clusterControl.brokerRegistrations().get(1).toRecord(options));
+ assertEquals(new ApiMessageAndVersion(new RegisterBrokerRecord().
setBrokerEpoch(100).setBrokerId(2).setRack(null).
setEndPoints(new BrokerEndpointCollection(Collections.singleton(
new BrokerEndpoint().setSecurityProtocol(SecurityProtocol.PLAINTEXT.id).
setPort((short) 9094).
setName("PLAINTEXT").
setHost("example.com")).iterator())).
- setFenced(true), expectedVersion))),
- clusterControl.iterator(Long.MAX_VALUE));
+ setFenced(true), expectedVersion),
Review Comment:
nit: looks misaligned
##########
server-common/src/test/java/org/apache/kafka/queue/KafkaEventQueueTest.java:
##########
@@ -240,4 +242,29 @@ public void handleException(Throwable e) {
assertEquals(RejectedExecutionException.class, assertThrows(
ExecutionException.class, () -> future.get()).getCause().getClass());
}
-}
+
+ @Test
+ public void testEmpty() throws Exception {
+ KafkaEventQueue queue = new KafkaEventQueue(Time.SYSTEM, new LogContext(),
+ "testEmpty");
+ assertTrue(queue.isEmpty());
+ CompletableFuture<Void> future = new CompletableFuture<>();
+ queue.append(() -> future.get());
+ assertFalse(queue.isEmpty());
Review Comment:
This assertion is flaky locally. Can we use `waitForCondition` for all cases where we expect the queue to become empty?
##########
core/src/test/java/kafka/testkit/KafkaClusterTestKit.java:
##########
@@ -191,21 +191,36 @@ public KafkaClusterTestKit build() throws Exception {
KafkaRaftManager<ApiMessageAndVersion> raftManager = new KafkaRaftManager<>(
metaProperties, config, new MetadataRecordSerde(), metadataPartition, KafkaRaftServer.MetadataTopicId(),
Time.SYSTEM, new Metrics(), Option.apply(threadNamePrefix), connectFutureManager.future);
- ControllerServer controller = new ControllerServer(
- nodes.controllerProperties(node.id()),
- config,
- raftManager,
- Time.SYSTEM,
- new Metrics(),
- new MockControllerMetrics(),
- Option.apply(threadNamePrefix),
- connectFutureManager.future,
- KafkaRaftServer.configSchema(),
- raftManager.apiVersions(),
- bootstrapMetadata,
- metadataFaultHandler,
- fatalFaultHandler
- );
+ MetadataLoader metadataLoader = null;
+ ControllerServer controller = null;
+ try {
+ metadataLoader = new MetadataLoader.Builder().
+ setNodeId(node.id()).
+ setTime(Time.SYSTEM).
+ setThreadNamePrefix(threadNamePrefix).
+ setFaultHandler(fatalFaultHandler).
+ build();
+ controller = new ControllerServer(
+ nodes.controllerProperties(node.id()),
+ config,
+ raftManager,
+ Time.SYSTEM,
+ new Metrics(),
+ new MockControllerMetrics(),
+ Option.apply(threadNamePrefix),
+ connectFutureManager.future,
+ KafkaRaftServer.configSchema(),
+ raftManager.apiVersions(),
+ bootstrapMetadata,
+ metadataFaultHandler,
+ fatalFaultHandler,
+ metadataLoader);
+ } catch (Throwable e) {
+ log.error("Error creating controller {}", node.id(), e);
+ metadataLoader.close();
+ controller.shutdown();
Review Comment:
There should probably be a null check. Same for `broker` below.
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
Review Comment:
nit: pull these two lines outside the loop since they do not depend on the record
##########
metadata/src/main/java/org/apache/kafka/image/publisher/SnapshotEmitter.java:
##########
@@ -0,0 +1,118 @@
+/*
+ * 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.image.MetadataImage;
+import org.apache.kafka.image.MetadataProvenance;
+import org.apache.kafka.image.writer.ImageWriterOptions;
+import org.apache.kafka.image.writer.RaftSnapshotWriter;
+import org.apache.kafka.raft.RaftClient;
+import org.apache.kafka.server.common.ApiMessageAndVersion;
+import org.apache.kafka.snapshot.SnapshotWriter;
+import org.slf4j.Logger;
+
+import java.util.Optional;
+
+public class SnapshotEmitter implements SnapshotGenerator.Emitter {
+ private final static int DEFAULT_BATCH_SIZE = 100;
+
+ public static class Builder {
+ private int nodeId = 0;
+ private RaftClient<ApiMessageAndVersion> raftClient = null;
+ private int batchSize = DEFAULT_BATCH_SIZE;
+
+ public Builder setNodeId(int nodeId) {
+ this.nodeId = nodeId;
+ return this;
+ }
+
+ public Builder setRaftClient(RaftClient<ApiMessageAndVersion> raftClient) {
+ this.raftClient = raftClient;
+ return this;
+ }
+
+ public Builder setBatchSize(int batchSize) {
+ this.batchSize = batchSize;
+ return this;
+ }
+
+ public SnapshotEmitter build() {
+ if (raftClient == null) throw new RuntimeException("You must set the raftClient.");
+ return new SnapshotEmitter(nodeId,
+ raftClient,
+ batchSize);
+ }
+ }
+
+ /**
+ * The slf4j logger to use.
