Updated class diagram png and added UCLS file

event-queue/src/main/java/com/iluwatar/event/queue/App.java

@@ -47,15 +47,13 @@ public class App {
    * @throws IOException when there is a problem with the audio file loading
    * @throws UnsupportedAudioFileException  when the loaded audio file is unsupported 
    */
-  public static void main(String[] args) throws UnsupportedAudioFileException, IOException, InterruptedException {
+  public static void main(String[] args) throws UnsupportedAudioFileException, IOException {
-    Audio audio = Audio.getInstance();
+    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
-    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    Audio.playSound(Audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
-    audio.playSound(audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
     
     System.out.println("Press Enter key to stop the program...");
-    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
+    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-      br.read();
+    br.read();
-    }
+    Audio.stopService();
-    audio.stopService();
   }
 }

event-queue/src/main/java/com/iluwatar/event/queue/Audio.java

@@ -23,9 +23,6 @@
 
 package com.iluwatar.event.queue;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.io.File;
 import java.io.IOException;
 
@@ -41,56 +38,49 @@ import javax.sound.sampled.UnsupportedAudioFileException;
  *
  */
 public class Audio {
-  private static final Logger LOGGER = LoggerFactory.getLogger(Audio.class);
-  private static final Audio INSTANCE = new Audio();
 
   private static final int MAX_PENDING = 16;
 
-  private int headIndex;
+  private static int headIndex;
 
-  private int tailIndex;
+  private static int tailIndex;
 
-  private volatile Thread updateThread = null;
+  private static Thread updateThread = null;
 
-  private PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
+  private static PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
-
-  // Visible only for testing purposes
-  Audio() {
-
-  }
-
-  public static Audio getInstance() {
-    return INSTANCE;
-  }
 
   /**
-   * This method stops the Update Method's thread and waits till service stops.
+   * This method stops the Update Method's thread. 
    */
-  public synchronized void stopService() throws InterruptedException {
+  public static synchronized void stopService() {
     if (updateThread != null) {
       updateThread.interrupt();
     }
-    updateThread.join();
-    updateThread = null;
   }
   
   /**
    * This method check the Update Method's thread is started.
    * @return boolean
    */
-  public synchronized boolean isServiceRunning() {
+  public static synchronized boolean isServiceRunning() {
-    return updateThread != null && updateThread.isAlive();
+    if (updateThread != null && updateThread.isAlive() ) {
+      return true;
+    } else {
+      return false;
+    }
   }
 
   /**
    * Starts the thread for the Update Method pattern if it was not started previously.
    * Also when the thread is is ready initializes the indexes of the queue 
    */
-  public void init() {
+  public static void init() {
     if (updateThread == null) {
-      updateThread = new Thread(() -> {
+      updateThread = new Thread(new Runnable() {
-        while (!Thread.currentThread().isInterrupted()) {
+        public void run() {
-          update();
+          while (!Thread.currentThread().isInterrupted()) {
+            Audio.update();
+          }
         }
       });
     }
@@ -100,7 +90,7 @@ public class Audio {
   /**
    * This is a synchronized thread starter
    */
-  private synchronized void startThread() {
+  public static synchronized void startThread() {
     if (!updateThread.isAlive()) {
       updateThread.start();
       headIndex = 0;
@@ -113,7 +103,7 @@ public class Audio {
    * @param stream is the AudioInputStream for the method
    * @param volume is the level of the audio's volume 
    */
-  public void playSound(AudioInputStream stream, float volume) {
+  public static void playSound(AudioInputStream stream, float volume) {
     init();
     // Walk the pending requests.
     for (int i = headIndex; i != tailIndex; i = (i + 1) % MAX_PENDING) {
@@ -133,7 +123,7 @@ public class Audio {
    * This method uses the Update Method pattern.
    * It takes the audio from the queue and plays it
    */
-  private void update() {
+  public static void update() {
     // If there are no pending requests, do nothing.
     if (headIndex == tailIndex) {
       return;
@@ -146,11 +136,13 @@ public class Audio {
       clip.open(audioStream);
       clip.start();
     } catch (LineUnavailableException e) {
-      LOGGER.trace("Error occoured while loading the audio: The line is unavailable", e);
+      System.err.println("Error occoured while loading the audio: The line is unavailable");
+      e.printStackTrace();
     } catch (IOException e) {
-      LOGGER.trace("Input/Output error while loading the audio", e);
+      System.err.println("Input/Output error while loading the audio");
+      e.printStackTrace();
     } catch (IllegalArgumentException e) {
-      LOGGER.trace("The system doesn't support the sound: " + e.getMessage(), e);
+      System.err.println("The system doesn't support the sound: " + e.getMessage());
     }
   }
 
