func findTask(whoAmI string, stopper *utils.Stopper) (string, database.Notification) {
for {
// Find a notification to send.
node, notification, err := database.FindOneNotificationToSend(database.GetDefaultNotificationWrapper())
if err != nil {
log.Warningf("could not get notification to send: %s", err)
}
// No notification or error: wait.
if notification == nil || err != nil {
if !stopper.Sleep(checkInterval) {
return "", nil
}
continue
}
// Lock the notification.
if hasLock, _ := database.Lock(node, lockDuration, whoAmI); hasLock {
log.Infof("found and locked a notification: %s", notification.GetName())
return node, notification
}
}
}
// Run pops notifications from the database, lock them, send them, mark them as
// send and unlock them
//
// It uses an exponential backoff when POST requests fail
func (notifier *HTTPNotifier) Run(st *utils.Stopper) {
defer st.End()
whoAmI := uuid.New()
log.Infof("HTTP notifier started. URL: %s. Lock Identifier: %s", notifier.url, whoAmI)
for {
node, notification, err := database.FindOneNotificationToSend(database.GetDefaultNotificationWrapper())
if notification == nil || err != nil {
if err != nil {
log.Warningf("could not get notification to send: %s.", err)
}
if !st.Sleep(checkInterval) {
break
}
continue
}
// Try to lock the notification
hasLock, hasLockUntil := database.Lock(node, lockDuration, whoAmI)
if !hasLock {
continue
}
for backOff := time.Duration(0); ; backOff = timeutil.ExpBackoff(backOff, maxBackOff) {
// Backoff, it happens when an error occurs during the communication
// with the notification endpoint
if backOff > 0 {
// Renew lock before going to sleep if necessary
if time.Now().Add(backOff).After(hasLockUntil.Add(-refreshLockAnticipation)) {
hasLock, hasLockUntil = database.Lock(node, lockDuration, whoAmI)
if !hasLock {
log.Warning("lost lock ownership, aborting")
break
}
}
// Sleep
if !st.Sleep(backOff) {
return
}
}
// Get notification content
content, err := notification.GetContent()
if err != nil {
log.Warningf("could not get content of notification '%s': %s", notification.GetName(), err.Error())
break
}
// Marshal the notification content
jsonContent, err := json.Marshal(struct {
Name, Type string
Content interface{}
}{
Name: notification.GetName(),
Type: notification.GetType(),
Content: content,
})
if err != nil {
log.Errorf("could not marshal content of notification '%s': %s", notification.GetName(), err.Error())
break
}
// Post notification
req, _ := http.NewRequest("POST", notifier.url, bytes.NewBuffer(jsonContent))
req.Header.Set("Content-Type", "application/json")
client := &http.Client{}
res, err := client.Do(req)
if err != nil {
log.Warningf("could not post notification '%s': %s", notification.GetName(), err.Error())
continue
}
res.Body.Close()
if res.StatusCode != 200 && res.StatusCode != 201 {
log.Warningf("could not post notification '%s': got status code %d", notification.GetName(), res.StatusCode)
continue
}
// Mark the notification as sent
database.MarkNotificationAsSent(node)
log.Infof("sent notification '%s' successfully", notification.GetName())
break
}
if hasLock {
database.Unlock(node, whoAmI)
}
}
log.Info("HTTP notifier stopped")
}