microlinkhq / browserless / 28333399682

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github

Committed by web-flow

Commit Message

perf(screencast): ack synchronously on the non-backpressure path (#814)

* perf(screencast): ack synchronously on the non-backpressure path

The #813 follow-up modeled onScreencastFrame as an async function, so every
frame paid an async hop — a Promise allocation plus a microtask for the
`await` — even though onFrame is synchronous on the common path (muxer.write
only returns a promise when ffmpeg stdin applies backpressure).

Restore the promise-aware shape: run onFrame, and when it returns a non-thenable
(the common case) ack synchronously in the same tick. Only when it returns a
real promise do we build the deferred-ack chain. Behavior is unchanged on every
path — sync throw is still swallowed, the async ack still guards `stopped`, and
`Promise.resolve(result)` keeps it safe for non-Promise thenables.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(screencast): guard sync ack paths against a reentrant stop()

The sync fast paths acked directly, bypassing the `stopped` guard the async
path uses. If onFrame synchronously calls stop() and then returns undefined (the
"capture N frames then stop" pattern) or throws, the frame still sent
Page.screencastFrameAck after teardown — the stale-ack race the async path
already guarded against.

Route every ack through an `ackIfActive` helper so sync and async paths share
the one invariant: never ack a torn-down session.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

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641 of 799 branches covered (80.23%)

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24 of 24 new or added lines in 1 file covered. (100.0%)

8 existing lines in 1 file now uncovered.

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