From ff929b75ad8f2d11316c4be8310b56a19828a299 Mon Sep 17 00:00:00 2001
From: Hu Zongtang <zongtanghu@gmail.com>
Date: Fri, 17 Jul 2020 16:12:08 +0800
Subject: [PATCH] [ISSUE#3356]fix no throw exception when publish event but no
 subsciber. (#3363)

---
 .../nacos/common/notify/NotifyCenter.java     |  4 +-
 .../nacos/common/notify/NotifyCenterTest.java | 39 ++++++++++++++-----
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/common/src/main/java/com/alibaba/nacos/common/notify/NotifyCenter.java b/common/src/main/java/com/alibaba/nacos/common/notify/NotifyCenter.java
index 1798203cf40..059fee9fbc3 100644
--- a/common/src/main/java/com/alibaba/nacos/common/notify/NotifyCenter.java
+++ b/common/src/main/java/com/alibaba/nacos/common/notify/NotifyCenter.java
@@ -290,7 +290,9 @@ private static boolean publishEvent(final Class<? extends Event> eventType, fina
             EventPublisher publisher = INSTANCE.publisherMap.get(topic);
             return publisher.publish(event);
         }
-        throw new NoSuchElementException("There are no [" + topic + "] publishers for this event, please register");
+        
+        LOGGER.warn("There are no [{}] publishers for this event, please register", topic);
+        return false;
     }
     
     /**
diff --git a/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java b/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
index 6bf98fa9819..a7163938d00 100644
--- a/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
+++ b/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
@@ -35,6 +35,7 @@
 public class NotifyCenterTest {
     
     private static class TestSlowEvent extends SlowEvent {
+    
     }
     
     private static class TestEvent extends Event {
@@ -330,9 +331,11 @@ public void onEvent(Event event) {
     }
     
     private static class TestSlowEvent1 extends SlowEvent {
+    
     }
     
     private static class TestSlowEvent2 extends SlowEvent {
+    
     }
     
     @Test
@@ -343,10 +346,10 @@ public void testMutipleSlowEventsListenedBySubscriber() throws Exception {
         
         final AtomicInteger count1 = new AtomicInteger(0);
         final AtomicInteger count2 = new AtomicInteger(0);
-    
+        
         final CountDownLatch latch1 = new CountDownLatch(3);
         final CountDownLatch latch2 = new CountDownLatch(3);
-    
+        
         NotifyCenter.registerSubscriber(new Subscriber<TestSlowEvent1>() {
             @Override
             public void onEvent(TestSlowEvent1 event) {
@@ -365,7 +368,7 @@ public Class<? extends Event> subscribeType() {
             public void onEvent(TestSlowEvent2 event) {
                 count2.incrementAndGet();
                 latch2.countDown();
-    
+                
             }
             
             @Override
@@ -373,26 +376,28 @@ public Class<? extends Event> subscribeType() {
                 return TestSlowEvent2.class;
             }
         });
-    
+        
         for (int i = 0; i < 3; i++) {
             Assert.assertTrue(NotifyCenter.publishEvent(new TestSlowEvent1()));
             Assert.assertTrue(NotifyCenter.publishEvent(new TestSlowEvent2()));
         }
-    
+        
         ThreadUtils.sleep(2000L);
-    
+        
         latch1.await(3000L, TimeUnit.MILLISECONDS);
         latch2.await(3000L, TimeUnit.MILLISECONDS);
-    
+        
         Assert.assertEquals(3, count1.get());
         Assert.assertEquals(3, count2.get());
-    
+        
     }
     
     private static class TestSlowEvent3 extends SlowEvent {
+    
     }
     
     private static class TestSlowEvent4 extends SlowEvent {
+    
     }
     
     @Test
@@ -408,7 +413,7 @@ public void testMutipleSlowEventsListenedBySmartsubscriber() throws Exception {
         final CountDownLatch latch2 = new CountDownLatch(3);
         
         NotifyCenter.registerSubscriber(new SmartSubscriber() {
-    
+            
             @Override
             public void onEvent(Event event) {
                 if (event instanceof TestSlowEvent3) {
@@ -421,7 +426,7 @@ public void onEvent(Event event) {
                     latch2.countDown();
                 }
             }
-    
+            
             @Override
             public List<Class<? extends Event>> subscribeTypes() {
                 List<Class<? extends Event>> subTypes = new ArrayList<Class<? extends Event>>();
@@ -447,9 +452,11 @@ public List<Class<? extends Event>> subscribeTypes() {
     }
     
     private static class TestSlowEvent5 extends SlowEvent {
+    
     }
     
     private static class TestEvent6 extends Event {
+    
     }
     
     @Test
@@ -502,4 +509,16 @@ public List<Class<? extends Event>> subscribeTypes() {
         Assert.assertEquals(3, count2.get());
         
     }
+    
+    private static class TestEvent7 extends Event {
+    
+    }
+    
+    @Test
+    public void testPublishEventByNoSubscriber() {
+        
+        for (int i = 0; i < 3; i++) {
+            Assert.assertFalse(NotifyCenter.publishEvent(new TestEvent7()));
+        }
+    }
 }