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[PHP-WASM] Transfer event stdin streams across workers - #4060
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Pull request overview
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Adds support for transferring ReadableStream instances nested inside worker-dispatched events (e.g., stdin on a PHPWorker event) across the Comlink boundary, including a Safari fallback via MessagePort, and validates the behavior with a Playwright test.
Changes:
- Register Comlink transfer handlers for
ReadableStream<Uint8Array>and for event objects that contain nested streams. - Update
PHPWorker.dispatchEvent()to teestdinstreams so each listener receives a transferable branch. - Add a Playwright worker + spec to verify multi-listener delivery and that the source stream remains live during reads.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/php-wasm/web/src/test/readable-stream-transfer.spec.ts | New Playwright spec validating cross-worker stream transfer to multiple listeners. |
| packages/php-wasm/web/src/test/playwright/readable-stream-worker.ts | New worker script that emits an event containing a ReadableStream payload. |
| packages/php-wasm/web/src/test/playwright/browser-globals.ts | Exposes worker-spawn + API-consumption helpers and the worker URL to the browser test page. |
| packages/php-wasm/web/playwright.config.ts | Includes the new stream-transfer spec in the Playwright run. |
| packages/php-wasm/universal/src/lib/php-worker.ts | Tees readable stdin streams per listener to avoid one-time transfer limitations. |
| packages/php-wasm/universal/src/lib/api.ts | Adds Comlink transfer handlers for ReadableStream and nested-stream event payloads (Safari fallback via MessagePort). |
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PHPWorkercan now deliver an event whosestdinremains a liveReadableStreamacross the browser worker boundary. Comlink applies transfer handlers only to the top-level value, so a stream stored in an event'sstdinproperty otherwise reachespostMessage()without a transfer list and structured cloning fails.The event handler serializes
stdinthrough a dedicated stream handler. It transfers the stream directly when the runtime supports that operation and uses the existingMessagePortbridge otherwise. The bridge transfers owned chunk copies becauseReadableStream.tee()branches share chunk objects and detaching one branch's buffer must not invalidate the others. Consumer cancellation travels back over the port and cancels the source reader.A stream can only be transferred once, so
PHPWorkergives each listener its own tee branch. Slow listeners may queue unread chunks because this transport does not coordinate backpressure between branches.Browser-worker tests cover native stream transfer and the forced
MessagePortfallback, including incremental delivery to two listeners and source cancellation after both tee branches cancel.This is the worker transport required by #3996. It adds no sendmail behavior.