mirror of https://github.com/grpc/grpc-go.git
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
/*
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*
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* Copyright 2020 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 testutils
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import (
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"fmt"
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"sync"
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"google.golang.org/grpc/internal/wrr"
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)
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// testWRR is a deterministic WRR implementation.
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//
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// The real implementation does random WRR. testWRR makes the balancer behavior
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// deterministic and easier to test.
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//
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// With {a: 2, b: 3}, the Next() results will be {a, a, b, b, b}.
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type testWRR struct {
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itemsWithWeight []struct {
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item any
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weight int64
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}
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length int
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mu sync.Mutex
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idx int // The index of the item that will be picked
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count int64 // The number of times the current item has been picked.
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}
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// NewTestWRR return a WRR for testing. It's deterministic instead of random.
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func NewTestWRR() wrr.WRR {
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return &testWRR{}
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}
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func (twrr *testWRR) Add(item any, weight int64) {
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twrr.itemsWithWeight = append(twrr.itemsWithWeight, struct {
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item any
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weight int64
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}{item: item, weight: weight})
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twrr.length++
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}
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func (twrr *testWRR) Next() any {
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twrr.mu.Lock()
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iww := twrr.itemsWithWeight[twrr.idx]
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twrr.count++
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if twrr.count >= iww.weight {
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twrr.idx = (twrr.idx + 1) % twrr.length
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twrr.count = 0
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}
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twrr.mu.Unlock()
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return iww.item
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}
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func (twrr *testWRR) String() string {
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return fmt.Sprint(twrr.itemsWithWeight)
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}
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