Fix javadoc warnings in ExecutorServiceUtil

[yangtools.git] / common / util / src / main / java / org / opendaylight / yangtools / util / ExecutorServiceUtil.java

diff --git a/common/util/src/main/java/org/opendaylight/yangtools/util/ExecutorServiceUtil.java b/common/util/src/main/java/org/opendaylight/yangtools/util/ExecutorServiceUtil.java
index 36f729fb8ff69210e475ad67f8466f3dd973f5f0..6ca961f789ad5a78c206e39975136c3a6b6d367f 100644 (file)
--- a/common/util/src/main/java/org/opendaylight/yangtools/util/ExecutorServiceUtil.java
+++ b/common/util/src/main/java/org/opendaylight/yangtools/util/ExecutorServiceUtil.java
@@ -7,52 +7,58 @@
  */
 package org.opendaylight.yangtools.util;
 
+import com.google.common.util.concurrent.ForwardingBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.RejectedExecutionHandler;
 import java.util.concurrent.ThreadPoolExecutor;
-
+import java.util.concurrent.TimeUnit;
+import org.eclipse.jdt.annotation.NonNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.google.common.util.concurrent.ForwardingBlockingQueue;
-
 /**
  * Utility methods for dealing with {@link ExecutorService}s.
  */
 public final class ExecutorServiceUtil {
     private static final class WaitInQueueExecutionHandler implements RejectedExecutionHandler {
         @Override
+        @SuppressWarnings("checkstyle:parameterName")
         public void rejectedExecution(final Runnable r, final ThreadPoolExecutor executor) {
+            if (executor.isShutdown()) {
+                throw new RejectedExecutionException("Executor has been shutdown.");
+            }
+
             try {
                 executor.getQueue().put(r);
             } catch (InterruptedException e) {
-                LOG.debug("Intterupted while waiting for queue", e);
-                throw new RejectedExecutionException("Interrupted while waiting for queue", e);
+                LOG.debug("Interrupted while attempting to put to the queue", e);
+                throw new RejectedExecutionException("Interrupted while attempting to put to the queue", e);
             }
         }
     }
 
     private static final Logger LOG = LoggerFactory.getLogger(ExecutorServiceUtil.class);
-    private static final RejectedExecutionHandler WAIT_IN_QUEUE_HANDLER = new WaitInQueueExecutionHandler();
+    private static final @NonNull RejectedExecutionHandler WAIT_IN_QUEUE_HANDLER = new WaitInQueueExecutionHandler();
 
     private ExecutorServiceUtil() {
-        throw new UnsupportedOperationException("Utility class");
+        // Hidden on purpose
     }
 
     /**
-     * Create a {@link BlockingQueue} which does not allow for non-blocking addition to the queue.
-     * This is useful with {@link #waitInQueueExecutionHandler()} to turn force a
-     * {@link ThreadPoolExecutor} to create as many threads as it is configured to before starting
-     * to fill the queue.
+     * Creates a {@link BlockingQueue} which does not allow for non-blocking addition to the queue. This is useful with
+     * {@link #waitInQueueExecutionHandler()} to turn force a {@link ThreadPoolExecutor} to create as many threads as it
+     * is configured to before starting to fill the queue.
      *
+     * @param <E> type of elements
      * @param delegate Backing blocking queue.
      * @return A new blocking queue backed by the delegate
      */
-    public <E> BlockingQueue<E> offerFailingBlockingQueue(final BlockingQueue<E> delegate) {
-        return new ForwardingBlockingQueue<E>() {
+    public static <E> @NonNull BlockingQueue<E> offerFailingBlockingQueue(final BlockingQueue<E> delegate) {
+        return new ForwardingBlockingQueue<>() {
             @Override
+            @SuppressWarnings("checkstyle:parameterName")
             public boolean offer(final E o) {
                 return false;
             }
@@ -65,12 +71,33 @@ public final class ExecutorServiceUtil {
     }
 
     /**
-     * Return a {@link RejectedExecutionHandler} which blocks on the {@link ThreadPoolExecutor}'s
-     * backing queue if a new thread cannot be spawned.
+     * Returns a {@link RejectedExecutionHandler} which blocks on the {@link ThreadPoolExecutor}'s backing queue if a
+     * new thread cannot be spawned.
      *
      * @return A shared RejectedExecutionHandler instance.
      */
-    public RejectedExecutionHandler waitInQueueExecutionHandler() {
+    public static @NonNull RejectedExecutionHandler waitInQueueExecutionHandler() {
         return WAIT_IN_QUEUE_HANDLER;
     }
+
+    /**
+     * Tries to shutdown the given executor gracefully by awaiting termination for the given timeout period. If the
+     * timeout elapses before termination, the executor is forcefully shutdown.
+     *
+     * @param executor Executor to shut down
+     * @param timeout timeout period
+     * @param unit timeout unit
+     */
+    public static void tryGracefulShutdown(final @NonNull ExecutorService executor, final long timeout,
+            final @NonNull TimeUnit unit) {
+        executor.shutdown();
+
+        try {
+            if (!executor.awaitTermination(timeout, unit)) {
+                executor.shutdownNow();
+            }
+        } catch (InterruptedException e) {
+            executor.shutdownNow();
+        }
+    }
 }