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|
package beanstalk
import (
"fmt"
"github.com/beanstalkd/go-beanstalk"
"github.com/cenkalti/backoff/v4"
"strings"
"sync"
"time"
)
var connErrors = []string{"pipe", "read tcp", "write tcp", "connection", "EOF"}
// creates new connections
type connFactory interface {
newConn() (*conn, error)
}
// conn protects allocation for one connection between
// threads and provides reconnecting capabilities.
type conn struct {
tout time.Duration
conn *beanstalk.Conn
alive bool
free chan interface{}
dead chan interface{}
stop chan interface{}
lock *sync.Cond
}
// creates new beanstalk connection and reconnect watcher.
func newConn(network, addr string, tout time.Duration) (cn *conn, err error) {
cn = &conn{
tout: tout,
alive: true,
free: make(chan interface{}, 1),
dead: make(chan interface{}, 1),
stop: make(chan interface{}),
lock: sync.NewCond(&sync.Mutex{}),
}
cn.conn, err = beanstalk.Dial(network, addr)
if err != nil {
return nil, err
}
go cn.watch(network, addr)
return cn, nil
}
// reset the connection and reconnect watcher.
func (cn *conn) Close() error {
cn.lock.L.Lock()
defer cn.lock.L.Unlock()
close(cn.stop)
for cn.alive {
cn.lock.Wait()
}
return nil
}
// acquire connection instance or return error in case of timeout. When mandratory set to true
// timeout won't be applied.
func (cn *conn) acquire(mandatory bool) (*beanstalk.Conn, error) {
// do not apply timeout on mandatory connections
if mandatory {
select {
case <-cn.stop:
return nil, fmt.Errorf("connection closed")
case <-cn.free:
return cn.conn, nil
}
}
select {
case <-cn.stop:
return nil, fmt.Errorf("connection closed")
case <-cn.free:
return cn.conn, nil
default:
// *2 to handle commands called right after the connection reset
tout := time.NewTimer(cn.tout * 2)
select {
case <-cn.stop:
tout.Stop()
return nil, fmt.Errorf("connection closed")
case <-cn.free:
tout.Stop()
return cn.conn, nil
case <-tout.C:
return nil, fmt.Errorf("unable to allocate connection (timeout %s)", cn.tout)
}
}
}
// release acquired connection.
func (cn *conn) release(err error) error {
if isConnError(err) {
// reconnect is required
cn.dead <- err
} else {
cn.free <- nil
}
return err
}
// watch and reconnect if dead
func (cn *conn) watch(network, addr string) {
cn.free <- nil
t := time.NewTicker(WatchThrottleLimit)
defer t.Stop()
for {
select {
case <-cn.dead:
// simple throttle limiter
<-t.C
// try to reconnect
// TODO add logging here
expb := backoff.NewExponentialBackOff()
expb.MaxInterval = cn.tout
reconnect := func() error {
conn, err := beanstalk.Dial(network, addr)
if err != nil {
fmt.Println(fmt.Sprintf("redial: error during the beanstalk dialing, %s", err.Error()))
return err
}
// TODO ADD LOGGING
fmt.Println("------beanstalk successfully redialed------")
cn.conn = conn
cn.free <- nil
return nil
}
err := backoff.Retry(reconnect, expb)
if err != nil {
fmt.Println(fmt.Sprintf("redial failed: %s", err.Error()))
cn.dead <- nil
}
case <-cn.stop:
cn.lock.L.Lock()
select {
case <-cn.dead:
case <-cn.free:
}
// stop underlying connection
cn.conn.Close()
cn.alive = false
cn.lock.Signal()
cn.lock.L.Unlock()
return
}
}
}
// isConnError indicates that error is related to dead socket.
func isConnError(err error) bool {
if err == nil {
return false
}
for _, errStr := range connErrors {
// golang...
if strings.Contains(err.Error(), errStr) {
return true
}
}
return false
}
|
