Poorvankbhatia commented on code in PR #6: URL: https://github.com/apache/flink-connector-redis-streams/pull/6#discussion_r3170124129
########## flink-connector-redis-streams/src/main/java/org/apache/flink/connector/redis/streams/source/reader/split/RedisStreamsSplitReader.java: ########## @@ -0,0 +1,983 @@ +/* + * 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.flink.connector.redis.streams.source.reader.split; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds; +import org.apache.flink.connector.base.source.reader.splitreader.SplitReader; +import org.apache.flink.connector.base.source.reader.splitreader.SplitsAddition; +import org.apache.flink.connector.base.source.reader.splitreader.SplitsChange; +import org.apache.flink.connector.redis.streams.source.config.RedisStreamsSourceConfig; +import org.apache.flink.connector.redis.streams.source.config.StartupMode; +import org.apache.flink.connector.redis.streams.source.split.RedisStreamsSourceSplit; + +import io.lettuce.core.AbstractRedisClient; +import io.lettuce.core.ClientOptions; +import io.lettuce.core.Consumer; +import io.lettuce.core.RedisClient; +import io.lettuce.core.RedisConnectionException; +import io.lettuce.core.RedisURI; +import io.lettuce.core.StreamMessage; +import io.lettuce.core.XGroupCreateArgs; +import io.lettuce.core.XReadArgs; +import io.lettuce.core.api.StatefulConnection; +import io.lettuce.core.cluster.ClusterClientOptions; +import io.lettuce.core.cluster.ClusterTopologyRefreshOptions; +import io.lettuce.core.cluster.RedisClusterClient; +import io.lettuce.core.cluster.api.sync.RedisClusterCommands; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.io.IOException; +import java.time.Duration; +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.Deque; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.locks.ReentrantLock; + +/** + * Split reader that fetches records from Redis Streams via consumer groups and defers XACK until + * the next completed Flink checkpoint. + */ +@Internal +public class RedisStreamsSplitReader + implements SplitReader<StreamMessage<String, String>, RedisStreamsSourceSplit> { + + private static final Logger LOG = LoggerFactory.getLogger(RedisStreamsSplitReader.class); + + private static final long INITIAL_RECONNECT_DELAY_MS = 100L; + private static final long MAX_RECONNECT_DELAY_MS = 30000L; + private static final double BACKOFF_MULTIPLIER = 1.5; + private static final int MAX_CONSUMER_GROUP_RETRIES = 3; + private static final long CONSUMER_GROUP_RETRY_DELAY_MS = 100L; + + private final RedisStreamsSourceConfig config; + private final int subtaskId; + private final ReentrantLock stateLock = new ReentrantLock(); + + // Owned by the fetch thread; commands is also read by the checkpoint thread under stateLock. + private AbstractRedisClient redisClient; + private StatefulConnection<String, String> connection; + private RedisClusterCommands<String, String> commands; + + private final AtomicBoolean wokenUp = new AtomicBoolean(false); + + // Guarded by stateLock. + + private final Map<String, RedisStreamsSourceSplit> assignedSplits = new HashMap<>(); + private final Set<String> pausedSplits = new HashSet<>(); + private final Map<String, Deque<String>> deferredAcks = new HashMap<>(); + private final Map<String, CircuitBreaker> splitCircuitBreakers = new HashMap<>(); + // checkpointId -> splitId -> max #IDs to ack from front of deferredAcks at that barrier. + private final Map<Long, Map<String, Integer>> checkpointAckSnapshots = new HashMap<>(); + private final Map<String, String> pendingRecoveryOffset = new HashMap<>(); + private final Set<String> pendingRecoveryComplete = new HashSet<>(); + private final Set<String> needsGroupInit = new HashSet<>(); + // Drops late/out-of-order notifyCheckpointComplete calls. + private long maxCommittedCheckpointId = -1L; + + // Fetch-thread-only. + private long nextReconnectDelayMs = INITIAL_RECONNECT_DELAY_MS; + private long lastConnectionFailureTime = 0L; + private boolean connectionInitialized = false; + + public RedisStreamsSplitReader(RedisStreamsSourceConfig config, int subtaskId) { + this.config = config; + this.subtaskId = subtaskId; + } + + private void initializeConnection() { + try { + RedisClusterCommands<String, String> sync; + if (config.isClusterMode()) { + List<RedisURI> seeds = buildClusterSeedUris(config); + RedisClusterClient cluster = RedisClusterClient.create(seeds); + // Auto-reconnect off (we own backoff). Topology refresh on so MOVED/ASK and + // failovers are picked up. + ClusterTopologyRefreshOptions topology = + ClusterTopologyRefreshOptions.builder() + .enablePeriodicRefresh( + Duration.ofMillis( + config.getClusterTopologyRefreshPeriodMs())) + .enableAllAdaptiveRefreshTriggers() + .build(); + cluster.setOptions( + ClusterClientOptions.builder() + .autoReconnect(false) + .topologyRefreshOptions(topology) + .build()); + io.lettuce.core.cluster.api.StatefulRedisClusterConnection<String, String> conn = + cluster.connect(); + this.redisClient = cluster; + this.connection = conn; + sync = conn.sync(); + LOG.info( + "Connected to Redis Cluster (seeds={}, topologyRefresh={}ms)", + config.getClusterNodes(), + config.getClusterTopologyRefreshPeriodMs()); + } else { + RedisURI.Builder uriBuilder = + RedisURI.builder() + .withHost(config.getHost()) + .withPort(config.getPort()) + .withDatabase(config.getDatabase()) + .withTimeout(Duration.ofSeconds(5)); + if (config.getPassword() != null && !config.getPassword().isEmpty()) { + uriBuilder.withPassword(config.getPassword().toCharArray()); + } + RedisClient client = RedisClient.create(uriBuilder.build()); + // Auto-reconnect off — we own backoff. + client.setOptions(ClientOptions.builder().autoReconnect(false).build()); + io.lettuce.core.api.StatefulRedisConnection<String, String> conn = client.connect(); + this.redisClient = client; + this.connection = conn; + sync = conn.sync(); + LOG.info("Connected to Redis at {}:{}", config.getHost(), config.getPort()); + } + stateLock.lock(); + try { + this.commands = sync; + } finally { + stateLock.unlock(); + } + this.nextReconnectDelayMs = INITIAL_RECONNECT_DELAY_MS; + this.lastConnectionFailureTime = 0L; + this.connectionInitialized = true; + } catch (Exception e) { + LOG.error("Failed to initialize Redis connection", e); + cleanupConnection(); + handleConnectionFailure(); + } + } + + private static List<RedisURI> buildClusterSeedUris(RedisStreamsSourceConfig cfg) { + List<RedisURI> uris = new ArrayList<>(cfg.getClusterNodes().size()); + for (String node : cfg.getClusterNodes()) { + int colon = node.lastIndexOf(':'); + String host = node.substring(0, colon); + int port = Integer.parseInt(node.substring(colon + 1)); + RedisURI.Builder b = + RedisURI.builder() + .withHost(host) + .withPort(port) + .withTimeout(Duration.ofSeconds(5)); + if (cfg.getPassword() != null && !cfg.getPassword().isEmpty()) { + b.withPassword(cfg.getPassword().toCharArray()); + } + // Cluster does not honour SELECT, so database is always 0. + uris.add(b.build()); + } + return uris; + } + + private void handleConnectionFailure() { + lastConnectionFailureTime = System.currentTimeMillis(); + nextReconnectDelayMs = + Math.min( + (long) (nextReconnectDelayMs * BACKOFF_MULTIPLIER), MAX_RECONNECT_DELAY_MS); + LOG.warn("Connection failure detected. Will retry in {} ms", nextReconnectDelayMs); + } + + private boolean ensureConnected() { + try { + if (!connectionInitialized || connection == null || !connection.isOpen()) { + long timeSinceLastFailure = System.currentTimeMillis() - lastConnectionFailureTime; + if (lastConnectionFailureTime > 0 && timeSinceLastFailure < nextReconnectDelayMs) { + return false; + } + LOG.info("Reconnecting to Redis (delay was {} ms)", nextReconnectDelayMs); + cleanupConnection(); + initializeConnection(); + if (connection != null && connection.isOpen()) { + try { + commands.ping(); + LOG.info("Redis connection re-established and verified"); + return true; + } catch (Exception e) { + LOG.error("Redis health check failed after reconnect", e); + cleanupConnection(); + handleConnectionFailure(); + return false; + } + } + return false; + } + return true; + } catch (Exception e) { + LOG.error("Error checking connection status", e); + cleanupConnection(); + handleConnectionFailure(); + return false; + } + } + + @Override + public RecordsWithSplitIds<StreamMessage<String, String>> fetch() throws IOException { + if (wokenUp.compareAndSet(true, false)) { + return RedisStreamsRecords.empty(); + } + + retryPendingGroupInit(); + + Map<String, RedisStreamsSourceSplit> splitsToFetch; + stateLock.lock(); + try { + if (assignedSplits.isEmpty()) { + return RedisStreamsRecords.empty(); + } + splitsToFetch = new HashMap<>(); + for (Map.Entry<String, RedisStreamsSourceSplit> entry : assignedSplits.entrySet()) { + String splitId = entry.getKey(); + if (pausedSplits.contains(splitId)) { + continue; + } + if (needsGroupInit.contains(splitId)) { + continue; + } + CircuitBreaker breaker = splitCircuitBreakers.get(splitId); + if (breaker != null && breaker.isOpen()) { + LOG.debug("Circuit breaker open for split {}, skipping fetch", splitId); + continue; + } + Deque<String> deferred = deferredAcks.get(splitId); + if (deferred != null && deferred.size() >= config.getMaxDeferredAckQueueSize()) { + LOG.debug( + "Deferred