Merge branch 'master' into async-method-invocation-explanation

.all-contributorsrc

@@ -1431,15 +1431,6 @@
       "contributions": [
         "code"
       ]
-    },
-    {
-      "login": "qfxl",
-      "name": "yonghong Xu",
-      "avatar_url": "https://avatars.githubusercontent.com/u/14086462?v=4",
-      "profile": "https://xuyonghong.cn/",
-      "contributions": [
-        "doc"
-      ]
     }
   ],
   "contributorsPerLine": 4,

.github/workflows/maven-pr-builder.yml

@@ -29,7 +29,7 @@ name: Java PR Builder
 on:
   pull_request:
     branches: [ master ]
-    types: [ opened, reopened, synchronize, labeled, unlabeled ]
+    types: [ opened, reopened, synchronize ]
 
 jobs:
   build:

README.md

@@ -10,7 +10,7 @@
 [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
 [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-158-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-157-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 <br/>
@@ -311,7 +311,6 @@ This project is licensed under the terms of the MIT license.
   </tr>
   <tr>
     <td align="center"><a href="https://github.com/noamgrinch"><img src="https://avatars.githubusercontent.com/u/31648669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Noam Greenshtain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=noamgrinch" title="Code">💻</a></td>
-    <td align="center"><a href="https://xuyonghong.cn/"><img src="https://avatars.githubusercontent.com/u/14086462?v=4?s=100" width="100px;" alt=""/><br /><sub><b>yonghong Xu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qfxl" title="Documentation">📖</a></td>
   </tr>
 </table>
 

balking/README.md

@@ -9,131 +9,19 @@ tags:
 ---
 
 ## Intent
-
+Balking Pattern is used to prevent an object from executing certain code if it is an
-Balking Pattern is used to prevent an object from executing a certain code if it is in an incomplete 
+incomplete or inappropriate state
-or inappropriate state.
-
-## Explanation
-
-Real world example
-
-> There's a start-button in a washing machine to initiate the laundry washing. When the washing 
-> machine is inactive the button works as expected, but if it's already washing the button does
-> nothing.
-
-In plain words
-
-> Using the balking pattern, a certain code executes only if the object is in particular state.
-
-Wikipedia says
-
-> The balking pattern is a software design pattern that only executes an action on an object when 
-> the object is in a particular state. For example, if an object reads ZIP files and a calling 
-> method invokes a get method on the object when the ZIP file is not open, the object would "balk" 
-> at the request.
-
-**Programmatic Example**
-
-In this example implementation, `WashingMachine` is an object that has two states in which it can 
-be: ENABLED and WASHING. If the machine is ENABLED, the state changes to WASHING using a thread-safe
-method. On the other hand, if it already has been washing and any other thread executes `wash()` 
-it won't do that and returns without doing anything.
-
-Here are the relevant parts of the `WashingMachine` class.
-
-```java
-@Slf4j
-public class WashingMachine {
-
-  private final DelayProvider delayProvider;
-  private WashingMachineState washingMachineState;
-
-  public WashingMachine(DelayProvider delayProvider) {
-    this.delayProvider = delayProvider;
-    this.washingMachineState = WashingMachineState.ENABLED;
-  }
-
-  public WashingMachineState getWashingMachineState() {
-    return washingMachineState;
-  }
-
-  public void wash() {
-    synchronized (this) {
-      var machineState = getWashingMachineState();
-      LOGGER.info("{}: Actual machine state: {}", Thread.currentThread().getName(), machineState);
-      if (this.washingMachineState == WashingMachineState.WASHING) {
-        LOGGER.error("Cannot wash if the machine has been already washing!");
-        return;
-      }
-      this.washingMachineState = WashingMachineState.WASHING;
-    }
-    LOGGER.info("{}: Doing the washing", Thread.currentThread().getName());
-    this.delayProvider.executeAfterDelay(50, TimeUnit.MILLISECONDS, this::endOfWashing);
-  }
-
-  public synchronized void endOfWashing() {
-    washingMachineState = WashingMachineState.ENABLED;
-    LOGGER.info("{}: Washing completed.", Thread.currentThread().getId());
-  }
-}
-```
-
-Here's the simple `DelayProvider` interface used by the `WashingMachine`.
-
-```java
-public interface DelayProvider {
-  void executeAfterDelay(long interval, TimeUnit timeUnit, Runnable task);
-}
-```
-
-Now we introduce the application using the `WashingMachine`.
-
-```java
-  public static void main(String... args) {
-    final var washingMachine = new WashingMachine();
-    var executorService = Executors.newFixedThreadPool(3);
-    for (int i = 0; i < 3; i++) {
-      executorService.execute(washingMachine::wash);
-    }
-    executorService.shutdown();
-    try {
-      executorService.awaitTermination(10, TimeUnit.SECONDS);
-    } catch (InterruptedException ie) {
-      LOGGER.error("ERROR: Waiting on executor service shutdown!");
-      Thread.currentThread().interrupt();
-    }
-  }
-```
-
-Here is the console output of the program.
-
-```
-14:02:52.268 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-2: Actual machine state: ENABLED
-14:02:52.272 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-2: Doing the washing
-14:02:52.272 [pool-1-thread-3] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-3: Actual machine state: WASHING
-14:02:52.273 [pool-1-thread-3] ERROR com.iluwatar.balking.WashingMachine - Cannot wash if the machine has been already washing!
-14:02:52.273 [pool-1-thread-1] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-1: Actual machine state: WASHING
-14:02:52.273 [pool-1-thread-1] ERROR com.iluwatar.balking.WashingMachine - Cannot wash if the machine has been already washing!
-14:02:52.324 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - 14: Washing completed.
-```
 
