Some small refactor

src/main/java/com/alibaba/druid/pool/ha/PropertiesUtils.java

@@ -17,6 +17,7 @@ package com.alibaba.druid.pool.ha;
 
 import com.alibaba.druid.support.logging.Log;
 import com.alibaba.druid.support.logging.LogFactory;
+import com.alibaba.druid.util.StringUtils;
 
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -98,4 +99,17 @@ public class PropertiesUtils {
         }
         return nameList;
     }
+
+    public static Properties filterPrefix(Properties properties, String prefix) {
+        if (properties == null || prefix == null || prefix.isEmpty()) {
+            return properties;
+        }
+        Properties result = new Properties();
+        for (String n : properties.stringPropertyNames()) {
+            if (n.startsWith(prefix)) {
+                result.setProperty(n, properties.getProperty(n));
+            }
+        }
+        return result;
+    }
 }

src/main/java/com/alibaba/druid/pool/ha/node/FileNodeListener.java

@@ -24,6 +24,8 @@ import java.util.Properties;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * A NodeList that monitors the change of a file.
@@ -33,6 +35,7 @@ import java.util.concurrent.TimeUnit;
 public class FileNodeListener extends NodeListener {
     private final static Log LOG = LogFactory.getLog(FileNodeListener.class);
 
+    private Lock lock = new ReentrantLock();
     private String file = null;
     private String prefix = "";
     private int intervalSeconds = 60;
@@ -54,10 +57,16 @@ public class FileNodeListener extends NodeListener {
         executor.scheduleAtFixedRate(new Runnable() {
             @Override
             public void run() {
+                if (!lock.tryLock()) {
+                    LOG.info("Can not acquire the lock, skip this time.");
+                    return;
+                }
                 try {
                     update();
                 } catch (Exception e) {
                     LOG.error("Can NOT update the node list.", e);
+                } finally {
+                    lock.unlock();
                 }
             }
         }, intervalSeconds, intervalSeconds, TimeUnit.SECONDS);
@@ -95,7 +104,7 @@ public class FileNodeListener extends NodeListener {
             }
         }
 
-        List<NodeEvent> events = NodeEvent.getEventListFromProperties(getProperties(), properties);
+        List<NodeEvent> events = NodeEvent.getEventsByDiffProperties(getProperties(), properties);
         if (events != null && !events.isEmpty()) {
             setProperties(properties);
         }

src/main/java/com/alibaba/druid/pool/ha/node/NodeEvent.java

@@ -38,7 +38,7 @@ public class NodeEvent {
      *
      * @return A List of AddEvent and DelEvent
      */
-    public static List<NodeEvent> getEventListFromProperties(Properties previous, Properties next) {
+    public static List<NodeEvent> getEventsByDiffProperties(Properties previous, Properties next) {
         List<String> prevNames = PropertiesUtils.loadNameList(previous, "");
         List<String> nextNames = PropertiesUtils.loadNameList(next, "");
 
@@ -62,7 +62,7 @@ public class NodeEvent {
         return list;
     }
 
-    private static List<NodeEvent> generateEvents(Properties properties, List<String> names, NodeEventTypeEnum type) {
+    public static List<NodeEvent> generateEvents(Properties properties, List<String> names, NodeEventTypeEnum type) {
         List<NodeEvent> list = new ArrayList<NodeEvent>();
         for (String n : names) {
             NodeEvent event = new NodeEvent();

src/main/java/com/alibaba/druid/pool/ha/node/NodeListener.java

@@ -66,25 +66,24 @@ public abstract class NodeListener extends Observable {
      * Fire the refresh() method and notify the Observer.
      *
      * @see #refresh()
+     * @see #update(List)
      */
     public void update() {
-        if (!lock.tryLock()) {
-            LOG.info("Can not acquire the lock, skip this time.");
-            return;
-        }
-        try {
-            List<NodeEvent> events = refresh();
-            if (events != null && !events.isEmpty()) {
-                this.lastUpdateTime = new Date();
-                NodeEvent[] arr = new NodeEvent[events.size()];
-                for (int i = 0; i < events.size(); i++) {
-                    arr[i] = events.get(i);
-                }
-                this.setChanged();
-                this.notifyObservers(arr);
+        update(refresh());
+    }
+
+    /**
+     * Notify the Observer.
+     */
+    public void update(List<NodeEvent> events) {
+        if (events != null && !events.isEmpty()) {
+            this.lastUpdateTime = new Date();
+            NodeEvent[] arr = new NodeEvent[events.size()];
+            for (int i = 0; i < events.size(); i++) {
+                arr[i] = events.get(i);
             }
-        } finally {
-            lock.unlock();
+            this.setChanged();
+            this.notifyObservers(arr);
         }
     }
 

src/test/java/com/alibaba/druid/pool/ha/node/NodeEventTest.java

@@ -14,14 +14,14 @@ public class NodeEventTest {
         Properties p1 = new Properties();
         Properties p2 = new Properties();
 
-        List<NodeEvent> list = NodeEvent.getEventListFromProperties(p1, p2);
+        List<NodeEvent> list = NodeEvent.getEventsByDiffProperties(p1, p2);
         assertTrue(list.isEmpty());
 
         p1.setProperty("foo.url", "foo_url");
         p1.setProperty("foo.username", "foo_username");
         p1.setProperty("foo.password", "foo_password");
 
-        list = NodeEvent.getEventListFromProperties(p1, p2);
+        list = NodeEvent.getEventsByDiffProperties(p1, p2);
         assertEquals(1, list.size());
         NodeEvent event = list.get(0);
         assertEquals(NodeEventTypeEnum.DELETE, event.getType());
@@ -30,7 +30,7 @@ public class NodeEventTest {
         assertEquals("foo_username", event.getUsername());
         assertEquals("foo_password", event.getPassword());
 
-        list = NodeEvent.getEventListFromProperties(p2, p1);
+        list = NodeEvent.getEventsByDiffProperties(p2, p1);
         assertEquals(1, list.size());
         event = list.get(0);
         assertEquals(NodeEventTypeEnum.ADD, event.getType());