+ */
+ private final Logger log;
+
+ /**
+ * The RaftClient to use.
+ */
+ private final RaftClient<ApiMessageAndVersion> raftClient;
+
+ /**
+ * The maximum number of records to put in each batch.
+ */
+ private final int batchSize;
+
+ private SnapshotEmitter(
+ int nodeId,
+ RaftClient<ApiMessageAndVersion> raftClient,
+ int batchSize
+ ) {
+ this.log = new LogContext("[SnapshotEmitter id=" + nodeId + "] ").logger(SnapshotEmitter.class);
+ this.raftClient = raftClient;
+ this.batchSize = batchSize;
+ }
+
+ @Override
+ public void emit(MetadataImage image) {
+ MetadataProvenance provenance = image.provenance();
+ Optional<SnapshotWriter<ApiMessageAndVersion>> snapshotWriter =
+ raftClient.createSnapshot(provenance.offset(),
+ provenance.epoch(),
+ provenance.lastContainedLogTimeMs());
+ if (!snapshotWriter.isPresent()) {
+ log.error("Not generating {} because it already exists.", provenance.snapshotName());
+ return;
+ }
+ try (RaftSnapshotWriter writer = new RaftSnapshotWriter(snapshotWriter.get(), batchSize)) {
+ image.write(writer, new ImageWriterOptions.Builder().
+ setMetadataVersion(image.features().metadataVersion()).
+ build());
+ writer.close(true);
+ } catch (Throwable e) {
+ log.error("Encountered error while writing {}", provenance.snapshotName(), e);
+ throw e;
+ } finally {
+ try {
+ snapshotWriter.get().close();
Review Comment:
This would be clearer without using the try-with-resources, which would also end up closing the writer. I do not know which logic will execute first. Perhaps it's best not to depend on the order.
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
+ lastContainedLogTimeMs = batch.appendTimestamp();
+ indexWithinBatch++;
+ }
+ metrics.updateBatchSize(batch.records().size());
+ lastOffset = batch.lastOffset();
+ numBytes += batch.sizeInBytes();
+ numBatches++;
+ }
+ MetadataProvenance provenance =
+ new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs);
+ long elapsedNs = time.nanoseconds() - startNs;
+ // TODO: this metric should be renamed something like "delta processing time"
+ metrics.updateBatchProcessingTime(elapsedNs);
+ return new LogDeltaManifest(provenance,
+ numBatches,
+ elapsedNs,
+ numBytes);
+ }
+
+ /**
+ * Handle a change in the metadata version.
+ *
+ * @param delta The metadata delta we're working with.
+ * @param change The change we're handling.
+ * @param changeOffset The offset of the change.
+ * @param preChangeEpoch The log epoch BEFORE the change.
+ */
+ void handleMetadataVersionChange(
+ MetadataDelta delta,
+ MetadataVersionChange change,
+ long changeOffset,
+ int preChangeEpoch,
+ long lastContainedLogTimeMs
+ ) {
+ // First, we materialize the current metadata image and send it to all the publishers that
+ // are interested in preVersionChange images. The most important one is the publisher which
+ // writes snapshots out to disk.
+ MetadataProvenance provenance =
+ new MetadataProvenance(changeOffset - 1, preChangeEpoch, lastContainedLogTimeMs);
+ PreVersionChangeManifest manifest = new PreVersionChangeManifest(provenance, change);
+ MetadataImage preVersionChangeImage = delta.apply(provenance);
+ for (MetadataPublisher publisher : publishers) {
+ try {
+ publisher.publishPreVersionChangeImage(delta, preVersionChangeImage, manifest);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error publishing pre-version change image at offset " +
+ provenance.offset() + " with publisher " + publisher.name(), e);
+ }
+ }
+ // Then, we clear the current delta and write out the current image to it in the new format.
+ // If any metadata was lost, we just log it here. We cannot prevent the losses because the
+ // decision to change the metadata version was already taken by the controller.
+ delta.clear();
+ ImageReWriter writer = new ImageReWriter(delta);
+ preVersionChangeImage.write(writer, new ImageWriterOptions.Builder().
+ setMetadataVersion(change.newVersion()).
+ setLossHandler(loss -> {
+ log.warn("{}", loss.getMessage());
+ }).
+ build());
+ }
+
+ @Override
+ public void handleSnapshot(SnapshotReader<ApiMessageAndVersion> reader) {
+ eventQueue.append(() -> {
+ try {
+ MetadataDelta delta = new MetadataDelta.Builder().
+ setImage(image).
