flink-runtime/src/test/java/org/apache/flink/runtime/source/coordinator/ExecutorNotifierTest.java

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to you under the Apache License, Version 2.0 (the
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      http://www.apache.org/licenses/LICENSE-2.0

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*/

package org.apache.flink.runtime.source.coordinator;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;

/** Unit tests for ExecutorNotifier. */
public class ExecutorNotifierTest {
    private ScheduledExecutorService workerExecutor;
    private ExecutorService executorToNotify;
    private ExecutorNotifier notifier;
    private Throwable exceptionInHandler;
    private CountDownLatch exceptionInHandlerLatch;

    @Before
    public void setup() {
        this.exceptionInHandler = null;
        this.exceptionInHandlerLatch = new CountDownLatch(1);
        this.workerExecutor =
                Executors.newSingleThreadScheduledExecutor(r -> new Thread(r, "worker-thread"));
        this.executorToNotify =
                Executors.newSingleThreadExecutor(
                        r -> {
                            Thread t = new Thread(r, "main-thread");
                            t.setUncaughtExceptionHandler(
                                    (thread, e) -> {
                                        exceptionInHandler = e;
                                        exceptionInHandlerLatch.countDown();
                                    });
                            return t;
                        });
        this.notifier = new ExecutorNotifier(this.workerExecutor, this.executorToNotify);
    }

    @After
    public void tearDown() throws InterruptedException {
        notifier.close();
        closeExecutorToNotify();
    }

    @Test
    public void testBasic() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(1);
        AtomicInteger result = new AtomicInteger(0);
        notifier.notifyReadyAsync(
                () -> 1234,
                (v, e) -> {
                    result.set(v);
                    latch.countDown();
                });
        latch.await();
        closeExecutorToNotify();
        assertEquals(1234, result.get());
    }

    @Test
    public void testExceptionInCallable() {
        Exception exception = new Exception("Expected exception.");
        notifier.notifyReadyAsync(
                () -> {
                    throw exception;
                },
                (v, e) -> {
                    assertEquals(exception, e);
                    assertNull(v);
                });
    }

    @Test
    public void testExceptionInHandlerWhenHandlingException() throws InterruptedException {
        Exception exception1 = new Exception("Expected exception.");
        RuntimeException exception2 = new RuntimeException("Expected exception.");
        CountDownLatch latch = new CountDownLatch(1);
        notifier.notifyReadyAsync(
                () -> {
                    throw exception1;
                },
                (v, e) -> {
                    assertEquals(exception1, e);
                    assertNull(v);
                    latch.countDown();
                    throw exception2;
                });
        latch.await();
        closeExecutorToNotify();
        // The uncaught exception handler may fire after the executor has shutdown.
        // We need to wait on the countdown latch here.
        exceptionInHandlerLatch.await(10000L, TimeUnit.MILLISECONDS);
        assertEquals(exception2, exceptionInHandler);
    }

    @Test
    public void testExceptionInHandlerWhenHandlingResult() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(1);
        RuntimeException exception = new RuntimeException("Expected exception.");
        notifier.notifyReadyAsync(
                () -> 1234,
                (v, e) -> {
                    latch.countDown();
                    throw exception;
                });
        latch.await();
        closeExecutorToNotify();
        // The uncaught exception handler may fire after the executor has shutdown.
        // We need to wait on the countdown latch here.
        exceptionInHandlerLatch.await(10000L, TimeUnit.MILLISECONDS);
        assertEquals(exception, exceptionInHandler);
    }

    private void closeExecutorToNotify() throws InterruptedException {
        executorToNotify.shutdown();
        executorToNotify.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
    }
}