// Subscribe prepares the peer to consume messages.
func (c *Peer) Subscribe() error {
// Subscription names must start with a lowercase letter, end with a
// lowercase letter or number, and contain only lowercase letters, numbers,
// dashes, underscores or periods.
c.subscription = strings.ToLower(fmt.Sprintf("x%sx", broker.GenerateName()))
exists, err := pubsub.SubExists(c.context, c.subscription)
if err != nil {
return err
}
if exists {
return fmt.Errorf("Subscription %s already exists", c.subscription)
}
if err := pubsub.CreateSub(c.context, c.subscription, topic, 0, ""); err != nil {
return err
}
go c.ack()
go func() {
// TODO: Can we avoid using atomic flag?
for atomic.LoadInt32(&c.stopped) != stopped {
messages, err := pubsub.PullWait(c.context, c.subscription, bufferSize)
if err != nil {
// Timed out.
continue
}
ids := make([]string, len(messages))
for i, message := range messages {
ids[i] = message.AckID
c.messages <- message.Data
}
c.acks <- ids
}
}()
return nil
}
func consumePubSubMsgs(projectId string, topicName string) <-chan []byte {
msgC := make(chan []byte, 100)
subName := topicName + "-2loggly"
ackDeadline := time.Second * 20
client, err := google.DefaultClient(context.Background(), pubsub.ScopePubSub)
if err != nil {
logFatal(LogData{
"event": "pubsub.error.auth",
"error": err.Error(),
})
}
ctx := cloud.NewContext(projectId, client)
isSub, err := pubsub.SubExists(ctx, subName)
if err != nil {
logFatal(LogData{
"event": "pubsub.error.subexists",
"error": err.Error(),
})
}
if !isSub {
err = pubsub.CreateSub(ctx, subName, topicName, ackDeadline, "")
if err != nil {
logFatal(LogData{
"event": "pubsub.error.createsub",
"error": err.Error(),
})
}
}
go func() {
var lastAckErr error
var lastDecodeErr error
for {
msgs, err := pubsub.PullWait(ctx, subName, 20)
if err != nil {
logInfo(LogData{
"event": "pubsub.error.pull",
"error": err.Error(),
})
time.Sleep(time.Second)
continue
}
lastAckErr = nil
lastDecodeErr = nil
for _, m := range msgs {
jsonBytes, err := msgToLogJson(m.Data)
if err != nil {
lastDecodeErr = err
} else {
msgC <- jsonBytes
}
err = pubsub.Ack(ctx, subName, m.AckID)
if err != nil {
lastAckErr = err
}
}
// protect against flood of logs from this application
// when acks/decodes fail but adding rollup & sleep delay
if lastAckErr != nil {
logInfo(LogData{
"event": "pubsub.error.ack",
"error": lastAckErr.Error(),
})
time.Sleep(time.Second)
}
if lastDecodeErr != nil {
logInfo(LogData{
"event": "pubsub.error.decode",
"error": lastDecodeErr.Error(),
})
time.Sleep(time.Second)
}
}
}()
return msgC
}
func (s *pubSubServiceImpl) SubExists(sub string) (bool, error) {
return pubsub.SubExists(s.ctx, sub)
}