+ build();
+ SnapshotManifest manifest = loadSnapshot(delta, reader);
+ try {
+ image = delta.apply(manifest.provenance());
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error generating new metadata image from " +
+ "snapshot at offset " + reader.lastContainedLogOffset(), e);
+ return;
+ }
+ 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. Additionally, it is an error for a version change to occur unless
+ * it is the very first record. 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());
+ return new SnapshotManifest(provenance,
+ time.nanoseconds() - startNs);
+ }
+
+ @Override
+ public void handleLeaderChange(LeaderAndEpoch leaderAndEpoch) {
+ eventQueue.append(() -> {
+ currentLeaderAndEpoch = leaderAndEpoch;
+ });
+ }
+
+ /**
+ * Install a list of publishers. When a publisher is installed, we will publish a MetadataDelta
+ * to it which contains the entire current image.
+ *
+ * @param newPublishers The publishers to install.
+ *
+ * @return A future which yields null when the publishers have been added, or
+ * an exception if the installation failed.
+ */
+ public CompletableFuture<Void> installPublishers(List<? extends MetadataPublisher> newPublishers) {
+ if (newPublishers.isEmpty()) return CompletableFuture.completedFuture(null);
+ CompletableFuture<Void> future = new CompletableFuture<>();
+ eventQueue.beginShutdown("installPublishers", () -> {
Review Comment:
Should be `append`, right? Same for `removeAndClosePublisher`. Do we have tests that are failing?
##########
core/src/test/scala/unit/kafka/server/metadata/BrokerMetadataListenerTest.scala:
##########
@@ -1,413 +0,0 @@
-/**
- * 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 kafka.server.metadata
-
-import java.util
-import java.util.concurrent.atomic.AtomicReference
-import java.util.{Collections, Optional}
-import org.apache.kafka.common.metadata.{FeatureLevelRecord, PartitionChangeRecord, PartitionRecord, RegisterBrokerRecord, TopicRecord}
-import org.apache.kafka.common.metrics.Metrics
-import org.apache.kafka.common.utils.Time
-import org.apache.kafka.common.{Endpoint, Uuid}
-import org.apache.kafka.image.{MetadataDelta, MetadataImage}
-import org.apache.kafka.metadata.util.SnapshotReason
-import org.apache.kafka.metadata.{BrokerRegistration, RecordTestUtils, VersionRange}
-import org.apache.kafka.server.common.{ApiMessageAndVersion, MetadataVersion}
-import org.apache.kafka.server.fault.{FaultHandler, MockFaultHandler}
-import org.junit.jupiter.api.Assertions.{assertEquals, assertTrue}
-import org.junit.jupiter.api.{AfterEach, Test}
-
-import scala.jdk.CollectionConverters._
-
-class BrokerMetadataListenerTest {
- private val metadataLoadingFaultHandler = new MockFaultHandler("metadata loading")
-
- @AfterEach
- def verifyNoFaults(): Unit = {
- metadataLoadingFaultHandler.maybeRethrowFirstException()
- }
-
- private def newBrokerMetadataListener(
- metrics: BrokerServerMetrics = BrokerServerMetrics(new Metrics()),
- snapshotter: Option[MetadataSnapshotter] = None,
- maxBytesBetweenSnapshots: Long = 1000000L,
- faultHandler: FaultHandler = metadataLoadingFaultHandler
- ): BrokerMetadataListener = {
- new BrokerMetadataListener(
- brokerId = 0,
- time = Time.SYSTEM,
- threadNamePrefix = None,
- maxBytesBetweenSnapshots = maxBytesBetweenSnapshots,
- snapshotter = snapshotter,
- brokerMetrics = metrics,
- _metadataLoadingFaultHandler = faultHandler
- )
- }
-
- @Test
- def testCreateAndClose(): Unit = {
- val listener = newBrokerMetadataListener()
- listener.close()
- }
-
- @Test
- def testPublish(): Unit = {
- val metrics = BrokerServerMetrics(new Metrics())
- val listener = newBrokerMetadataListener(metrics = metrics)
- try {
- val unfencedTimestamp = 300L
- listener.handleCommit(
- RecordTestUtils.mockBatchReader(
- 100,
- unfencedTimestamp,
- util.Arrays.asList(new ApiMessageAndVersion(new RegisterBrokerRecord().
- setBrokerId(0).
- setBrokerEpoch(100L).
- setFenced(false).
- setRack(null).
- setIncarnationId(Uuid.fromString("GFBwlTcpQUuLYQ2ig05CSg")), 0.toShort))
- )
- )
- val imageRecords = listener.getImageRecords().get()
- assertEquals(0, imageRecords.size())
- assertEquals(100L, listener.highestMetadataOffset)
- assertEquals(0L, metrics.lastAppliedRecordOffset.get)
- assertEquals(0L, metrics.lastAppliedRecordTimestamp.get)
- assertEquals(0L, metrics.metadataLoadErrorCount.get)
- assertEquals(0L, metrics.metadataApplyErrorCount.get)
-
- val fencedTimestamp = 500L
- val fencedLastOffset = 200L
- listener.handleCommit(
- RecordTestUtils.mockBatchReader(
- fencedLastOffset,
- fencedTimestamp,
- util.Arrays.asList(new ApiMessageAndVersion(new RegisterBrokerRecord().