@@ -161,7 +153,7 @@ public class Audio {
    * @throws UnsupportedAudioFileException when the audio file is not supported 
    * @throws IOException when the file is not readable
    */
-  public AudioInputStream getAudioStream(String filePath)
+  public static AudioInputStream getAudioStream(String filePath) 
       throws UnsupportedAudioFileException, IOException {
     return AudioSystem.getAudioInputStream(new File(filePath).getAbsoluteFile());
   }
@@ -170,7 +162,7 @@ public class Audio {
    * Returns with the message array of the queue 
    * @return PlayMessage[]
    */
-  public PlayMessage[] getPendingAudio() {
+  public static PlayMessage[] getPendingAudio() {
     return pendingAudio;
   }
 

event-queue/src/test/java/com/iluwatar/event/queue/AudioTest.java

@@ -23,7 +23,6 @@
 
 package com.iluwatar.event.queue;
 
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import javax.sound.sampled.UnsupportedAudioFileException;
@@ -40,12 +39,6 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  */
 public class AudioTest {
 
-  private Audio audio;
-
-  @BeforeEach
-  void createAudioInstance() {
-    audio = new Audio();
-  }
   /**
    * Test here that the playSound method works correctly
    * @throws UnsupportedAudioFileException when the audio file is not supported 
@@ -54,15 +47,13 @@ public class AudioTest {
    */
   @Test
   public void testPlaySound() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
     // test that service is started
-    assertTrue(audio.isServiceRunning());
+    assertTrue(Audio.isServiceRunning());
     // adding a small pause to be sure that the sound is ended
     Thread.sleep(5000);
-
-    audio.stopService();
     // test that service is finished
-    assertFalse(audio.isServiceRunning());
+    assertFalse(!Audio.isServiceRunning());
   }
 
   /**
@@ -73,18 +64,16 @@ public class AudioTest {
    */
   @Test
   public void testQueue() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    assertTrue(audio.getPendingAudio().length > 0);
+    assertTrue(Audio.getPendingAudio().length > 0);
     // test that service is started
-    assertTrue(audio.isServiceRunning());
+    assertTrue(Audio.isServiceRunning());
     // adding a small pause to be sure that the sound is ended
     Thread.sleep(10000);
-
-    audio.stopService();
     // test that service is finished
-    assertFalse(audio.isServiceRunning());
+    assertFalse(!Audio.isServiceRunning());
   }
 
 }

throttling/etc/throttling-pattern.ucls

@@ -0,0 +1,88 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.2.2" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
+  associations="true" dependencies="false" nesting-relationships="true" router="FAN">  
+  <class id="1" language="java" name="com.iluwatar.throttling.CallsCount" project="throttling" 
+    file="/throttling/src/main/java/com/iluwatar/throttling/CallsCount.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="211" width="256" x="656" y="228"/>    
+    <display autosize="false" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="2" language="java" name="com.iluwatar.throttling.Tenant" project="throttling" 
+    file="/throttling/src/main/java/com/iluwatar/throttling/Tenant.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="465" y="524"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="3" language="java" name="com.iluwatar.throttling.B2BService" project="throttling" 
+    file="/throttling/src/main/java/com/iluwatar/throttling/B2BService.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="464" y="192"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <interface id="4" language="java" name="com.iluwatar.throttling.timer.Throttler" project="throttling" 
+    file="/throttling/src/main/java/com/iluwatar/throttling/timer/Throttler.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="167" y="174"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </interface>  
+  <class id="5" language="java" name="com.iluwatar.throttling.timer.ThrottleTimerImpl" project="throttling" 
+    file="/throttling/src/main/java/com/iluwatar/throttling/timer/ThrottleTimerImpl.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="166" y="396"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <association id="6">    
+    <end type="SOURCE" refId="3" navigable="false">      
+      <attribute id="7" name="callsCount"/>      
+      <multiplicity id="8" minimum="0" maximum="1"/>    
+    </end>    
+    <end type="TARGET" refId="1" navigable="true"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <dependency id="9">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
+  <dependency id="10">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="2"/>  
+  </dependency>  
+  <association id="11">    
+    <end type="SOURCE" refId="5" navigable="false">      
+      <attribute id="12" name="callsCount"/>      
+      <multiplicity id="13" minimum="0" maximum="1"/>    
+    </end>    
+    <end type="TARGET" refId="1" navigable="true"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <dependency id="14">    
+    <end type="SOURCE" refId="2"/>    
+    <end type="TARGET" refId="1"/>  
+  </dependency>  
+  <realization id="15">    
+    <end type="SOURCE" refId="5"/>    
+    <end type="TARGET" refId="4"/>  
+  </realization>  
+  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+    sort-features="false" accessors="true" visibility="true">    
+    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
+    <operations public="true" package="true" protected="true" private="true" static="true"/>  
+  </classifier-display>  
+  <association-display labels="true" multiplicity="true"/>
+</class-diagram>

