Example Client: Implementation of a Consumer with reconnection support

[andygrunwald]

example_client_test.go shows a great way how to build a Producer with reconnection support.

The Consuming part is not covering the reconnection support:

amqp091-go/example_client_test.go

Lines 257 to 274 in 51fade5

	// Stream will continuously put queue items on the channel.
	// It is required to call delivery.Ack when it has been
	// successfully processed, or delivery.Nack when it fails.
	// Ignoring this will cause data to build up on the server.
	func (session *Session) Stream() (<-chan amqp.Delivery, error) {
	if !session.isReady {
	return nil, errNotConnected
	}
	return session.channel.Consume(
	session.name,
	"", // Consumer
	false, // Auto-Ack
	false, // Exclusive
	false, // No-local
	false, // No-Wait
	nil, // Args
	)
	}

Even if reconnection support is mentioned as a non-goal for the library itself, I do think showcasing this in the example might be a good thing.

Right now, the implementation is only possible with a hack involved.
Mainly due to these two issues:

• Consumer channel isn't closed in the event of unexpected disconnection #18
• Connection/Channel Deadlock #32

These deadlocks prevent the consumer delivery channel to be closed during an unexpected connection loss (e.g., when the RabbitMQ server goes down).

[DanielePalaia]

@andygrunwald Now that we understood what happened in #18 I think the example you propose can be just like an extension to the example we made in the documentation on how to handle channels for NotifyClose to avoid the deadlock for a consumer?

[andygrunwald]

Yeah, exactly. I was waiting for #18/#32.
I have it implemented incl. the deadlock in one of my projects.

If you are good with it, I would make a PR in the next few days and playback my implementation into the example client. Might take a few days.

[DanielePalaia]

Sure! good enough! Thanks @andygrunwald

[lukebakken]

This gives an example of auto-reconnection as well:

4ce2c8e

[metalrex100]

@andygrunwald any updates with your example client?

[andygrunwald]

@metalrex100 Still on my list. My client is working in production since quite some time. Will check if I can make some time in the next days to push it back.