#66 Balking Pattern

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

@@ -0,0 +1,53 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.balking;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class App {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+  /**
+   * @param args the command line arguments - not used
+   */
+  public static void main(String... args) {
+    final WashingMachine washingMachine = new WashingMachine();
+    ExecutorService 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!");
+    }
+  }
+
+}

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

@@ -0,0 +1,73 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.balking;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class WashingMachine {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(WashingMachine.class);
+
+  private WashingMachineState washingMachineState;
+
+  public WashingMachine() {
+    washingMachineState = WashingMachineState.ENABLED;
+  }
+
+  public WashingMachineState getWashingMachineState() {
+    return washingMachineState;
+  }
+
+  /**
+   * Method responsible for washing
+   * if the object is in appropriate state
+   */
+  public void wash() {
+    synchronized (this) {
+      LOGGER.info("{}: Actual machine state: {}", Thread.currentThread().getName(), getWashingMachineState());
+      if (washingMachineState == WashingMachineState.WASHING) {
+        LOGGER.error("ERROR: Cannot wash if the machine has been already washing!");
+        return;
+      }
+      washingMachineState = WashingMachineState.WASHING;
+    }
+    LOGGER.info("{}: Doing the washing", Thread.currentThread().getName());
+    try {
+      Thread.sleep(50);
+    } catch (InterruptedException ie) {
+      ie.printStackTrace();
+    }
+    endOfWashing();
+  }
+
+  /**
+   * Method responsible of ending the washing
+   * by changing machine state
+   */
+  public synchronized void endOfWashing() {
+    washingMachineState = WashingMachineState.ENABLED;
+    LOGGER.info("{}: Washing completed.", Thread.currentThread().getId());
+  }
+
+}

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

@@ -0,0 +1,25 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.balking;
+
+public enum WashingMachineState {ENABLED, WASHING}

balking/src/test/java/com/iluwatar/balking/AppTest.java

@@ -0,0 +1,32 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.balking;
+
+public class AppTest {
+  @org.junit.Test
+  public void main() throws Exception {
+    String[] args = {};
+    App.main(args);
+  }
+
+}

balking/src/test/java/com/iluwatar/balking/WashingMachineTest.java

@@ -0,0 +1,62 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.balking;
+
+import org.junit.Test;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.*;
+
+public class WashingMachineTest {
+
+  private volatile WashingMachineState machineStateGlobal;
+
+  @Test
+  public void wash() throws Exception {
+    WashingMachine washingMachine = new WashingMachine();
+    ExecutorService executorService = Executors.newFixedThreadPool(2);
+    executorService.execute(washingMachine::wash);
+    executorService.execute(() -> {
+      washingMachine.wash();
+      machineStateGlobal = washingMachine.getWashingMachineState();
+    });
+    executorService.shutdown();
+    try {
+      executorService.awaitTermination(10, TimeUnit.SECONDS);
+    } catch (InterruptedException ie) {
+      ie.printStackTrace();
+    }
+    assertEquals(WashingMachineState.WASHING, machineStateGlobal);
+  }
+
+  @Test
+  public void endOfWashing() throws Exception {
+    WashingMachine washingMachine = new WashingMachine();
+    washingMachine.wash();
+    assertEquals(WashingMachineState.ENABLED, washingMachine.getWashingMachineState());
+  }
+
+}