Work on #403, incorporate review changes

promise/README.md

@@ -3,10 +3,11 @@ layout: pattern
 title: Promise
 folder: promise
 permalink: /patterns/promise/
-categories: Structural
+categories: Concurrency
 tags:
  - Java
- - Concurrency
+ - Functional
+ - Reactive
  - Difficulty-Intermediate
 ---
 

promise/etc/promise.ucls

@@ -74,38 +74,38 @@
       <operations public="true" package="true" protected="true" private="false" static="true"/>    
     </display>  
   </class>  
-  <realization id="9">    
+  <generalization id="9">    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="2"/>  
-  </realization>  
-  <dependency id="10">    
-    <end type="SOURCE" refId="8"/>    
-    <end type="TARGET" refId="1"/>  
-  </dependency>  
-  <generalization id="11">    
     <end type="SOURCE" refId="1"/>    
     <end type="TARGET" refId="3"/>  
   </generalization>  
-  <dependency id="12">    
+  <realization id="10">    
-    <end type="SOURCE" refId="1"/>    
+    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="4"/>  
+    <end type="TARGET" refId="2"/>  
-  </dependency>  
+  </realization>  
-  <dependency id="13">    
+  <dependency id="11">    
-    <end type="SOURCE" refId="1"/>    
-    <end type="TARGET" refId="7"/>  
-  </dependency>  
-  <dependency id="14">    
-    <end type="SOURCE" refId="8"/>    
-    <end type="TARGET" refId="4"/>  
-  </dependency>  
-  <dependency id="15">    
     <end type="SOURCE" refId="1"/>    
     <end type="TARGET" refId="6"/>  
   </dependency>  
-  <dependency id="16">    
+  <dependency id="12">    
+    <end type="SOURCE" refId="8"/>    
+    <end type="TARGET" refId="1"/>  
+  </dependency>  
+  <dependency id="13">    
+    <end type="SOURCE" refId="8"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
+  <dependency id="14">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="7"/>  
+  </dependency>  
+  <dependency id="15">    
     <end type="SOURCE" refId="1"/>    
     <end type="TARGET" refId="5"/>  
   </dependency>  
+  <dependency id="16">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
   <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"/>    

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

@@ -22,6 +22,15 @@
  */
 package com.iluwatar.promise;
 
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.net.URL;
+import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
@@ -44,6 +53,8 @@ import java.util.concurrent.Executors;
  * <li> Prevents callback hell and provides callback aggregation
  * </ul>
  * 
+ * <p>
+ * 
  * @see CompletableFuture
  */
 public class App {
@@ -68,23 +79,57 @@ public class App {
 
   private static void promiseUsage(Executor executor)
       throws InterruptedException, ExecutionException {
-    Promise<Integer> consumedPromise = new Promise<>();
+    String urlString = "https://raw.githubusercontent.com/iluwatar/java-design-patterns/Promise/promise/README.md";
-    consumedPromise.fulfillInAsync(() -> {
+    Promise<Integer> lineCountPromise = new Promise<String>().fulfillInAsync(() -> {
-      Thread.sleep(1000);
+      return downloadFile(urlString);
-      return 10;
+    }, executor).then(fileLocation -> {
-    }, executor).then(value -> {
+      return countLines(fileLocation);
-      System.out.println("Consumed int value: " + value);
     });
     
-    Promise<String> transformedPromise = new Promise<>();
+    Promise<Map<Character, Integer>> charFrequencyPromise = new Promise<String>().fulfillInAsync(() -> {
-    transformedPromise.fulfillInAsync(() -> {
+      return String.valueOf(downloadFile(urlString));
-      Thread.sleep(1000);
+    }, executor).then(fileLocation -> {
-      return "10";
+      return characterFrequency(fileLocation);
-    }, executor).then(value -> { return Integer.parseInt(value); }).then(value -> {
-      System.out.println("Consumed transformed int value: " + value);
     });
     
-    consumedPromise.get();
+    lineCountPromise.get();
-    transformedPromise.get();
+    System.out.println("Line count is: " + lineCountPromise.get());
+    charFrequencyPromise.get();
+    System.out.println("Char frequency is: " + charFrequencyPromise.get());
+  }
+
+  private static Map<Character, Integer> characterFrequency(String fileLocation) {
+    // TODO Auto-generated method stub
+    return null;
+  }
+
+  private static Integer countLines(String fileLocation) {
+    int lineCount = 0;
+    try (Reader reader = new FileReader(fileLocation); 
+        BufferedReader bufferedReader = new BufferedReader(reader);) {
+      for (String line; (line = bufferedReader.readLine()) != null; ) {
+        lineCount++;
+      }
+    } catch (IOException ex) {
+      ex.printStackTrace();
+    }
+    return lineCount;
+  }
+
+  private static String downloadFile(String urlString) throws InterruptedException, IOException {
+    URL url = new URL(urlString);
+    File file = File.createTempFile("promise_pattern", null);
+    try (Reader reader = new InputStreamReader(url.openStream()); 
+        BufferedReader bufferedReader = new BufferedReader(reader);
+        FileWriter writer = new FileWriter(file)) {
+      for (String line; (line = bufferedReader.readLine()) != null; ) {
+        writer.write(line);
+        writer.write("\n");
+      }
+    } catch (IOException ex) {
+      ex.printStackTrace();
+    }
+    System.out.println("File downloaded at: " + file.getAbsolutePath());
+    return file.getAbsolutePath();
   }
 }

promise/src/main/java/com/iluwatar/promise/Promise.java

@@ -120,11 +120,11 @@ public class Promise<T> extends PromiseSupport<T> {
    */
   private class ConsumeAction implements Runnable {
 
-    private Promise<T> src;
+    private final Promise<T> src;
-    private Promise<Void> dest;
+    private final Promise<Void> dest;
-    private Consumer<? super T> action;
+    private final Consumer<? super T> action;
 
-    ConsumeAction(Promise<T> src, Promise<Void> dest, Consumer<? super T> action) {
+    private ConsumeAction(Promise<T> src, Promise<Void> dest, Consumer<? super T> action) {
       this.src = src;
       this.dest = dest;
       this.action = action;
@@ -147,11 +147,11 @@ public class Promise<T> extends PromiseSupport<T> {
    */
   private class TransformAction<V> implements Runnable {
 
-    private Promise<T> src;
+    private final Promise<T> src;
-    private Promise<V> dest;
+    private final Promise<V> dest;
-    private Function<? super T, V> func;
+    private final Function<? super T, V> func;
 
-    TransformAction(Promise<T> src, Promise<V> dest, Function<? super T, V> func) {
+    private TransformAction(Promise<T> src, Promise<V> dest, Function<? super T, V> func) {
       this.src = src;
       this.dest = dest;
       this.func = func;

promise/src/main/java/com/iluwatar/promise/PromiseSupport.java

@@ -33,15 +33,15 @@ import java.util.concurrent.TimeoutException;
  */
 class PromiseSupport<T> implements Future<T> {
 
-  static final int RUNNING = 1;
+  private static final int RUNNING = 1;
-  static final int FAILED = 2;
+  private static final int FAILED = 2;
-  static final int COMPLETED = 3;
+  private static final int COMPLETED = 3;
 
-  final Object lock;
+  private final Object lock;
 
-  volatile int state = RUNNING;
+  private volatile int state = RUNNING;
-  T value;
+  private T value;
-  Exception exception;
+  private Exception exception;
 
   PromiseSupport() {
     this.lock = new Object();