Go语言中并发访问Map的安全策略

package main

import (
    "fmt"
    "sync"
    "time"
)

// SafeMap 是一个并发安全的map封装
type SafeMap struct {
    mu    sync.RWMutex
    data  map[string]interface{}
}

// NewSafeMap 创建并返回一个新的SafeMap实例
func NewSafeMap() *SafeMap {
    return &SafeMap{
        data: make(map[string]interface{}),
    }
}

// Load 从SafeMap中读取一个值
func (sm *SafeMap) Load(key string) (interface{}, bool) {
    sm.mu.RLock() // 获取读锁
    defer sm.mu.RUnlock() // 确保读锁被释放
    val, ok := sm.data[key]
    return val, ok
}

// Store 向SafeMap中写入一个值
func (sm *SafeMap) Store(key string, value interface{}) {
    sm.mu.Lock() // 获取写锁
    defer sm.mu.Unlock() // 确保写锁被释放
    sm.data[key] = value
}

// Delete 从SafeMap中删除一个键值对
func (sm *SafeMap) Delete(key string) {
    sm.mu.Lock() // 获取写锁
    defer sm.mu.Unlock() // 确保写锁被释放
    delete(sm.data, key)
}

// Len 返回SafeMap中元素的数量
func (sm *SafeMap) Len() int {
    sm.mu.RLock() // 获取读锁
    defer sm.mu.RUnlock() // 确保读锁被释放
    return len(sm.data)
}

func main() {
    safeMap := NewSafeMap()
    var wg sync.WaitGroup

    // 启动多个goroutine进行写入操作
    for i := 0; i < 5; i++ {
        wg.Add(1)
        go func(id int) {
            defer wg.Done()
            key := fmt.Sprintf("key%d", id)
            value := fmt.Sprintf("value%d", id*100)
            safeMap.Store(key, value)
            fmt.Printf("Writer %d: Stored %s: %s\n", id, key, value)
        }(i)
    }

    // 启动多个goroutine进行读取操作
    for i := 0; i < 10; i++ {
        wg.Add(1)
        go func(id int) {
            defer wg.Done()
            // 尝试读取可能还未写入的键
            time.Sleep(time.Millisecond * time.Duration(id*10)) // 错开读取时间
            key := fmt.Sprintf("key%d", id%5) // 读取之前写入的键
            val, ok := safeMap.Load(key)
            if ok {
                fmt.Printf("Reader %d: Loaded %s: %v\n", id, key, val)
            } else {
                fmt.Printf("Reader %d: Key %s not found\n", id, key)
            }
        }(i)
    }

    wg.Wait() // 等待所有goroutine完成
    fmt.Printf("Final map length: %d\n", safeMap.Len())

    // 验证最终数据
    for i := 0; i < 5; i++ {
        key := fmt.Sprintf("key%d", i)
        val, ok := safeMap.Load(key)
        if ok {
            fmt.Printf("Final check: %s = %v\n", key, val)
        }
    }
}