/
stub.go
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/
stub.go
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/*
*
* Copyright 2020 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 stub implements a balancer for testing purposes.
package stub
import (
"encoding/json"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/serviceconfig"
)
// BalancerFuncs contains all balancer.Balancer functions with a preceding
// *BalancerData parameter for passing additional instance information. Any
// nil functions will never be called.
type BalancerFuncs struct {
// Init is called after ClientConn and BuildOptions are set in
// BalancerData. It may be used to initialize BalancerData.Data.
Init func(*BalancerData)
// ParseConfig is used for parsing LB configs, if specified.
ParseConfig func(json.RawMessage) (serviceconfig.LoadBalancingConfig, error)
UpdateClientConnState func(*BalancerData, balancer.ClientConnState) error
ResolverError func(*BalancerData, error)
UpdateSubConnState func(*BalancerData, balancer.SubConn, balancer.SubConnState)
Close func(*BalancerData)
ExitIdle func(*BalancerData)
}
// BalancerData contains data relevant to a stub balancer.
type BalancerData struct {
// ClientConn is set by the builder.
ClientConn balancer.ClientConn
// BuildOptions is set by the builder.
BuildOptions balancer.BuildOptions
// Data may be used to store arbitrary user data.
Data interface{}
}
type bal struct {
bf BalancerFuncs
bd *BalancerData
}
func (b *bal) UpdateClientConnState(c balancer.ClientConnState) error {
if b.bf.UpdateClientConnState != nil {
return b.bf.UpdateClientConnState(b.bd, c)
}
return nil
}
func (b *bal) ResolverError(e error) {
if b.bf.ResolverError != nil {
b.bf.ResolverError(b.bd, e)
}
}
func (b *bal) UpdateSubConnState(sc balancer.SubConn, scs balancer.SubConnState) {
if b.bf.UpdateSubConnState != nil {
b.bf.UpdateSubConnState(b.bd, sc, scs)
}
}
func (b *bal) Close() {
if b.bf.Close != nil {
b.bf.Close(b.bd)
}
}
func (b *bal) ExitIdle() {
if b.bf.ExitIdle != nil {
b.bf.ExitIdle(b.bd)
}
}
type bb struct {
name string
bf BalancerFuncs
}
func (bb bb) Build(cc balancer.ClientConn, opts balancer.BuildOptions) balancer.Balancer {
b := &bal{bf: bb.bf, bd: &BalancerData{ClientConn: cc, BuildOptions: opts}}
if b.bf.Init != nil {
b.bf.Init(b.bd)
}
return b
}
func (bb bb) Name() string { return bb.name }
func (bb bb) ParseConfig(lbCfg json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
if bb.bf.ParseConfig != nil {
return bb.bf.ParseConfig(lbCfg)
}
return nil, nil
}
// Register registers a stub balancer builder which will call the provided
// functions. The name used should be unique.
func Register(name string, bf BalancerFuncs) {
balancer.Register(bb{name: name, bf: bf})
}