ACK queue for split {} at capacity ({})", + splitId, + config.getMaxDeferredAckQueueSize()); + continue; + } + splitsToFetch.put(splitId, entry.getValue()); + } + } finally { + stateLock.unlock(); + } + + if (splitsToFetch.isEmpty()) { + return RedisStreamsRecords.empty(); + } + + if (!ensureConnected()) { + LOG.warn( + "Redis connection unavailable; skipping fetch. Next retry in {} ms", + nextReconnectDelayMs); + return RedisStreamsRecords.empty(); + } + + Map<String, Collection<StreamMessage<String, String>>> recordsBySplit = new HashMap<>(); + Set<String> finishedInThisFetch = new HashSet<>(); + + for (Map.Entry<String, RedisStreamsSourceSplit> entry : splitsToFetch.entrySet()) { + if (wokenUp.compareAndSet(true, false)) { + break; + } + String splitId = entry.getKey(); + RedisStreamsSourceSplit split = entry.getValue(); + try { + FetchResult result = fetchFromSplit(split); + if (!result.messages.isEmpty()) { + recordsBySplit.put(splitId, result.messages); + } + if (result.finished) { + finishedInThisFetch.add(splitId); + LOG.info("Split {} reached its stopping bound", splitId); + } + } catch (RedisConnectionException e) { + LOG.warn("Redis connection error for split {}: {}", splitId, e.getMessage()); + cleanupConnection(); + handleConnectionFailure(); + recordSplitFailure(splitId); + break; + } catch (Exception e) { + if (e.getMessage() != null && e.getMessage().contains("NOGROUP")) { + LOG.warn("Consumer group missing for split {}; will retry init", splitId); + stateLock.lock(); + try { + needsGroupInit.add(splitId); + } finally { + stateLock.unlock(); + } + } else { + LOG.error("Unexpected error fetching from split {}", splitId, e); + recordSplitFailure(splitId); + } + } + } + + stateLock.lock(); + try { + for (Map.Entry<String, Collection<StreamMessage<String, String>>> entry : + recordsBySplit.entrySet()) { + String splitId = entry.getKey(); + Collection<StreamMessage<String, String>> records = entry.getValue(); + if (records.isEmpty()) { + continue; + } + Deque<String> deferred = + deferredAcks.computeIfAbsent(splitId, k -> new ArrayDeque<>()); + for (StreamMessage<String, String> msg : records) { + deferred.addLast(msg.getId()); + } + CircuitBreaker breaker = splitCircuitBreakers.get(splitId); + if (breaker != null) { + breaker.recordSuccess(); + } + } + // Finished splits keep their deferred queue so the next checkpoint can XACK them. + for (String splitId : finishedInThisFetch) { + assignedSplits.remove(splitId); + pendingRecoveryComplete.remove(splitId); + pendingRecoveryOffset.remove(splitId); + needsGroupInit.remove(splitId); + pausedSplits.remove(splitId); + } + } finally { + stateLock.unlock(); + } + + return new RedisStreamsRecords(recordsBySplit, finishedInThisFetch); + } + + private void recordSplitFailure(String splitId) { + stateLock.lock(); + try { + splitCircuitBreakers + .computeIfAbsent( + splitId, + k -> + new CircuitBreaker( + config.getCircuitBreakerFailureThreshold(), + config.getCircuitBreakerOpenDurationMs())) + .recordFailure(); + } finally { + stateLock.unlock(); + } + } + + private static final class FetchResult { + static final FetchResult EMPTY_NOT_FINISHED = + new FetchResult(Collections.emptyList(), false); + + final List<StreamMessage<String, String>> messages; + final boolean finished; + + FetchResult(List<StreamMessage<String, String>> messages, boolean finished) { + this.messages = messages; + this.finished = finished; + } + } + + private FetchResult fetchFromSplit(RedisStreamsSourceSplit split) throws Exception { + String streamKey = split.getStreamKey(); + String stoppingId = split.getStoppingEntryId(); + Consumer<String> consumer = + Consumer.from( + config.getConsumerGroup(), config.getConsumerName() + "-" + subtaskId); + + boolean inRecovery; + String pendingOffset; + stateLock.lock(); + try { + inRecovery = !pendingRecoveryComplete.contains(streamKey); + pendingOffset = pendingRecoveryOffset.getOrDefault(streamKey, "0"); + } finally { + stateLock.unlock(); + } + + if (inRecovery) { + XReadArgs pendingReadArgs = XReadArgs.Builder.count(config.getBatchSize()); + List<StreamMessage<String, String>> pending = + commands.xreadgroup( + consumer, + pendingReadArgs, + XReadArgs.StreamOffset.from(streamKey, pendingOffset)); + + if (pending != null && !pending.isEmpty()) { + String lastPendingId = pending.get(pending.size() - 1).getId(); + // Defensive: bail out if the offset did not advance (would otherwise spin). + if (lastPendingId.equals(pendingOffset)) { Review Comment: Can u clarify the point of this check? -- This is an automated message from the Apache Git Service. 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