Remote dictionary service (redis) is an in-memory key-value data structure store used as a cache/database. Generally, it used as a cache in front of another persistent database to speed up application performance.
Redis provides in-built support for various data structures such as
- strings
- hashes
- lists
- sets
- sorted sets with range queries
- bitmaps
- hyperloglogs
- geospatial indexes
- streams
Architecture
An overview of redis architecture is available at architecturenotes
Install on Ubuntu
Refer to official redis docs
Golang Client
Redis office site list various redis clients here. I decided to try out Redigo
Create a RedisPool
Create a redispool object using following code
package redispool
import (
"fmt"
"os"
"time"
"github.com/gomodule/redigo/redis"
)
// default redis TCP port
const defaultRedisPort = 6379
// RedisServer ... redis server to connect to
var RedisServer = func() string {
// $REDIS_SERVER takes precedence
server := os.Getenv("REDIS_SERVER")
if server == "" {
// otherwise use the localhost:6379
server = fmt.Sprintf("localhost:%d", defaultRedisPort)
}
return server
}()
// RedisPool ... redis connection pool
var RedisPool = redis.Pool{
// check the health of an idle connection before the connection is used again
TestOnBorrow: testIdleConn,
MaxIdle: 2, // Maximum number of idle connections in the pool
IdleTimeout: 2 * time.Minute, // Close connections after remaining idle for this duration.
Dial: dialRedis,
}
func testIdleConn(c redis.Conn, _ time.Time) error {
fmt.Println("Ping connection")
reply, err := c.Do("Ping")
fmt.Printf("TestOnBorrow :: Redis reply %v\n", reply)
return err
}
func dialRedis() (redis.Conn, error) {
c, err := redis.Dial("tcp", RedisServer)
if err != nil {
fmt.Printf("Dial (%s) failed: %v\n", RedisServer, err)
return nil, err
}
fmt.Printf("opened redis connection to %s\n", RedisServer)
return c, nil
}
Check Connection to redis server
Use the following code to check connection
package main
import (
"fmt"
"github.com/manoj-gupta/cloud/redispool"
)
func main() {
conn := redispool.RedisPool.Get()
defer func() {
fmt.Printf("closing redis connection to %s\n", redispool.RedisServer)
conn.Close()
}()
}
Running the program should generate output
$ go run redispool/app/main.go
opened redis connection to localhost:6379
closing redis connection to localhost:6379
Test GET/SET
Add the following code in main.go to see how GET and SET works for basic data types
if _, err := conn.Do("SET", stringKey, "Hello Redis"); err != nil {
fmt.Printf("Can not update %s err:%v\n", stringKey, err)
os.Exit(1)
}
if val, err := redis.String(conn.Do("GET", stringKey)); err != nil {
fmt.Printf("Can not read %s err:%v\n", stringKey, err)
os.Exit(1)
} else {
fmt.Printf("READ Success --> key:%s val:%s\n", stringKey, val)
}
Running the program should generate the output
$ go run redispool/app/main.go
opened redis connection to localhost:6379
READ Success --> key:redis-string-key val:Hello Redis
closing redis connection to localhost:6379