Class GracefulSwitchLoadBalancer
- java.lang.Object
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- io.grpc.LoadBalancer
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- io.grpc.util.ForwardingLoadBalancer
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- io.grpc.util.GracefulSwitchLoadBalancer
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@ExperimentalApi("https://github.com/grpc/grpc-java/issues/5999") @NotThreadSafe public final class GracefulSwitchLoadBalancer extends ForwardingLoadBalancer
A load balancer that gracefully swaps to a new lb policy. If the channel is currently in a state other than READY, the new policy will be swapped into place immediately. Otherwise, the channel will keep using the old policy until the new policy reports READY or the old policy exits READY.The balancer must
switch to
a policy prior tohandling resolved addresses
for the first time.
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Nested Class Summary
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Nested classes/interfaces inherited from class io.grpc.LoadBalancer
LoadBalancer.CreateSubchannelArgs, LoadBalancer.ErrorPicker, LoadBalancer.Factory, LoadBalancer.FixedResultPicker, LoadBalancer.Helper, LoadBalancer.PickResult, LoadBalancer.PickSubchannelArgs, LoadBalancer.ResolvedAddresses, LoadBalancer.Subchannel, LoadBalancer.SubchannelPicker, LoadBalancer.SubchannelStateListener
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Field Summary
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Fields inherited from class io.grpc.LoadBalancer
ATTR_HEALTH_CHECKING_CONFIG, EMPTY_PICKER, HAS_HEALTH_PRODUCER_LISTENER_KEY, HEALTH_CONSUMER_LISTENER_ARG_KEY, IS_PETIOLE_POLICY
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Constructor Summary
Constructors Constructor Description GracefulSwitchLoadBalancer(LoadBalancer.Helper helper)
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description protected LoadBalancer
delegate()
Returns the underlying balancer.java.lang.String
delegateType()
void
handleSubchannelState(LoadBalancer.Subchannel subchannel, ConnectivityStateInfo stateInfo)
Deprecated.void
shutdown()
The channel asks the load-balancer to shutdown.void
switchTo(LoadBalancer.Factory newBalancerFactory)
Gracefully switch to a new policy defined by the given factory, if the given factory isn't equal to the current one.-
Methods inherited from class io.grpc.util.ForwardingLoadBalancer
canHandleEmptyAddressListFromNameResolution, handleNameResolutionError, handleResolvedAddresses, requestConnection, toString
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Methods inherited from class io.grpc.LoadBalancer
acceptResolvedAddresses
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Constructor Detail
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GracefulSwitchLoadBalancer
public GracefulSwitchLoadBalancer(LoadBalancer.Helper helper)
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Method Detail
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switchTo
public void switchTo(LoadBalancer.Factory newBalancerFactory)
Gracefully switch to a new policy defined by the given factory, if the given factory isn't equal to the current one.
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delegate
protected LoadBalancer delegate()
Description copied from class:ForwardingLoadBalancer
Returns the underlying balancer.- Specified by:
delegate
in classForwardingLoadBalancer
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handleSubchannelState
@Deprecated public void handleSubchannelState(LoadBalancer.Subchannel subchannel, ConnectivityStateInfo stateInfo)
Deprecated.Description copied from class:LoadBalancer
Handles a state change on a Subchannel.The initial state of a Subchannel is IDLE. You won't get a notification for the initial IDLE state.
If the new state is not SHUTDOWN, this method should create a new picker and call
Helper.updateBalancingState()
. Failing to do so may result in unnecessary delays of RPCs. Please refer toPickResult.withSubchannel()
's javadoc for more information.SHUTDOWN can only happen in two cases. One is that LoadBalancer called
LoadBalancer.Subchannel.shutdown()
earlier, thus it should have already discarded this Subchannel. The other is that Channel is doing aforced shutdown
or has already terminated, thus there won't be further requests to LoadBalancer. Therefore, the LoadBalancer usually don't need to react to a SHUTDOWN state.- Overrides:
handleSubchannelState
in classForwardingLoadBalancer
- Parameters:
subchannel
- the involved SubchannelstateInfo
- the new state
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shutdown
public void shutdown()
Description copied from class:LoadBalancer
The channel asks the load-balancer to shutdown. No more methods on this class will be called after this method. The implementation should shutdown all Subchannels and OOB channels, and do any other cleanup as necessary.- Overrides:
shutdown
in classForwardingLoadBalancer
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delegateType
public java.lang.String delegateType()
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