executor: adds panic handler

[chris-ramon]

Overview

• graphql: adds PanicHandler type.
• graphql: adds Params.PanicHandler field.
• executor: calls PanicHandler when there's a panic while resolving a field.
• closes: Custom panic handler #243
• built on top of: Add a PanicHandler executor field #252 — thanks a lot @scottjg 👍

Test plan

• Unit test.

[coveralls]

Coverage increased (+0.009%) to 82.091% when pulling 47767e0 on panic-handler into 7731016 on master.

[scottjg]

@chris-ramon thanks for your help with this patch!

i was going over your changes and i have a question... originally my patch would only call the panic handler on an actual panic. it appears with your changes, it gets called when a resolver returns any errors (maybe due to reverting the change here b63c4f0#diff-58bccd1b2cfaf06d4d4ac893e4712c88L592 ). was that intentional? if so, is it possible to distinguish between a panic and an error in the panic handler? i think everything gets flattened to a graphql formatted error type so i'm not sure if it's possible.

[coveralls]

Coverage increased (+0.009%) to 82.234% when pulling 451533e on panic-handler into 9b5a661 on master.

[jekiapp]

I stuck around on this problem also, I need to know where the stacktrace of the panic in my resolver. is this patch possible to solve that?
I used to manually add

defer func() {
	if r := recover(); r != nil {
		log.Println("panic: ", string(debug.Stack()))
		panic(r)
	}
}()

on every resolver.
So with this handler I should print with debug.Stack() in the handler?
and also why this PR still not merged to master yet, or should I use another version for using this patch?

[rodrigo-brito]

@chris-ramon Do you have any forecast for the release?

[niondir]

looking forward to get this merged.

[rodrigo-brito]

It will capture all erros from GraphQL. If you see here. All errors was given by panic(). Changing the return to value (error), can solve the problem.

[phifty]

any updates on this?

[jpascal]

any updates on this?

[maddsua]

Looking forward to have this merged, really need an option to add custom panic handler 👀