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Posted to jira@kafka.apache.org by "ijuma (via GitHub)" <gi...@apache.org> on 2023/02/03 06:06:31 UTC
[GitHub] [kafka] ijuma commented on a diff in pull request #13040: KAFKA-14480 Move/Rewrite ProducerStateManager to storage module.
ijuma commented on code in PR #13040:
URL: https://github.com/apache/kafka/pull/13040#discussion_r1095387492
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storage/src/main/java/org/apache/kafka/server/log/internals/ProducerStateManager.java:
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@@ -0,0 +1,671 @@
+/*
+ * 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.server.log.internals;
+
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.protocol.types.ArrayOf;
+import org.apache.kafka.common.protocol.types.Field;
+import org.apache.kafka.common.protocol.types.Schema;
+import org.apache.kafka.common.protocol.types.SchemaException;
+import org.apache.kafka.common.protocol.types.Struct;
+import org.apache.kafka.common.protocol.types.Type;
+import org.apache.kafka.common.record.RecordBatch;
+import org.apache.kafka.common.utils.ByteUtils;
+import org.apache.kafka.common.utils.Crc32C;
+import org.apache.kafka.common.utils.Time;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.text.NumberFormat;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.OptionalLong;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Maintains a mapping from ProducerIds to metadata about the last appended entries (e.g.
+ * epoch, sequence number, last offset, etc.)
+ * <p>
+ * The sequence number is the last number successfully appended to the partition for the given identifier.
+ * The epoch is used for fencing against zombie writers. The offset is the one of the last successful message
+ * appended to the partition.
+ * <p>
+ * As long as a producer id is contained in the map, the corresponding producer can continue to write data.
+ * However, producer ids can be expired due to lack of recent use or if the last written entry has been deleted from
+ * the log (e.g. if the retention policy is "delete"). For compacted topics, the log cleaner will ensure
+ * that the most recent entry from a given producer id is retained in the log provided it hasn't expired due to
+ * age. This ensures that producer ids will not be expired until either the max expiration time has been reached,
+ * or if the topic also is configured for deletion, the segment containing the last written offset has
+ * been deleted.
+ */
+public class ProducerStateManager {
+ private static final Logger log = LoggerFactory.getLogger(ProducerStateManager.class.getName());
+
+ // Remove these once UnifiedLog moves to storage module.
+ public static final String DELETED_FILE_SUFFIX = ".deleted";
+ public static final String PRODUCER_SNAPSHOT_FILE_SUFFIX = ".snapshot";
+
+ public static final long LATE_TRANSACTION_BUFFER_MS = 5 * 60 * 1000;
+
+ private static final short PRODUCER_SNAPSHOT_VERSION = 1;
+ private static final String VERSION_FIELD = "version";
+ private static final String CRC_FIELD = "crc";
+ private static final String PRODUCER_ID_FIELD = "producer_id";
+ private static final String LAST_SEQUENCE_FIELD = "last_sequence";
+ private static final String PRODUCER_EPOCH_FIELD = "epoch";
+ private static final String LAST_OFFSET_FIELD = "last_offset";
+ private static final String OFFSET_DELTA_FIELD = "offset_delta";
+ private static final String TIMESTAMP_FIELD = "timestamp";
+ private static final String PRODUCER_ENTRIES_FIELD = "producer_entries";
+ private static final String COORDINATOR_EPOCH_FIELD = "coordinator_epoch";
