Go运行Grule引擎实现计费规则管理

Go运行Grule引擎实现计费规则管理

• github位置: https://github.com/hyperjumptech/grule-rule-engine

# 安装grule模块
go get -u github.com/hyperjumptech/grule-rule-engine

Grule的示例代码

• 示例位置: https://github.com/hyperjumptech/grule-rule-engine/tree/master/examples
  • 使用 go test 运行

  cd examples
  $ go test NumberExponentExample_test.go 
  ok      command-line-arguments  0.011s
  

• Grule规则
  • rule {} 表示规则
  • salience 10 表示优先级为10
    • 优先级高的先执行

type ExponentData struct {
	Check float64
	Set   float64
}

/*
    条件部分 (when)：
    当ExponentData 结构体中的 Check 等于 6.67428e-11 时，规则会触发
    动作部分 (then)：
    当条件满足时，将 ExponentData 结构体中的 Set 设置为 .12345E+5
    然後，使用 Retract("ExponentCheck") 將這個规则從工作记忆中移除，
    以防止它再次被觸發。
*/

const ExponentRule = `
rule  ExponentCheck  "User Related Rule"  salience 10 {
	when 
		ExponentData.Check == 6.67428e-11
	Then
		ExponentData.Set = .12345E+5;
		Retract("ExponentCheck");
}
`
// 往下是 运行"github.com/stretchr/testify/assert"的测试代码, 忽略
func TestEvaluateAndAssignExponentNumber(t *testing.T) {
	exponent := &ExponentData{
		Check: 6.67428e-11,
		Set:   0,
	}
	...
}

• 总结：Grule规则使用 when 判断条件, 当条件满足时执行 then

编写计费规则代码

• 仿照示例代码，编写计费规则代码
  • 对云服务器 cpu 计费, 每小时 0.05元 * 核数
  • 对云服务器 内存 计费, 每小时 0.01元 * GB

  const (
    rule = `
    rule CalculateCost "Calculate the total cost based on CPU and Memory usage" {
      when 
          CloudResource.CPU > 0 &&
          CloudResource.Memory > 0
      then
          costPerCPUHour = 0.05;
          costPerGBMemoryHour = 0.01;
          cpuCost = CloudResource.CPU * costPerCPUHour;
          memoryCost = CloudResource.Memory * costPerGBMemoryHour;
          CloudResource.TotalCost = cpuCost + memoryCost;
          Retract("CalculateCost");
    }
    `
  )
  

  • 将 cpu 内存 总费用 封装为结构体

  type CloudResource struct {
      CPU       float64
      Memory    float64
      TotalCost float64
  }
  

• 使用 go test 执行完整代码

package example

import (
    "testing"

    "github.com/hyperjumptech/grule-rule-engine/ast"
    "github.com/hyperjumptech/grule-rule-engine/builder"
    "github.com/hyperjumptech/grule-rule-engine/engine"
    "github.com/hyperjumptech/grule-rule-engine/pkg"
    "github.com/stretchr/testify/assert"
)

const (
    rule = `
rule CalculateCost "Calculate the total cost based on CPU and Memory usage" {
    when 
        CloudResource.CPU > 0 &&
        CloudResource.Memory > 0
    then
        costPerCPUHour = 0.05;
        costPerGBMemoryHour = 0.01;
        cpuCost = CloudResource.CPU * costPerCPUHour;
        memoryCost = CloudResource.Memory * costPerGBMemoryHour;
        CloudResource.TotalCost = cpuCost + memoryCost;
        Retract("CalculateCost");
}
`
)

type CloudResource struct {
    CPU       float64
    Memory    float64
    TotalCost float64
}

func TestCloudResource(t *testing.T) {
    myResource := &CloudResource{
        CPU:    2,
        Memory: 4,
    }
    dataContext := ast.NewDataContext()
    err := dataContext.Add("CloudResource", myResource)
    if err != nil {
        t.Fatal(err)
    }
    lib := ast.NewKnowledgeLibrary()
    ruleBuilder := builder.NewRuleBuilder(lib)
    err = ruleBuilder.BuildRuleFromResource("Test", "0.1.1", pkg.NewBytesResource([]byte(rule)))
    assert.NoError(t, err)
    kb, err := lib.NewKnowledgeBaseInstance("Test", "0.1.1")
    assert.NoError(t, err)
    eng1 := &engine.GruleEngine{MaxCycle: 1}
    err = eng1.Execute(dataContext, kb)
    assert.NoError(t, err)

    // 檢查計算出的總成本
    expectedTotalCost := (2 * 0.05) + (4 * 0.01)
    assert.Equal(t, expectedTotalCost, myResource.TotalCost)
}

• 总结: 使用 assert.Equal 校验 expectedTotalCost ，最后得出结果

$ go test
PASS
ok      grule_study/example/test        0.007s