- setBrokerId(1).
- setBrokerEpoch(200L).
- setFenced(true).
- setRack(null).
- setIncarnationId(Uuid.fromString("QkOQtNKVTYatADcaJ28xDg")), 0.toShort))
- )
- )
- listener.startPublishing(new MetadataPublisher {
- override def publish(delta: MetadataDelta, newImage: MetadataImage): Unit = {
- assertEquals(200L, newImage.highestOffsetAndEpoch().offset)
- assertEquals(new BrokerRegistration(0, 100L,
- Uuid.fromString("GFBwlTcpQUuLYQ2ig05CSg"), Collections.emptyList[Endpoint](),
- Collections.emptyMap[String, VersionRange](), Optional.empty[String](), false, false),
- delta.clusterDelta().broker(0))
- assertEquals(new BrokerRegistration(1, 200L,
- Uuid.fromString("QkOQtNKVTYatADcaJ28xDg"), Collections.emptyList[Endpoint](),
- Collections.emptyMap[String, VersionRange](), Optional.empty[String](), true, false),
- delta.clusterDelta().broker(1))
- }
-
- override def publishedOffset: Long = -1
- }).get()
-
- assertEquals(fencedLastOffset, metrics.lastAppliedRecordOffset.get)
- assertEquals(fencedTimestamp, metrics.lastAppliedRecordTimestamp.get)
- assertEquals(0L, metrics.metadataLoadErrorCount.get)
- assertEquals(0L, metrics.metadataApplyErrorCount.get)
- } finally {
- listener.close()
- }
- }
-
- class MockMetadataSnapshotter extends MetadataSnapshotter {
- var image = MetadataImage.EMPTY
- val failure = new AtomicReference[Throwable](null)
- var activeSnapshotOffset = -1L
- var prevCommittedOffset = -1L
- var prevCommittedEpoch = -1
- var prevLastContainedLogTime = -1L
-
- override def maybeStartSnapshot(lastContainedLogTime: Long, newImage: MetadataImage, reason: Set[SnapshotReason]): Boolean = {
- try {
- if (activeSnapshotOffset == -1L) {
- assertTrue(prevCommittedOffset <= newImage.highestOffsetAndEpoch().offset)
- assertTrue(prevCommittedEpoch <= newImage.highestOffsetAndEpoch().epoch)
- assertTrue(prevLastContainedLogTime <= lastContainedLogTime)
- prevCommittedOffset = newImage.highestOffsetAndEpoch().offset
- prevCommittedEpoch = newImage.highestOffsetAndEpoch().epoch
- prevLastContainedLogTime = lastContainedLogTime
- image = newImage
- activeSnapshotOffset = newImage.highestOffsetAndEpoch().offset
- true
- } else {
- false
- }
- } catch {
- case t: Throwable => failure.compareAndSet(null, t)
- }
- }
- }
-
- class MockMetadataPublisher extends MetadataPublisher {
- var image = MetadataImage.EMPTY
-
- override def publish(delta: MetadataDelta, newImage: MetadataImage): Unit = {
- image = newImage
- }
-
- override def publishedOffset: Long = -1
- }
-
- private val FOO_ID = Uuid.fromString("jj1G9utnTuCegi_gpnRgYw")
- private val BAR_ID = Uuid.fromString("SzN5j0LvSEaRIJHrxfMAlg")
-
- private def generateManyRecords(listener: BrokerMetadataListener,
- endOffset: Long): Unit = {
- (0 to 10000).foreach { _ =>
- listener.handleCommit(
- RecordTestUtils.mockBatchReader(
- endOffset,
- 0,
- util.Arrays.asList(
- new ApiMessageAndVersion(new PartitionChangeRecord().
- setPartitionId(0).
- setTopicId(FOO_ID).
- setRemovingReplicas(Collections.singletonList(1)), 0.toShort),
- new ApiMessageAndVersion(new PartitionChangeRecord().
- setPartitionId(0).
- setTopicId(FOO_ID).
- setRemovingReplicas(Collections.emptyList()), 0.toShort)
- )
- )
- )
- }
- listener.getImageRecords().get()
- }
-
- private def generateBadRecords(listener: BrokerMetadataListener,
- endOffset: Long): Unit = {
- listener.handleCommit(
- RecordTestUtils.mockBatchReader(
- endOffset,
- 0,
- util.Arrays.asList(
- new ApiMessageAndVersion(new PartitionChangeRecord().
- setPartitionId(0).
- setTopicId(BAR_ID).
- setRemovingReplicas(Collections.singletonList(1)), 0.toShort),
- new ApiMessageAndVersion(new PartitionChangeRecord().
- setPartitionId(0).
- setTopicId(BAR_ID).
