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From: rmetzger <git@git.apache.org>
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References: <git-pr-1911-flink@git.apache.org>
In-Reply-To: <git-pr-1911-flink@git.apache.org>
Subject: [GitHub] flink pull request: [FLINK-3229] Flink streaming consumer
 for AWS ...
Content-Type: text/plain
Message-Id: <20160422203637.5B9EBDFCDF@git1-us-west.apache.org>
Date: Fri, 22 Apr 2016 20:36:37 +0000 (UTC)

Github user rmetzger commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1911#discussion_r60799474
  
    --- Diff: flink-streaming-connectors/flink-connector-kinesis/src/main/java/org/apache/flink/streaming/connectors/kinesis/internals/KinesisDataFetcher.java ---
    @@ -0,0 +1,300 @@
    +/*
    + * 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.streaming.connectors.kinesis.internals;
    +
    +import com.amazonaws.auth.AWSCredentialsProvider;
    +import com.amazonaws.services.kinesis.model.GetRecordsResult;
    +import com.amazonaws.services.kinesis.model.Record;
    +import com.amazonaws.services.kinesis.model.ShardIteratorType;
    +import org.apache.flink.streaming.api.functions.source.SourceFunction;
    +import org.apache.flink.streaming.connectors.kinesis.model.KinesisStreamShard;
    +import org.apache.flink.streaming.connectors.kinesis.model.SentinelSequenceNumber;
    +import org.apache.flink.streaming.connectors.kinesis.proxy.KinesisProxy;
    +import org.apache.flink.streaming.connectors.kinesis.serialization.KinesisDeserializationSchema;
    +import org.apache.flink.streaming.connectors.kinesis.util.AWSUtil;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import java.io.IOException;
    +import java.nio.ByteBuffer;
    +import java.util.Map;
    +import java.util.HashMap;
    +import java.util.List;
    +import java.util.ArrayList;
    +import java.util.Properties;
    +import java.util.concurrent.atomic.AtomicReference;
    +
    +import static com.google.common.base.Preconditions.checkNotNull;
    +
    +/**
    + * A Kinesis Data Fetcher that consumes data from a specific set of Kinesis shards.
    + * The fetcher spawns a single thread for connection to each shard.
    + */
    +public class KinesisDataFetcher {
    +
    +	private static final Logger LOG = LoggerFactory.getLogger(KinesisDataFetcher.class);
    +
    +	/** Config properties for the Flink Kinesis Consumer */
    +	private final Properties configProps;
    +
    +	/** The AWS credentials provider as specified in config properties */
    +	private final AWSCredentialsProvider credentials;
    +
    +	/** The name of the consumer task that this fetcher was instantiated */
    +	private final String taskName;
    +
    +	/** Information of the shards that this fetcher handles, along with the sequence numbers that they should start from */
    +	private HashMap<KinesisStreamShard, String> assignedShardsWithStartingSequenceNum;
    +
    +	/** Reference to the thread that executed run() */
    +	private volatile Thread mainThread;
    +
    +	/** Reference to the first error thrown by any of the spawned shard connection threads */
    +	private final AtomicReference<Throwable> error;
    +
    +	private volatile boolean running = true;
    +
    +	/**
    +	 * Creates a new Kinesis Data Fetcher for the specified set of shards
    +	 *
    +	 * @param assignedShards the shards that this fetcher will pull data from
    +	 * @param configProps the configuration properties of this Flink Kinesis Consumer
    +	 * @param taskName the task name of this consumer task
    +	 */
    +	public KinesisDataFetcher(List<KinesisStreamShard> assignedShards, Properties configProps, String taskName) {
