io.grpc.protobuf.services.HealthCheckingLoadBalancerUtil Maven / Gradle / Ivy
/*
* Copyright 2018 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.protobuf.services;
import io.grpc.ExperimentalApi;
import io.grpc.LoadBalancer;
import io.grpc.LoadBalancer.Helper;
import io.grpc.internal.ExponentialBackoffPolicy;
import io.grpc.internal.GrpcUtil;
/**
* Utility for enabling
*
* client-side health checking for {@link LoadBalancer}s.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/5025")
public final class HealthCheckingLoadBalancerUtil {
private HealthCheckingLoadBalancerUtil() {
}
/**
* Creates a health-checking-capable LoadBalancer. This method is used to implement
* health-checking-capable {@link io.grpc.LoadBalancer.Factory}s, which will typically written
* this way:
*
*
* public class HealthCheckingFooLbFactory extends LoadBalancer.Factory {
* // This is the original balancer implementation that doesn't have health checking
* private final LoadBalancer.Factory fooLbFactory;
*
* ...
*
* // Returns the health-checking-capable version of FooLb
* public LoadBalancer newLoadBalancer(Helper helper) {
* return HealthCheckingLoadBalancerUtil.newHealthCheckingLoadBalancer(fooLbFactory, helper);
* }
* }
*
*
* As a requirement for the original LoadBalancer, it must call
* {@code Helper.createSubchannel()} from the {@link Helper#getSynchronizationContext()
* Synchronization Context}, or {@code createSubchannel()} will throw.
*
* @param factory the original factory that implements load-balancing logic without health
* checking
* @param helper the helper passed to the resulting health-checking LoadBalancer.
*/
public static LoadBalancer newHealthCheckingLoadBalancer(
LoadBalancer.Factory factory, Helper helper) {
HealthCheckingLoadBalancerFactory hcFactory =
new HealthCheckingLoadBalancerFactory(
factory, new ExponentialBackoffPolicy.Provider(),
GrpcUtil.STOPWATCH_SUPPLIER);
return hcFactory.newLoadBalancer(helper);
}
}