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/*
*
* Copyright 2017 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 grpc
import (
"errors"
"fmt"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/connectivity"
)
// PickFirstBalancerName is the name of the pick_first balancer.
const PickFirstBalancerName = "pick_first"
func newPickfirstBuilder() balancer.Builder {
return &pickfirstBuilder{}
}
type pickfirstBuilder struct{}
func (*pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
return &pickfirstBalancer{cc: cc}
}
func (*pickfirstBuilder) Name() string {
return PickFirstBalancerName
}
type pickfirstBalancer struct {
state connectivity.State
cc balancer.ClientConn
sc balancer.SubConn
}
func (b *pickfirstBalancer) ResolverError(err error) {
switch b.state {
case connectivity.TransientFailure, connectivity.Idle, connectivity.Connecting:
// Set a failing picker if we don't have a good picker.
b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.TransientFailure,
Picker: &picker{err: fmt.Errorf("name resolver error: %v", err)},
})
}
if logger.V(2) {
logger.Infof("pickfirstBalancer: ResolverError called with error %v", err)
}
}
func (b *pickfirstBalancer) UpdateClientConnState(cs balancer.ClientConnState) error {
if len(cs.ResolverState.Addresses) == 0 {
b.ResolverError(errors.New("produced zero addresses"))
return balancer.ErrBadResolverState
}
if b.sc == nil {
var err error
b.sc, err = b.cc.NewSubConn(cs.ResolverState.Addresses, balancer.NewSubConnOptions{})
if err != nil {
if logger.V(2) {
logger.Errorf("pickfirstBalancer: failed to NewSubConn: %v", err)
}
b.state = connectivity.TransientFailure
b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.TransientFailure,
Picker: &picker{err: fmt.Errorf("error creating connection: %v", err)},
})
return balancer.ErrBadResolverState
}
b.state = connectivity.Idle
b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.Idle, Picker: &picker{result: balancer.PickResult{SubConn: b.sc}}})
b.sc.Connect()
} else {
b.cc.UpdateAddresses(b.sc, cs.ResolverState.Addresses)
b.sc.Connect()
}
return nil
}
func (b *pickfirstBalancer) UpdateSubConnState(sc balancer.SubConn, s balancer.SubConnState) {
if logger.V(2) {
logger.Infof("pickfirstBalancer: UpdateSubConnState: %p, %v", sc, s)
}
if b.sc != sc {
if logger.V(2) {
logger.Infof("pickfirstBalancer: ignored state change because sc is not recognized")
}
return
}
b.state = s.ConnectivityState
if s.ConnectivityState == connectivity.Shutdown {
b.sc = nil
return
}
switch s.ConnectivityState {
case connectivity.Ready:
b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &picker{result: balancer.PickResult{SubConn: sc}}})
case connectivity.Connecting:
b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &picker{err: balancer.ErrNoSubConnAvailable}})
case connectivity.Idle:
b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &idlePicker{sc: sc}})
case connectivity.TransientFailure:
b.cc.UpdateState(balancer.State{
ConnectivityState: s.ConnectivityState,
Picker: &picker{err: s.ConnectionError},
})
}
}
func (b *pickfirstBalancer) Close() {
}
func (b *pickfirstBalancer) ExitIdle() {
if b.sc != nil && b.state == connectivity.Idle {
b.sc.Connect()
}
}
type picker struct {
result balancer.PickResult
err error
}
func (p *picker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
return p.result, p.err
}
// idlePicker is used when the SubConn is IDLE and kicks the SubConn into
// CONNECTING when Pick is called.
type idlePicker struct {
sc balancer.SubConn
}
func (i *idlePicker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
i.sc.Connect()
return balancer.PickResult{}, balancer.ErrNoSubConnAvailable
}
func init() {
balancer.Register(newPickfirstBuilder())
}
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