Singleton Pattern Connection Pool

connection_pool.go

package main

import (
	"fmt"
	"sync"
)

// DB type
type DB struct{}

func (s *DB) name() string {
	return "Joe Doe"
}

// ConnectionPool type
type ConnectionPool struct {
	sync.RWMutex

	items map[string]interface{}
}

// NewConnectionPool creates a new instance of ConnectionPool
func NewConnectionPool() ConnectionPool {
	return ConnectionPool{items: make(map[string]interface{})}
}

// Get a key from a concurrent map
func (c *ConnectionPool) Get(key string) (interface{}, bool) {
	c.Lock()
	defer c.Unlock()

	value, ok := c.items[key]

	return value, ok
}

// Set a key in a concurrent map
func (c *ConnectionPool) Set(key string, value interface{}) {
	c.Lock()
	defer c.Unlock()

	c.items[key] = value
}

// Remove removes a key
func (c *ConnectionPool) Remove(key string) {
	c.Lock()
	defer c.Unlock()

	delete(c.items, key)
}

var cp ConnectionPool

func init() {
	cp = NewConnectionPool()
}

func main() {
	if _, ok := cp.Get("db"); !ok {
		cp.Set("db", &DB{})
	}

	v, _ := cp.Get("db")

	fmt.Println(v.(*DB).name())
}