fix thread blocked problem of etcd watcher

[Yan1025]

in the previous version of EtcdDataSource, when the flowRules defined in the etcd change and trigger etcd watcher, there will be a following error: 2022-12-07 14:36:03.592 [vertx-blocked-thread-checker] WARN io.vertx.core.impl.BlockedThreadChecker [?:?] - Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 2336 ms, time limit is 2000 ms 2022-12-07 14:36:04.592 [vertx-blocked-thread-checker] WARN io.vertx.core.impl.BlockedThreadChecker [?:?] - Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 3337 ms, time limit is 2000 ms 2022-12-07 14:36:05.592 [vertx-blocked-thread-checker] WARN io.vertx.core.impl.BlockedThreadChecker [?:?] - Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 4337 ms, time limit is 2000 ms 2022-12-07 14:36:06.595 [vertx-blocked-thread-checker] WARN io.vertx.core.impl.BlockedThreadChecker [?:?] - Thread Thread[vert.x-eventloop-thread-0,5,main] has been blocked for 5337 ms, time limit is 2000 ms io.vertx.core.VertxException: Thread blocked
at sun.misc.Unsafe.park(Native Method)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.CompletableFuture$Signaller.block(CompletableFuture.java:1707)
at java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3334)
at java.util.concurrent.CompletableFuture.waitingGet(CompletableFuture.java:1742)
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1908)
at com.htsc.fst.saas.infrastructure.component.EtcdDataSource.readSource(EtcdDataSource.java:92)
at com.htsc.fst.saas.infrastructure.component.EtcdDataSource.readSource(EtcdDataSource.java:23)
at com.alibaba.csp.sentinel.datasource.AbstractDataSource.loadConfig(AbstractDataSource.java:44)
at com.htsc.fst.saas.infrastructure.component.EtcdDataSource.lambda$initWatcher$0(EtcdDataSource.java:74)
at com.htsc.fst.saas.infrastructure.component.EtcdDataSource$$Lambda$480/1375681611.accept(Unknown Source)
at io.etcd.jetcd.Watch$1.onNext(Watch.java:183)
at io.etcd.jetcd.impl.WatchImpl$WatcherImpl.onNext(WatchImpl.java:310)
at io.etcd.jetcd.impl.WatchImpl$WatcherImpl$$Lambda$488/2088661957.handle(Unknown Source

I guess the reason is : when the watcher hold etcd Client, you can't use etcd Client in the Watch's consumer function. Besides the problem above, use getKeyValue() in the watchEvent can reduce once invoke with etcd server to getting the latest flowRules :)

Describe what this PR does / why we need it

Does this pull request fix one issue?

Describe how you did it

Describe how to verify it

Special notes for reviews

[CLAassistant]

All committers have signed the CLA.

[Yan1025]

Describe what this PR does / why we need it: it's a bug and a waste of invoke
Does this pull request fix one issue?: no, i found it and commit the bug fix immediately
Describe how you did it: the code committed can describe it
Describe how to verify it: it's a must-appear bug when flowRules in the etcd server change
Special notes for reviews: nothing more

[sczyh30]

Could you please sign the CLA here: https://cla-assistant.io/alibaba/Sentinel?pullRequest=2991

[Yan1025]

Now i have signed the CLA and send the PDF to opensource@alibaba-inc.com

[sczyh30]

cc @LProDreamAll Any suggestions?

[LProDreamAll]

@sczyh30 @Yan1025

com.alibaba.csp.sentinel.datasource.etcd.EtcdDataSource#initWatcher

private void initWatcher() {
watcher = client.getWatchClient().watch(ByteSequence.from(key, charset), (watchResponse) -> {
for (WatchEvent watchEvent : watchResponse.getEvents()) {
WatchEvent.EventType eventType = watchEvent.getEventType();
if (eventType == WatchEvent.EventType.PUT) {
try {
T newValue = loadConfig();
getProperty().updateValue(newValue);
} catch (Exception e) {
RecordLog.warn("[EtcdDataSource] Failed to update config", e);
}
} else if (eventType == WatchEvent.EventType.DELETE) {
RecordLog.info("[EtcdDataSource] Cleaning config for key <{}>", key);
getProperty().updateValue(null);
}
}
});
}

Solution

private void initWatcher() {
watcher = client.getWatchClient().watch(ByteSequence.from(key, charset), (watchResponse) -> {
for (WatchEvent watchEvent : watchResponse.getEvents()) {
WatchEvent.EventType eventType = watchEvent.getEventType();

if (eventType == WatchEvent.EventType.PUT) {
try {
String newValueJson = watchEvent.getKeyValue().getValue().toString(charset);
T newValue = parser.convert(newValueJson);
} catch (Exception e) {
RecordLog.warn("[EtcdDataSource] Failed to update config", e);
}
} else if (eventType == WatchEvent.EventType.DELETE) {
RecordLog.info("[EtcdDataSource] Cleaning config for key <{}>", key);
getProperty().updateValue(null);
}
}
});
}

[LProDreamAll]

@Yan1025 @sczyh30
toString() should be toString(charset)

[Yan1025]

@Yan1025 @sczyh30 toString() should be toString(charset)

Thanks for your pertinent suggestion and i have optimized my pull request

[sczyh30]

LGTM

[sczyh30]

Thanks for contributing!