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xds: have cluster balancer cancel cluster watcher only during shutdown 

Previously when CdsConfig is changed, the old cluster watcher is canceled immediately even it's in graceful switch period, so the old cluster balancer won't receive any new updates. This behavior is not as good/clean as cancelling the old watch only once the old cluster balancer is shutdown.
This commit is contained in:
ZHANG Dapeng 2020-02-14 10:58:50 -08:00 committed by GitHub
parent 5555ec9a35
commit cd049ed48b
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 20 additions and 41 deletions
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59
xds/src/main/java/io/grpc/xds/CdsLoadBalancer.java
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@ -59,12 +59,9 @@ public final class CdsLoadBalancer extends LoadBalancer {
// The following fields become non-null once handleResolvedAddresses() successfully.
// Most recent CdsConfig.
// Most recent cluster name.
@Nullable
private CdsConfig cdsConfig;
// Most recent ClusterWatcher.
@Nullable
private ClusterWatcher clusterWatcher;
private String clusterName;
@Nullable
private ObjectPool<XdsClient> xdsClientPool;
@Nullable
@ -110,29 +107,19 @@ public final class CdsLoadBalancer extends LoadBalancer {
}
CdsConfig newCdsConfig = (CdsConfig) lbConfig;
// If CdsConfig is changed, do a graceful switch.
if (!newCdsConfig.equals(cdsConfig)) {
LoadBalancer.Factory fixedCdsConfigBalancerFactory =
new FixedCdsConfigBalancerFactory(newCdsConfig);
switchingLoadBalancer.switchTo(fixedCdsConfigBalancerFactory);
// If cluster is changed, do a graceful switch.
if (!newCdsConfig.name.equals(clusterName)) {
LoadBalancer.Factory clusterBalancerFactory = new ClusterBalancerFactory(newCdsConfig.name);
switchingLoadBalancer.switchTo(clusterBalancerFactory);
}
switchingLoadBalancer.handleResolvedAddresses(resolvedAddresses);
// The clusterWatcher is also updated after switchingLoadBalancer.handleResolvedAddresses().
cdsConfig = newCdsConfig;
clusterName = newCdsConfig.name;
}
@Override
public void handleNameResolutionError(Status error) {
channelLogger.log(ChannelLogLevel.ERROR, "Name resolution error: {0}", error);
// Go into TRANSIENT_FAILURE if we have not yet received any cluster resource. Otherwise,
// we keep running with the data we had previously.
if (clusterWatcher == null) {
helper.updateBalancingState(TRANSIENT_FAILURE, new ErrorPicker(error));
} else {
switchingLoadBalancer.handleNameResolutionError(error);
}
switchingLoadBalancer.handleNameResolutionError(error);
}
@Override
@ -151,32 +138,28 @@ public final class CdsLoadBalancer extends LoadBalancer {
}
/**
* A load balancer factory that provides a load balancer for a given CdsConfig.
* A load balancer factory that provides a load balancer for a given cluster.
*/
private final class FixedCdsConfigBalancerFactory extends LoadBalancer.Factory {
private final class ClusterBalancerFactory extends LoadBalancer.Factory {
final CdsConfig cdsConfig;
final CdsConfig oldCdsConfig;
final ClusterWatcher oldClusterWatcher;
final String clusterName;
FixedCdsConfigBalancerFactory(CdsConfig cdsConfig) {
this.cdsConfig = cdsConfig;
oldCdsConfig = CdsLoadBalancer.this.cdsConfig;
oldClusterWatcher = CdsLoadBalancer.this.clusterWatcher;
ClusterBalancerFactory(String clusterName) {
this.clusterName = clusterName;
}
@Override
public boolean equals(Object o) {
if (!(o instanceof FixedCdsConfigBalancerFactory)) {
if (!(o instanceof ClusterBalancerFactory)) {
return false;
}
FixedCdsConfigBalancerFactory that = (FixedCdsConfigBalancerFactory) o;
return cdsConfig.equals(that.cdsConfig);
ClusterBalancerFactory that = (ClusterBalancerFactory) o;
return clusterName.equals(that.clusterName);
}
@Override
public int hashCode() {
return Objects.hash(super.hashCode(), cdsConfig);
return Objects.hash(super.hashCode(), clusterName);
}
@Override
@ -207,7 +190,7 @@ public final class CdsLoadBalancer extends LoadBalancer {
if (clusterWatcher.edsBalancer != null) {
clusterWatcher.edsBalancer.shutdown();
}
xdsClient.cancelClusterDataWatch(cdsConfig.name, clusterWatcher);
xdsClient.cancelClusterDataWatch(clusterName, clusterWatcher);
}
}
@ -215,11 +198,7 @@ public final class CdsLoadBalancer extends LoadBalancer {
public void handleResolvedAddresses(ResolvedAddresses resolvedAddresses) {
if (clusterWatcher == null) {
clusterWatcher = new ClusterWatcherImpl(helper, resolvedAddresses);
xdsClient.watchClusterData(cdsConfig.name, clusterWatcher);
if (oldCdsConfig != null) {
xdsClient.cancelClusterDataWatch(oldCdsConfig.name, oldClusterWatcher);
}
CdsLoadBalancer.this.clusterWatcher = clusterWatcher;
xdsClient.watchClusterData(clusterName, clusterWatcher);
}
}
};

2
xds/src/test/java/io/grpc/xds/CdsLoadBalancerTest.java
View File

@ -264,7 +264,6 @@ public class CdsLoadBalancerTest {
ArgumentCaptor<ClusterWatcher> clusterWatcherCaptor2 = ArgumentCaptor.forClass(null);
verify(xdsClient).watchClusterData(eq("bar.googleapis.com"), clusterWatcherCaptor2.capture());
verify(xdsClient).cancelClusterDataWatch("foo.googleapis.com", clusterWatcher1);
ClusterWatcher clusterWatcher2 = clusterWatcherCaptor2.getValue();
clusterWatcher2.onClusterChanged(
@ -301,6 +300,7 @@ public class CdsLoadBalancerTest {
edsLbHelper2.updateBalancingState(ConnectivityState.READY, picker2);
verify(helper).updateBalancingState(ConnectivityState.READY, picker2);
verify(edsLoadBalancer1).shutdown();
verify(xdsClient).cancelClusterDataWatch("foo.googleapis.com", clusterWatcher1);
clusterWatcher2.onClusterChanged(
ClusterUpdate.newBuilder()