- setRemovingReplicas(Collections.emptyList()), 0.toShort)
- )
- )
- )
- listener.getImageRecords().get()
- }
-
- @Test
- def testHandleCommitsWithNoSnapshotterDefined(): Unit = {
- val listener = newBrokerMetadataListener(maxBytesBetweenSnapshots = 1000L)
- try {
- val brokerIds = 0 to 3
-
- registerBrokers(listener, brokerIds, endOffset = 100L)
- createTopicWithOnePartition(listener, replicas = brokerIds, endOffset = 200L)
- listener.getImageRecords().get()
- assertEquals(200L, listener.highestMetadataOffset)
-
- generateManyRecords(listener, endOffset = 1000L)
- assertEquals(1000L, listener.highestMetadataOffset)
- } finally {
- listener.close()
- }
- }
-
- @Test
- def testCreateSnapshot(): Unit = {
- val snapshotter = new MockMetadataSnapshotter()
- val listener = newBrokerMetadataListener(snapshotter = Some(snapshotter),
- maxBytesBetweenSnapshots = 1000L)
- try {
- val brokerIds = 0 to 3
-
- registerBrokers(listener, brokerIds, endOffset = 100L)
- createTopicWithOnePartition(listener, replicas = brokerIds, endOffset = 200L)
- listener.getImageRecords().get()
- assertEquals(200L, listener.highestMetadataOffset)
-
- // Check that we generate at least one snapshot once we see enough records.
- assertEquals(-1L, snapshotter.prevCommittedOffset)
- generateManyRecords(listener, 1000L)
- assertEquals(1000L, snapshotter.prevCommittedOffset)
- assertEquals(1000L, snapshotter.activeSnapshotOffset)
- snapshotter.activeSnapshotOffset = -1L
-
- // Test creating a new snapshot after publishing it.
- val publisher = new MockMetadataPublisher()
- listener.startPublishing(publisher).get()
- generateManyRecords(listener, 2000L)
- listener.getImageRecords().get()
- assertEquals(2000L, snapshotter.activeSnapshotOffset)
- assertEquals(2000L, snapshotter.prevCommittedOffset)
-
- // Test how we handle the snapshotter returning false.
- generateManyRecords(listener, 3000L)
- assertEquals(2000L, snapshotter.activeSnapshotOffset)
- generateManyRecords(listener, 4000L)
- assertEquals(2000L, snapshotter.activeSnapshotOffset)
- snapshotter.activeSnapshotOffset = -1L
- generateManyRecords(listener, 5000L)
- assertEquals(5000L, snapshotter.activeSnapshotOffset)
- assertEquals(null, snapshotter.failure.get())
- } finally {
- listener.close()
- }
- }
-
- @Test
- def testNotSnapshotAfterMetadataVersionChangeBeforePublishing(): Unit = {
Review Comment:
Are all of these tests recreated somewhere?
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
+ lastContainedLogTimeMs = batch.appendTimestamp();
+ indexWithinBatch++;
+ }
+ metrics.updateBatchSize(batch.records().size());
+ lastOffset = batch.lastOffset();
+ numBytes += batch.sizeInBytes();
+ numBatches++;
+ }
+ MetadataProvenance provenance =
+ new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs);
+ long elapsedNs = time.nanoseconds() - startNs;
+ // TODO: this metric should be renamed something like "delta processing time"
+ metrics.updateBatchProcessingTime(elapsedNs);
+ return new LogDeltaManifest(provenance,
+ numBatches,
+ elapsedNs,
+ numBytes);
+ }
+
+ /**
+ * Handle a change in the metadata version.
+ *
+ * @param delta The metadata delta we're working with.
+ * @param change The change we're handling.
+ * @param changeOffset The offset of the change.
+ * @param preChangeEpoch The log epoch BEFORE the change.
+ */
+ void handleMetadataVersionChange(
+ MetadataDelta delta,
+ MetadataVersionChange change,
+ long changeOffset,
+ int preChangeEpoch,
+ long lastContainedLogTimeMs
+ ) {
+ // First, we materialize the current metadata image and send it to all the publishers that
Review Comment:
It would be helpful to add some motivation for this. Is it for recovery if something goes wrong after upgrade/downgrade?
##########
core/src/main/scala/kafka/server/KafkaConfig.scala:
##########
@@ -726,6 +728,7 @@ object KafkaConfig {
val MetadataLogDirDoc = "This configuration determines where we put the metadata log for clusters in KRaft mode. " +
"If it is not set, the metadata log is placed in the first log directory from log.dirs."
val MetadataSnapshotMaxNewRecordBytesDoc = "This is the maximum number of bytes in the log between the latest snapshot and the high-watermark needed before generating a new snapshot."
+ val MetadataSnapshotMaxIntervalMsDoc = "This is the maximum number of milliseconds that can elapse between the previous metadata snapshot and the next one."
Review Comment:
Perhaps add something like this?
> In other words, metadata snapshots will be generated at least as frequently as specified by this configuration. Note that if `metadata.log.max.record.bytes.between.snapshots` bytes of new data is reached before the full specified interval completes, then the snapshot will still be generated.
