forked from lukashes/pg
/
listener.go
98 lines (88 loc) · 1.81 KB
/
listener.go
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package pg
import (
"fmt"
"time"
)
// Not thread-safe.
type Listener struct {
db *DB
_cn *conn
closed bool
}
func (l *Listener) conn(readTimeout time.Duration) (*conn, error) {
if l._cn == nil {
return nil, errListenerClosed
}
l._cn.SetReadTimeout(readTimeout)
l._cn.SetWriteTimeout(l.db.opt.WriteTimeout)
return l._cn, nil
}
func (l *Listener) Listen(channels ...string) error {
cn, err := l.conn(l.db.opt.ReadTimeout)
if err != nil {
return err
}
for _, name := range channels {
if err := writeQueryMsg(cn.buf, "LISTEN ?", F(name)); err != nil {
return err
}
}
return cn.Flush()
}
func (l *Listener) Receive() (channel string, payload string, err error) {
return l.ReceiveTimeout(0)
}
func (l *Listener) ReceiveTimeout(readTimeout time.Duration) (channel, payload string, err error) {
cn, err := l.conn(readTimeout)
if err != nil {
return "", "", err
}
for {
c, msgLen, err := cn.ReadMsgType()
if err != nil {
return "", "", err
}
switch c {
case commandCompleteMsg:
_, err := cn.ReadN(msgLen)
if err != nil {
return "", "", err
}
case readyForQueryMsg:
_, err := cn.ReadN(msgLen)
if err != nil {
return "", "", err
}
case errorResponseMsg:
e, err := cn.ReadError()
if err != nil {
return "", "", err
}
return "", "", e
case notificationResponseMsg:
_, err := cn.ReadInt32()
if err != nil {
return "", "", err
}
channel, err = cn.ReadString()
if err != nil {
return "", "", err
}
payload, err = cn.ReadString()
if err != nil {
return "", "", err
}
return channel, payload, nil
default:
return "", "", fmt.Errorf("pg: unexpected message %q", c)
}
}
}
func (l *Listener) Close() error {
if l._cn == nil {
return errListenerClosed
}
err := l.db.pool.Remove(l._cn)
l._cn = nil
return err
}