Memory cache usage

Memory cache usage

Overview

This section mainly describes the use of cache.

Preparing

Create

Function signature:
    NewCache func(expire time.Duration, opts ...CacheOption) (*Cache, error)
description:
    create cache objects.
Attention:
    1. expire: expiration time
    2. opts: Action option
    2.1 WithLimit: Set maximum cache data
    2.2 WithName: Setup cache name, output log printing
return value:
    1. *Cache: cache object
    2. error: create result

Methodological description

1 Set

Function signature:
    Set func(key string, value interface{})
description:
    add value to cache.
Attention:
    1. key: key
    2. value: value

Example:
    cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }
    cache.Set("first", "first element")

2 SetWithExpire

Function signature:
    SetWithExpire func(key string, value interface{}, expire time.Duration)cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }
    cache.SetWithExpire("first", "first element", time.Second)
description:
    add value to cache and specify expiration time
to participate:
    1. key: key
    2. value: value
    3. expire: Expiration Time

Example:
    cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }
    cache.SetWithExpire("first", "first element", time.Second)

3 Get

Function signature:
    Get func(key string) (interface{}, bool)
description:
    query cache
join:
    key: key

returned value:
    1. interface{}: value
    2. bool: exists

Example:
    cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }
    cache.Set("first", "first element")

    v, exist := cache.Get("first")
    if !exist {
        // deal with not exist
    }
    value, ok := v.(string)
    if !ok {
        // deal with type error
    }
    // use value

4 Del

Function signature:
    Del func(key string)
description:
    Delete cache.
Attention:
    1. key: key
    2. value: value

Example:
    cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }
    cache.Del("first")

4 Take

Function signature:
    Take funcTake(key string, fetch func() (interface{}, error)) (interface{}, error)
description:
    Fetch function returns the result if cache exists and if cache does not exist.
Attention:
    1. key: key
    2. fetch: Custom return result

Example:
    cache, err := NewCache(time.Second*2, WithName("any"))
    if err != nil {
        log.Fatal(err)
    }

    v, err := cache.Take("first", func() (interface{}, error) {
        return "first element", nil
    })
    println(v) // output: first element

    cache.Set("first", "first element 2")

    v, err = cache.Take("first", func() (interface{}, error) {
        return "first element", nil
    })
    println(v) // // output: first element 2