+ * 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; + +/** + * In Balking Design Pattern if an object’s method is invoked when it is in an inappropriate state, + * 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 + * + * 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 is changed into WASHING that any other thread can't invoke this action on this and then do the job. + * On the other hand if it have been already washing and any other thread execute wash() + * it can't do that once again and returns doing nothing. + */ + +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!"); + } + } + +} diff --git a/balking/src/main/java/com/iluwatar/balking/WashingMachine.java b/balking/src/main/java/com/iluwatar/balking/WashingMachine.java new file mode 100644 index 000000000..2167a0e52 --- /dev/null +++ b/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()); + } + +} diff --git a/balking/src/main/java/com/iluwatar/balking/WashingMachineState.java b/balking/src/main/java/com/iluwatar/balking/WashingMachineState.java new file mode 100644 index 000000000..40a5b2f38 --- /dev/null +++ b/balking/src/main/java/com/iluwatar/balking/WashingMachineState.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; + +/** + * WashingMachineState enum describes in which state machine is, + * it can be enabled and ready to work as well as during washing + */ + +public enum WashingMachineState { + ENABLED, WASHING +} diff --git a/balking/src/test/java/com/iluwatar/balking/AppTest.java b/balking/src/test/java/com/iluwatar/balking/AppTest.java new file mode 100644 index 000000000..df104b901 --- /dev/null +++ b/balking/src/test/java/com/iluwatar/balking/AppTest.java @@ -0,0 +1,39 @@ +/** + * 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; + +/** + * Application test + */ +public class AppTest { + + @Test + public void main() throws Exception { + String[] args = {}; + App.main(args); + } + +} \ No newline at end of file diff --git a/balking/src/test/java/com/iluwatar/balking/WashingMachineTest.java b/balking/src/test/java/com/iluwatar/balking/WashingMachineTest.java new file mode 100644 index 000000000..3dc87d64f --- /dev/null +++ b/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());
+ }
+
+}
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index d2ea715a7..925aea6ed 100644
--- a/pom.xml
+++ b/pom.xml
@@ -135,6 +135,7 @@