Add Service Executor Start and Wake State Test

Author: alhusseain

queue-based-load-leveling/src/main/java/com/iluwatar/queue/load/leveling/MessageQueue.java

@@ -36,6 +36,7 @@
 public class MessageQueue {
 
   private final BlockingQueue<Message> blkQueue;
+  public final Object serviceExecutorWait = new Object();
 
   // Default constructor when called creates Blocking Queue object. 
   public MessageQueue() {
@@ -50,8 +51,8 @@ public void submitMsg(Message msg) {
     try {
       if (null != msg) {
         blkQueue.add(msg);
-        synchronized (ServiceExecutor.serviceExecutorWait) {
-          ServiceExecutor.serviceExecutorWait.notifyAll();
+        synchronized (serviceExecutorWait) {
+          serviceExecutorWait.notifyAll();
         }
       }
     } catch (Exception e) {

queue-based-load-leveling/src/main/java/com/iluwatar/queue/load/leveling/ServiceExecutor.java

@@ -33,7 +33,6 @@
 @Slf4j
 public class ServiceExecutor implements Runnable {
   private final MessageQueue msgQueue;
-  public static final Object serviceExecutorWait = new Object();
   public ServiceExecutor(MessageQueue msgQueue) {
     this.msgQueue = msgQueue;
   }
@@ -50,8 +49,8 @@ public void run() {
           LOGGER.info(msg + " is served.");
         } else {
           LOGGER.info("Service Executor: Waiting for Messages to serve .. ");
-          synchronized (serviceExecutorWait) {
-            serviceExecutorWait.wait();
+          synchronized (msgQueue.serviceExecutorWait) {
+            msgQueue.serviceExecutorWait.wait();
           }
         }
       }

queue-based-load-leveling/src/test/java/com/iluwatar/queue/load/leveling/TaskGenSrvExeTest.java

@@ -24,14 +24,17 @@
  */
 package com.iluwatar.queue.load.leveling;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Test;
 
 /**
  * Test case for submitting Message to Blocking Queue by TaskGenerator and retrieve the message by
  * ServiceExecutor.
  */
+@Slf4j
 class TaskGenSrvExeTest {
 
   @Test
@@ -53,4 +56,36 @@ void taskGeneratorTest() {
     assertNotNull(srvExeThr);
   }
 
+  /**
+   * Tests that service executor waits at start since no message is sent to execute upon.
+   * @throws InterruptedException
+   */
+  @Test
+  void serviceExecutorStartStateTest() throws InterruptedException {
+    var msgQueue = new MessageQueue();
+    var srvRunnable = new ServiceExecutor(msgQueue);
+    var srvExeThr = new Thread(srvRunnable);
+    srvExeThr.start();
+    Thread.sleep(200); // sleep a little until service executor thread waits
+    LOGGER.info("Current Service Executor State: " + srvExeThr.getState());
+    assertEquals(srvExeThr.getState(), Thread.State.WAITING);
+
+  }
+
+  @Test
+  void serviceExecutorWakeStateTest() throws InterruptedException {
+    var msgQueue = new MessageQueue();
+    var srvRunnable = new ServiceExecutor(msgQueue);
+    var srvExeThr = new Thread(srvRunnable);
+    srvExeThr.start();
+    Thread.sleep(200); // sleep a little until service executor thread waits
+    synchronized (msgQueue.serviceExecutorWait){
+      msgQueue.serviceExecutorWait.notifyAll();
+    }
+    var srvExeState = srvExeThr.getState();
+    LOGGER.info("Current Service Executor State: " + srvExeState);
+    assertEquals(srvExeState, Thread.State.RUNNABLE);
+
+  }
+
 }