/*
* Author, Copyright: Oleg Borodin <onborodin@gmail.com>
*/
package main
import (
"context"
"fmt"
"log"
"time"
"os"
"errors"
"github.com/jmoiron/sqlx"
"github.com/jackc/pgx/v4/pgxpool"
_ "github.com/jackc/pgx/v4/stdlib"
)
type Server struct {
Dbp *sqlx.DB
Pool *pgxpool.Pool
}
const (
DbUsername string = "e2api"
DbPassword string = "e2api"
DbHostname string = "localhost"
DbPort int = 5432
DbName string = "e2api"
)
func (this *Server) OpenDB() error {
var err error
dbUrl := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
DbUsername,
DbPassword,
DbHostname,
DbPort,
DbName)
this.Dbp, err = sqlx.Open("pgx", dbUrl)
if err != nil {
return err
}
err = this.Dbp.Ping()
if err != nil {
return err
}
return err
}
func (this *Server) OpenPool() error {
var err error
dbUri := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
DbUsername,
DbPassword,
DbHostname,
DbPort,
DbName)
this.Pool, err = pgxpool.Connect(context.Background(), dbUri)
if err != nil {
return err
}
//
return err
}
func (this *Server) Listen() error {
var err error
if this.Pool == nil {
return errors.New("empty pool reference")
}
conn, err := this.Pool.Acquire(context.Background())
if err != nil {
return err
}
defer conn.Release()
_, err = conn.Exec(context.Background(), "LISTEN notes")
if err != nil {
return err
}
for {
notification, err := conn.Conn().WaitForNotification(context.Background())
if err != nil {
log.Println("error waiting for notification:", err)
time.Sleep(10 * time.Millisecond)
}
log.Println("accepted message from pid:", notification.PID,
"channel:", notification.Channel,
"payload:", notification.Payload)
}
}
func (this *Server) SendLoop() {
var err error
var message string = "foobar"
for {
time.Sleep(1 * time.Second)
_, err = this.Pool.Exec(context.Background(), "SELECT pg_notify('notes', $1)", message)
if err != nil {
log.Println("error sending notification:", err)
}
}
}
func NewServer() *Server {
return &Server{
}
}
func main() {
var err error
server := NewServer()
err = server.OpenDB()
if err != nil {
log.Println("unable open database:", err)
os.Exit(1)
}
err = server.OpenPool()
if err != nil {
log.Println("unable open pool:", err)
os.Exit(1)
}
go func() {
err = server.Listen()
if err != nil {
log.Println("unable start listener:", err)
os.Exit(1)
}
}()
if err != nil {
log.Println("unable start listener:", err)
os.Exit(1)
}
server.SendLoop()
}
