noob-se7en commented on code in PR #15261: URL: https://github.com/apache/pinot/pull/15261#discussion_r2014962975
########## pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/ConsumerCoordinator.java: ########## @@ -0,0 +1,302 @@ +/** + * 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.pinot.core.data.manager.realtime; + +import com.google.common.annotations.VisibleForTesting; +import com.google.common.base.Preconditions; +import java.util.Map; +import java.util.concurrent.Semaphore; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; +import javax.annotation.Nullable; +import org.apache.helix.model.IdealState; +import org.apache.pinot.common.metrics.ServerMetrics; +import org.apache.pinot.common.metrics.ServerTimer; +import org.apache.pinot.common.utils.LLCSegmentName; +import org.apache.pinot.common.utils.helix.HelixHelper; +import org.apache.pinot.segment.local.data.manager.SegmentDataManager; +import org.apache.pinot.spi.config.table.ingestion.StreamIngestionConfig; +import org.apache.pinot.spi.utils.CommonConstants; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +/** + * The ConsumerCoordinator coordinates the offline->consuming helix transitions. + */ +public class ConsumerCoordinator { + + private static final Logger LOGGER = LoggerFactory.getLogger(ConsumerCoordinator.class); + + private final Semaphore _semaphore; + private final boolean _enforceConsumptionInOrder; + private final Condition _condition; + private final Lock _lock; + private final ServerMetrics _serverMetrics; + private volatile int _maxSegmentSeqNumRegistered = -1; + private final boolean _alwaysRelyOnIdealState; + private final RealtimeTableDataManager _realtimeTableDataManager; + private final AtomicBoolean _isFirstTransitionProcessed; + private static final long WAIT_INTERVAL_MS = TimeUnit.MINUTES.toMillis(3); + + public ConsumerCoordinator(boolean enforceConsumptionInOrder, RealtimeTableDataManager realtimeTableDataManager) { + _semaphore = new Semaphore(1); + _lock = new ReentrantLock(); + _condition = _lock.newCondition(); + _enforceConsumptionInOrder = enforceConsumptionInOrder; + _realtimeTableDataManager = realtimeTableDataManager; + StreamIngestionConfig streamIngestionConfig = realtimeTableDataManager.getStreamIngestionConfig(); + if (streamIngestionConfig != null) { + // if isUseIdealStateToCalculatePreviousSegment is true, server relies on ideal state to fetch previous segment + // to a segment for all helix transitions. + _alwaysRelyOnIdealState = streamIngestionConfig.isUseIdealStateToCalculatePreviousSegment(); + } else { + _alwaysRelyOnIdealState = false; + } + _isFirstTransitionProcessed = new AtomicBoolean(false); + _serverMetrics = ServerMetrics.get(); + } + + void acquire(LLCSegmentName llcSegmentName) + throws InterruptedException { + long startTimeMs; + + if (_enforceConsumptionInOrder) { + startTimeMs = System.currentTimeMillis(); + + waitForPrevSegment(llcSegmentName); + + _serverMetrics.addTimedTableValue(_realtimeTableDataManager.getTableName(), + ServerTimer.PREV_SEGMENT_WAIT_DURATION_MS, System.currentTimeMillis() - startTimeMs, TimeUnit.MILLISECONDS); + } + + startTimeMs = System.currentTimeMillis(); + while (!_semaphore.tryAcquire(WAIT_INTERVAL_MS, TimeUnit.MILLISECONDS)) { + LOGGER.warn("Failed to acquire partitionGroup consumer semaphore in: {} ms. Retrying.", + System.currentTimeMillis() - startTimeMs); + } + } + + void release() { + _semaphore.release(); + } + + @VisibleForTesting + Semaphore getSemaphore() { + return _semaphore; + } + + void trackSegment(LLCSegmentName llcSegmentName) { + _lock.lock(); + try { + if (!_alwaysRelyOnIdealState) { + _maxSegmentSeqNumRegistered = Math.max(_maxSegmentSeqNumRegistered, llcSegmentName.getSequenceNumber()); + } + // notify all helix threads waiting for their offline -> consuming segment's prev segment to be loaded + _condition.signalAll(); + } finally { + _lock.unlock(); + } + } + + private void waitForPrevSegment(LLCSegmentName currSegment) + throws InterruptedException { + + if (_alwaysRelyOnIdealState || !_isFirstTransitionProcessed.get()) { + // if _alwaysRelyOnIdealState or no offline -> consuming transition has been processed, it means rely on + // ideal state to fetch previous segment. + acquireSegmentRelyingOnIdealState(currSegment); + + // the first transition will always be prone to error, consider edge case where segment previous to current + // helix transition's segment was deleted and this server came alive after successful deletion. the prev + // segment will not exist, hence first transition is handled using isFirstTransitionSuccessful. + _isFirstTransitionProcessed.compareAndSet(false, true); + return; + } + + // rely on _maxSegmentSeqNumRegistered watermark for previous segment. + if (awaitForPreviousSegmentSequenceNumber(currSegment, WAIT_INTERVAL_MS)) { + return; + } + + // tried using prevSegSeqNumber watermark, but could not acquire the previous segment. + // fallback to acquire prev segment from ideal state. + acquireSegmentRelyingOnIdealState(currSegment); + } + + private void acquireSegmentRelyingOnIdealState(LLCSegmentName currSegment) + throws InterruptedException { + LLCSegmentName previousLLCSegmentName = getPreviousSegment(currSegment); + if (previousLLCSegmentName == null) { + // previous segment can only be null if either all the previous segments are deleted or this is the starting + // sequence segment of the partition Group. + return; + } + String previousSegment = previousLLCSegmentName.getSegmentName(); + + SegmentDataManager segmentDataManager = _realtimeTableDataManager.acquireSegment(previousSegment); + try { + long startTimeMs = System.currentTimeMillis(); + _lock.lock(); + try { + while (segmentDataManager == null) { + // if segmentDataManager == null, it means segment is not loaded in the server. + // wait until it's loaded. + while (!_condition.await(WAIT_INTERVAL_MS, TimeUnit.MILLISECONDS)) { + LOGGER.warn("Semaphore access denied to segment: {}. Waiting on previous segment: {} since: {} ms.", + currSegment.getSegmentName(), previousSegment, System.currentTimeMillis() - startTimeMs); + // waited until timeout, fetch previous segment again from ideal state as previous segment might be + // changed in ideal state. + previousLLCSegmentName = getPreviousSegment(currSegment); + if (previousLLCSegmentName == null) { + return; + } + previousSegment = previousLLCSegmentName.getSegmentName(); + } + segmentDataManager = _realtimeTableDataManager.acquireSegment(previousSegment); + } + } finally { + _lock.unlock(); + } + } finally { + if (segmentDataManager != null) { + _realtimeTableDataManager.releaseSegment(segmentDataManager); + } + } + } + + /*** + * @param currSegment is the segment of current helix transition. + * @param timeoutMs is max time to wait in millis + * @return true if previous Segment was registered to the server, else false. + * @throws InterruptedException + */ + @VisibleForTesting + boolean awaitForPreviousSegmentSequenceNumber(LLCSegmentName currSegment, long timeoutMs) + throws InterruptedException { + long startTimeMs = System.currentTimeMillis(); + int prevSeqNum = currSegment.getSequenceNumber() - 1; + _lock.lock(); + try { + while (_maxSegmentSeqNumRegistered < prevSeqNum) { Review Comment: why? -- This is an automated message from the Apache Git Service. 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