viney-shih/go-cache

package cache

import (
    "context"
    "time"
)

// Adapter is the interface communicating with shared/local caches.
type Adapter interface {
    MGet(context context.Context, keys []string) ([]Value, error)
    MSet(context context.Context, keyVals map[string][]byte, ttl time.Duration, options ...MSetOptions) error
    Del(context context.Context, keys ...string) error
}

// MSetOptions is an alias for functional argument.
type MSetOptions func(opts *msetOptions)

type msetOptions struct {
    onCostAdd   func(key string, cost int)
    onCostEvict func(key string, cost int)
}

// WithOnCostAddFunc sets up the callback when adding the cache with key and cost.
func WithOnCostAddFunc(f func(key string, cost int)) MSetOptions {
    return func(opts *msetOptions) {
        opts.onCostAdd = f
    }
}

// WithOnCostEvictFunc sets up the callback when evicting the cache with key and cost.
func WithOnCostEvictFunc(f func(key string, cost int)) MSetOptions {
    return func(opts *msetOptions) {
        opts.onCostEvict = f
    }
}

func loadMSetOptions(options ...MSetOptions) *msetOptions {
    opts := &msetOptions{}
    for _, option := range options {
        option(opts)
    }

    return opts
}

// Value is returned by MGet()
type Value struct {
    // Valid stands for existing in cache or not.
    Valid bool
    // Bytes stands for the return value in byte format.
    Bytes []byte
}