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[ISSUE #4090]Fail faster to keep consistent state #4094

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[ISSUE #4090]Fail faster to keep consistent state #4094

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4a53d35
fail faster to keep consistent state.
dugenkui03 Apr 1, 2022
052ca2c
fail faster to keep consistent state.
dugenkui03 Apr 1, 2022
7fc4a6e
fail faster to keep consistent state
dugenkui03 Apr 25, 2022
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17 changes: 14 additions & 3 deletions client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
import org.apache.rocketmq.common.MixAll;
import org.apache.rocketmq.common.UtilAll;
import org.apache.rocketmq.common.consumer.ConsumeFromWhere;
import org.apache.rocketmq.common.help.FAQUrl;
import org.apache.rocketmq.common.message.MessageExt;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.common.protocol.NamespaceUtil;
Expand Down Expand Up @@ -223,13 +224,14 @@ public DefaultLitePullConsumer(final String namespace, final String consumerGrou
}

@Override
public void start() throws MQClientException {
public synchronized void start() throws MQClientException {
checkServiceState();
setTraceDispatcher();
setConsumerGroup(NamespaceUtil.wrapNamespace(this.getNamespace(), this.consumerGroup));
this.defaultLitePullConsumerImpl.start();
if (null != traceDispatcher) {
if (null != this.traceDispatcher) {
try {
traceDispatcher.start(this.getNamesrvAddr(), this.getAccessChannel());
this.traceDispatcher.start(this.getNamesrvAddr(), this.getAccessChannel());
} catch (MQClientException e) {
log.warn("trace dispatcher start failed ", e);
}
Expand Down Expand Up @@ -532,6 +534,15 @@ public void setCustomizedTraceTopic(String customizedTraceTopic) {
this.customizedTraceTopic = customizedTraceTopic;
}

private void checkServiceState() throws MQClientException {
if (!this.defaultLitePullConsumerImpl.isCreateJust()) {
throw new MQClientException("The PullConsumer service state is not CREATE_JUST, maybe started once, "
+ this.defaultLitePullConsumerImpl.getServiceState()
+ FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),
null);
}
}

private void setTraceDispatcher() {
if (isEnableMsgTrace()) {
try {
Expand Down
10 changes: 9 additions & 1 deletion ...t/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultLitePullConsumerImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,7 @@ public class DefaultLitePullConsumerImpl implements MQConsumerInner {

private final ArrayList<FilterMessageHook> filterMessageHookList = new ArrayList<FilterMessageHook>();

private volatile ServiceState serviceState = ServiceState.CREATE_JUST;
private ServiceState serviceState = ServiceState.CREATE_JUST;

protected MQClientInstance mQClientFactory;

Expand Down Expand Up @@ -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;
}

Comment on lines +274 to +281
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Is it necessary to add synchronized here？

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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。

public synchronized void start() throws MQClientException {
switch (this.serviceState) {
case CREATE_JUST:
Expand Down