Is retry handled from go client library for azure service bus? - azure

Question

I'm referencing to the client library in https://github.com/Azure/azure-service-bus-go. I was able to write a simple client which listens to a subscription and read the messages. If I drop the network, after a few seconds I could see the receive loop exiting with the error message "context canceled". I was hoping the client library will do some kind of retry mechanism and handle any connection issues or any server timeouts etc. Do we need to handle this our selves ? Also do we get any exceptions which we could identify and use it for this retrying mechanism ? Any sample code would be highly appreciated.
below is the sample code I tried (only including the vital parts).
err = subscription.Receive(ctx, servicebus.HandlerFunc(func(ctx context.Context, message *servicebus.Message) error {
fmt.Println(string(message.Data))
return message.Complete(ctx)
}))
if err != nil {
fmt.Println("FATAL: ", err)
return
}

Answer 1

Unfortunately, the older library doesn't do a good job of retrying, so you'll need to wrap the code in your own retry loop.
func demoReceiveWithRecovery(ns *servicebus.Namespace) {
parentCtx := context.TODO()
for {
q, err := ns.NewQueue(queueName)
if err != nil {
panic(err)
}
defer q.Close(parentCtx)
handler := servicebus.HandlerFunc(func(c context.Context, m *servicebus.Message) error {
log.Printf("Received message")
return m.Complete(c)
})
err = q.Receive(parentCtx, handler)
// check for potential recoverable situation
if err != nil && errors.Is(err, context.Canceled) {
// This workaround distinguishes between the handler cancelling because the
// library has disconnected vs the parent context (passed in by you) being cancelled.
if parentCtx.Err() != nil {
// our parent context cancelled, which caused the entire operation to be canceled
log.Printf("Cancelled by parent context")
return
} else {
// cancelled internally due to an error, we can restart the queue
log.Printf("Error occurred, restarting")
_ = q.Close(parentCtx)
continue
}
} else {
log.Printf("Other error, closing client and restarting: %s", err.Error())
_ = q.Close(parentCtx)
}
}
}
NOTE: This library was deprecated recently, but it was deprecated after you posted your question. The new package is here if you want to try it - azservicebus with a migration guide here to make things easier: migrationguide.md
The new package should recover properly in this scenario for receiving. There is an open bug in the new package I'm working on for the sending side to do recovery #16695.
If you want to ask further questions or have some feature requests you can submit those in the github issues for https://github.com/Azure/azure-sdk-for-go.