##########
core/src/main/scala/kafka/server/ControllerServer.scala:
##########
@@ -258,6 +264,14 @@ class ControllerServer(
shutdown()
throw e
}
+ config.dynamicConfig.addReconfigurables(this)
+ dynamicConfigHandlers = immutable.Map[String, ConfigHandler](
+ ConfigType.Broker -> new BrokerConfigHandler(config, quotaManagers))
+ controllerMetadataPublisher = new ControllerMetadataPublisher(
+ config,
+ dynamicConfigHandlers,
+ fatalFaultHandler)
+ metadataLoader.installPublishers(List().asJava)
Review Comment:
Don't we need the publisher in here? Do we have any integration tests which verify this all works?
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
+ lastContainedLogTimeMs = batch.appendTimestamp();
+ indexWithinBatch++;
+ }
+ metrics.updateBatchSize(batch.records().size());
+ lastOffset = batch.lastOffset();
+ numBytes += batch.sizeInBytes();
+ numBatches++;
+ }
+ MetadataProvenance provenance =
+ new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs);
+ long elapsedNs = time.nanoseconds() - startNs;
+ // TODO: this metric should be renamed something like "delta processing time"
Review Comment:
nit: can we move this comment to a jira?
##########
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:
This field is not accessed. Do we need it?
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
+ lastContainedLogTimeMs = batch.appendTimestamp();
+ indexWithinBatch++;
+ }
+ metrics.updateBatchSize(batch.records().size());
+ lastOffset = batch.lastOffset();
+ numBytes += batch.sizeInBytes();
+ numBatches++;
+ }
+ MetadataProvenance provenance =
+ new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs);
+ long elapsedNs = time.nanoseconds() - startNs;
+ // TODO: this metric should be renamed something like "delta processing time"
+ metrics.updateBatchProcessingTime(elapsedNs);
+ return new LogDeltaManifest(provenance,
+ numBatches,
+ elapsedNs,
+ numBytes);
+ }
+
+ /**
+ * Handle a change in the metadata version.
+ *
+ * @param delta The metadata delta we're working with.
+ * @param change The change we're handling.
+ * @param changeOffset The offset of the change.
+ * @param preChangeEpoch The log epoch BEFORE the change.
+ */
+ void handleMetadataVersionChange(
+ MetadataDelta delta,
+ MetadataVersionChange change,
+ long changeOffset,
+ int preChangeEpoch,
+ long lastContainedLogTimeMs
+ ) {
+ // First, we materialize the current metadata image and send it to all the publishers that
+ // are interested in preVersionChange images. The most important one is the publisher which
+ // writes snapshots out to disk.
+ MetadataProvenance provenance =
+ new MetadataProvenance(changeOffset - 1, preChangeEpoch, lastContainedLogTimeMs);
+ PreVersionChangeManifest manifest = new PreVersionChangeManifest(provenance, change);
+ MetadataImage preVersionChangeImage = delta.apply(provenance);
+ for (MetadataPublisher publisher : publishers) {
+ try {
+ publisher.publishPreVersionChangeImage(delta, preVersionChangeImage, manifest);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error publishing pre-version change image at offset " +
+ provenance.offset() + " with publisher " + publisher.name(), e);
+ }
+ }
+ // Then, we clear the current delta and write out the current image to it in the new format.
+ // If any metadata was lost, we just log it here. We cannot prevent the losses because the
+ // decision to change the metadata version was already taken by the controller.
+ delta.clear();
+ ImageReWriter writer = new ImageReWriter(delta);
+ preVersionChangeImage.write(writer, new ImageWriterOptions.Builder().
+ setMetadataVersion(change.newVersion()).
+ setLossHandler(loss -> {
+ log.warn("{}", loss.getMessage());
+ }).
+ build());
+ }
+
+ @Override
+ public void handleSnapshot(SnapshotReader<ApiMessageAndVersion> reader) {
+ eventQueue.append(() -> {
+ try {
+ MetadataDelta delta = new MetadataDelta.Builder().
+ setImage(image).
+ build();
+ SnapshotManifest manifest = loadSnapshot(delta, reader);
+ try {
+ image = delta.apply(manifest.provenance());
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error generating new metadata image from " +
+ "snapshot at offset " + reader.lastContainedLogOffset(), e);
+ return;
+ }
+ 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. Additionally, it is an error for a version change to occur unless
+ * it is the very first record. 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());
Review Comment:
This may still throw `MetadataVersionChangeException`, but we are not catching it. Am I missing something?
##########
core/src/main/scala/kafka/server/DynamicBrokerConfig.scala:
##########
@@ -269,6 +270,26 @@ class DynamicBrokerConfig(private val kafkaConfig: KafkaConfig) extends Logging
addBrokerReconfigurable(kafkaServer.logManager.producerStateManagerConfig)
}
+ /**
+ * Add reconfigurables to be notified when a dynamic controller config is updated.
+ */
+ def addReconfigurables(controller: ControllerServer): Unit = {
+ controller.authorizer match {
+ case Some(authz: Reconfigurable) => addReconfigurable(authz)
+ case _ =>
+ }
+ if (!kafkaConfig.processRoles.contains(BrokerRole)) {
+ // In combined mode, these elements are shared between broker and controller, and therefore
+ // don't need to be updated here (since the broker will do it.)
