mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-15 16:30:55 +01:00
82 lines
2.5 KiB
Go
82 lines
2.5 KiB
Go
/*
|
|
*
|
|
* 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 roundrobin defines a roundrobin balancer. Roundrobin balancer is
|
|
// installed as one of the default balancers in gRPC, users don't need to
|
|
// explicitly install this balancer.
|
|
package roundrobin
|
|
|
|
import (
|
|
"sync/atomic"
|
|
|
|
"google.golang.org/grpc/balancer"
|
|
"google.golang.org/grpc/balancer/base"
|
|
"google.golang.org/grpc/grpclog"
|
|
"google.golang.org/grpc/internal/grpcrand"
|
|
)
|
|
|
|
// Name is the name of round_robin balancer.
|
|
const Name = "round_robin"
|
|
|
|
var logger = grpclog.Component("roundrobin")
|
|
|
|
// newBuilder creates a new roundrobin balancer builder.
|
|
func newBuilder() balancer.Builder {
|
|
return base.NewBalancerBuilder(Name, &rrPickerBuilder{}, base.Config{HealthCheck: true})
|
|
}
|
|
|
|
func init() {
|
|
balancer.Register(newBuilder())
|
|
}
|
|
|
|
type rrPickerBuilder struct{}
|
|
|
|
func (*rrPickerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {
|
|
logger.Infof("roundrobinPicker: Build called with info: %v", info)
|
|
if len(info.ReadySCs) == 0 {
|
|
return base.NewErrPicker(balancer.ErrNoSubConnAvailable)
|
|
}
|
|
scs := make([]balancer.SubConn, 0, len(info.ReadySCs))
|
|
for sc := range info.ReadySCs {
|
|
scs = append(scs, sc)
|
|
}
|
|
return &rrPicker{
|
|
subConns: scs,
|
|
// Start at a random index, as the same RR balancer rebuilds a new
|
|
// picker when SubConn states change, and we don't want to apply excess
|
|
// load to the first server in the list.
|
|
next: uint32(grpcrand.Intn(len(scs))),
|
|
}
|
|
}
|
|
|
|
type rrPicker struct {
|
|
// subConns is the snapshot of the roundrobin balancer when this picker was
|
|
// created. The slice is immutable. Each Get() will do a round robin
|
|
// selection from it and return the selected SubConn.
|
|
subConns []balancer.SubConn
|
|
next uint32
|
|
}
|
|
|
|
func (p *rrPicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
|
|
subConnsLen := uint32(len(p.subConns))
|
|
nextIndex := atomic.AddUint32(&p.next, 1)
|
|
|
|
sc := p.subConns[nextIndex%subConnsLen]
|
|
return balancer.PickResult{SubConn: sc}, nil
|
|
}
|