summaryrefslogtreecommitdiff
path: root/vendor/google.golang.org/grpc/pickfirst.go
blob: f194d14a081673d079bd330547f8ee8d3de17cde (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
/*
 *
 * 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.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())
}