Golang implements memory cache

As Internet technology continues to develop, demand and data volume are also increasing. For some applications with large amounts of data, how to read and write data efficiently has become an important issue. Memory caching technology emerged as the times require and has become a key technology to improve data reading and writing efficiency and application performance. This article will discuss how to implement memory caching using golang.

What is memory cache?

Memory caching is a technology that caches data in memory to improve data reading and writing efficiency. Compared with obtaining data from disk or database for each read and write, in-memory cache can improve application performance by quickly reading and writing data in memory. Memory caching can be applied to various types of applications, such as web applications, games, databases, etc.

How does golang implement memory cache?

To implement memory caching in golang, you can use the map data structure. Map supports efficient read and write operations and can quickly store and query data. By saving data in a map, you can avoid frequent disk or database accesses, thereby improving application performance.

The following is a simple memory cache implemented using map:

package main

import (
    "fmt"
    "time"
)

type Cache struct {
    data     map[string]interface{}
    ttl      int64 //过期时间
    interval int64 //清理间隔
}

func NewCache(ttl int64, interval int64) *Cache {
    c := &Cache{
        data:     make(map[string]interface{}),
        ttl:      ttl,
        interval: interval,
    }

    go c.clean()
    return c
}

// 设置数据
func (c *Cache) Set(key string, val interface{}) {
    c.data[key] = val
}

// 获取数据
func (c *Cache) Get(key string) (interface{}, bool) {
    val, ok := c.data[key]
    if !ok {
        return nil, false
    }

    // 判断数据是否过期
    if time.Now().UnixNano() > val.(int64) {
        delete(c.data, key)
        return nil, false
    }

    return val, true
}

// 清理过期数据
func (c *Cache) clean() {
    for range time.Tick(time.Duration(c.interval) * time.Second) {
        for k, v := range c.data {
            if time.Now().UnixNano() > v.(int64) {
                delete(c.data, k)
            }
        }
    }
}

func main() {
    cache := NewCache(10, 5)

    cache.Set("foo", "bar")
    cache.Set("hello", "world")

    val, ok := cache.Get("foo")
    if ok {
        fmt.Println(val) // 输出 bar
    }

    time.Sleep(11 * time.Second)

    _, ok = cache.Get("foo")
    if !ok {
        fmt.Println("key has deleted") // 输出 key has deleted
    }
}

In the above code, the data field in the Cache structure is the map used to save data, and the ttl field is the expiration time , the interval field is the cleaning interval, and the go c.clean() statement in the NewCache function is used to start the coroutine for cleaning expired data. The Set and Get methods are used to set and obtain data respectively, and the clean method is used to clean expired data regularly.

What needs to be noted here is that during the get operation, it is necessary to determine whether the data has expired and delete it in time. In order to prevent data from occupying too much memory, we need to regularly clean up expired data to avoid memory leaks.

It should be noted that this implementation is just a simple example and cannot meet all needs. In actual applications, we need to improve it according to specific situations, such as concurrency control, memory limits, etc.

Summary

Using memory cache is a simple and effective way to improve application performance, and it is also very convenient to use map data structure to implement memory cache in golang. In actual development, we need to further optimize and expand it to meet more complex needs.

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