dwds does not block main execution on page reload

[iinozemtsev]

When I connect to the app from an IDE and set breakpoints, they aren't hit on page refresh.

Skimming through dev_handler.dart I suspect that the issue is here:

webdev/dwds/lib/src/handlers/dev_handler.dart

Lines 639 to 647 in c820e2a

	// We can take over a connection if there is no connectedInstanceId (this
	// means the client completely disconnected), or if the existing
	// AppConnection is in the KeepAlive state (this means it disconnected but
	// is still waiting for a possible reconnect - this happens during a page
	// reload).
	final canReconnect =
	services != null &&
	(services.connectedInstanceId == null ||
	existingConnection?.isInKeepAlivePeriod == true);

. canReconnect evaluates to false, because services.connectedInstanceId isn't null and the existing connection is not in keep alive period.

I started looking at how / when dev_handler detects disconnects, and at least for me it looks like when the page is refreshed, the sse connection is not cleared at all and _injectedConnections only grows with each refresh.

Any ideas how it worked/supposed to work?

cc @bkonyi @srujzs

[iinozemtsev]

It seems like websocket connection tries to solve a similar issue with isSameInstance (

webdev/dwds/lib/src/handlers/dev_handler.dart

Lines 706 to 708 in c820e2a

	// Allow connection reuse for page refreshes and same instance reconnections
	final isSameInstance =
	existingConnection?.request.instanceId == message.instanceId;

), but I struggle to undrestand how does it work if a client regenerates the dart app instance id on each refresh:

webdev/dwds/web/client.dart

Line 50 in c820e2a

dartAppInstanceId ??= const Uuid().v1();