Golang 関数のキャッシュ障害のシナリオと処理戦略

import "sync"

var m sync.Map

func Fibonacci(n int) int {
    if n < 2 {
        return n
    }

    var result int
    val, exists := m.Load(n)
    if exists {
        result = val.(int)
    } else {
        result = Fibonacci(n-1) + Fibonacci(n-2)
        m.Store(n, result)
    }

    return result
}

import (
    "sync"
    "time"
)

type entry struct {
    value interface{}
    expiry time.Time
}

var cache = sync.Map{}

func SetWithExpiry(key, value interface{}, expiry time.Duration) {
    cache.Store(key, &entry{value: value, expiry: time.Now().Add(expiry)})
}

func Get(key interface{}) (interface{}, bool) {
    val, exists := cache.Load(key)
    if !exists {
        return nil, false
    }
    entry := val.(*entry)
    if entry.expiry.Before(time.Now()) {
        cache.Delete(key)
        return nil, false
    }
    return entry.value, true
}

import (
    "context"
    "sync"
)

var results = sync.Map{}
var invalidations = make(chan struct{})

func Memoize(ctx context.Context, f func() (interface{}, error)) (interface{}, error) {
    key := f
    val, ok := results.Load(key)
    if ok {
        return val.(interface{}), nil
    }

    result, err := f()
    if err != nil {
        return nil, err
    }

    invalidations <- struct{}{} // 触发缓存失效
    results.Store(key, result)
    return result, nil
}

import (
    "sync"
    "time"
)

type product struct {
    ID    int
    Price float64
}

var cache = sync.Map{}

// GetProductPrice 从缓存获取产品价格，如果缓存中没有，则从数据库中获取并缓存
func GetProductPrice(id int) (float64, error) {
    val, exists := cache.Load(id)
    if exists {
        return val.(float64), nil
    }

    product, err := getProductFromDatabase(id)
    if err != nil {
        return 0, err
    }

    cache.Store(id, product.Price)
    return product.Price, nil
}