tile38/vendor/github.com/tidwall/resp

RESP

RESP is a Go library that provides a reader, writer, and server implementation for the Redis RESP Protocol.

RESP is short for REdis Serialization Protocol. While the protocol was designed specifically for Redis, it can be used for other client-server software projects.

The RESP protocol has the advantages of being human readable and with performance of a binary protocol.

Features

• Reader and Writer types for streaming RESP values from files, networks, or byte streams.
• Server Implementation for creating your own RESP server. Clients use the same tools and libraries as Redis.
• Append-only File type for persisting RESP values to disk.

Installation

Install resp using the "go get" command:

go get github.com/tidwall/resp

The Go distribution is Resp's only dependency.

Documentation

• API Reference

Server

A Redis clone that implements the SET and GET commands.

• You can interact using the Redis CLI (redis-cli). http://redis.io/download
• Or, use the telnet by typing in "telnet localhost 6380" and type in "set key value" and "get key".
• Or, use a client library such as http://github.com/garyburd/redigo
• The "QUIT" command will close the connection.

package main

import (
    "errors"
    "log"
    "sync"
    "github.com/tidwall/resp"
)

func main() {
    var mu sync.RWMutex
    kvs := make(map[string]string)
    s := resp.NewServer()
    s.HandleFunc("set", func(conn *resp.Conn, args []resp.Value) bool {
        if len(args) != 3 {
            conn.WriteError(errors.New("ERR wrong number of arguments for 'set' command"))
        } else {
            mu.Lock()
            kvs[args[1].String()] = args[2].String()
            mu.Unlock()
            conn.WriteSimpleString("OK")
        }
        return true
    })
    s.HandleFunc("get", func(conn *resp.Conn, args []resp.Value) bool {
        if len(args) != 2 {
            conn.WriteError(errors.New("ERR wrong number of arguments for 'get' command"))
        } else {
            mu.RLock()
            s, ok := kvs[args[1].String()]
            mu.RUnlock()
            if !ok {
                conn.WriteNull()
            } else {
                conn.WriteString(s)
            }
        }
        return true
    })
    if err := s.ListenAndServe(":6379"); err != nil {
        log.Fatal(err)
    }
}

Reader

The resp Reader type allows for an application to read raw RESP values from a file, network, or byte stream.

raw := "*3\r\n$3\r\nset\r\n$6\r\nleader\r\n$7\r\nCharlie\r\n"
raw += "*3\r\n$3\r\nset\r\n$8\r\nfollower\r\n$6\r\nSkyler\r\n"
rd := resp.NewReader(bytes.NewBufferString(raw))
for {
    v, _, err := rd.ReadValue()
    if err == io.EOF {
        break
    }
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("Read %s\n", v.Type())
    if v.Type() == Array {
        for i, v := range v.Array() {
            fmt.Printf("  #%d %s, value: '%s'\n", i, v.Type(), v)
        }
    }
}
// Output:
// Read Array
//   #0 BulkString, value: 'set'
//   #1 BulkString, value: 'leader'
//   #2 BulkString, value: 'Charlie'
// Read Array
//   #0 BulkString, value: 'set'
//   #1 BulkString, value: 'follower'
//   #2 BulkString, value: 'Skyler'

Writer

The resp Writer type allows for an application to write raw RESP values to a file, network, or byte stream.

var buf bytes.Buffer
wr := resp.NewWriter(&buf)
wr.WriteArray([]resp.Value{resp.StringValue("set"), resp.StringValue("leader"), resp.StringValue("Charlie")})
wr.WriteArray([]resp.Value{resp.StringValue("set"), resp.StringValue("follower"), resp.StringValue("Skyler")})
fmt.Printf("%s", buf.String())
// Output:
// *3\r\n$3\r\nset\r\n$6\r\nleader\r\n$7\r\nCharlie\r\n
// *3\r\n$3\r\nset\r\n$8\r\nfollower\r\n$6\r\nSkyler\r\n

Append-Only File

An append only file (AOF) allows your application to persist values to disk. It's very easy to use, and includes the same level of durablilty and binary format as Redis AOF Persistence.

Check out the AOF documentation for more information

// create and fill an appendonly file
aof, err := resp.OpenAOF("appendonly.aof")
if err != nil {
    log.Fatal(err)
}
// append a couple values and close the file
aof.Append(resp.MultiBulkValue("set", "leader", "Charlie"))
aof.Append(resp.MultiBulkValue("set", "follower", "Skyler"))
aof.Close()

// reopen and scan all values
aof, err = resp.OpenAOF("appendonly.aof")
if err != nil {
    log.Fatal(err)
}
defer aof.Close()
aof.Scan(func(v Value) {
    fmt.Printf("%s\n", v.String())
})

// Output:
// [set leader Charlie]
// [set follower Skyler]
}

Clients

There are bunches of RESP Clients. Most any client that supports Redis will support this implementation.

Contact

Josh Baker @tidwall

License

Tile38 source code is available under the MIT License.