Persistence and recovery mechanism of golang function cache

GoLang function cache persistence and recovery mechanism can be implemented through the following steps: Use encoding to serialize the cache content into a file. Read and deserialize the cache contents from the file on program restart. Using a persistent cache avoids unnecessary duplication of calculations and ensures that calculation results are retained across application restarts.

Persistence and recovery mechanism of GoLang function cache

In GoLang, function cache is an optimization technology that stores calculation results in memory. Reduce the computational overhead of function calls. However, cached content may be lost when the application is restarted or a system failure occurs. This article will introduce how to implement the persistence and recovery mechanism of function cache to ensure that the cache content is still available after the application is restarted.

Persistence

To persist the function cache, you can use the following steps:

1. Use encoding/json to encode the cache content into characters section array.
2. Write a byte array to a file, such as cache.json.

// 将缓存对象序列化到文件中
func SaveCache(cache map[string]interface{}) error {
    data, err := json.Marshal(cache)
    if err != nil {
        return err
    }

    f, err := os.Create("cache.json")
    if err != nil {
        return err
    }
    defer f.Close()

    _, err = f.Write(data)
    if err != nil {
        return err
    }

    return nil
}

Restore

To restore the persistent function cache, you can use the following steps:

1. From a file (such as cache.json) to read the byte array.
2. Deserialize the byte array using encoding/json to recreate the cache object.

// 从文件中加载并反序列化缓存
func LoadCache() (map[string]interface{}, error) {
    data, err := ioutil.ReadFile("cache.json")
    if err != nil {
        return nil, err
    }

    cache := make(map[string]interface{})
    if err := json.Unmarshal(data, &cache); err != nil {
        return nil, err
    }

    return cache, nil
}

Practical case

Consider the following function Fib(n), used to calculate the nth Fibonacci number. We can use function cache to store already calculated Fibonacci numbers to avoid unnecessary repeated calculations.

// 计算第 n 个斐波那契数
func Fib(n int) int {
    if n < 2 {
        return n
    }

    cache := make(map[int]int)  // 作为函数缓存

    return fibHelper(n, cache)
}

// 使用函数缓存重复计算斐波那契数
func fibHelper(n int, cache map[int]int) int {
    if _, ok := cache[n]; !ok {
        cache[n] = fibHelper(n-1, cache) + fibHelper(n-2, cache)
    }

    return cache[n]
}

By wrapping the Fib function in a closure with the cache parameter, we can persist and restore the function cache.

// 重载后的 Fib 函数，接受一个作为参数的缓存
func FibWithCache(cache *map[int]int, n int) int {
    if *cache == nil {
        // 初始化缓存时从文件中加载
        cacheToLoad, err := LoadCache()
        if err != nil {
            *cache = make(map[int]int)
        } else {
            *cache = cacheToLoad
        }
    }

    return fibHelper(n, *cache)
}

Now, every time FibWithCache is called, it will use and modify the same function cache *cache. By reloading the cache from the file after a program restart, we ensure that the calculation results are preserved even if the application terminates.

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