Respect Context Deadline

[RaniSputnik]

Have added context timeout to graphql.Execute, this seemed the most appropriate place to put it. A couple of concerns I have;

• Nested resolve functions could still be started after a context has already been cancelled
• Not sure of the performance implications of these changes - doesn't look too bad to me but I hasn't been benchmarked
• The go func inside of Execute's pretty messy now, the same select is repeated three times
• The tests run slower after this change as they need to wait for the context timeout. I've kept this to 100ms for now, so not a massive deal - but it might be better to kick off this test in parallel.

Feedback very much appreciated!

Closes #184

[coveralls]

Coverage increased (+0.05%) to 83.532% when pulling 3a996ee on RaniSputnik:context-deadline into 22050ee on graphql-go:master.

[coveralls]

Coverage increased (+0.04%) to 83.529% when pulling e95c164 on RaniSputnik:context-deadline into 22050ee on graphql-go:master.

[chris-ramon]

Have added context timeout to graphql.Execute, this seemed the most appropriate place to put it. A couple of concerns I have;

Nested resolve functions could still be started after a context has already been cancelled
Not sure of the performance implications of these changes - doesn't look too bad to me but I hasn't been benchmarked
The go func inside of Execute's pretty messy now, the same select is repeated three times
The tests run slower after this change as they need to wait for the context timeout. I've kept this to 100ms for now, so not a massive deal - but it might be better to kick off this test in parallel.
Feedback very much appreciated!

Thanks a lot @RaniSputnik!

Nested resolve functions could still be started after a context has already been cancelled

I think it's fine, if graphql results contain errors, clients will either retry or something else.

Not sure of the performance implications of these changes - doesn't look too bad to me but I hasn't been benchmarked

I don't think there are perf. implications, if so we will handle it on new PR's

The go func inside of Execute's pretty messy now, the same select is repeated three times

Could not agree more, looking forward to code clean-up inside the Execute function.

The tests run slower after this change as they need to wait for the context timeout. I've kept this to 100ms for now, so not a massive deal - but it might be better to kick off this test in parallel.

IMHO 100ms is fine for now.

LGTM 👍 🚢