+ addReconfigurable(controller.kafkaYammerMetrics)
+ addReconfigurable(new DynamicMetricsReporters(
+ kafkaConfig.brokerId, controller.config, controller.metrics, controller.clusterId))
+ }
+ // TODO: add dynamic thread pool resizing here
Review Comment:
nit: create jiras. We need one for the quota callback as well.
##########
metadata/src/main/java/org/apache/kafka/image/publisher/SnapshotEmitter.java:
##########
@@ -0,0 +1,118 @@
+/*
+ * 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.image.MetadataImage;
+import org.apache.kafka.image.MetadataProvenance;
+import org.apache.kafka.image.writer.ImageWriterOptions;
+import org.apache.kafka.image.writer.RaftSnapshotWriter;
+import org.apache.kafka.raft.RaftClient;
+import org.apache.kafka.server.common.ApiMessageAndVersion;
+import org.apache.kafka.snapshot.SnapshotWriter;
+import org.slf4j.Logger;
+
+import java.util.Optional;
+
+public class SnapshotEmitter implements SnapshotGenerator.Emitter {
+ private final static int DEFAULT_BATCH_SIZE = 100;
+
+ public static class Builder {
+ private int nodeId = 0;
+ private RaftClient<ApiMessageAndVersion> raftClient = null;
+ private int batchSize = DEFAULT_BATCH_SIZE;
+
+ public Builder setNodeId(int nodeId) {
+ this.nodeId = nodeId;
+ return this;
+ }
+
+ public Builder setRaftClient(RaftClient<ApiMessageAndVersion> raftClient) {
+ this.raftClient = raftClient;
+ return this;
+ }
+
+ public Builder setBatchSize(int batchSize) {
+ this.batchSize = batchSize;
+ return this;
+ }
+
+ public SnapshotEmitter build() {
+ if (raftClient == null) throw new RuntimeException("You must set the raftClient.");
+ return new SnapshotEmitter(nodeId,
+ raftClient,
+ batchSize);
+ }
+ }
+
+ /**
+ * The slf4j logger to use.
+ */
+ private final Logger log;
+
+ /**
+ * The RaftClient to use.
+ */
+ private final RaftClient<ApiMessageAndVersion> raftClient;
+
+ /**
+ * The maximum number of records to put in each batch.
+ */
+ private final int batchSize;
+
+ private SnapshotEmitter(
+ int nodeId,
+ RaftClient<ApiMessageAndVersion> raftClient,
+ int batchSize
+ ) {
+ this.log = new LogContext("[SnapshotEmitter id=" + nodeId + "] ").logger(SnapshotEmitter.class);
+ this.raftClient = raftClient;
+ this.batchSize = batchSize;
+ }
+
+ @Override
+ public void emit(MetadataImage image) {
Review Comment:
nit: maybe we could call this `maybeEmit` or return a boolean or something. Just to make it clear that a snapshot may or may not be emitted by the call.
##########
metadata/src/main/java/org/apache/kafka/image/loader/LogDeltaManifest.java:
##########
@@ -0,0 +1,106 @@
+/*
+ * 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.image.MetadataProvenance;
+
+import java.util.Objects;
+
+
+/**
+ * Contains information about a set of changes that were loaded from the metadata log.
+ */
+public class LogDeltaManifest {
+ /**
+ * The highest offset and epoch included in this delta, inclusive.
+ */
+ private final MetadataProvenance provenance;
+
+ /**
+ * The number of batches that were loaded.
+ */
+ private final int numBatches;
Review Comment:
Seems we didn't need this and `elapsedNs` below?
##########
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:
Perhaps we should add a thread name prefix?
##########
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.");
Review Comment:
nit: if this is required, perhaps we should pass it in the constructor
##########
metadata/src/main/java/org/apache/kafka/image/loader/SnapshotManifest.java:
##########
@@ -0,0 +1,77 @@
+/*
+ * 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.image.MetadataProvenance;
+
+import java.util.Objects;
+
+
+/**
+ * Contains information about a snapshot that was loaded.
+ */
+public class SnapshotManifest {
+ /**
+ * The source of this snapshot.
+ */
+ private final MetadataProvenance provenance;
+
+ /**
+ * The time in microseconds that it took to load the snapshot.
+ */
+ private final long elapsedNs;
+
+ public SnapshotManifest(
+ MetadataProvenance provenance,
+ long elapsedNs
+ ) {
+ this.provenance = provenance;
+ this.elapsedNs = elapsedNs;
+ }
+
+ public MetadataProvenance provenance() {
+ return provenance;
+ }
+
+ public long elapsedNs() {
Review Comment:
I don't think this is used. Can we remove it?
##########
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, "");
+ resetSnapshotCounters();
+ }
+
+ @Override
+ public String name() {
+ return "SnapshotGenerator";
+ }
+
+ void resetSnapshotCounters() {
+ this.bytesSinceLastSnapshot = 0L;
+ this.lastSnapshotTimeNs = time.nanoseconds();
+ }
+
+ @Override
+ public void publishSnapshot(
+ MetadataDelta delta,
+ MetadataImage newImage,
+ SnapshotManifest manifest
+ ) {
+ // Reset the snapshot counters because we just read a snapshot.
