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libuv reports the event loop metrics exposed through `performance.nodeTiming.uvMetricsInfo` as `uint64_t` counters, but they were copied into an `Int32Array` (and, before that, converted using `v8::Integer::New()`), so they wrapped around after 2^31 on long-running processes. Store the metrics in a `Float64Array` instead. Values are now exact up to `Number.MAX_SAFE_INTEGER`. Assisted-by: OpenCode Signed-off-by: James M Snell <jasnell@gmail.com>
`performanceNodeTiming.uvMetricsInfo` is a property, not a method, so document its value using `Type:` rather than `Returns:`. Assisted-by: OpenCode Signed-off-by: James M Snell <jasnell@gmail.com>
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`performance.nodeTiming.uvMetricsInfo` returns the libuv event loop metrics as numbers, which are only exact up to `Number.MAX_SAFE_INTEGER`. Add `uvMetricsInfoBigInt`, which returns the same metrics as bigints backed by `uint64_t` storage, carrying the full 64-bit range reported by libuv. A single native call fills both a `Float64Array` and a `BigUint64Array`, so `uvMetricsInfo` does not pay for bigint allocation and conversion. The new property is omitted from `toJSON()`, as `JSON.stringify()` cannot serialize bigints. Assisted-by: OpenCode Signed-off-by: James M Snell <jasnell@gmail.com>
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
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libuv reports the event loop metrics exposed through
performance.nodeTiming.uvMetricsInfoasuint64_tcounters, butthey were copied into an
Int32Array(and, before that, convertedusing
v8::Integer::New()), so they wrapped around after 2^31 onlong-running processes. While such large numbers aren't typical,
they are possible, making the current implementation flawed.
This PR stores the metrics in a
Float64Arrayinstead. Values arenow exact up to
Number.MAX_SAFE_INTEGER.We also introduce a parallel
uvMetricsInfoBigIntwhose values arerepresented as
bigintto represent the fully correct value.Note that the corrected handling using
Float64Arrayvs.Int32Arrayadds roughly 1-6ns per call overhead to the fact that v8 must create
a
HeapNumberfrom theFloat64Arrayelement while theInt32Arrayallows it to use SMI. Given the typical usage pattern here, however,
6ns is unlikely to be noticed but it will show up in the unrealistic
microbenchmark.