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|
package redis
import (
"fmt"
"strings"
"sync"
"time"
"github.com/gomodule/redigo/redis"
"github.com/jpillora/backoff"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"gitlab.com/gitlab-org/gitlab-workhorse/internal/log"
)
var (
keyWatcher = make(map[string][]chan string)
keyWatcherMutex sync.Mutex
redisReconnectTimeout = backoff.Backoff{
//These are the defaults
Min: 100 * time.Millisecond,
Max: 60 * time.Second,
Factor: 2,
Jitter: true,
}
keyWatchers = promauto.NewGauge(
prometheus.GaugeOpts{
Name: "gitlab_workhorse_keywatcher_keywatchers",
Help: "The number of keys that is being watched by gitlab-workhorse",
},
)
totalMessages = promauto.NewCounter(
prometheus.CounterOpts{
Name: "gitlab_workhorse_keywatcher_total_messages",
Help: "How many messages gitlab-workhorse has received in total on pubsub.",
},
)
)
const (
keySubChannel = "workhorse:notifications"
)
// KeyChan holds a key and a channel
type KeyChan struct {
Key string
Chan chan string
}
func processInner(conn redis.Conn) error {
defer conn.Close()
psc := redis.PubSubConn{Conn: conn}
if err := psc.Subscribe(keySubChannel); err != nil {
return err
}
defer psc.Unsubscribe(keySubChannel)
for {
switch v := psc.Receive().(type) {
case redis.Message:
totalMessages.Inc()
dataStr := string(v.Data)
msg := strings.SplitN(dataStr, "=", 2)
if len(msg) != 2 {
log.WithError(fmt.Errorf("keywatcher: invalid notification: %q", dataStr)).Error()
continue
}
key, value := msg[0], msg[1]
notifyChanWatchers(key, value)
case error:
log.WithError(fmt.Errorf("keywatcher: pubsub receive: %v", v)).Error()
// Intermittent error, return nil so that it doesn't wait before reconnect
return nil
}
}
}
func dialPubSub(dialer redisDialerFunc) (redis.Conn, error) {
conn, err := dialer()
if err != nil {
return nil, err
}
// Make sure Redis is actually connected
conn.Do("PING")
if err := conn.Err(); err != nil {
conn.Close()
return nil, err
}
return conn, nil
}
// Process redis subscriptions
//
// NOTE: There Can Only Be One!
func Process() {
log.Info("keywatcher: starting process loop")
for {
conn, err := dialPubSub(workerDialFunc)
if err != nil {
log.WithError(fmt.Errorf("keywatcher: %v", err)).Error()
time.Sleep(redisReconnectTimeout.Duration())
continue
}
redisReconnectTimeout.Reset()
if err = processInner(conn); err != nil {
log.WithError(fmt.Errorf("keywatcher: process loop: %v", err)).Error()
}
}
}
func notifyChanWatchers(key, value string) {
keyWatcherMutex.Lock()
defer keyWatcherMutex.Unlock()
if chanList, ok := keyWatcher[key]; ok {
for _, c := range chanList {
c <- value
keyWatchers.Dec()
}
delete(keyWatcher, key)
}
}
func addKeyChan(kc *KeyChan) {
keyWatcherMutex.Lock()
defer keyWatcherMutex.Unlock()
keyWatcher[kc.Key] = append(keyWatcher[kc.Key], kc.Chan)
keyWatchers.Inc()
}
func delKeyChan(kc *KeyChan) {
keyWatcherMutex.Lock()
defer keyWatcherMutex.Unlock()
if chans, ok := keyWatcher[kc.Key]; ok {
for i, c := range chans {
if kc.Chan == c {
keyWatcher[kc.Key] = append(chans[:i], chans[i+1:]...)
keyWatchers.Dec()
break
}
}
if len(keyWatcher[kc.Key]) == 0 {
delete(keyWatcher, kc.Key)
}
}
}
// WatchKeyStatus is used to tell how WatchKey returned
type WatchKeyStatus int
const (
// WatchKeyStatusTimeout is returned when the watch timeout provided by the caller was exceeded
WatchKeyStatusTimeout WatchKeyStatus = iota
// WatchKeyStatusAlreadyChanged is returned when the value passed by the caller was never observed
WatchKeyStatusAlreadyChanged
// WatchKeyStatusSeenChange is returned when we have seen the value passed by the caller get changed
WatchKeyStatusSeenChange
// WatchKeyStatusNoChange is returned when the function had to return before observing a change.
// Also returned on errors.
WatchKeyStatusNoChange
)
// WatchKey waits for a key to be updated or expired
func WatchKey(key, value string, timeout time.Duration) (WatchKeyStatus, error) {
kw := &KeyChan{
Key: key,
Chan: make(chan string, 1),
}
addKeyChan(kw)
defer delKeyChan(kw)
currentValue, err := GetString(key)
if err != nil {
return WatchKeyStatusNoChange, fmt.Errorf("keywatcher: redis GET: %v", err)
}
if currentValue != value {
return WatchKeyStatusAlreadyChanged, nil
}
select {
case currentValue := <-kw.Chan:
if currentValue == "" {
return WatchKeyStatusNoChange, fmt.Errorf("keywatcher: redis GET failed")
}
if currentValue == value {
return WatchKeyStatusNoChange, nil
}
return WatchKeyStatusSeenChange, nil
case <-time.After(timeout):
return WatchKeyStatusTimeout, nil
}
}
|