+ resetSnapshotCounters();
+ }
+
+ @Override
+ public void publishPreVersionChangeImage(
+ MetadataDelta delta,
+ MetadataImage preVersionChangeImage,
+ PreVersionChangeManifest manifest
+ ) {
+ scheduleEmit("the metadata version changed", preVersionChangeImage);
+ }
+
+ @Override
+ public void publishLogDelta(
+ MetadataDelta delta,
+ MetadataImage newImage,
+ LogDeltaManifest manifest
+ ) {
+ bytesSinceLastSnapshot += manifest.numBytes();
+ if (bytesSinceLastSnapshot >= minBytesSinceLastSnapshot) {
+ if (eventQueue.isEmpty()) {
+ scheduleEmit("we have replayed at least " + minBytesSinceLastSnapshot +
+ " bytes", newImage);
+ }
+ } else if (minTimeSinceLastSnapshotNs != 0 &&
Review Comment:
I thought the intent was to disable time-based snapshots with -1.
##########
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;
+
+ /**
+ * 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);
+ 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;
+ }
+ 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 (MetadataVersionChangeException e) {
+ handleMetadataVersionChange(delta,
+ e.change(),
+ batch.baseOffset() + indexWithinBatch,
+ lastEpoch,
+ lastContainedLogTimeMs);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error loading metadata log record from offset " +
+ batch.baseOffset() + indexWithinBatch, e);
+ }
+ lastEpoch = batch.epoch();
+ lastContainedLogTimeMs = batch.appendTimestamp();
+ indexWithinBatch++;
+ }
+ metrics.updateBatchSize(batch.records().size());
+ lastOffset = batch.lastOffset();
+ numBytes += batch.sizeInBytes();
+ numBatches++;
+ }
+ MetadataProvenance provenance =
+ new MetadataProvenance(lastOffset, lastEpoch, lastContainedLogTimeMs);
+ long elapsedNs = time.nanoseconds() - startNs;
+ // TODO: this metric should be renamed something like "delta processing time"
+ metrics.updateBatchProcessingTime(elapsedNs);
+ return new LogDeltaManifest(provenance,
+ numBatches,
+ elapsedNs,
+ numBytes);
+ }
+
+ /**
+ * Handle a change in the metadata version.
+ *
+ * @param delta The metadata delta we're working with.
+ * @param change The change we're handling.
+ * @param changeOffset The offset of the change.
+ * @param preChangeEpoch The log epoch BEFORE the change.
+ */
+ void handleMetadataVersionChange(
+ MetadataDelta delta,
+ MetadataVersionChange change,
+ long changeOffset,
+ int preChangeEpoch,
+ long lastContainedLogTimeMs
+ ) {
+ // First, we materialize the current metadata image and send it to all the publishers that
+ // are interested in preVersionChange images. The most important one is the publisher which
+ // writes snapshots out to disk.
+ MetadataProvenance provenance =
+ new MetadataProvenance(changeOffset - 1, preChangeEpoch, lastContainedLogTimeMs);
+ PreVersionChangeManifest manifest = new PreVersionChangeManifest(provenance, change);
+ MetadataImage preVersionChangeImage = delta.apply(provenance);
+ for (MetadataPublisher publisher : publishers) {
+ try {
+ publisher.publishPreVersionChangeImage(delta, preVersionChangeImage, manifest);
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error publishing pre-version change image at offset " +
+ provenance.offset() + " with publisher " + publisher.name(), e);
+ }
+ }
+ // Then, we clear the current delta and write out the current image to it in the new format.
+ // If any metadata was lost, we just log it here. We cannot prevent the losses because the
+ // decision to change the metadata version was already taken by the controller.
+ delta.clear();
+ ImageReWriter writer = new ImageReWriter(delta);
+ preVersionChangeImage.write(writer, new ImageWriterOptions.Builder().
+ setMetadataVersion(change.newVersion()).
+ setLossHandler(loss -> {
+ log.warn("{}", loss.getMessage());
+ }).
+ build());
+ }
+
+ @Override
+ public void handleSnapshot(SnapshotReader<ApiMessageAndVersion> reader) {
+ eventQueue.append(() -> {
+ try {
+ MetadataDelta delta = new MetadataDelta.Builder().
+ setImage(image).
+ build();
+ SnapshotManifest manifest = loadSnapshot(delta, reader);
+ try {
+ image = delta.apply(manifest.provenance());
+ } catch (Throwable e) {
+ faultHandler.handleFault("Error generating new metadata image from " +
+ "snapshot at offset " + reader.lastContainedLogOffset(), e);
+ return;
+ }
+ 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. Additionally, it is an error for a version change to occur unless
+ * it is the very first record. 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;
Review Comment:
Not sure how useful this index is given the presence of control records in the snapshot. Why not use the offset from `Batch` as we do when processing log records?
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