Split wall and monotonic clock semantics - #6807
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✅ No new issues found.
Reviewed changes
- Clock interface split:
currentTimeNanos*redefined as Unix wall-clock timestamps; newmonotonicTimeNanos*members added for elapsed duration measurement. JSDoc on both explicitly documents suitability and gotchas. - Wall-clock re-anchoring (
wallTimeNanos): Periodically (min 1s interval) re-computes the monotonic→wall origin when skew fromDate.now()exceeds 1 second, plus on wall-clock backward movement. Correctly handles both sudden and gradual drift. - Monotonic source selection:
process.hrtime.bigint()→performance.now()→ non-decreasingDate.now()fallback. The fallback'spreviousguard ensures it never decreases. - Duration migration:
Effect.timed,Effect.trackDuration, andSink.withDuration(and transitivelySink.timed) switch fromcurrentTimeNanosUnsafetomonotonicTimeNanosUnsafe. All tracing/log/metric timestamp call sites correctly remain on wall clock. - TestClock dual counters:
adjustand forwardsetTimeadvance both wall and monotonic; backwardsetTimeadvances only wall, preserving monotonic as a non-decreasing counter. Sleep deadlines advance monotonic to match. - Test coverage: Live-clock regression test with mocked
process.hrtime.bigint/Date.now, wall-backward duration tests fortimed/trackDuration/withDuration, TestClock counter tests for all adjustment scenarios, and OTel clock alignment test updated. - Changeset:
"effect": minorcorrectly flags the breaking change for customClockimplementors.
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✅ No new issues found.
Reviewed changes
- Removed skew-check rate limiting (
wallTimeNanos): EliminatedlastCheckMillis/checkIntervalMillisguard; skew vsDate.now()is now checked every call instead of at minimum 1s intervals. Fewer state variables, andDate.now()is cheap enough that the per-call check is harmless. - Simplified
Date.now()fallback: InitializedprevioustoBigInt(0)instead ofbigint | undefined, removing theundefinedbranch. The first call always sets it higher sinceDate.now()after epoch is always> 0. - Fixed floating-point precision in
advanceTo: ReplacedMath.floor(timestamp * 1e6) - Math.floor(currentTimestamp * 1e6)withMath.round(deltaMillis * 1_000_000). The old two-floorapproach could lose up to 1ns per term from floating-point truncation;Math.roundon the delta is exact for integer deltas and simpler. - Simplified live-clock regression test: Replaced
Effect.acquireUseReleasewithEffect.gen+Effect.ensuring— same assertions, far fewer indirections. - Added far-future precision test: Verifies
setTimeat timestamp1_000_000_000_000produces correct monotonic nanos withMath.round.
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Type
Description
Fixes
Clock.currentTimeNanospermanently drifting from wall time when the runtime's monotonic clock pauses during host suspension or advances at a different rate fromDate.now().Previously, the live clock established its wall-clock origin once and never revisited it. This could leave nanosecond timestamps behind or ahead of Unix wall time for the lifetime of the process.
Changes
Clock.Clock:monotonicTimeNanosUnsafe()monotonicTimeNanosClock.monotonicTimeNanos.currentTimeMillisandcurrentTimeNanosas Unix-epoch wall-clock timestamps.process.hrtime.bigint()performance.now()Date.now()fallbackEffect.timedEffect.trackDurationSink.withDurationandSink.timedTestClockindependent wall and monotonic counters.effectminor changeset covering the required custom-Clockmigration.Tests
TestClockadjustment, forwardsetTime, backwardsetTime, and intermediate sleep deadlines.Local validation:
pnpm checkpassed.pnpm lintpassed.Related