Distributed work queue primitive

Change-Id: Ia8e531e6611ec502399edec376ccc00522e47994
diff --git a/core/store/primitives/src/test/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueTest.java b/core/store/primitives/src/test/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueTest.java
new file mode 100644
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+++ b/core/store/primitives/src/test/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueTest.java
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+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed 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.onosproject.store.primitives.resources.impl;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.UUID;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import io.atomix.Atomix;
+import io.atomix.AtomixClient;
+import io.atomix.resource.ResourceType;
+
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.onlab.util.Tools;
+import org.onosproject.store.service.Task;
+import org.onosproject.store.service.WorkQueueStats;
+
+import com.google.common.util.concurrent.Uninterruptibles;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Unit tests for {@link AtomixWorkQueue}.
+ */
+public class AtomixWorkQueueTest extends AtomixTestBase {
+
+    private static final Duration DEFAULT_PROCESSING_TIME = Duration.ofMillis(100);
+    private static final byte[] DEFAULT_PAYLOAD = "hello world".getBytes();
+
+    @BeforeClass
+    public static void preTestSetup() throws Throwable {
+        createCopycatServers(1);
+    }
+
+    @AfterClass
+    public static void postTestCleanup() throws Exception {
+        clearTests();
+    }
+
+    @Override
+    protected ResourceType resourceType() {
+        return new ResourceType(AtomixWorkQueue.class);
+    }
+
+    @Test
+    public void testAdd() throws Throwable {
+        String queueName = UUID.randomUUID().toString();
+        Atomix atomix1 = createAtomixClient();
+        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] item = DEFAULT_PAYLOAD;
+        queue1.addOne(item).join();
+
+        Atomix atomix2 = createAtomixClient();
+        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] task2 = DEFAULT_PAYLOAD;
+        queue2.addOne(task2).join();
+
+        WorkQueueStats stats = queue1.stats().join();
+        assertEquals(stats.totalPending(), 2);
+        assertEquals(stats.totalInProgress(), 0);
+        assertEquals(stats.totalCompleted(), 0);
+    }
+
+    @Test
+    public void testAddMultiple() throws Throwable {
+        String queueName = UUID.randomUUID().toString();
+        Atomix atomix1 = createAtomixClient();
+        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] item1 = DEFAULT_PAYLOAD;
+        byte[] item2 = DEFAULT_PAYLOAD;
+        queue1.addMultiple(Arrays.asList(item1, item2)).join();
+
+        WorkQueueStats stats = queue1.stats().join();
+        assertEquals(stats.totalPending(), 2);
+        assertEquals(stats.totalInProgress(), 0);
+        assertEquals(stats.totalCompleted(), 0);
+    }
+
+    @Test
+    public void testTakeAndComplete() throws Throwable {
+        String queueName = UUID.randomUUID().toString();
+        Atomix atomix1 = createAtomixClient();
+        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] item1 = DEFAULT_PAYLOAD;
+        queue1.addOne(item1).join();
+
+        Atomix atomix2 = createAtomixClient();
+        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
+        Task<byte[]> removedTask = queue2.take().join();
+
+        WorkQueueStats stats = queue2.stats().join();
+        assertEquals(stats.totalPending(), 0);
+        assertEquals(stats.totalInProgress(), 1);
+        assertEquals(stats.totalCompleted(), 0);
+
+        assertTrue(Arrays.equals(removedTask.payload(), item1));
+        queue2.complete(Arrays.asList(removedTask.taskId())).join();
+
+        stats = queue1.stats().join();
+        assertEquals(stats.totalPending(), 0);
+        assertEquals(stats.totalInProgress(), 0);
+        assertEquals(stats.totalCompleted(), 1);
+
+        // Another take should return null
+        assertNull(queue2.take().join());
+    }
+
+    @Test
+    public void testUnexpectedClientClose() throws Throwable {
+        String queueName = UUID.randomUUID().toString();
+        Atomix atomix1 = createAtomixClient();
+        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] item1 = DEFAULT_PAYLOAD;
+        queue1.addOne(item1).join();
+
+        AtomixClient atomix2 = createAtomixClient();
+        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
+        queue2.take().join();
+
+        WorkQueueStats stats = queue1.stats().join();
+        assertEquals(0, stats.totalPending());
+        assertEquals(1, stats.totalInProgress());
+        assertEquals(0, stats.totalCompleted());
+
+        atomix2.close().join();
+
+        stats = queue1.stats().join();
+        assertEquals(1, stats.totalPending());
+        assertEquals(0, stats.totalInProgress());
+        assertEquals(0, stats.totalCompleted());
+    }
+
+    @Test
+    public void testAutomaticTaskProcessing() throws Throwable {
+        String queueName = UUID.randomUUID().toString();
+        Atomix atomix1 = createAtomixClient();
+        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
+        Executor executor = Executors.newSingleThreadExecutor();
+
+        CountDownLatch latch1 = new CountDownLatch(1);
+        queue1.registerTaskProcessor(s -> latch1.countDown(), 2, executor);
+
+        AtomixClient atomix2 = createAtomixClient();
+        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
+        byte[] item1 = DEFAULT_PAYLOAD;
+        queue2.addOne(item1).join();
+
+        Uninterruptibles.awaitUninterruptibly(latch1, 500, TimeUnit.MILLISECONDS);
+        queue1.stopProcessing();
+
+        byte[] item2 = DEFAULT_PAYLOAD;
+        byte[] item3 = DEFAULT_PAYLOAD;
+
+        Tools.delay((int) DEFAULT_PROCESSING_TIME.toMillis());
+
+        queue2.addMultiple(Arrays.asList(item2, item3)).join();
+
+        WorkQueueStats stats = queue1.stats().join();
+        assertEquals(2, stats.totalPending());
+        assertEquals(0, stats.totalInProgress());
+        assertEquals(1, stats.totalCompleted());
+
+        CountDownLatch latch2 = new CountDownLatch(2);
+        queue1.registerTaskProcessor(s -> latch2.countDown(), 2, executor);
+
+        Uninterruptibles.awaitUninterruptibly(latch2, 500, TimeUnit.MILLISECONDS);
+    }
+}