    +		this.configProps = checkNotNull(configProps);
    +		this.credentials = AWSUtil.getCredentialsProvider(configProps);
    +		this.assignedShardsWithStartingSequenceNum = new HashMap<>();
    +		for (KinesisStreamShard shard : assignedShards) {
    +			assignedShardsWithStartingSequenceNum.put(shard, SentinelSequenceNumber.SENTINEL_SEQUENCE_NUMBER_NOT_SET.toString());
    +		}
    +		this.taskName = taskName;
    +		this.error = new AtomicReference<>();
    +	}
    +
    +	/**
    +	 * Advance a shard's starting sequence number to a specified value
    +	 *
    +	 * @param streamShard the shard to perform the advance on
    +	 * @param sequenceNum the sequence number to advance to
    +	 */
    +	public void advanceSequenceNumberTo(KinesisStreamShard streamShard, String sequenceNum) {
    +		if (!assignedShardsWithStartingSequenceNum.containsKey(streamShard)) {
    +			throw new IllegalArgumentException("Can't advance sequence number on a shard we are not going to read.");
    +		}
    +		assignedShardsWithStartingSequenceNum.put(streamShard, sequenceNum);
    +	}
    +
    +	public <T> void run(SourceFunction.SourceContext<T> sourceContext,
    +						KinesisDeserializationSchema<T> deserializationSchema,
    +						HashMap<KinesisStreamShard, String> lastSequenceNums) throws Exception {
    +
    +		if (assignedShardsWithStartingSequenceNum == null || assignedShardsWithStartingSequenceNum.size() == 0) {
    +			throw new IllegalArgumentException("No shards set to read for this fetcher");
    +		}
    +
    +		this.mainThread = Thread.currentThread();
    +
    +		LOG.info("Reading from shards " + assignedShardsWithStartingSequenceNum);
    +
    +		// create a thread for each individual shard
    +		ArrayList<ShardConsumerThread<?>> consumerThreads = new ArrayList<>(assignedShardsWithStartingSequenceNum.size());
    +		for (Map.Entry<KinesisStreamShard, String> assignedShard : assignedShardsWithStartingSequenceNum.entrySet()) {
    +			ShardConsumerThread<T> thread = new ShardConsumerThread<>(this, configProps, assignedShard.getKey(),
    +				assignedShard.getValue(), sourceContext, deserializationSchema, lastSequenceNums);
    +			thread.setName(String.format("ShardConsumer - %s - %s/%s",
    +				taskName, assignedShard.getKey().getStreamName() ,assignedShard.getKey().getShardId()));
    +			thread.setDaemon(true);
    +			consumerThreads.add(thread);
    +		}
    +
    +		// check that we are viable for running for the last time before starting threads
    +		if (!running) {
    +			return;
    +		}
    +
    +		for (ShardConsumerThread<?> shardConsumer : consumerThreads) {
    +			LOG.info("Starting thread {}", shardConsumer.getName());
    +			shardConsumer.start();
    +		}
    +
    +		// wait until all consumer threads are done, or until the fetcher is aborted, or until
    +		// an error occurred in one of the consumer threads
    +		try {
    +			boolean consumersStillRunning = true;
    +			while (running && error.get() == null && consumersStillRunning) {
    +				try {
    +					// wait for the consumer threads. if an error occurs, we are interrupted
    +					for (ShardConsumerThread<?> consumerThread : consumerThreads) {
    +						consumerThread.join();
    +					}
    +
    +					// check if there are consumer threads still running
    +					consumersStillRunning = false;
    +					for (ShardConsumerThread<?> consumerThread : consumerThreads) {
    +						consumersStillRunning = consumersStillRunning | consumerThread.isAlive();
    +					}
    +				} catch (InterruptedException e) {
    +					// ignore
    +				}
    +			}
    +
    +			// make sure any asynchronous error is noticed
    +			Throwable error = this.error.get();
    +			if (error != null) {
