metrics: implement batch observer #429
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This patch adds an implementation of the metrics batch observer. The API is not identical to the example in [the spec](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/metrics/api.md#batch-observer) as it is inconvenient to register metrics after they are moved into the observer callback in rust. Instead the `Meter::batch_observer` method accepts a closure in which instruments can be registered before being moved into the callback. ```rust meter.batch_observer(|batch| { let inst = batch.u64_sum_observer("example").init(); move |result| { result.observe(&[KeyValue::new("a", "1")], inst.observation(42)]); } }); ```
Codecov Report
@@ Coverage Diff @@
## master #429 +/- ##
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+ Coverage 48.76% 48.85% +0.08%
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Files 66 66
Lines 5438 5453 +15
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+ Hits 2652 2664 +12
- Misses 2786 2789 +3
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| { | ||
| let observer = builder(BatchObserver::new(self))?; | ||
| self.core | ||
| .new_batch_observer(AsyncRunner::Batch(Box::new(observer))) |
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I'd probably just inline the call to builder() here, so you don't have to name the intermediate.
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Are you suggesting this specifically?
self.core
.new_batch_observer(AsyncRunner::Batch(Box::new(builder(BatchObserver::new(
self,
))?)))There was a problem hiding this comment.
Yeah. Maybe the way rustfmt treats it's not actually an improvement in this case...
| { | ||
| let observer = builder(BatchObserver::new(self)); | ||
| self.core | ||
| .new_batch_observer(AsyncRunner::Batch(Box::new(observer))) |
@djc yeah it's not ideal, not sure that there is better syntax for this type of setup currently though. Can iterate on this API if someone comes up with a cleaner way of expressing this as metrics still are not stable. |
This patch adds an implementation of the metrics batch observer. The API is not identical to the example in the spec as it is inconvenient to register metrics after they are moved into the observer callback in rust. Instead the
Meter::batch_observermethod accepts a closure in which instruments can be registered before being moved into the callback.