net.devh.boot.grpc.client.nameresolver

Class DiscoveryClientNameResolver

java.lang.Object

io.grpc.NameResolver

net.devh.boot.grpc.client.nameresolver.DiscoveryClientNameResolver

public class DiscoveryClientNameResolver
extends io.grpc.NameResolver

The DiscoveryClientNameResolver resolves the service hosts and their associated gRPC port using the channel's name and spring's cloud DiscoveryClient. The ports are extracted from the gRPC_port metadata.

Nested Class Summary

Nested classes/interfaces inherited from class io.grpc.NameResolver

io.grpc.NameResolver.Args, io.grpc.NameResolver.ConfigOrError, io.grpc.NameResolver.Factory, io.grpc.NameResolver.Listener, io.grpc.NameResolver.Listener2, io.grpc.NameResolver.ResolutionResult, io.grpc.NameResolver.ResolutionResultAttr, io.grpc.NameResolver.ServiceConfigParser

Constructor Summary

Constructors

Constructor and Description
DiscoveryClientNameResolver(String name, org.springframework.cloud.client.discovery.DiscoveryClient client, io.grpc.NameResolver.Args args, io.grpc.internal.SharedResourceHolder.Resource<Executor> executorResource, Consumer<DiscoveryClientNameResolver> shutdownHook) Creates a new DiscoveryClientNameResolver.

Method Summary

Modifier and Type	Method and Description
protected List<org.springframework.cloud.client.ServiceInstance>	discoverServers() Discovers matching service instances.
protected io.grpc.Attributes	getAttributes(org.springframework.cloud.client.ServiceInstance serviceInstance) Gets the attributes from the service instance for later use in a load balancer.
protected int	getGrpcPort(org.springframework.cloud.client.ServiceInstance instance) Extracts the gRPC server port from the given service instance.
protected String	getName() Gets the name of the service to get the instances of.
String	getServiceAuthority()
protected boolean	isActive() Checks whether this resolver is active.
protected boolean	needsToUpdateConnections(List<org.springframework.cloud.client.ServiceInstance> newInstanceList) Checks whether this instance should update its connections.
void	refresh()
void	refreshFromExternal() Triggers a refresh on the listener from non-grpc threads.
void	shutdown()
void	start(io.grpc.NameResolver.Listener2 listener)
String	toString()

Methods inherited from class io.grpc.NameResolver

start

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DiscoveryClientNameResolver

public DiscoveryClientNameResolver(String name,
                                   org.springframework.cloud.client.discovery.DiscoveryClient client,
                                   io.grpc.NameResolver.Args args,
                                   io.grpc.internal.SharedResourceHolder.Resource<Executor> executorResource,
                                   Consumer<DiscoveryClientNameResolver> shutdownHook)

Creates a new DiscoveryClientNameResolver.

Parameters:

name - The name of the service to look up.

client - The client used to look up the service addresses.

args - The name resolver args.

executorResource - The executor resource.

shutdownHook - The optional cleaner used during shutdown()

Method Detail

getName

protected final String getName()

Gets the name of the service to get the instances of.

Returns:

The name associated with this resolver.

isActive

protected final boolean isActive()

Checks whether this resolver is active. E.g. #start has been called, but not #shutdown().

Returns:

True, if there is a listener attached. False, otherwise.

getServiceAuthority

public final String getServiceAuthority()

Specified by:

getServiceAuthority in class io.grpc.NameResolver

start

public void start(io.grpc.NameResolver.Listener2 listener)

Overrides:

start in class io.grpc.NameResolver

refresh

public void refresh()

Overrides:

refresh in class io.grpc.NameResolver

refreshFromExternal

public void refreshFromExternal()

Triggers a refresh on the listener from non-grpc threads. This method can safely be called, even if the listener hasn't been started yet.

See Also:

refresh()

discoverServers

protected List<org.springframework.cloud.client.ServiceInstance> discoverServers()

Discovers matching service instances. Can be overwritten to apply some custom filtering.

Returns:

A list of service instances to use.

getGrpcPort

protected int getGrpcPort(org.springframework.cloud.client.ServiceInstance instance)

Extracts the gRPC server port from the given service instance. Can be overwritten for a custom port mapping.

Parameters:

instance - The instance to extract the port from.

Returns:

The gRPC server port.

Throws:

IllegalArgumentException - If the specified port definition couldn't be parsed.

getAttributes

protected io.grpc.Attributes getAttributes(org.springframework.cloud.client.ServiceInstance serviceInstance)

Gets the attributes from the service instance for later use in a load balancer. Can be overwritten to convert custom attributes.

Parameters:

serviceInstance - The service instance to get them from.

Returns:

The newly created attributes for the given instance.

needsToUpdateConnections

protected boolean needsToUpdateConnections(List<org.springframework.cloud.client.ServiceInstance> newInstanceList)

Checks whether this instance should update its connections.

Parameters:

newInstanceList - The new instances that should be compared to the stored ones.

Returns:

True, if the given instance list contains different entries than the stored ones.

shutdown

public void shutdown()

Specified by:

shutdown in class io.grpc.NameResolver

toString

public String toString()

Overrides:

toString in class Object