Add support for scala 2.13 async operations #109
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Hi @junder31 , nice work!! For the app you emailed me, I now see |
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@XiXiaPdx yes the app I sent you includes all the changes I have been working on. That includes the akka-http change I have a PR open for, this PR, and one more that fixes an issue with the scalapb-grpc clients that I have not submitted a PR for. These three changes have all the scala/play applications at my company instrumented quite well. We do have some other scala teams that use different frameworks and libraries that I will be working on in the coming weeks/months that may result in some more PRs. |
| @NewField | ||
| private AgentBridge.TokenAndRefCount tokenAndRefCount; | ||
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| private Transformation_Instrumentation(final Function1 _fun, final ExecutionContext _ec, final Try<T> _arg, final int _xform) { |
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Hi @junder31, I think you could remove this weave method. We instrumented the constructor in 2.12 due to an issue with Akka-http linking. It would also allow removing the token newfield and @Trace on submitWithValue, the latter of which is causing the ProducerConsumerWithFutures.testProducerConsumer test to fail with extra segments.
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@tspring I made the changes you suggested. I'll give it a shot on one of my apps and see if instrumentation is still working. The test case at least passing now.
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@tspring looks like I'm still getting the transactions segments I was expecting on my app as well with these changes.
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Thanks @junder31 , we appreciate your work on this. Last thing, I fixed the github actions issue preventing the tests from passing but it looks like you'll need merge/rebase main. |
| * Override the submitWithValue so we can replace it with our wrapped version. | ||
| * It plays similar role to the 2.12 setter for "value" on the old CallbackRunnable | ||
| */ | ||
| public final Promise.Transformation submitWithValue(final Try<T> resolved) { |
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I might be wrong, but shouldn't we have this annotation here?
@Trace(async = true, excludeFromTransactionTrace = true)This way the segments are reported and it allows to align the ProducerConsumerWithFutures.testProducerConsumer test with how it looks for 2.12.
Currently it has zero segments reported.
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Hi, the annotation with async=true should only be necessary when calling Token::link. For the 2.12 instrumentation we had to create a second token in the CallbackRunnable constructor to fix an issue Akka-Http. It's not clear to me the Java/scala.concurrent.impl.CallbackRunnable/value_$eq segments are valuable and ideally they wouldn't be included in traces either, but I'd be interested to hear if you find them useful?
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I don't believe they are useful. Until I worked on the scala instrumentation I had no idea that method even existed. I think most scala users would actually find those segments confusing because they are completely unaware that futures work like that under the hood.
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I don't have a strong opinion here. If for practical purposes it's better to leave these segments out - I'm totally fine with it. Just pointed out the difference in behavior here.
Overview
This adds support for async operations in scala 2.13. In scala 2.12 the mechanism that was instrumented was CallbackRunnable. In 2.13 this class no longer exists. Transformation now preforms a similar role. The instrumentation on Transformation is fairly similar to the CallbackRunnable instrumentation from previous version of the scala instrumentation.
Testing
This passes the same tests that the older instrumentation provided. I have also deployed it with one of my scala2.13 applications and verified that the transaction traces contain all the asynchronous work I expected to be included.
Checks
Are your contributions backwards compatible with relevant frameworks and APIs? N/A
Does your code contain any breaking changes? N/A
Does your code introduce any new dependencies? Just scala2.13 which is being instrumented.