Implementing redis with Golang

Redis is a popular NoSQL database. It is widely popular for its high-speed reading and writing capabilities and ultra-high data storage capabilities, and can be widely used in various fields.

Golang is a relatively new and fast programming language. It is also excellent in high-concurrency scenarios and is widely used in distributed systems. So how to use Golang to implement Redis?

First of all, we need to understand the underlying implementation principle of Redis. The core structure of Redis is the key-value pair, and all operations of Redis are based on this. When implementing Redis, we need to create a structure to represent key-value pairs. This structure can be stored in memory or serialized and stored on the hard disk.

The following is a simple sample code:

type Redis struct {
    data map[string]string
}

func New() *Redis {
    return &Redis{
        data: make(map[string]string),
    }
}

func (r *Redis) Get(key string) (string, error) {
    value, ok := r.data[key]
    if !ok {
        return "", errors.New("Key not found")
    }
    return value, nil
}

func (r *Redis) Set(key string, value string) error {
    r.data[key] = value
    return nil
}

func (r *Redis) Delete(key string) error {
    delete(r.data, key)
    return nil
}

In this sample code, we create a Redis structure, which contains a map type data member that can implement key Storage of value pairs. The Get, Set and Delete functions implement the get, set and delete operations of Redis respectively.

Next, we can implement the network part of Redis by combining Golang's built-in network library. We need to create a TCP server for Redis, parse the Redis protocol into operations, operate on the key values, and return the results to the client.

The following is a simple implementation code using the net, bufio and fmt modules:

func (r *Redis) ListenAndServe(addr string) error {
    ln, err := net.Listen("tcp", addr)
    if err != nil {
        return err
    }
    defer ln.Close()

    for {
        conn, err := ln.Accept()
        if err != nil {
            log.Println("Failed to accept connection:", err)
            continue
        }
        go r.serveConn(conn)
    }

    return nil
}

func (r *Redis) serveConn(conn net.Conn) {
    defer conn.Close()

    reader := bufio.NewReader(conn)
    writer := bufio.NewWriter(conn)

    for {
        // Read command
        cmdLine, _, err := reader.ReadLine()
        if err != nil {
            log.Println("Failed to read from connection:", err)
            break
        }

        // Parse command
        parts := strings.Split(string(cmdLine), " ")
        if len(parts) < 1 {
            err := fmt.Errorf("Invalid command")
            log.Println(err.Error())
            fmt.Fprintln(writer, fmt.Sprintf("%s
", err.Error()))
            writer.Flush()
            continue
        }

        var result string
        switch strings.ToLower(parts[0]) {
        case "get":
            if len(parts) != 2 {
                err := fmt.Errorf("Invalid command")
                log.Println(err.Error())
                fmt.Fprintln(writer, fmt.Sprintf("%s
", err.Error()))
                writer.Flush()
                continue
            }
            value, err := r.Get(parts[1])
            if err != nil {
                log.Println("Failed to get value for key:", parts[1], err)
                result = "$-1
"
            } else {
                result = fmt.Sprintf("$%d
%s
", len(value), value)
            }
        case "set":
            if len(parts) != 3 {
                err := fmt.Errorf("Invalid command")
                log.Println(err.Error())
                fmt.Fprintln(writer, fmt.Sprintf("%s
", err.Error()))
                writer.Flush()
                continue
            }
            err := r.Set(parts[1], parts[2])
            if err != nil {
                log.Println("Failed to set value:", err)
                result = "-ERR
"
            } else {
                result = "+OK
"
            }
        case "delete":
            if len(parts) != 2 {
                err := fmt.Errorf("Invalid command")
                log.Println(err.Error())
                fmt.Fprintln(writer, fmt.Sprintf("%s
", err.Error()))
                writer.Flush()
                continue
            }
            err := r.Delete(parts[1])
            if err != nil {
                log.Println("Failed to delete value for key:", parts[1], err)
                result = "-ERR
"
            } else {
                result = "+OK
"
            }
        default:
            err := fmt.Errorf("Invalid command")
            log.Println(err.Error())
            fmt.Fprintln(writer, fmt.Sprintf("%s
", err.Error()))
            writer.Flush()
            continue
        }

        // Write response
        fmt.Fprint(writer, result)
        writer.Flush()
    }
}

In this implementation code, we use the ListenAndServe function to create a TCP server to listen to messages sent from the client The incoming connection is then used to process the connection request using the serveConn function, which involves Redis protocol parsing and key-value pair operations, and finally returns a response to the client.

To summarize, using Golang to implement Redis can allow us to better understand the implementation principle of Redis. At the same time, due to the characteristics of Golang, an efficient and high-concurrency Redis server can be realized.

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