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