Tracing now works for SentryHttpMessageHandler even when there is no active transaction

[jamescrosswell]

Resolves #2931

Problem summary

This logic in the SentryHttpMessageHandler means spans only gets created by SentryHttpMessageHandler if there is already an active transaction set on the scope.:

sentry-dotnet/src/Sentry/SentryHttpMessageHandler.cs

Lines 66 to 69 in 043cb5f

	var span = _hub.GetSpan()?.StartChild(
	"http.client",
	$"{method} {url}" // e.g. "GET https://example.com"
	);

If I add this to a MAUI event handler, a span for the HttpClient request is sent correctly as part of the transaction:

        var transaction = SentrySdk.StartTransaction("OnCounterClicked", "Scour the web");
        SentrySdk.ConfigureScope(scope => scope.Transaction = transaction);
        try
        {
            var messageHandler = new SentryHttpMessageHandler();
            var httpClient = new HttpClient(messageHandler, true);
            var html = await httpClient.GetStringAsync("https://example.com/");
            CounterBtn.Text = html;
        }
        finally
        {
            transaction.Finish();
        }

Solution

I've used Hub.StartSpan instead. This either creates a transaction (if no transaction is set on the scope) or create a child span of the transaction (if a transaction has been set on the scope).

[bitsandfoxes]

Can we find a solution where there is no need to differentiate between Hub and HubAdapter? The hub vs _realHub thing makes my head spin.

.

[bitsandfoxes]

Is this going to work with Requests? Afaik there needs to be a Span within the Transaction?

[bitsandfoxes]

Is this going to work with Requests? Afaik there needs to be a Span within the Transaction?

I think this is unrelated to the fix here. If it didn't work before, this won't break it.