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naming_instance_chooser.go
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/
naming_instance_chooser.go
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/*
* Copyright 1999-2020 Alibaba Group Holding Ltd.
*
* 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 naming_client
import (
"math/rand"
"sort"
"github.com/wubin1989/nacos-sdk-go/v2/model"
)
type Chooser struct {
data []model.Instance
totals []int
max int
}
type instance []model.Instance
func (a instance) Len() int {
return len(a)
}
func (a instance) Swap(i, j int) {
a[i], a[j] = a[j], a[i]
}
func (a instance) Less(i, j int) bool {
return a[i].Weight < a[j].Weight
}
// NewChooser initializes a new Chooser for picking from the provided Choices.
func newChooser(instances []model.Instance) Chooser {
sort.Sort(instance(instances))
totals := make([]int, len(instances))
runningTotal := 0
for i, c := range instances {
runningTotal += int(c.Weight)
totals[i] = runningTotal
}
return Chooser{data: instances, totals: totals, max: runningTotal}
}
func (chs Chooser) pick() model.Instance {
r := rand.Intn(chs.max) + 1
i := sort.SearchInts(chs.totals, r)
return chs.data[i]
}