flink-connectors/flink-connector-kafka-0.9/src/test/java/org/apache/flink/streaming/connectors/kafka/internal/HandoverTest.java

/*
 * 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.kafka.internal;

import org.apache.flink.streaming.connectors.kafka.internal.Handover.WakeupException;
import org.apache.flink.util.ExceptionUtils;

import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.junit.Test;

import java.io.IOException;
import java.util.Collections;
import java.util.Random;
import java.util.concurrent.TimeoutException;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.fail;
import static org.mockito.Mockito.mock;

/**
 * Tests for the {@link Handover} between Kafka Consumer Thread and the fetcher's main thread.
 */
public class HandoverTest {

	// ------------------------------------------------------------------------
	//  test produce / consumer
	// ------------------------------------------------------------------------

	@Test
	public void testWithVariableProducer() throws Exception {
		runProducerConsumerTest(500, 2, 0);
	}

	@Test
	public void testWithVariableConsumer() throws Exception {
		runProducerConsumerTest(500, 0, 2);
	}

	@Test
	public void testWithVariableBoth() throws Exception {
		runProducerConsumerTest(500, 2, 2);
	}

	// ------------------------------------------------------------------------
	//  test error propagation
	// ------------------------------------------------------------------------

	@Test
	public void testPublishErrorOnEmptyHandover() throws Exception {
		final Handover handover = new Handover();

		Exception error = new Exception();
		handover.reportError(error);

		try {
			handover.pollNext();
			fail("should throw an exception");
		}
		catch (Exception e) {
			assertEquals(error, e);
		}
	}

	@Test
	public void testPublishErrorOnFullHandover() throws Exception {
		final Handover handover = new Handover();
		handover.produce(createTestRecords(), Collections.emptyMap());

		IOException error = new IOException();
		handover.reportError(error);

		try {
			handover.pollNext();
			fail("should throw an exception");
		}
		catch (Exception e) {
			assertEquals(error, e);
		}
	}

	@Test
	public void testExceptionMarksClosedOnEmpty() throws Exception {
		final Handover handover = new Handover();

		IllegalStateException error = new IllegalStateException();
		handover.reportError(error);

		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	@Test
	public void testExceptionMarksClosedOnFull() throws Exception {
		final Handover handover = new Handover();
		handover.produce(createTestRecords(), Collections.emptyMap());

		LinkageError error = new LinkageError();
		handover.reportError(error);

		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	// ------------------------------------------------------------------------
	//  test closing behavior
	// ------------------------------------------------------------------------

	@Test
	public void testCloseEmptyForConsumer() throws Exception {
		final Handover handover = new Handover();
		handover.close();

		try {
			handover.pollNext();
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	@Test
	public void testCloseFullForConsumer() throws Exception {
		final Handover handover = new Handover();
		handover.produce(createTestRecords(), Collections.emptyMap());
		handover.close();

		try {
			handover.pollNext();
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	@Test
	public void testCloseEmptyForProducer() throws Exception {
		final Handover handover = new Handover();
		handover.close();

		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	@Test
	public void testCloseFullForProducer() throws Exception {
		final Handover handover = new Handover();
		handover.produce(createTestRecords(), Collections.emptyMap());
		handover.close();

		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail("should throw an exception");
		}
		catch (Handover.ClosedException e) {
			// expected
		}
	}

	// ------------------------------------------------------------------------
	//  test wake up behavior
	// ------------------------------------------------------------------------

	@Test
	public void testWakeupDoesNotWakeWhenEmpty() throws Exception {
		Handover handover = new Handover();
		handover.wakeupProducer();

		// produce into a woken but empty handover
		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
		}
		catch (WakeupException e) {
			fail();
		}

		// handover now has records, next time we wakeup and produce it needs
		// to throw an exception
		handover.wakeupProducer();
		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail("should throw an exception");
		}
		catch (WakeupException e) {
			// expected
		}

		// empty the handover
		assertNotNull(handover.pollNext());

		// producing into an empty handover should work
		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
		}
		catch (WakeupException e) {
			fail();
		}
	}

