mail queue

bot/queue.go

@@ -0,0 +1,154 @@
+package bot
+
+import (
+	"strconv"
+	"time"
+)
+
+const (
+	defaultMaxQueueItems = 1
+	defaultMaxQueueTries = 100
+)
+
+// ProcessQueue starts queue processing
+func (b *Bot) ProcessQueue() {
+	b.log.Debug("staring queue processing...")
+	cfg := b.getBotSettings()
+
+	maxItems := cfg.QueueItems()
+	if maxItems == 0 {
+		maxItems = defaultMaxQueueItems
+	}
+
+	maxTries := cfg.QueueTries()
+	if maxTries == 0 {
+		maxTries = defaultMaxQueueTries
+	}
+
+	b.popqueue(maxItems, maxTries)
+	b.log.Debug("ended queue processing")
+}
+
+// popqueue gets emails from queue and tries to send them,
+// if an email was sent successfully - it will be removed from queue
+func (b *Bot) popqueue(maxItems, maxTries int) {
+	b.lock(acQueueKey)
+	defer b.unlock(acQueueKey)
+	index, err := b.lp.GetAccountData(acQueueKey)
+	if err != nil {
+		b.log.Error("cannot get queue index: %v", err)
+	}
+
+	i := 0
+	for id, itemkey := range index {
+		if i > maxItems {
+			b.log.Debug("finished re-deliveries from queue")
+			return
+		}
+		if dequeue := b.processQueueItem(itemkey, maxTries); dequeue {
+			b.log.Debug("email %s has been delivered", id)
+			err = b.dequeueEmail(id)
+			if err != nil {
+				b.log.Error("cannot dequeue email %s: %v", id, err)
+			}
+		}
+		i++
+	}
+}
+
+// processQueueItem tries to process an item from queue
+// returns should the item be dequeued or not
+func (b *Bot) processQueueItem(itemkey string, maxRetries int) bool {
+	b.lock(itemkey)
+	defer b.unlock(itemkey)
+
+	item, err := b.lp.GetAccountData(itemkey)
+	if err != nil {
+		b.log.Error("cannot retrieve a queue item %s: %v", itemkey, err)
+		return false
+	}
+	attempts, err := strconv.Atoi(item["attempts"])
+	if err != nil {
+		b.log.Error("cannot parse attempts of %s: %v", itemkey, err)
+		return false
+	}
+	if attempts > maxRetries {
+		return true
+	}
+
+	err = b.sendmail(item["from"], item["to"], item["data"])
+	if err == nil {
+		b.log.Debug("email %s from queue was delivered")
+		return true
+	}
+
+	b.log.Debug("attempted to deliver email id=%s, retry=%s, but it's not ready yet: %v", item["id"], item["attempts"], err)
+	attempts++
+	item["attempts"] = strconv.Itoa(attempts)
+	err = b.lp.SetAccountData(itemkey, item)
+	if err != nil {
+		b.log.Error("cannot update attempt count on email %s: %v", itemkey, err)
+	}
+
+	return false
+}
+
+// enqueueEmail adds an email to the queue
+func (b *Bot) enqueueEmail(id, from, to, data string) error {
+	itemkey := acQueueKey + "." + id
+	item := map[string]string{
+		"attemptedAt": time.Now().UTC().Format(time.RFC1123Z),
+		"attempts":    "0",
+		"data":        data,
+		"from":        from,
+		"to":          to,
+		"id":          id,
+	}
+
+	b.lock(itemkey)
+	defer b.unlock(itemkey)
+	err := b.lp.SetAccountData(itemkey, item)
+	if err != nil {
+		b.log.Error("cannot enqueue email id=%s: %v", id, err)
+		return err
+	}
+
+	b.lock(acQueueKey)
+	defer b.unlock(acQueueKey)
+	queueIndex, err := b.lp.GetAccountData(acQueueKey)
+	if err != nil {
+		b.log.Error("cannot get queue index: %v", err)
+		return err
+	}
+	queueIndex[id] = itemkey
+	err = b.lp.SetAccountData(acQueueKey, queueIndex)
+	if err != nil {
+		b.log.Error("cannot save queue index: %v", err)
+		return err
+	}
+
+	return nil
+}
+
+// dequeueEmail removes an email from the queue
+func (b *Bot) dequeueEmail(id string) error {
+	index, err := b.lp.GetAccountData(acQueueKey)
+	if err != nil {
+		b.log.Error("cannot get queue index: %v", err)
+		return err
+	}
+	itemkey := index[id]
+	if itemkey == "" {
+		itemkey = acQueueKey + "." + id
+	}
+	delete(index, id)
+	err = b.lp.SetAccountData(acQueueKey, index)
+	if err != nil {
+		b.log.Error("cannot update queue index: %v", err)
+		return err
+	}
+
+	b.lock(itemkey)
+	defer b.unlock(itemkey)
+	return b.lp.SetAccountData(itemkey, nil)
+}