/
balancer.go
91 lines (77 loc) · 2.04 KB
/
balancer.go
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package nacos
import (
"errors"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/balancer/base"
"google.golang.org/grpc/resolver"
"math/rand"
"sync"
"sync/atomic"
"time"
)
const (
Name = "tag_round_robin"
productionTag = "_production" // production tag
ctxValue = "tag"
)
var (
r = rand.New(rand.NewSource(time.Now().UnixNano()))
mu sync.Mutex
NoMatchConErr = errors.New("no match found conn")
)
// NewBuilder creates a new weight balancer builder.
func newVersionBuilder() {
// balancer.Builder
builder := base.NewBalancerBuilder(Name, &rrPickerBuilder{}, base.Config{HealthCheck: true})
balancer.Register(builder)
return
}
type rrPickerBuilder struct {
}
func (rp *rrPickerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {
if len(info.ReadySCs) == 0 {
return base.NewErrPicker(balancer.ErrNoSubConnAvailable)
}
var scs = make(map[string][]balancer.SubConn, len(info.ReadySCs))
for conn, addr := range info.ReadySCs {
tag := productionTag
if nodeTag := GetNodeTag(addr.Address); nodeTag != "" {
tag = nodeTag
}
scs[tag] = append(scs[tag], conn)
}
if len(scs) == 0 {
return base.NewErrPicker(balancer.ErrNoSubConnAvailable)
}
mu.Lock()
next := r.Intn(len(scs))
mu.Unlock()
return &rrPicker{
subConns: scs,
next: uint32(next),
}
}
type rrPicker struct {
subConns map[string][]balancer.SubConn
next uint32
}
// Pick 选择合适的子链接发送请求
func (p *rrPicker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
tag := info.Ctx.Value("tag").(string)
nodeTag := productionTag
if tag != "" && len(p.subConns[tag]) > 0 { // 有标签
nodeTag = tag
}
subConns := p.subConns[nodeTag]
if len(subConns) == 0 {
return balancer.PickResult{}, NoMatchConErr
}
subConnsLen := uint32(len(subConns))
nextIndex := atomic.AddUint32(&p.next, 1)
sc := subConns[nextIndex%subConnsLen]
return balancer.PickResult{SubConn: sc}, nil
}
func GetNodeTag(attr resolver.Address) string {
v := attr.Attributes.Value(ctxValue).(*map[string]string)
return (*v)[ctxValue]
}