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dex/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker.go
2020-01-31 10:32:00 +01:00

92 lines
2.2 KiB
Go

// Copyright 2018 The etcd 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 picker
import (
"fmt"
"go.uber.org/zap"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/resolver"
)
// Picker defines balancer Picker methods.
type Picker interface {
balancer.Picker
String() string
}
// Config defines picker configuration.
type Config struct {
// Policy specifies etcd clientv3's built in balancer policy.
Policy Policy
// Logger defines picker logging object.
Logger *zap.Logger
// SubConnToResolverAddress maps each gRPC sub-connection to an address.
// Basically, it is a list of addresses that the Picker can pick from.
SubConnToResolverAddress map[balancer.SubConn]resolver.Address
}
// Policy defines balancer picker policy.
type Policy uint8
const (
// Error is error picker policy.
Error Policy = iota
// RoundrobinBalanced balances loads over multiple endpoints
// and implements failover in roundrobin fashion.
RoundrobinBalanced
// Custom defines custom balancer picker.
// TODO: custom picker is not supported yet.
Custom
)
func (p Policy) String() string {
switch p {
case Error:
return "picker-error"
case RoundrobinBalanced:
return "picker-roundrobin-balanced"
case Custom:
panic("'custom' picker policy is not supported yet")
default:
panic(fmt.Errorf("invalid balancer picker policy (%d)", p))
}
}
// New creates a new Picker.
func New(cfg Config) Picker {
switch cfg.Policy {
case Error:
panic("'error' picker policy is not supported here; use 'picker.NewErr'")
case RoundrobinBalanced:
return newRoundrobinBalanced(cfg)
case Custom:
panic("'custom' picker policy is not supported yet")
default:
panic(fmt.Errorf("invalid balancer picker policy (%d)", cfg.Policy))
}
}