+ private static final String CURRENT_TXN_FIRST_OFFSET_FIELD = "current_txn_first_offset";
+
+ private static final int VERSION_OFFSET = 0;
+ private static final int CRC_OFFSET = VERSION_OFFSET + 2;
+ private static final int PRODUCER_ENTRIES_OFFSET = CRC_OFFSET + 4;
+
+ private static final Schema PRODUCER_SNAPSHOT_ENTRY_SCHEMA = new Schema(new Field(PRODUCER_ID_FIELD, Type.INT64, "The producer ID"), new Field(PRODUCER_EPOCH_FIELD, Type.INT16, "Current epoch of the producer"), new Field(LAST_SEQUENCE_FIELD, Type.INT32, "Last written sequence of the producer"), new Field(LAST_OFFSET_FIELD, Type.INT64, "Last written offset of the producer"), new Field(OFFSET_DELTA_FIELD, Type.INT32, "The difference of the last sequence and first sequence in the last written batch"), new Field(TIMESTAMP_FIELD, Type.INT64, "Max timestamp from the last written entry"), new Field(COORDINATOR_EPOCH_FIELD, Type.INT32, "The epoch of the last transaction coordinator to send an end transaction marker"), new Field(CURRENT_TXN_FIRST_OFFSET_FIELD, Type.INT64, "The first offset of the on-going transaction (-1 if there is none)"));
+ private static final Schema PID_SNAPSHOT_MAP_SCHEMA = new Schema(new Field(VERSION_FIELD, Type.INT16, "Version of the snapshot file"), new Field(CRC_FIELD, Type.UNSIGNED_INT32, "CRC of the snapshot data"), new Field(PRODUCER_ENTRIES_FIELD, new ArrayOf(PRODUCER_SNAPSHOT_ENTRY_SCHEMA), "The entries in the producer table"));
+ private final TopicPartition topicPartition;
+ private volatile File logDir;
+ private final int maxTransactionTimeoutMs;
+ private final ProducerStateManagerConfig producerStateManagerConfig;
+ private final Time time;
+
+ private ConcurrentSkipListMap<Long, SnapshotFile> snapshots;
+
+ private final Map<Long, ProducerStateEntry> producers = new HashMap<>();
+ private long lastMapOffset = 0L;
+ private long lastSnapOffset = 0L;
+
+ // Keep track of the last timestamp from the oldest transaction. This is used
+ // to detect (approximately) when a transaction has been left hanging on a partition.
+ // We make the field volatile so that it can be safely accessed without a lock.
+ private volatile long oldestTxnLastTimestamp = -1L;
+
+ // ongoing transactions sorted by the first offset of the transaction
+ private final TreeMap<Long, TxnMetadata> ongoingTxns = new TreeMap<>();
+
+ // completed transactions whose markers are at offsets above the high watermark
+ private final TreeMap<Long, TxnMetadata> unreplicatedTxns = new TreeMap<>();
+
+ public ProducerStateManager(TopicPartition topicPartition, File logDir, int maxTransactionTimeoutMs, ProducerStateManagerConfig producerStateManagerConfig, Time time) throws IOException {
+ this.topicPartition = topicPartition;
+ this.logDir = logDir;
+ this.maxTransactionTimeoutMs = maxTransactionTimeoutMs;
+ this.producerStateManagerConfig = producerStateManagerConfig;
+ this.time = time;
+ snapshots = loadSnapshots();
+ }
+
+ public int maxTransactionTimeoutMs() {
+ return maxTransactionTimeoutMs;
+ }
+
+ public ProducerStateManagerConfig producerStateManagerConfig() {
+ return producerStateManagerConfig;
+ }
+
+ public boolean hasLateTransaction(long currentTimeMs) {
+ long lastTimestamp = oldestTxnLastTimestamp;
+ return lastTimestamp > 0 && (currentTimeMs - lastTimestamp) > maxTransactionTimeoutMs + ProducerStateManager.LATE_TRANSACTION_BUFFER_MS;
+ }
+
+ public void truncateFullyAndReloadSnapshots() throws IOException {
+ log.info("Reloading the producer state snapshots");
+ truncateFullyAndStartAt(0L);
+ snapshots = loadSnapshots();
+ }
+
+
+ /**
+ * Load producer state snapshots by scanning the _logDir.