throttling/src/main/java/com/iluwatar/throttling/App.java

@@ -53,14 +53,14 @@ public class App {
    * @param args main arguments
    */
   public static void main(String[] args) {
-
+    CallsCount callsCount = new CallsCount();
-    Tenant adidas = new Tenant("Adidas", 5);
+    Tenant adidas = new Tenant("Adidas", 5, callsCount);
-    Tenant nike = new Tenant("Nike", 6);
+    Tenant nike = new Tenant("Nike", 6, callsCount);
 
     ExecutorService executorService = Executors.newFixedThreadPool(2);
     
-    executorService.execute(() -> makeServiceCalls(adidas));
+    executorService.execute(() -> makeServiceCalls(adidas, callsCount));
-    executorService.execute(() -> makeServiceCalls(nike));
+    executorService.execute(() -> makeServiceCalls(nike, callsCount));
     
     executorService.shutdown();
     try {
@@ -73,9 +73,9 @@ public class App {
   /**
    * Make calls to the B2BService dummy API
    */
-  private static void makeServiceCalls(Tenant tenant) {
+  private static void makeServiceCalls(Tenant tenant, CallsCount callsCount) {
-    Throttler timer = new ThrottleTimerImpl(10);
+    Throttler timer = new ThrottleTimerImpl(10, callsCount);
-    B2BService service = new B2BService(timer);
+    B2BService service = new B2BService(timer, callsCount);
     for (int i = 0; i < 20; i++) {
       service.dummyCustomerApi(tenant);
 //    Sleep is introduced to keep the output in check and easy to view and analyze the results.

throttling/src/main/java/com/iluwatar/throttling/B2BService.java

@@ -35,8 +35,10 @@ import java.util.concurrent.ThreadLocalRandom;
 class B2BService {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(B2BService.class);
+  private final CallsCount callsCount;
 
-  public B2BService(Throttler timer) {
+  public B2BService(Throttler timer, CallsCount callsCount) {
+    this.callsCount = callsCount;
     timer.start();
   }
 
@@ -46,13 +48,13 @@ class B2BService {
    */
   public int dummyCustomerApi(Tenant tenant) {
     String tenantName = tenant.getName();
-    long count = CallsCount.getCount(tenantName);
+    long count = callsCount.getCount(tenantName);
     LOGGER.debug("Counter for {} : {} ", tenant.getName(), count);
     if (count >= tenant.getAllowedCallsPerSecond()) {
       LOGGER.error("API access per second limit reached for: {}", tenantName);
       return -1;
     }
-    CallsCount.incrementCount(tenantName);
+    callsCount.incrementCount(tenantName);
     return getRandomCustomerId();
   }
 

throttling/src/main/java/com/iluwatar/throttling/CallsCount.java

@@ -38,13 +38,13 @@ import java.util.concurrent.atomic.AtomicLong;
 public final class CallsCount {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(CallsCount.class);
-  private static Map<String, AtomicLong> tenantCallsCount = new ConcurrentHashMap<>();
+  private Map<String, AtomicLong> tenantCallsCount = new ConcurrentHashMap<>();
 
