mirror of
https://github.com/kubernetes-sigs/prometheus-adapter.git
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a293b2bf94
Travis seems to be having issues pulling deps, so we'll have to check in the vendor directory and prevent the makefile from trying to regenerate it normally.
79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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// Package roundrobin defines a roundrobin balancer. Roundrobin balancer is
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// installed as one of the default balancers in gRPC, users don't need to
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// explicitly install this balancer.
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package roundrobin
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import (
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"sync"
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"golang.org/x/net/context"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/balancer/base"
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"google.golang.org/grpc/grpclog"
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"google.golang.org/grpc/resolver"
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)
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// Name is the name of round_robin balancer.
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const Name = "round_robin"
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// newBuilder creates a new roundrobin balancer builder.
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func newBuilder() balancer.Builder {
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return base.NewBalancerBuilder(Name, &rrPickerBuilder{})
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}
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func init() {
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balancer.Register(newBuilder())
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}
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type rrPickerBuilder struct{}
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func (*rrPickerBuilder) Build(readySCs map[resolver.Address]balancer.SubConn) balancer.Picker {
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grpclog.Infof("roundrobinPicker: newPicker called with readySCs: %v", readySCs)
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var scs []balancer.SubConn
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for _, sc := range readySCs {
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scs = append(scs, sc)
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}
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return &rrPicker{
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subConns: scs,
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}
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}
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type rrPicker struct {
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// subConns is the snapshot of the roundrobin balancer when this picker was
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// created. The slice is immutable. Each Get() will do a round robin
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// selection from it and return the selected SubConn.
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subConns []balancer.SubConn
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mu sync.Mutex
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next int
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}
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func (p *rrPicker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
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if len(p.subConns) <= 0 {
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return nil, nil, balancer.ErrNoSubConnAvailable
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}
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p.mu.Lock()
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sc := p.subConns[p.next]
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p.next = (p.next + 1) % len(p.subConns)
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p.mu.Unlock()
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return sc, nil, nil
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}
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