    +				throw new Exception(error.getMessage(), error);
    +			}
    +		} finally {
    +			for (ShardConsumerThread<?> consumerThread : consumerThreads) {
    +				if (consumerThread.isAlive()) {
    +					consumerThread.cancel();
    +				}
    +			}
    +		}
    +	}
    +
    +	public void close() throws IOException {
    +		this.running = false;
    +	}
    +
    +	public void stopWithError(Throwable throwable) {
    +		if (this.error.compareAndSet(null, throwable)) {
    +			if (mainThread != null) {
    +				mainThread.interrupt();
    +			}
    +		}
    +	}
    +
    +	/**
    +	 *
    +	 *
    +	 * @param <T>
    +	 */
    +	private static class ShardConsumerThread<T> extends Thread {
    +
    +		private final SourceFunction.SourceContext<T> sourceContext;
    +		private final KinesisDeserializationSchema<T> deserializer;
    +		private final HashMap<KinesisStreamShard, String> seqNoState;
    +
    +		private final KinesisProxy kinesisProxy;
    +
    +		private final KinesisDataFetcher ownerRef;
    +
    +		private final KinesisStreamShard assignedShard;
    +
    +		private String lastSequenceNum;
    +		private String nextShardItr;
    +
    +		private volatile boolean running = true;
    +
    +		public ShardConsumerThread(KinesisDataFetcher ownerRef,
    +								Properties props,
    +								KinesisStreamShard assignedShard,
    +								String lastSequenceNum,
    +								SourceFunction.SourceContext<T> sourceContext,
    +								KinesisDeserializationSchema<T> deserializer,
    +								HashMap<KinesisStreamShard, String> seqNumState) {
    +			this.ownerRef = checkNotNull(ownerRef);
    +			this.assignedShard = checkNotNull(assignedShard);
    +			this.lastSequenceNum = checkNotNull(lastSequenceNum);
    +			this.sourceContext = checkNotNull(sourceContext);
    +			this.deserializer = checkNotNull(deserializer);
    +			this.seqNoState = checkNotNull(seqNumState);
    +			this.kinesisProxy = new KinesisProxy(props);
    +		}
    +
    +		@Override
    +		public void run() {
    +			try {
    +				if (lastSequenceNum.equals(SentinelSequenceNumber.SENTINEL_LATEST_SEQUENCE_NUM.toString())) {
    +					// if the shard is already closed, there will be no latest next record to get for this shard
    +					if (assignedShard.isClosed()) {
    +						nextShardItr = null;
    +					} else {
    +						nextShardItr = kinesisProxy.getShardIterator(assignedShard, ShardIteratorType.LATEST.toString(), null);
    +					}
    +				} else if (lastSequenceNum.equals(SentinelSequenceNumber.SENTINEL_EARLIEST_SEQUENCE_NUM.toString())) {
    +					nextShardItr = kinesisProxy.getShardIterator(assignedShard, ShardIteratorType.TRIM_HORIZON.toString(), null);
    +				} else if (lastSequenceNum.equals(SentinelSequenceNumber.SENTINEL_SHARD_ENDING_SEQUENCE_NUM.toString())) {
    +					nextShardItr = null;
    +				} else {
    +					nextShardItr = kinesisProxy.getShardIterator(assignedShard, ShardIteratorType.AFTER_SEQUENCE_NUMBER.toString(), lastSequenceNum);
    +				}
    +
    +				long lastNextShardItrUpdateMillis = System.currentTimeMillis();
    +				boolean noRecordsOnLastFetch = false;
    +				while(running) {
    +					if (nextShardItr == null) {
    +						lastSequenceNum = SentinelSequenceNumber.SENTINEL_SHARD_ENDING_SEQUENCE_NUM.toString();
    +
    +						synchronized (sourceContext.getCheckpointLock()) {
    +							seqNoState.put(assignedShard, lastSequenceNum);
    +						}
    +
    +						break;
    +					} else {
    +						if (noRecordsOnLastFetch) {
    +							if (System.currentTimeMillis() - lastNextShardItrUpdateMillis >= 290000) {
    --- End diff --
    
    Okay, sounds good.


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