+ */
+ private ConcurrentSkipListMap<Long, SnapshotFile> loadSnapshots() throws IOException {
+ ConcurrentSkipListMap<Long, SnapshotFile> offsetToSnapshots = new ConcurrentSkipListMap<>();
+ List<SnapshotFile> snapshotFiles = listSnapshotFiles(logDir);
+ for (SnapshotFile snapshotFile : snapshotFiles) {
+ offsetToSnapshots.put(snapshotFile.offset, snapshotFile);
+ }
+ return offsetToSnapshots;
+ }
+
+ /**
+ * Scans the log directory, gathering all producer state snapshot files. Snapshot files which do not have an offset
+ * corresponding to one of the provided offsets in segmentBaseOffsets will be removed, except in the case that there
+ * is a snapshot file at a higher offset than any offset in segmentBaseOffsets.
+ * <p>
+ * The goal here is to remove any snapshot files which do not have an associated segment file, but not to remove the
+ * largest stray snapshot file which was emitted during clean shutdown.
+ */
+ public void removeStraySnapshots(Collection<Long> segmentBaseOffsets) throws IOException {
+ OptionalLong maxSegmentBaseOffset = segmentBaseOffsets.isEmpty() ? OptionalLong.empty() : OptionalLong.of(segmentBaseOffsets.stream().max(Long::compare).get());
+
+ HashSet<Long> baseOffsets = new HashSet<>(segmentBaseOffsets);
+ Optional<SnapshotFile> latestStraySnapshot = Optional.empty();
+
+ ConcurrentSkipListMap<Long, SnapshotFile> snapshots = loadSnapshots();
+ for (SnapshotFile snapshot : snapshots.values()) {
+ long key = snapshot.offset;
+ if (latestStraySnapshot.isPresent()) {
+ SnapshotFile prev = latestStraySnapshot.get();
+ if (!baseOffsets.contains(key)) {
+ // this snapshot is now the largest stray snapshot.
+ prev.deleteIfExists();
+ snapshots.remove(prev.offset);
+ latestStraySnapshot = Optional.of(snapshot);
+ }
+ } else {
+ if (!baseOffsets.contains(key)) {
+ latestStraySnapshot = Optional.of(snapshot);
+ }
+ }
+ }
+
+ // Check to see if the latestStraySnapshot is larger than the largest segment base offset, if it is not,
+ // delete the largestStraySnapshot.
+ if (latestStraySnapshot.isPresent() && maxSegmentBaseOffset.isPresent()) {
+ long strayOffset = latestStraySnapshot.get().offset;
+ long maxOffset = maxSegmentBaseOffset.getAsLong();
+ if (strayOffset < maxOffset) {
+ SnapshotFile removedSnapshot = snapshots.remove(strayOffset);
+ if (removedSnapshot != null) {
+ removedSnapshot.deleteIfExists();
+ }
+ }
+ }
+
+ this.snapshots = snapshots;
+ }
+
+ /**
+ * An unstable offset is one which is either undecided (i.e. its ultimate outcome is not yet known),
+ * or one that is decided, but may not have been replicated (i.e. any transaction which has a COMMIT/ABORT
+ * marker written at a higher offset than the current high watermark).
+ */
+ public Optional<LogOffsetMetadata> firstUnstableOffset() {
+ Optional<LogOffsetMetadata> unreplicatedFirstOffset = Optional.ofNullable(unreplicatedTxns.firstEntry()).map(e -> e.getValue().firstOffset);
+ Optional<LogOffsetMetadata> undecidedFirstOffset = Optional.ofNullable(ongoingTxns.firstEntry()).map(e -> e.getValue().firstOffset);
+ Optional<LogOffsetMetadata> result;
+ if (!unreplicatedFirstOffset.isPresent()) result = undecidedFirstOffset;
+ else if (!undecidedFirstOffset.isPresent()) result = unreplicatedFirstOffset;
+ else if (undecidedFirstOffset.get().messageOffset < unreplicatedFirstOffset.get().messageOffset)
+ result = undecidedFirstOffset;
+ else result = unreplicatedFirstOffset;
+
+ return result;
+ }
+
+ /**
+ * Acknowledge all transactions which have been completed before a given offset. This allows the LSO
+ * to advance to the next unstable offset.
