github.com/cloudwego/hertz@v0.9.3/pkg/app/client/loadbalance/weight_random_test.go (about)

     1  /*
     2   * Copyright 2022 CloudWeGo Authors
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  package loadbalance
    18  
    19  import (
    20  	"math"
    21  	"testing"
    22  
    23  	"github.com/cloudwego/hertz/pkg/app/client/discovery"
    24  	"github.com/cloudwego/hertz/pkg/common/test/assert"
    25  )
    26  
    27  func TestWeightedBalancer(t *testing.T) {
    28  	balancer := NewWeightedBalancer()
    29  	// nil
    30  	ins := balancer.Pick(discovery.Result{})
    31  	assert.DeepEqual(t, ins, nil)
    32  
    33  	// empty instance
    34  	e := discovery.Result{
    35  		Instances: make([]discovery.Instance, 0),
    36  		CacheKey:  "a",
    37  	}
    38  	balancer.Rebalance(e)
    39  	ins = balancer.Pick(e)
    40  	assert.DeepEqual(t, ins, nil)
    41  
    42  	// one instance
    43  	insList := []discovery.Instance{
    44  		discovery.NewInstance("tcp", "127.0.0.1:8888", 20, nil),
    45  	}
    46  	e = discovery.Result{
    47  		Instances: insList,
    48  		CacheKey:  "b",
    49  	}
    50  	balancer.Rebalance(e)
    51  	for i := 0; i < 100; i++ {
    52  		ins = balancer.Pick(e)
    53  		assert.DeepEqual(t, ins.Weight(), 20)
    54  	}
    55  
    56  	// multi instances, weightSum > 0
    57  	insList = []discovery.Instance{
    58  		discovery.NewInstance("tcp", "127.0.0.1:8881", 10, nil),
    59  		discovery.NewInstance("tcp", "127.0.0.1:8882", 20, nil),
    60  		discovery.NewInstance("tcp", "127.0.0.1:8883", 50, nil),
    61  		discovery.NewInstance("tcp", "127.0.0.1:8884", 100, nil),
    62  		discovery.NewInstance("tcp", "127.0.0.1:8885", 200, nil),
    63  		discovery.NewInstance("tcp", "127.0.0.1:8886", 500, nil),
    64  	}
    65  
    66  	var weightSum int
    67  	for _, ins := range insList {
    68  		weight := ins.Weight()
    69  		weightSum += weight
    70  	}
    71  
    72  	n := 10000000
    73  	pickedStat := map[int]int{}
    74  	e = discovery.Result{
    75  		Instances: insList,
    76  		CacheKey:  "c",
    77  	}
    78  	balancer.Rebalance(e)
    79  	for i := 0; i < n; i++ {
    80  		ins = balancer.Pick(e)
    81  		weight := ins.Weight()
    82  		if pickedCnt, ok := pickedStat[weight]; ok {
    83  			pickedStat[weight] = pickedCnt + 1
    84  		} else {
    85  			pickedStat[weight] = 1
    86  		}
    87  	}
    88  
    89  	for _, ins := range insList {
    90  		weight := ins.Weight()
    91  		expect := float64(weight) / float64(weightSum) * float64(n)
    92  		actual := float64(pickedStat[weight])
    93  		delta := math.Abs(expect - actual)
    94  		assert.DeepEqual(t, true, delta/expect < 0.01)
    95  	}
    96  
    97  	// have instances that weight < 0
    98  	insList = []discovery.Instance{
    99  		discovery.NewInstance("tcp", "127.0.0.1:8881", 10, nil),
   100  		discovery.NewInstance("tcp", "127.0.0.1:8882", -10, nil),
   101  	}
   102  	e = discovery.Result{
   103  		Instances: insList,
   104  		CacheKey:  "d",
   105  	}
   106  	balancer.Rebalance(e)
   107  	for i := 0; i < 1000; i++ {
   108  		ins = balancer.Pick(e)
   109  		assert.DeepEqual(t, 10, ins.Weight())
   110  	}
   111  }