Fix JdbcLockRegistry tests

https://build.spring.io/browse/INT-MASTER-901

The `JdbcLockRegistryDifferentClientTests.testOnlyOneLock()` relies
on the `ArrayList.isEmpty()` state to proceed with the logic.
But since the `ArrayList.size` property is not `volatile`, there is no
guarantee for the proper state in the multi-threaded environment like
we have in this test-case.

* Replace `ArrayList` in the test with the `LinkedBlockingQueue` which
already rely on the `AtomicInteger` for the `size` property
* Fix `JdbcLockRegistry` tests to shutdown used `ExecutorService` s
to ensure set free threads after test suite execution.

**Cherry-pick to 4.3.x**

Author: artembilan

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/lock/JdbcLockRegistryDifferentClientTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,6 +45,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@@ -97,9 +98,7 @@ public void close() {
 
 	@Test
 	public void testSecondThreadLoses() throws Exception {
-
 		for (int i = 0; i < 100; i++) {
-
 			final JdbcLockRegistry registry1 = this.registry;
 			final JdbcLockRegistry registry2 = this.child.getBean(JdbcLockRegistry.class);
 			final Lock lock1 = registry1.obtain("foo");
@@ -108,41 +107,38 @@ public void testSecondThreadLoses() throws Exception {
 			final CountDownLatch latch2 = new CountDownLatch(1);
 			final CountDownLatch latch3 = new CountDownLatch(1);
 			lock1.lockInterruptibly();
-			Executors.newSingleThreadExecutor().execute(() -> {
-				Lock lock2 = registry2.obtain("foo");
-				try {
-					latch1.countDown();
-					lock2.lockInterruptibly();
-					latch2.await(10, TimeUnit.SECONDS);
-					locked.set(true);
-				}
-				catch (InterruptedException e) {
-					Thread.currentThread().interrupt();
-				}
-				finally {
-					lock2.unlock();
-					latch3.countDown();
-				}
-			});
+			new SimpleAsyncTaskExecutor()
+					.execute(() -> {
+						Lock lock2 = registry2.obtain("foo");
+						try {
+							latch1.countDown();
+							lock2.lockInterruptibly();
+							latch2.await(10, TimeUnit.SECONDS);
+							locked.set(true);
+						}
+						catch (InterruptedException e) {
+							Thread.currentThread().interrupt();
+						}
+						finally {
+							lock2.unlock();
+							latch3.countDown();
+						}
+					});
 			assertTrue(latch1.await(10, TimeUnit.SECONDS));
 			assertFalse(locked.get());
 			lock1.unlock();
 			latch2.countDown();
 			assertTrue(latch3.await(10, TimeUnit.SECONDS));
 			assertTrue(locked.get());
-
 		}
-
 	}
 
 	@Test
 	public void testBothLock() throws Exception {
-
 		for (int i = 0; i < 100; i++) {
-
 			final JdbcLockRegistry registry1 = this.registry;
 			final JdbcLockRegistry registry2 = this.child.getBean(JdbcLockRegistry.class);
-			final List<String> locked = new ArrayList<String>();
+			final List<String> locked = new ArrayList<>();
 			final CountDownLatch latch = new CountDownLatch(2);
 			ExecutorService pool = Executors.newFixedThreadPool(2);
 			pool.execute(() -> {
@@ -189,9 +185,8 @@ public void testBothLock() throws Exception {
 			// eventually they both get the lock and release it
 			assertTrue(locked.contains("1"));
 			assertTrue(locked.contains("2"));
-
+			pool.shutdownNow();
 		}
-
 	}
 
 	@Test
@@ -202,17 +197,16 @@ public void testOnlyOneLock() throws Exception {
 
 	private void testOnlyOneLock(String id) throws Exception {
 		for (int i = 0; i < 100; i++) {
-
-			final List<String> locked = new ArrayList<String>();
+			final BlockingQueue<String> locked = new LinkedBlockingQueue<>();
 			final CountDownLatch latch = new CountDownLatch(20);
 			ExecutorService pool = Executors.newFixedThreadPool(6);
 			ArrayList<Callable<Boolean>> tasks = new ArrayList<Callable<Boolean>>();
+			final DefaultLockRepository client = (id == null) ?
+					new DefaultLockRepository(this.dataSource) :
+					new DefaultLockRepository(this.dataSource, id);
+			client.afterPropertiesSet();
+			this.context.getAutowireCapableBeanFactory().autowireBean(client);
 			for (int j = 0; j < 20; j++) {
-				final DefaultLockRepository client = (id == null) ?
-						new DefaultLockRepository(this.dataSource) :
-						new DefaultLockRepository(this.dataSource, id);
-				client.afterPropertiesSet();
-				this.context.getAutowireCapableBeanFactory().autowireBean(client);
 				Callable<Boolean> task = () -> {
 					Lock lock = new JdbcLockRegistry(client).obtain("foo");
 					try {
@@ -240,12 +234,10 @@ private void testOnlyOneLock(String id) throws Exception {
 			pool.invokeAll(tasks);
 
 			assertTrue(latch.await(10, TimeUnit.SECONDS));
-			// eventually they both get the lock and release it
 			assertEquals(1, locked.size());
 			assertTrue(locked.contains("done"));
-
+			pool.shutdownNow();
 		}
-
 	}
 
