mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-11-01 07:33:12 +08:00
Chris Tate
9021a03133
A shared view written to stdout or stderr went out in 64 KiB pieces through scr_stdio_write, so a replaced process.stdout.write received the first piece alone, and a false return, which only reports backpressure, ended the loop: a view larger than 64 KiB lost the rest. With a write hook, the view is now copied whole and passed in one call, as Node passes it; the bounded pieces go to the stream itself through scr_stdio_write_raw, which never stops early. tests/corpus/shared-bytes-stdio-write.ts replaces process.stdout.write with a function that records each chunk's length and returns false, and writes a 150,000-byte shared view through it.
41 lines
1.6 KiB
TypeScript
41 lines
1.6 KiB
TypeScript
// process.stdout.write and process.stderr.write of views into a SharedArrayBuffer that a worker
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// filled: a view larger than one write chunk (64 KiB), at a byte offset, one shorter than a chunk,
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// and an empty one.
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import { Worker, isMainThread, parentPort, workerData } from "node:worker_threads";
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type Fill = { buffer: SharedArrayBuffer };
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if (isMainThread) {
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const sab = new SharedArrayBuffer(200_000);
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const worker = new Worker(new URL(import.meta.url), { workerData: { buffer: sab } });
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worker.on("message", () => {
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process.stdout.write(new Uint8Array(sab, 1000, 150_000));
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process.stdout.write("\n");
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process.stdout.write(new Uint8Array(sab, 0, 0));
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process.stdout.write(new Uint8Array(sab, 160_000, 20_000));
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process.stdout.write("\n");
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process.stderr.write(new Uint8Array(sab, 63, 70_000));
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process.stderr.write("\n");
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// A replaced write receives the whole view in one call, even when it
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// returns false.
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const out = process.stdout as unknown as Record<string, unknown>;
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const original = out["write"];
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const sizes: number[] = [];
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out["write"] = (chunk: unknown): boolean => {
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sizes.push(typeof chunk === "string" ? chunk.length : (chunk as Uint8Array).length);
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return false;
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};
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const accepted = process.stdout.write(new Uint8Array(sab, 1000, 150_000));
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out["write"] = original;
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console.log("replaced", accepted, sizes.join(","));
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console.log("done");
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});
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} else {
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const bytes = new Uint8Array((workerData as Fill).buffer);
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for (let i = 0; i < bytes.length; i++) bytes[i] = i % 64 === 63 ? 10 : 65 + (i % 26);
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parentPort!.postMessage("filled");
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}
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