Platform Tracing: fallback transaction name

[bessey]

Enable a developer to provide the platform trace API a fallback name to
use when a query name is not provided.

Note that this is a fallback, the query name is preferred when
available.

Testing is limited to Datadog and New Relic.

Support is within any tracer that delegates to
PlatformTracing#transaction_name, which appears to include AppSignal
and Scout. Not sure if that is exhaustive.

Fixes #3769

[bessey]

@rmosolgo FYI I am finding that the test suite hangs on v1.13 when I run it locally with rake test, running with TESTOPTS="--verbose" I can see the output before it hangs is:

GraphQL::Dataloader::AsyncDataloader::With libev_scheduler#test_0001_runs IO in parallel by default

So perhaps I am missing a libev dependency and it doesn't handle it so gracefully.

So for now I am targetting v1.12 (actually, we have not yet upgraded to v1.13 so I would prefer to target v1.12 either way, but we can live on a fork until v1.13 if necessary).

[rmosolgo]

Looking good so far! If you don't mind adding some test for this behavior, that'd be great. Do you plan to use the .call feature? If not, I'd rather leave it out until someone actually needs it. (Just more for me to maintain, otherwise 😅 )

it hangs

Oh! I found that GitHub actions failed when libev_scheduler was installed, too. Maybe that was why.

[rmosolgo]

sorry, personally, I have a hard time with multi-return methods, because I end up forgetting the different "exits" that the method has. if you don't mind:

Suggested change

	if selected_op
	op_type = selected_op.operation_type
	op_name = selected_op.name || "anonymous"
	elsif fallback_name = fallback_transaction_name(query.context)
	return "GraphQL/#{fallback_name}"
	else
	op_type = "query"
	op_name = "anonymous"
	end
	"GraphQL/#{op_type}.#{op_name}"
	txn_name = if selected_op
	op_type = selected_op.operation_type
	op_name = selected_op.name || "anonymous"
	"#{op_type}.#{op_name}"
	elsif (fallback_name = fallback_transaction_name(query.context))
	fallback_name
	else
	"query.anonymous"
	end
	"GraphQL/#{txn_name}"

[bessey]

Looking good so far! If you don't mind adding some test for this behavior, that'd be great. Do you plan to use the .call feature? If not, I'd rather leave it out until someone actually needs it. (Just more for me to maintain, otherwise sweat_smile )

You made me do what I should have from the beginning: measured :D

I wanted to avoid a SHA / SHA2 digest generation when it wouldn't be used. In practice, this is so close to instant its not worth the complexity

irb(main):003:0> string = "ANCASDJASFSDFSDF"*1000
=> "ANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCASDJASFSDFSDFANCA...
irb(main):008:0> Benchmark.measure { Digest::SHA2.hexdigest(string) }.real
=> 0.00020213398966006935

If I am not mistaken, that's 0.2ms. Will remove that change. And incorporate your other comment.

If you don't mind adding some test for this behavior, that'd be great

This is next on my to do, I have left some empty tests for now so we can agree on scope. Do these seem reasonable to you? One for my snowflake implementation in Datadog, and one for the general purpose implementation, in a tracer that relies on that implementation

[rmosolgo]

Yep, this scope LGTM 😎

[bessey]

I have implemented the specs and got it working on master rather than 1.12, ready for review!

[rmosolgo]

Thanks for this improvement!

[rmosolgo]

Suggested change

	add_field GraphQL::Types::Relay::NodeField
	include GraphQL::Types::Relay::HasNodeField

There was a bug here fixed in master since this branch came off: #3791

[rmosolgo]

I'll merge this and fix it on master