Merge pull request #3921 from denis-zhdanov/BAEL-1423-jctools

BAEL-1423 Java Concurrency Utility with JCTools Library
2018-04-20 00:40:23 +02:00
parent ed9f3fa2e2 0bb4359ac3
commit fa74f05d60
4 changed files with 219 additions and 0 deletions
@@ -0,0 +1,86 @@
+package com.baeldung.jctools;
+
+import org.jctools.queues.SpscArrayQueue;
+import org.jctools.queues.SpscChunkedArrayQueue;
+import org.junit.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.IntConsumer;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+public class JCToolsUnitTest {
+
+    @Test
+    public void givenMultipleProducers_whenSpscQueueUsed_thenNoWarningOccurs() throws InterruptedException {
+        SpscArrayQueue<Integer> queue = new SpscArrayQueue<Integer>(2);
+
+        Thread producer1 = new Thread(() -> {
+            queue.offer(1);
+        });
+        producer1.start();
+        producer1.join();
+
+        Thread producer2 = new Thread(() -> {
+            queue.offer(2);
+        });
+        producer2.start();
+        producer2.join();
+
+        Set<Integer> fromQueue = new HashSet<>();
+        Thread consumer = new Thread(() -> queue.drain(fromQueue::add));
+        consumer.start();
+        consumer.join();
+
+        assertThat(fromQueue).containsOnly(1, 2);
+    }
+
+    @Test
+    public void whenQueueIsFull_thenNoMoreElementsCanBeAdded() throws InterruptedException {
+        SpscChunkedArrayQueue<Integer> queue = new SpscChunkedArrayQueue<>(8, 16);
+        assertThat(queue.capacity()).isEqualTo(16);
+
+        CountDownLatch startConsuming = new CountDownLatch(1);
+        CountDownLatch awakeProducer = new CountDownLatch(1);
+        AtomicReference<Throwable> error = new AtomicReference<>();
+        Thread producer = new Thread(() -> {
+            IntStream.range(0, queue.capacity()).forEach(i -> {
+                assertThat(queue.offer(i)).isTrue();
+            });
+            assertThat(queue.offer(queue.capacity())).isFalse();
+            startConsuming.countDown();
+            try {
+                awakeProducer.await();
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+
+            assertThat(queue.offer(queue.capacity())).isTrue();
+        });
+        producer.setUncaughtExceptionHandler((t, e) -> {
+            error.set(e);
+            startConsuming.countDown();
+        });
+        producer.start();
+
+        startConsuming.await();
+
+        if (error.get() != null) {
+            fail("Producer's assertion failed", error.get());
+        }
+
+        Set<Integer> fromQueue = new HashSet<>();
+        queue.drain(fromQueue::add);
+        awakeProducer.countDown();
+        producer.join();
+        queue.drain(fromQueue::add);
+
+        assertThat(fromQueue).containsAll(IntStream.range(0, 17).boxed().collect(Collectors.toSet()));
+    }
+}