微服务中的事务：SAGA 模式概述部分

<code class="go">package main

import (
    "fmt"
    "log"
)

// 定义步骤和补偿类型
type Step func() error
type Compensation func()

// SAGA结构体
type Saga struct {
    steps        []Step
    compensations []Compensation
}

func (s *Saga) AddStep(step Step, compensation Compensation) {
    s.steps = append(s.steps, step)
    s.compensations = append([]Compensation{compensation}, s.compensations...)
}

func (s *Saga) Execute() {
    for i, step := range s.steps {
        if err := step(); err != nil {
            log.Printf("Step %d failed: %v. Rolling back...\n", i+1, err)
            for _, compensation := range s.compensations {
                compensation()
            }
            return
        }
    }
    fmt.Println("Transaction completed successfully!")
}

func main() {
    saga := &Saga{}

    // 步骤1：验证患者和保险信息
    saga.AddStep(
        func() error {
            fmt.Println("Step 1: Verifying patient and insurance details...")
            // 模拟成功
            return nil
        },
        func() { fmt.Println("Compensation 1: Notify patient of verification failure.") },
    )

    // 步骤2：安排手术
    saga.AddStep(
        func() error {
            fmt.Println("Step 2: Scheduling procedure...")
            // 模拟成功
            return nil
        },
        func() { fmt.Println("Compensation 2: Cancel procedure schedule.") },
    )

    // 步骤3：预留医疗用品
    saga.AddStep(
        func() error {
            fmt.Println("Step 3: Reserving medical supplies...")
            // 模拟成功
            return nil
        },
        func() { fmt.Println("Compensation 3: Release reserved supplies.") },
    )

    // 步骤4：处理账单
    saga.AddStep(
        func() error {
            fmt.Println("Step 4: Processing billing...")
            // 模拟失败
            return fmt.Errorf("billing service unavailable")
        },
        func() { fmt.Println("Compensation 4: Reverse any pending charges.") },
    )

    // 执行SAGA
    saga.Execute()
}</code>