   /**
    * Add a new tenant to the map.
    * @param tenantName name of the tenant.
    */
-  public static void addTenant(String tenantName) {
+  public void addTenant(String tenantName) {
     tenantCallsCount.putIfAbsent(tenantName, new AtomicLong(0));
   }
   
@@ -52,7 +52,7 @@ public final class CallsCount {
    * Increment the count of the specified tenant.
    * @param tenantName name of the tenant.
    */
-  public static void incrementCount(String tenantName) {
+  public void incrementCount(String tenantName) {
     tenantCallsCount.get(tenantName).incrementAndGet();
   }
   
@@ -61,14 +61,14 @@ public final class CallsCount {
    * @param tenantName name of the tenant.
    * @return the count of the tenant.
    */
-  public static long getCount(String tenantName) {
+  public long getCount(String tenantName) {
     return tenantCallsCount.get(tenantName).get();
   }
   
   /**
    * Resets the count of all the tenants in the map.
    */
-  public static void reset() {
+  public void reset() {
     LOGGER.debug("Resetting the map.");
     for (Entry<String, AtomicLong> e : tenantCallsCount.entrySet()) {
       tenantCallsCount.put(e.getKey(), new AtomicLong(0));

throttling/src/main/java/com/iluwatar/throttling/Tenant.java

@@ -38,13 +38,13 @@ public class Tenant {
    * @param allowedCallsPerSecond The number of calls allowed for a particular tenant.
    * @throws InvalidParameterException If number of calls is less than 0, throws exception.
    */
-  public Tenant(String name, int allowedCallsPerSecond) {
+  public Tenant(String name, int allowedCallsPerSecond, CallsCount callsCount) {
     if (allowedCallsPerSecond < 0) {
       throw new InvalidParameterException("Number of calls less than 0 not allowed");
     }
     this.name = name;
     this.allowedCallsPerSecond = allowedCallsPerSecond;
-    CallsCount.addTenant(name);
+    callsCount.addTenant(name);
   }
 
   public String getName() {

throttling/src/main/java/com/iluwatar/throttling/timer/ThrottleTimerImpl.java

@@ -37,10 +37,12 @@ import com.iluwatar.throttling.CallsCount;
  */
 public class ThrottleTimerImpl implements Throttler {
 
-  private int throttlePeriod;
+  private final int throttlePeriod;
-  
+  private final CallsCount callsCount;
-  public ThrottleTimerImpl(int throttlePeriod) {
+
+  public ThrottleTimerImpl(int throttlePeriod, CallsCount callsCount) {
     this.throttlePeriod = throttlePeriod;
+    this.callsCount = callsCount;
   }
   
   /**
@@ -51,7 +53,7 @@ public class ThrottleTimerImpl implements Throttler {
     new Timer(true).schedule(new TimerTask() {
       @Override
       public void run() {
-        CallsCount.reset();
+        callsCount.reset();
       }
     }, 0, throttlePeriod);
   }

throttling/src/test/java/com/iluwatar/throttling/B2BServiceTest.java

@@ -33,18 +33,19 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  */
 public class B2BServiceTest {
 
-  @Disabled
+  private CallsCount callsCount = new CallsCount();
+
   @Test
   public void dummyCustomerApiTest() {
-    Tenant tenant = new Tenant("testTenant", 2);
+    Tenant tenant = new Tenant("testTenant", 2, callsCount);
     // In order to assure that throttling limits will not be reset, we use an empty throttling implementation
     Throttler timer = () -> { };
-    B2BService service = new B2BService(timer);
+    B2BService service = new B2BService(timer, callsCount);
 
     for (int i = 0; i < 5; i++) {
       service.dummyCustomerApi(tenant);
     }
-    long counter = CallsCount.getCount(tenant.getName());
+    long counter = callsCount.getCount(tenant.getName());
     assertEquals(2, counter, "Counter limit must be reached");
   }
 }

throttling/src/test/java/com/iluwatar/throttling/TenantTest.java

@@ -36,7 +36,7 @@ public class TenantTest {
   @Test
   public void constructorTest() {
     assertThrows(InvalidParameterException.class, () -> {
-      Tenant tenant = new Tenant("FailTenant", -1);
+      Tenant tenant = new Tenant("FailTenant", -1, new CallsCount());
     });
   }
 }