[GitHub] [rocketmq] dugenkui03 commented on a diff in pull request #4094: [ISSUE #4090]Fail faster to keep consistent state

[GitBox <gi...@apache.org>]

dugenkui03 commented on code in PR #4094:
URL: https://github.com/apache/rocketmq/pull/4094#discussion_r844625217


##########
client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultLitePullConsumerImpl.java:
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@@ -271,6 +271,14 @@ public synchronized boolean isRunning() {
         return this.serviceState == ServiceState.RUNNING;
     }
 
+    public synchronized boolean isCreateJust() {
+        return this.serviceState == ServiceState.CREATE_JUST;
+    }
+
+    public synchronized ServiceState getServiceState() {
+        return this.serviceState;
+    }
+

Review Comment:
   `serviceState` is in a  wrong/incompletable state before `synchronized #start()` return, since the value of `serviceState` is modified several times in `synchronized #start()`. `synchronized` in `isCreateJust` and `getServiceState` avoid read `wrong/incompletable` value.
   
   > `synchronized #start()`中对`serviceState`进行了多次更新、并且方法返回之前的状态是 不正确/不完整 的，`synchronized `是为了避免读取到这些 不正确/不完整 的状态。而且我注意到在该pr之前，`serviceState`的修改和读取也都使用了`synchronized`加锁、这已经可以保证`serviceState`的可见性了，因此`serviceState`上的`volatile`修饰符似乎是多余的。



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