Send message await forever

[jack8525]

Where do you suspect the issue?

Issue in mesh library, e.g. packets being dropped

Version

4.1.0 (latest)

Describe the issue

_ = try? await globalMeshNetworkManager?.send(meshMessage, to: MeshAddress(sendMessageTask.address), using: applicationKey)

I send an AcknowledgedMeshMessage but get bearerDidClose error.

this else isn't handled, so the library awaits forever. What should I do?

[philips77]

Thank you for reporting the issue. I'll look into it and come back to you.

[philips77]

For Acknowledged messages there's a timer on Access Layer that should try to retransmit the message and time out eventually.

[philips77]

OK. I see where the issue may occur.

AccessLayer sets the repeat & timeout timer only for acknowledge messages sent to a Unicast Address:

IOS-nRF-Mesh-Library/nRFMeshProvision/Layers/Access Layer/AccessLayer.swift

Lines 239 to 244 in 293210d

	// Set timers for the acknowledged messages.
	// Acknowledged messages sent to a Group address won't await a Status.
	if message is AcknowledgedMeshMessage,
	destination.address.isUnicast {
	createReliableContext(for: pdu, sentFrom: element, withTtl: initialTtl, using: keySet)
	}

That means, that acknowledged messages sent to a Group Address (or Virtual Address) don't get that timer set. Such messages may be sent to 0+ nodes and the transmitter can receive 0+ responses. In that case, it is the underlying layer that should notify the network manager, just like for unacknowledged messages.

However, as you pointed out, when the Acknowledged Mesh Message is unsegmented, like ConfigOnOffSet, and sending the message fails, the network manager is never notified:

IOS-nRF-Mesh-Library/nRFMeshProvision/Layers/Lower Transport Layer/LowerTransportLayer.swift

Lines 257 to 260 in 293210d

	if !pdu.message!.isAcknowledged {
	networkManager.notifyAbout(error: error, duringSendingMessage: pdu.message!,
	from: localElement, to: pdu.destination)
	}

I'll prepare a fix.

[philips77]

[philips77]

Btw, for multicast addresses it is recommended not to use Acknowledged messages, but their Unacknowledged counterparts. This significantly decreases the traffic in the network.

[philips77]

Hmm... I did some more digging and seems like the Network Layer doesn't throw bearerDidClose when the message is sent to a group address, as such message may be handled internally:

IOS-nRF-Mesh-Library/nRFMeshProvision/Layers/Network Layer/NetworkLayer.swift

Lines 156 to 167 in 293210d

	// Loopback interface.
	if shouldLoopback(networkPdu) {
	handle(incomingPdu: networkPdu.pdu, ofType: type)
	// Messages sent with TTL = 1 will only be sent locally.
	guard ttl != 1 else { return }
	if isLocalUnicastAddress(networkPdu.destination) {
	// No need to send messages targeting local Unicast Addresses.
	return
	}
	// If the message was sent locally, don't report Bearer closer error.
	try? transmitter.send(networkPdu.pdu, ofType: type)
	} else {

This is the shouldLoopback method:

IOS-nRF-Mesh-Library/nRFMeshProvision/Layers/Network Layer/NetworkLayer.swift

Lines 444 to 450 in 293210d

	/// Returns whether the PDU should loop back for local processing.
	///
	/// - parameter networkPdu: The PDU to check.
	func shouldLoopback(_ networkPdu: NetworkPdu) -> Bool {
	let address = networkPdu.destination
	return address.isGroup || address.isVirtual || isLocalUnicastAddress(address)
	}

As you're getting that error, that means, that you're sending the message to a Unicast Address. In that case, the network manager should wait until the response is received from the target, which happens on Access Layer.
I'll leave #600 open, but don't think it's required.

[philips77]

Could you say what message are you trying to send exactly, what are your network parameters (default?) and what is the destination address of the message?

[jack8525]

Thank you for your help. I just send some GenericOnOffSet to a Unicast Address when not connected.In this case, a timeout will not be thrown?

[philips77]

There will be a timeout. The timeout is set using:

IOS-nRF-Mesh-Library/nRFMeshProvision/Layers/NetworkParameters.swift

Lines 219 to 230 in 293210d

	/// Sets the timeout for receiving a response to an acknowledged access message.
	///
	/// The ``MeshNetworkDelegate/meshNetworkManager(_:failedToSendMessage:from:to:error:)-7iylf``
	/// callback will be called when the response is not received before the timeout expires..
	///
	/// - parameter timeout: The timeout after which the ``AccessError/timeout``
	/// is reported. This shall be set to a minimum of 30 seconds,
	/// which is also the default value.
	/// - seeAlso: ``NetworkParameters/acknowledgmentMessageTimeout``
	public func discardAcknowledgedMessages(after timeout: TimeInterval) {
	networkParameters.acknowledgmentMessageTimeout = timeout
	}

Documentatuion

[jack8525]

I found failedToSendMessage is no callback. Because Address change to MeshMessage.
After fix it.
I can handle the timeout here.

[jack8525]

Can I handle deliveryCallbacks here?