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- package roundrobin
- import (
- "sync"
- "golang.org/x/net/context"
- "google.golang.org/grpc/balancer"
- "google.golang.org/grpc/balancer/base"
- "google.golang.org/grpc/grpclog"
- "google.golang.org/grpc/resolver"
- )
- const Name = "round_robin"
- func newBuilder() balancer.Builder {
- return base.NewBalancerBuilder(Name, &rrPickerBuilder{})
- }
- func init() {
- balancer.Register(newBuilder())
- }
- type rrPickerBuilder struct{}
- func (*rrPickerBuilder) Build(readySCs map[resolver.Address]balancer.SubConn) balancer.Picker {
- grpclog.Infof("roundrobinPicker: newPicker called with readySCs: %v", readySCs)
- var scs []balancer.SubConn
- for _, sc := range readySCs {
- scs = append(scs, sc)
- }
- return &rrPicker{
- subConns: scs,
- }
- }
- type rrPicker struct {
-
-
-
- subConns []balancer.SubConn
- mu sync.Mutex
- next int
- }
- func (p *rrPicker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
- if len(p.subConns) <= 0 {
- return nil, nil, balancer.ErrNoSubConnAvailable
- }
- p.mu.Lock()
- sc := p.subConns[p.next]
- p.next = (p.next + 1) % len(p.subConns)
- p.mu.Unlock()
- return sc, nil, nil
- }
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