threaded mediator and memento

Author: totoLab

ingSoftware/designPatterns/src/main/java/comportamentali/mediator/Airplane.java

@@ -0,0 +1,48 @@
+package comportamentali.mediator;
+
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+public class Airplane extends Colleague implements Runnable {
+
+ private static int ID;
+ private int id;
+
+ public Airplane(Mediator mediator) {
+ super(mediator);
+ this.id = ++ID;
+ }
+
+ public boolean landingRequest() {
+ notify("Requesting landing...");
+ return mediator.landingRequest();
+ }
+
+ private void land() {
+ notify("Landing now");
+ ((ControlTower) mediator).landed();
+ }
+
+ @Override
+ public void run() {
+ Random random = new Random();
+ wait(random.nextInt(3, 20));
+ while (!landingRequest()) {
+ notify("Request rejected, not allowed to land now");
+ wait(4);
+ }
+ wait(random.nextInt(4, 7));
+ land();
+
+ }
+
+ void wait(int seconds) {
+ try {
+ TimeUnit.SECONDS.sleep(seconds);
+ } catch (InterruptedException e) {}
+ }
+
+ void notify(String message) {
+ System.out.println(id + ": " + message);
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/mediator/Client.java

@@ -0,0 +1,15 @@
+package comportamentali.mediator;
+
+public class Client {
+
+ public static void main(String[] args) {
+
+ Mediator controlTower = new ControlTower(5);
+ for (int i = 0; i < 10; i++) {
+ Runnable runnable = new Airplane(controlTower);
+ Thread thread = new Thread(runnable);
+ thread.start();
+ }
+
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/mediator/Colleague.java

@@ -0,0 +1,10 @@
+package comportamentali.mediator;
+
+public abstract class Colleague {
+
+ protected Mediator mediator;
+
+ public Colleague(Mediator mediator) {
+ this.mediator = mediator;
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/mediator/ControlTower.java

@@ -0,0 +1,37 @@
+package comportamentali.mediator;
+
+import java.util.concurrent.Semaphore;
+
+public class ControlTower implements Mediator {
+
+ private int landingRequests;
+ private final int maxLandingRequests;
+ private Semaphore mutex = new Semaphore(1);
+
+ public ControlTower(int maxLandingRequests) {
+ this.landingRequests = 0;
+ this.maxLandingRequests = maxLandingRequests;
+ }
+
+ public void landed() {
+ try {
+ mutex.acquire();
+ } catch (InterruptedException e) {}
+ if (landingRequests > 0) landingRequests--;
+ mutex.release();
+ }
+
+ @Override
+ public boolean landingRequest() {
+ try {
+ mutex.acquire();
+ } catch (InterruptedException e) {}
+ if (landingRequests >= maxLandingRequests) {
+ mutex.release();
+ return false;
+ }
+ landingRequests++;
+ mutex.release();
+ return true;
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/mediator/Mediator.java

@@ -0,0 +1,6 @@
+package comportamentali.mediator;
+
+public interface Mediator {
+
+ boolean landingRequest();
+}

ingSoftware/designPatterns/src/main/java/comportamentali/memento/Client.java

@@ -0,0 +1,29 @@
+package comportamentali.memento;
+
+import java.util.Random;
+
+public class Client {
+
+ public static void main(String[] args) {
+ Database database = new Database("people");
+
+ newTransaction(database, new String[]{"john", "doe", "johndoe@gmail.com"});
+ newTransaction(database, new String[]{"Cohen", "Oneal", "CohenOneal@gmail.com"});
+
+ System.out.println("\n" + database);
+ }
+
+ static void newTransaction(Database db, String[] row) {
+ MementoNarrow temp = db.save();
+ System.out.println("Transaction started");
+
+ Random random = new Random();
+ if (random.nextInt(0, 10) < 2) {
+ System.out.println("Transaction failed, restoring automatically");
+ db.restore(temp);
+ } else {
+ db.add(row);
+ System.out.println("Transaction finished");
+ }
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/memento/Database.java

@@ -0,0 +1,63 @@
+package comportamentali.memento;
+
+import java.util.*;
+
+public class Database {
+
+ private String name;
+ private List<String[]> rows;
+
+ public Database(String name) {
+ this.name = name;
+ rows = new ArrayList<>();
+
+ }
+
+ private class Memento implements MementoWide, MementoNarrow {
+
+ String name;
+ List<String[]> rows;
+ Date date;
+
+ public Memento(String name, List<String[]> rows) {
+ this.name = name;
+ this.rows = new ArrayList<>(rows);
+ this.date = new Date();
+ }
+
+ @Override
+ public List<String[]> getRows() {
+ return new ArrayList<>(rows);
+ }
+
+ @Override
+ public void setRows(List<String[]> rows) {
+ rows = new ArrayList<>(rows);
+ }
+ }
+
+ void add(String[] row) {
+ rows.add(row);
+ }
+
+ MementoNarrow save() {
+ MementoWide memento = new Memento(this.name, this.rows);
+ return (MementoNarrow) memento;
+ }
+
+ void restore(MementoNarrow memento) {
+ this.rows = new ArrayList<>(((MementoWide) memento).getRows());
+ };
+
+ @Override
+ public String toString() {
+ StringBuilder result = new StringBuilder();
+ result.append(name);
+ result.append("\n");
+ for (String[] row : rows) {
+ result.append(Arrays.toString(row));
+ result.append("\n");
+ }
+ return result.toString();
+ }
+}

ingSoftware/designPatterns/src/main/java/comportamentali/memento/MementoNarrow.java

@@ -0,0 +1,4 @@
+package comportamentali.memento;
+
+public interface MementoNarrow {
+}

ingSoftware/designPatterns/src/main/java/comportamentali/memento/MementoWide.java

@@ -0,0 +1,10 @@
+package comportamentali.memento;
+
+import java.util.List;
+
+public interface MementoWide {
+
+ List<String[]> getRows();
+ void setRows(List<String[]> rows);
+
+}