added new executor service factory impl

pi4j-core/src/main/java/com/pi4j/concurrent/DefaultExecutorServiceFactory.java

@@ -0,0 +1,106 @@
+package com.pi4j.concurrent;
+
+/*
+ * #%L
+ * **********************************************************************
+ * ORGANIZATION  :  Pi4J
+ * PROJECT       :  Pi4J :: Java Library (Core)
+ * FILENAME      :  DefaultExecutorServiceFactory.java  
+ * 
+ * This file is part of the Pi4J project. More information about 
+ * this project can be found here:  http://www.pi4j.com/
+ * **********************************************************************
+ * %%
+ * Copyright (C) 2012 - 2013 Pi4J
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadFactory;
+
+public class DefaultExecutorServiceFactory implements ExecutorServiceFactory {
+
+    public static int MAX_THREADS_IN_POOL = 25;
+    private static List<ExecutorService> singleThreadExecutorServices  = new ArrayList<ExecutorService>();
+    private static ScheduledExecutorService scheduledExecutorService = null;
+    private static ScheduledExecutorServiceWrapper executorServiceWrapper = null;
+
+    /**
+     * return an instance to the thread factory used to create new executor services
+     */
+    private ThreadFactory getThreadFactory(){
+        return Executors.defaultThreadFactory();
+    }
+
+    /**
+     * return an instance to the scheduled executor service (wrapper)
+     */
+    public ScheduledExecutorService getScheduledExecutorService(){
+        if(scheduledExecutorService == null){
+            scheduledExecutorService = Executors.newScheduledThreadPool(MAX_THREADS_IN_POOL, getThreadFactory());
+            executorServiceWrapper = new ScheduledExecutorServiceWrapper(scheduledExecutorService);
+        }
+
+        // we return the protected wrapper to prevent any consumers from 
+        // being able to shutdown the scheduled executor service
+        return executorServiceWrapper;
+    }
+
+    /**
+     * return a new instance of a single thread executor service
+     */
+    public ExecutorService newSingleThreadExecutorService(){
+
+        // create new single thread executor
+        ExecutorService singleThreadExecutorService = Executors.newSingleThreadExecutor(getThreadFactory());
+
+        // add new instance to managed collection
+        singleThreadExecutorServices.add(singleThreadExecutorService);
+
+        // return the new instance
+        return singleThreadExecutorService;
+    }
+
+    /**
+     * shutdown executor threads
+     */
+    public void shutdown(){
+
+        // shutdown each single thread executor in the managed collection
+        for(ExecutorService singleThreadExecutorService : singleThreadExecutorServices){
+            if(singleThreadExecutorService != null){
+                if(!singleThreadExecutorService.isShutdown()){
+                    // this is a forceful shutdown; 
+                    // don't wait for the active tasks to complete
+                    singleThreadExecutorService.shutdownNow();
+                }
+            }
+        }
+
+        // shutdown scheduled executor instance 
+        if(scheduledExecutorService != null){
+            if(!scheduledExecutorService.isShutdown()){
+                // this is a forceful shutdown; 
+                // don't wait for the scheduled tasks to complete
+                scheduledExecutorService.shutdownNow();
+            }
+        }
+    }
+}

pi4j-core/src/main/java/com/pi4j/concurrent/ExecutorServiceFactory.java

@@ -0,0 +1,39 @@
+package com.pi4j.concurrent;
+
+/*
+ * #%L
+ * **********************************************************************
+ * ORGANIZATION  :  Pi4J
+ * PROJECT       :  Pi4J :: Java Library (Core)
+ * FILENAME      :  ExecutorServiceFactory.java  
+ * 
+ * This file is part of the Pi4J project. More information about 
+ * this project can be found here:  http://www.pi4j.com/
+ * **********************************************************************
+ * %%
+ * Copyright (C) 2012 - 2013 Pi4J
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ScheduledExecutorService;
+
+public interface ExecutorServiceFactory
+{
+    public ScheduledExecutorService getScheduledExecutorService();
+    public ExecutorService newSingleThreadExecutorService();
+    public void shutdown();
+}

pi4j-core/src/main/java/com/pi4j/concurrent/ScheduledExecutorServiceWrapper.java

@@ -0,0 +1,141 @@
+package com.pi4j.concurrent;
+
+/*
+ * #%L
+ * **********************************************************************
+ * ORGANIZATION  :  Pi4J
+ * PROJECT       :  Pi4J :: Java Library (Core)
+ * FILENAME      :  ScheduledExecutorServiceWrapper.java  
+ * 
+ * This file is part of the Pi4J project. More information about 
+ * this project can be found here:  http://www.pi4j.com/
+ * **********************************************************************
+ * %%
+ * Copyright (C) 2012 - 2013 Pi4J
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+public class ScheduledExecutorServiceWrapper implements ScheduledExecutorService {
+
+    private ScheduledExecutorService service;
+
+    /**
+     * Default constructor
+     * @param service
+     */
+    public ScheduledExecutorServiceWrapper(ScheduledExecutorService service) {
+        this.service = service;
+    }
+
+    @Override
+    public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
+        return service.awaitTermination(timeout, unit);
+    }
+
+    @Override
+    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException {
+        return service.invokeAll(tasks);
+    }
+
+    @Override
+    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) 
+            throws InterruptedException {
+        return service.invokeAll(tasks, timeout, unit);
+    }
+
+    @Override
+    public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException {
+        return service.invokeAny(tasks);
+    }
+
+    @Override
+    public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        return service.invokeAny(tasks, timeout, unit);
+    }
+
+    @Override
+    public boolean isShutdown() {
+        return service.isShutdown();
+    }
+
+    @Override
+    public boolean isTerminated() {
+        return service.isShutdown();
+    }
+
+    @Override
+    public void shutdown() {
+        throw new UnsupportedOperationException("This scheduled executor service can only be shutdown by Pi4J.");
+    }
+
+    @Override
+    public List<Runnable> shutdownNow() {
+        throw new UnsupportedOperationException("This scheduled executor service can only be shutdown by Pi4J.");
+    }
+
+    @Override
+    public <T> Future<T> submit(Callable<T> task) {
+        return service.submit(task);
+    }
+
+    @Override
+    public Future<?> submit(Runnable task) {
+        return service.submit(task);
+    }
+
+    @Override
+    public <T> Future<T> submit(Runnable task, T result) {
+        return service.submit(task, result);
+    }
+
+    @Override
+    public void execute(Runnable command) {
+        service.execute(command);        
+    }
+
+    @Override
+    public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
+        return service.schedule(command, delay, unit);
+    }
+
+    @Override
+    public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
+        return service.schedule(callable, delay, unit);
+    }
+
+    @Override
+    public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period,
+            TimeUnit unit) {
+        return service.scheduleAtFixedRate(command, initialDelay, period, unit);
+    }
+
+    @Override
+    public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay,
+            long delay, TimeUnit unit) {
+        return service.scheduleWithFixedDelay(command, initialDelay, delay, unit);
+    }
+}