IO-259 - add stop(long) method that specifies the amount of time to wait before stopping the monitor - thanks to Dan Checkoway

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/io/trunk@1080843 13f79535-47bb-0310-9956-ffa450edef68

Author: Niall Pemberton

src/main/java/org/apache/commons/io/monitor/FileAlterationMonitor.java

@@ -147,12 +147,29 @@ public synchronized void start() throws Exception {
      * @throws Exception if an error occurs initializing the observer
      */
     public synchronized void stop() throws Exception {
+        stop(interval);
+    }
+
+    /**
+     * Stop monitoring.
+     *
+     * @param stopInterval the amount of time in milliseconds to wait for the thread to finish.
+     * A value of zero will wait until the thread to finished (see {@link Thread#join(long)})
+     * and a nagative value will stop the process immediately).
+     * @throws Exception if an error occurs initializing the observer
+     * @since Commons IO 2.1
+     */
+    public synchronized void stop(long stopInterval) throws Exception {
         if (running == false) {
             throw new IllegalStateException("Monitor is not running");
         }
         running = false;
         try {
-            thread.join(interval);
+            if (stopInterval < 0) {
+                thread.interrupt();
+            } else {
+                thread.join(stopInterval);
+            }
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();
         }