+ */
+ public void onHighWatermarkUpdated(long highWatermark) {
+ removeUnreplicatedTransactions(highWatermark);
+ }
+
+
+ /**
+ * The first undecided offset is the earliest transactional message which has not yet been committed
+ * or aborted. Unlike [[firstUnstableOffset]], this does not reflect the state of replication (i.e.
+ * whether a completed transaction marker is beyond the high watermark).
+ */
+ public OptionalLong firstUndecidedOffset() {
+ Map.Entry<Long, TxnMetadata> firstEntry = ongoingTxns.firstEntry();
+ return firstEntry != null ? OptionalLong.of(firstEntry.getValue().firstOffset.messageOffset) : OptionalLong.empty();
+ }
+
+ /**
+ * Returns the last offset of this map
+ */
+ public long mapEndOffset() {
+ return lastMapOffset;
+ }
+
+ /**
+ * Get a copy of the active producers
+ */
+ public Map<Long, ProducerStateEntry> activeProducers() {
+ return Collections.unmodifiableMap(producers);
+ }
+
+ public boolean isEmpty() {
+ return producers.isEmpty() && unreplicatedTxns.isEmpty();
+ }
+
+ private void loadFromSnapshot(long logStartOffset, long currentTime) throws IOException {
+ while (true) {
+ Optional<SnapshotFile> latestSnapshotFileOptional = latestSnapshotFile();
+ if (latestSnapshotFileOptional.isPresent()) {
+ SnapshotFile snapshot = latestSnapshotFileOptional.get();
+ try {
+ log.info("Loading producer state from snapshot file '{}'", snapshot.file());
+ Stream<ProducerStateEntry> loadedProducers = readSnapshot(snapshot.file()).stream().filter(producerEntry -> !isProducerExpired(currentTime, producerEntry));
+ loadedProducers.forEach(this::loadProducerEntry);
+ lastSnapOffset = snapshot.offset;
+ lastMapOffset = lastSnapOffset;
+ updateOldestTxnTimestamp();
+ return;
+ } catch (CorruptSnapshotException e) {
+ log.warn("Failed to load producer snapshot from '${snapshot.file}': ${e.getMessage}");
+ removeAndDeleteSnapshot(snapshot.offset);
+ }
+ } else {
+ lastSnapOffset = logStartOffset;
+ lastMapOffset = logStartOffset;
+ return;
+
+ }
+ }
+ }
+
+ public void loadProducerEntry(ProducerStateEntry entry) {
+ long producerId = entry.producerId();
+ producers.put(producerId, entry);
+ entry.currentTxnFirstOffset().ifPresent(offset -> ongoingTxns.put(offset, new TxnMetadata(producerId, offset)));
+ }
+
+ private boolean isProducerExpired(long currentTimeMs, ProducerStateEntry producerState) {
+ return !producerState.currentTxnFirstOffset().isPresent() && currentTimeMs - producerState.lastTimestamp() >= producerStateManagerConfig.producerIdExpirationMs();
+ }
+
+ /**
+ * Expire any producer ids which have been idle longer than the configured maximum expiration timeout.
+ */
+ public void removeExpiredProducers(long currentTimeMs) {
+ Set<Long> keys = producers.entrySet().stream().filter(entry -> isProducerExpired(currentTimeMs, entry.getValue())).map(Map.Entry::getKey).collect(Collectors.toSet());
+ for (Long key : keys) {
+ producers.remove(key);
+ }
+ }
+
+ /**
+ * Truncate the producer id mapping to the given offset range and reload the entries from the most recent
+ * snapshot in range (if there is one). We delete snapshot files prior to the logStartOffset but do not remove
+ * producer state from the map. This means that in-memory and on-disk state can diverge, and in the case of
+ * broker failover or unclean shutdown, any in-memory state not persisted in the snapshots will be lost, which
+ * would lead to UNKNOWN_PRODUCER_ID errors. Note that the log end offset is assumed to be less than or equal
+ * to the high watermark.
