io.grpc.NameResolverProvider Maven / Gradle / Ivy
/*
* Copyright 2016 The gRPC Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc;
import io.grpc.NameResolver.Factory;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.Collection;
import java.util.Collections;
/**
* Provider of name resolvers for name agnostic consumption.
*
* Implementations can be automatically discovered by gRPC via Java's SPI mechanism. For
* automatic discovery, the implementation must have a zero-argument constructor and include
* a resource named {@code META-INF/services/io.grpc.NameResolverProvider} in their JAR. The
* file's contents should be the implementation's class name. Implementations that need arguments in
* their constructor can be manually registered by {@link NameResolverRegistry#register}.
*
*
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 {@code false} from {@link #isAvailable()}.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/4159")
public abstract class NameResolverProvider extends NameResolver.Factory {
/**
* Whether this provider is available for use, taking the current environment into consideration.
* If {@code false}, no other methods are safe to be called.
*
* @since 1.0.0
*/
protected abstract boolean isAvailable();
/**
* 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.
*
* @since 1.0.0
*/
protected abstract int priority();
/**
* Returns the scheme associated with the provider. The provider normally should only create a
* {@link NameResolver} when target URI scheme matches the provider scheme. It temporarily
* delegates to {@link Factory#getDefaultScheme()} before {@link NameResolver.Factory} is
* deprecated in https://github.com/grpc/grpc-java/issues/7133.
*
*
The scheme should be lower-case.
*
* @since 1.40.0
* */
protected String getScheme() {
return getDefaultScheme();
}
/**
* Returns the {@link SocketAddress} types this provider's name-resolver is capable of producing.
* This enables selection of the appropriate {@link ManagedChannelProvider} for a channel.
*
* @return the {@link SocketAddress} types this provider's name-resolver is capable of producing.
*/
public Collection> getProducedSocketAddressTypes() {
return Collections.singleton(InetSocketAddress.class);
}
}