 ## Class diagram
-
 ![alt text](./etc/balking.png "Balking")
 
 ## Applicability
-
 Use the Balking pattern when
 
-* You want to invoke an action on an object only when it is in a particular state
+* you want to invoke an action on an object only when it is in a particular state
-* Objects are generally only in a state that is prone to balking temporarily but for an unknown 
+* objects are generally only in a state that is prone to balking temporarily
-  amount of time
+but for an unknown amount of time
 
 ## Related patterns
-
+* Guarded Suspension Pattern
-* [Guarded Suspension Pattern](https://java-design-patterns.com/patterns/guarded-suspension/)
+* Double Checked Locking Pattern
-* [Double Checked Locking Pattern](https://java-design-patterns.com/patterns/double-checked-locking/)
-
-## Credits
-
-* [Patterns in Java: A Catalog of Reusable Design Patterns Illustrated with UML, 2nd Edition, Volume 1](https://www.amazon.com/gp/product/0471227293/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0471227293&linkId=0e39a59ffaab93fb476036fecb637b99)

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

@@ -32,11 +32,11 @@ import lombok.extern.slf4j.Slf4j;
  * then the method will return without doing anything. Objects that use this pattern are generally
  * only in a state that is prone to balking temporarily but for an unknown amount of time
  *
- * <p>In this example implementation, {@link WashingMachine} is an object that has two states in
+ * <p>In this example implementation WashingMachine is an object that has two states in which it
- * which it can be: ENABLED and WASHING. If the machine is ENABLED, the state changes to WASHING
+ * can be: ENABLED and WASHING. If the machine is ENABLED the state is changed into WASHING that any
- * using a thread-safe method. On the other hand, if it already has been washing and any other
+ * other thread can't invoke this action on this and then do the job. On the other hand if it have
- * thread executes {@link WashingMachine#wash()} it won't do that and returns without doing
+ * been already washing and any other thread execute wash() it can't do that once again and returns
- * anything.
+ * doing nothing.
  */
 @Slf4j
 public class App {
@@ -54,12 +54,11 @@ public class App {
     }
     executorService.shutdown();
     try {
-      if (!executorService.awaitTermination(10, TimeUnit.SECONDS)) {
+      executorService.awaitTermination(10, TimeUnit.SECONDS);
-        executorService.shutdownNow();
-      }
     } catch (InterruptedException ie) {
       LOGGER.error("ERROR: Waiting on executor service shutdown!");
       Thread.currentThread().interrupt();
     }
   }
+
 }