+ */
+ public void truncateAndReload(long logStartOffset, long logEndOffset, long currentTimeMs) throws IOException {
+ // remove all out of range snapshots
+ for (SnapshotFile snapshot : snapshots.values()) {
+ if (snapshot.offset > logEndOffset || snapshot.offset <= logStartOffset) {
+ removeAndDeleteSnapshot(snapshot.offset);
+ }
+ }
+
+ if (logEndOffset != mapEndOffset()) {
+ producers.clear();
+ ongoingTxns.clear();
+ updateOldestTxnTimestamp();
+
+ // since we assume that the offset is less than or equal to the high watermark, it is
+ // safe to clear the unreplicated transactions
+ unreplicatedTxns.clear();
+ loadFromSnapshot(logStartOffset, currentTimeMs);
+ } else {
+ onLogStartOffsetIncremented(logStartOffset);
+ }
+ }
+
+ public ProducerAppendInfo prepareUpdate(long producerId, AppendOrigin origin) {
+ ProducerStateEntry currentEntry = lastEntry(producerId).orElse(ProducerStateEntry.empty(producerId));
+ return new ProducerAppendInfo(topicPartition, producerId, currentEntry, origin);
+ }
+
+
+ /**
+ * Update the mapping with the given append information
+ */
+ public void update(ProducerAppendInfo appendInfo) {
+ if (appendInfo.producerId() == RecordBatch.NO_PRODUCER_ID)
+ throw new IllegalArgumentException("Invalid producer id " + appendInfo.producerId() + " passed to update " + "for partition $topicPartition");
+
+ log.trace("Updated producer " + appendInfo.producerId() + " state to" + appendInfo);
+ ProducerStateEntry updatedEntry = appendInfo.toEntry();
+ ProducerStateEntry producerStateEntry = producers.get(appendInfo.producerId());
+ if (producerStateEntry != null) {
+ producerStateEntry.update(updatedEntry);
+ } else {
+ producers.put(appendInfo.producerId(), updatedEntry);
+ }
+
+ appendInfo.startedTransactions().forEach(txn -> ongoingTxns.put(txn.firstOffset.messageOffset, txn));
+
+ updateOldestTxnTimestamp();
+ }
+
+
+ private void updateOldestTxnTimestamp() {
+ Map.Entry<Long, TxnMetadata> firstEntry = ongoingTxns.firstEntry();
+ if (firstEntry == null) {
+ oldestTxnLastTimestamp = -1;
+ } else {
+ TxnMetadata oldestTxnMetadata = firstEntry.getValue();
+ ProducerStateEntry entry = producers.get(oldestTxnMetadata.producerId);
+ oldestTxnLastTimestamp = entry != null ? entry.lastTimestamp() : -1L;
+ }
+ }
+
+ public void updateMapEndOffset(long lastOffset) {
+ lastMapOffset = lastOffset;
+ }
+
+ /**
+ * Get the last written entry for the given producer id.
+ */
+ public Optional<ProducerStateEntry> lastEntry(long producerId) {
+ return Optional.ofNullable(producers.get(producerId));
+ }
+
+ /**
+ * Take a snapshot at the current end offset if one does not already exist.
+ */
+ public void takeSnapshot() throws IOException {
Review Comment:
We are trying to avoid making changes that could result in subtle breakage unless there is a strong reason to make the change and we have a high degree of confidence that it's safe to do so. With that in mind, what's the reason for making the change you are suggesting?
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