	@Test
	public void testWakeupWakesOnlyOnce() throws Exception {
		// create a full handover
		final Handover handover = new Handover();
		handover.produce(createTestRecords(), Collections.emptyMap());

		handover.wakeupProducer();

		try {
			handover.produce(createTestRecords(), Collections.emptyMap());
			fail();
		} catch (WakeupException e) {
			// expected
		}

		CheckedThread producer = new CheckedThread() {
			@Override
			public void go() throws Exception {
				handover.produce(createTestRecords(), Collections.emptyMap());
			}
		};
		producer.start();

		// the producer must go blocking
		producer.waitUntilThreadHoldsLock(10000);

		// release the thread by consuming something
		assertNotNull(handover.pollNext());
		producer.sync();
	}

	// ------------------------------------------------------------------------
	//  utilities
	// ------------------------------------------------------------------------

	private void runProducerConsumerTest(int numRecords, int maxProducerDelay, int maxConsumerDelay) throws Exception {
		// generate test data
		@SuppressWarnings({"unchecked", "rawtypes"})
		final ConsumerRecords<byte[], byte[]>[] data = new ConsumerRecords[numRecords];
		for (int i = 0; i < numRecords; i++) {
			data[i] = createTestRecords();
		}

		final Handover handover = new Handover();

		ProducerThread producer = new ProducerThread(handover, data, maxProducerDelay);
		ConsumerThread consumer = new ConsumerThread(handover, data, maxConsumerDelay);

		consumer.start();
		producer.start();

		// sync first on the consumer, so it propagates assertion errors
		consumer.sync();
		producer.sync();
	}

	@SuppressWarnings("unchecked")
	private static ConsumerRecords<byte[], byte[]> createTestRecords() {
		return mock(ConsumerRecords.class);
	}

	// ------------------------------------------------------------------------

	private abstract static class CheckedThread extends Thread {

		private volatile Throwable error;

		public abstract void go() throws Exception;

		@Override
		public void run() {
			try {
				go();
			}
			catch (Throwable t) {
				error = t;
			}
		}

		public void sync() throws Exception {
			join();
			if (error != null) {
				ExceptionUtils.rethrowException(error, error.getMessage());
			}
		}

		public void waitUntilThreadHoldsLock(long timeoutMillis) throws InterruptedException, TimeoutException {
			final long deadline = System.nanoTime() + timeoutMillis * 1_000_000;

			while (!isBlockedOrWaiting() && (System.nanoTime() < deadline)) {
				Thread.sleep(1);
			}

			if (!isBlockedOrWaiting()) {
				throw new TimeoutException();
			}
		}

		private boolean isBlockedOrWaiting() {
			State state = getState();
			return state == State.BLOCKED || state == State.WAITING || state == State.TIMED_WAITING;
		}
	}

	private static class ProducerThread extends CheckedThread {

		private final Random rnd = new Random();
		private final Handover handover;
		private final ConsumerRecords<byte[], byte[]>[] data;
		private final int maxDelay;

		private ProducerThread(Handover handover, ConsumerRecords<byte[], byte[]>[] data, int maxDelay) {
			this.handover = handover;
			this.data = data;
			this.maxDelay = maxDelay;
		}

		@Override
		public void go() throws Exception {
			for (ConsumerRecords<byte[], byte[]> rec : data) {
				handover.produce(rec, Collections.emptyMap());

				if (maxDelay > 0) {
					int delay = rnd.nextInt(maxDelay);
					Thread.sleep(delay);
				}
			}
		}
	}

	private static class ConsumerThread extends CheckedThread {

		private final Random rnd = new Random();
		private final Handover handover;
		private final ConsumerRecords<byte[], byte[]>[] data;
		private final int maxDelay;

		private ConsumerThread(Handover handover, ConsumerRecords<byte[], byte[]>[] data, int maxDelay) {
			this.handover = handover;
			this.data = data;
			this.maxDelay = maxDelay;
		}

		@Override
		public void go() throws Exception {
			for (ConsumerRecords<byte[], byte[]> rec : data) {
				Handover.ConsumerRecordsAndPositions next = handover.pollNext();

				assertEquals(rec, next.records());

				if (maxDelay > 0) {
					int delay = rnd.nextInt(maxDelay);
					Thread.sleep(delay);
				}
			}
		}
	}
}