A caching mechanism to implement efficient industrial automation algorithms in Golang.

With the continuous development of industrial automation technology, more and more companies are adopting efficient automation algorithms to improve production efficiency and quality. Among these algorithms, the caching mechanism is a very important link, which can significantly reduce the computational complexity and response time of the system. This article will introduce how to implement a caching mechanism for efficient industrial automation algorithms in Golang.

1. What is the caching mechanism?

The caching mechanism refers to storing frequently accessed data in the cache in a computer system to quickly respond to data access requests, reduce the number of CPU accesses to main memory, and thus improve the system response speed. Caching mechanisms are often used to reduce the response time of particularly computationally intensive computing tasks, such as control tasks in industrial automation algorithms.

2. Implementation methods of caching mechanism

In Golang, there are many ways to implement caching mechanism, among which the following are the more commonly used ones.

1. Using Golang's Cache library

Golang's Cache library is a lightweight library for caching data. It provides a variety of caching methods, such as Least Recently Used (LRU), Frequently Used (FU), Random Replacement (RR), etc. The caching mechanism can be easily implemented using the Cache library. The code example is as follows:

import (
    "fmt"
    "time"
    "github.com/patrickmn/go-cache"
)

func main() {
    c := cache.New(1*time.Minute, 5*time.Minute) //创建缓存，缓存有效期为1分钟，清理时间为5分钟
    c.Set("key", "value", cache.DefaultExpiration) //向缓存中添加数据
    value, found := c.Get("key") //从缓存中获取数据
    if found {
        fmt.Println(value)
    }
}

2. Using Golang’s Map data structure

Golang’s Map data structure can be easily used for implementation Caching mechanism, the code example is as follows:

import (
    "sync"
    "time"
)

type Cache struct {
    data map[string]interface{} //缓存数据
    mutex sync.Mutex //互斥锁
}

func (c *Cache) Get(key string) (interface{}, bool) {
    c.mutex.Lock()
    defer c.mutex.Unlock()
    value, found := c.data[key]
    if found {
        return value, true
    } else {
        return nil, false
    }
}

func (c *Cache) Set(key string, value interface{}, lifetime time.Duration) {
    c.mutex.Lock()
    defer c.mutex.Unlock()
    c.data[key] = value
    time.AfterFunc(lifetime, func() { //设置缓存过期时间
        delete(c.data, key)
    })
}

func main() {
    c := &Cache{data: make(map[string]interface{})} //创建缓存
    c.Set("key", "value", 1*time.Minute) //向缓存中添加数据
    value, found := c.Get("key") //从缓存中获取数据
    if found {
        fmt.Println(value)
    }
}

3. Using Golang’s Sync.Pool

Golang’s Sync.Pool is a pool for caching temporary objects, which can be used in Improve system performance in high concurrency environments. The caching mechanism can be easily implemented using Sync.Pool. The code example is as follows:

import (
    "sync"
)

var pool = sync.Pool{
    New: func() interface{} { return make([]byte, 1024) }, //创建缓存对象
}

func main() {
    obj := pool.Get().([]byte) //从缓存中获取数据
    defer pool.Put(obj) //将数据放回缓存
}

3. Application of caching mechanism

The caching mechanism in Golang is widely used in control tasks in industrial automation algorithms. Such as PID control, fuzzy control, etc. In these algorithms, the caching mechanism can significantly reduce the computational complexity and response time of the system and improve control accuracy and stability.

The following takes PID control as an example to introduce how to use the caching mechanism to optimize the control effect.

The PID controller is a classic controller that adds the three parts of the control variable error, change rate and integral error to obtain the controller output. In practical applications, PID controllers usually need to cache data such as errors, change rates, and integral errors in order to quickly respond to control signal updates. The code example is as follows:

type PIDController struct {
    kp float64 //比例系数
    ki float64 //积分系数
    kd float64 //微分系数
    dt float64 //采样时间
    err float64 //误差
    lastErr float64 //上一次误差
    integral float64 //积分累计
    cache *Cache //缓存
}

func (c *PIDController) Update(setPoint, processValue float64) float64 {
    c.err = setPoint - processValue //计算误差
    dc := (c.err - c.lastErr) / c.dt //计算变化率
    c.integral += c.err * c.dt //积分累计
    output := c.kp*c.err + c.ki*c.integral + c.kd*dc //计算控制器输出
    c.cache.Set("err", c.err, time.Second) //缓存误差
    c.cache.Set("dc", dc, time.Second) //缓存变化率
    c.cache.Set("integral", c.integral, time.Second) //缓存积分累计
    c.cache.Set("output", output, time.Second) //缓存控制器输出
    c.lastErr = c.err
    return output
}

func main() {
    c := &PIDController{
        kp: 1,
        ki: 0.1,
        kd: 0.01,
        dt: 0.01,
        cache: NewCache(),
    }
    for i := 0; i < 1000; i++ {
        output := c.Update(10, float64(i)) //更新控制器
        fmt.Println(output)
        time.Sleep(time.Millisecond * 10)
    }
}

In the above example code, we implement the caching mechanism in the PID controller by using the Cache library. Specifically, we cache four data of error, change rate, integral accumulation and controller output in the Update function to quickly respond to requests to update control signals. This can significantly reduce the computational complexity and response time of the system and improve control accuracy and stability.

4. Summary

Golang is an efficient programming language that supports a variety of caching mechanism implementation methods. In industrial automation algorithms, the caching mechanism is a very important link. It can significantly reduce the computational complexity and response time of the system and improve the accuracy and stability of the algorithm. This article introduces the method and sample code for implementing the caching mechanism of efficient industrial automation algorithms in Golang. I hope it will be helpful to readers.

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