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James M Snell
153ec89621
To stay cancellable while a source is pending, from() waits for every value of an async source through waitForNormalization(). For each value it created a PromiseWithResolvers(), raced it against the value with SafePromiseRace(), which wraps both in new promises, and ran an async function with try/finally. This was the largest per-batch cost of normalizing an async source. Wait with a single promise and a single reaction on the value instead, and reject that promise directly on cancellation. The outcome is unchanged: the value's result, its rejection, or the cancellation reason, whichever comes first, and the cancellation reason if the normalization was cancelled by the time the value fulfills. With an async generator yielding 16-byte chunks, pipeTo() is about 1.7x faster and iterating from() about 1.75x faster. Assisted-by: OpenCode Signed-off-by: James M Snell <jasnell@gmail.com> PR-URL: https://github.com/nodejs/node/pull/66648 Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>