 	@Test
@@ -255,35 +247,36 @@ public void testExclusiveAccess() throws Exception {
 		final DefaultLockRepository client2 = new DefaultLockRepository(dataSource);
 		client2.afterPropertiesSet();
 		Lock lock1 = new JdbcLockRegistry(client1).obtain("foo");
-		final BlockingQueue<Integer> data = new LinkedBlockingQueue<Integer>();
+		final BlockingQueue<Integer> data = new LinkedBlockingQueue<>();
 		final CountDownLatch latch1 = new CountDownLatch(1);
 		lock1.lockInterruptibly();
-		Executors.newSingleThreadExecutor().execute(() -> {
-			Lock lock2 = new JdbcLockRegistry(client2).obtain("foo");
-			try {
-				latch1.countDown();
-				StopWatch stopWatch = new StopWatch();
-				stopWatch.start();
-				lock2.lockInterruptibly();
-				stopWatch.stop();
-				data.add(4);
-				Thread.sleep(10);
-				data.add(5);
-				Thread.sleep(10);
-				data.add(6);
-			}
-			catch (InterruptedException e) {
-				Thread.currentThread().interrupt();
-			}
-			finally {
-				lock2.unlock();
-			}
-		});
+		new SimpleAsyncTaskExecutor()
+				.execute(() -> {
+					Lock lock2 = new JdbcLockRegistry(client2).obtain("foo");
+					try {
+						latch1.countDown();
+						StopWatch stopWatch = new StopWatch();
+						stopWatch.start();
+						lock2.lockInterruptibly();
+						stopWatch.stop();
+						data.add(4);
+						Thread.sleep(10);
+						data.add(5);
+						Thread.sleep(10);
+						data.add(6);
+					}
+					catch (InterruptedException e) {
+						Thread.currentThread().interrupt();
+					}
+					finally {
+						lock2.unlock();
+					}
+				});
 		assertTrue(latch1.await(10, TimeUnit.SECONDS));
 		data.add(1);
-		Thread.sleep(1000);
+		Thread.sleep(100);
 		data.add(2);
-		Thread.sleep(1000);
+		Thread.sleep(100);
 		data.add(3);
 		lock1.unlock();
 		for (int i = 0; i < 6; i++) {

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/lock/JdbcLockRegistryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,6 @@
 
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -38,20 +37,26 @@
 import org.junit.runner.RunWith;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.task.AsyncTaskExecutor;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.integration.test.util.TestUtils;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 /**
  * @author Dave Syer
+ * @author Artem Bilan
+ *
  * @since 4.3
  */
 @ContextConfiguration
 @RunWith(SpringJUnit4ClassRunner.class)
-@DirtiesContext // close at the end after class
+@DirtiesContext
 public class JdbcLockRegistryTests {
 
+	private final AsyncTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor();
+
 	@Autowired
 	private JdbcLockRegistry registry;
 
@@ -153,7 +158,7 @@ public void testTwoThreadsSecondFailsToGetLock() throws Exception {
 		lock1.lockInterruptibly();
 		final AtomicBoolean locked = new AtomicBoolean();
 		final CountDownLatch latch = new CountDownLatch(1);
-		Future<Object> result = Executors.newSingleThreadExecutor().submit(() -> {
+		Future<Object> result = this.taskExecutor.submit(() -> {
 			Lock lock2 = JdbcLockRegistryTests.this.registry.obtain("foo");
 			locked.set(lock2.tryLock(200, TimeUnit.MILLISECONDS));
 			latch.countDown();
@@ -181,7 +186,7 @@ public void testTwoThreads() throws Exception {
 		final CountDownLatch latch2 = new CountDownLatch(1);
 		final CountDownLatch latch3 = new CountDownLatch(1);
 		lock1.lockInterruptibly();
-		Executors.newSingleThreadExecutor().execute(() -> {
+		this.taskExecutor.execute(() -> {
 			Lock lock2 = JdbcLockRegistryTests.this.registry.obtain("foo");
 			try {
 				latch1.countDown();
@@ -217,7 +222,7 @@ public void testTwoThreadsDifferentRegistries() throws Exception {
 			final CountDownLatch latch2 = new CountDownLatch(1);
 			final CountDownLatch latch3 = new CountDownLatch(1);
 			lock1.lockInterruptibly();
-			Executors.newSingleThreadExecutor().execute(() -> {
+			this.taskExecutor.execute(() -> {
 				Lock lock2 = registry2.obtain("foo");
 				try {
 					latch1.countDown();
@@ -249,16 +254,17 @@ public void testTwoThreadsWrongOneUnlocks() throws Exception {
 		lock.lockInterruptibly();
 		final AtomicBoolean locked = new AtomicBoolean();
 		final CountDownLatch latch = new CountDownLatch(1);
-		Future<Object> result = Executors.newSingleThreadExecutor().submit(() -> {
-			try {
-				lock.unlock();
-			}
-			catch (Exception e) {
-				latch.countDown();
-				return e;
-			}
-			return null;
-		});
+		Future<Object> result =
+				this.taskExecutor.submit(() -> {
+					try {
+						lock.unlock();
+					}
+					catch (Exception e) {
+						latch.countDown();
+						return e;
+					}
+					return null;
+				});
 		assertTrue(latch.await(10, TimeUnit.SECONDS));
 		assertFalse(locked.get());
 		lock.unlock();