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// Copyright 2021 The etcd 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 resolver
import (
"go.etcd.io/etcd/client/v3/internal/endpoint"
"google.golang.org/grpc/resolver"
"google.golang.org/grpc/resolver/manual"
"google.golang.org/grpc/serviceconfig"
)
const (
Schema = "etcd-endpoints"
)
// EtcdManualResolver is a Resolver (and resolver.Builder) that can be updated
// using SetEndpoints.
type EtcdManualResolver struct {
*manual.Resolver
endpoints []string
serviceConfig *serviceconfig.ParseResult
}
func New(endpoints ...string) *EtcdManualResolver {
r := manual.NewBuilderWithScheme(Schema)
return &EtcdManualResolver{Resolver: r, endpoints: endpoints, serviceConfig: nil}
}
// Build returns itself for Resolver, because it's both a builder and a resolver.
func (r *EtcdManualResolver) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
r.serviceConfig = cc.ParseServiceConfig(`{"loadBalancingPolicy": "round_robin"}`)
if r.serviceConfig.Err != nil {
return nil, r.serviceConfig.Err
}
res, err := r.Resolver.Build(target, cc, opts)
if err != nil {
return nil, err
}
// Populates endpoints stored in r into ClientConn (cc).
r.updateState()
return res, nil
}
func (r *EtcdManualResolver) SetEndpoints(endpoints []string) {
r.endpoints = endpoints
r.updateState()
}
func (r EtcdManualResolver) updateState() {
if r.CC != nil {
addresses := make([]resolver.Address, len(r.endpoints))
for i, ep := range r.endpoints {
addr, serverName := endpoint.Interpret(ep)
addresses[i] = resolver.Address{Addr: addr, ServerName: serverName}
}
state := resolver.State{
Addresses: addresses,
ServiceConfig: r.serviceConfig,
}
r.UpdateState(state)
}
}
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