io.grpc

Class NameResolverProvider

java.lang.Object

io.grpc.NameResolver.Factory

io.grpc.NameResolverProvider

@Internal
public abstract class NameResolverProvider
extends NameResolver.Factory

Provider of name resolvers for name agnostic consumption.

Implementations should not throw. If they do, it may interrupt class loading. If exceptions may reasonably occur for implementation-specific reasons, implementations should generally handle the exception gracefully and return false from isAvailable().

Field Summary

Fields

Modifier and Type	Field and Description
static Attributes.Key<Integer>	PARAMS_DEFAULT_PORT The port number used in case the target or the underlying naming system doesn't provide a port number.

Constructor Summary

Constructors

Constructor and Description
NameResolverProvider()

Method Summary

Modifier and Type	Method and Description
static NameResolver.Factory	asFactory()
static Iterable<NameResolverProvider>	getCandidatesViaHardCoded(ClassLoader classLoader) Load providers from a hard-coded list.
static Iterable<NameResolverProvider>	getCandidatesViaServiceLoader(ClassLoader classLoader)
protected abstract boolean	isAvailable() Whether this provider is available for use, taking the current environment into consideration.
protected abstract int	priority() A priority, from 0 to 10 that this provider should be used, taking the current environment into consideration.
static List<NameResolverProvider>	providers() Returns non-null ClassLoader-wide providers, in preference order.

Methods inherited from class io.grpc.NameResolver.Factory

getDefaultScheme, newNameResolver

Methods inherited from class java.lang.Object

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

Field Detail

PARAMS_DEFAULT_PORT

public static final Attributes.Key<Integer> PARAMS_DEFAULT_PORT

The port number used in case the target or the underlying naming system doesn't provide a port number.

Constructor Detail

NameResolverProvider

public NameResolverProvider()

Method Detail

getCandidatesViaServiceLoader

public static Iterable<NameResolverProvider> getCandidatesViaServiceLoader(ClassLoader classLoader)

getCandidatesViaHardCoded

public static Iterable<NameResolverProvider> getCandidatesViaHardCoded(ClassLoader classLoader)

Load providers from a hard-coded list. This avoids using getResource(), which has performance problems on Android (see https://github.com/grpc/grpc-java/issues/2037). Any provider that may be used on Android is free to be added here.

providers

public static List<NameResolverProvider> providers()

Returns non-null ClassLoader-wide providers, in preference order.

asFactory

public static NameResolver.Factory asFactory()

isAvailable

protected abstract boolean isAvailable()

Whether this provider is available for use, taking the current environment into consideration. If false, no other methods are safe to be called.

priority

protected abstract int priority()

A priority, from 0 to 10 that this provider should be used, taking the current environment into consideration. 5 should be considered the default, and then tweaked based on environment detection. A priority of 0 does not imply that the provider wouldn't work; just that it should be last in line.