Initial commit

node_modules/execa/lib/pipe/streaming.js

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+import {finished} from 'node:stream/promises';
+import mergeStreams from '@sindresorhus/merge-streams';
+import {incrementMaxListeners} from '../utils/max-listeners.js';
+import {pipeStreams} from '../io/pipeline.js';
+
+// The piping behavior is like Bash.
+// In particular, when one subprocess exits, the other is not terminated by a signal.
+// Instead, its stdout (for the source) or stdin (for the destination) closes.
+// If the subprocess uses it, it will make it error with SIGPIPE or EPIPE (for the source) or end (for the destination).
+// If it does not use it, it will continue running.
+// This allows for subprocesses to gracefully exit and lower the coupling between subprocesses.
+export const pipeSubprocessStream = (sourceStream, destinationStream, maxListenersController) => {
+	const mergedStream = MERGED_STREAMS.has(destinationStream)
+		? pipeMoreSubprocessStream(sourceStream, destinationStream)
+		: pipeFirstSubprocessStream(sourceStream, destinationStream);
+	incrementMaxListeners(sourceStream, SOURCE_LISTENERS_PER_PIPE, maxListenersController.signal);
+	incrementMaxListeners(destinationStream, DESTINATION_LISTENERS_PER_PIPE, maxListenersController.signal);
+	cleanupMergedStreamsMap(destinationStream);
+	return mergedStream;
+};
+
+// We use `merge-streams` to allow for multiple sources to pipe to the same destination.
+const pipeFirstSubprocessStream = (sourceStream, destinationStream) => {
+	const mergedStream = mergeStreams([sourceStream]);
+	pipeStreams(mergedStream, destinationStream);
+	MERGED_STREAMS.set(destinationStream, mergedStream);
+	return mergedStream;
+};
+
+const pipeMoreSubprocessStream = (sourceStream, destinationStream) => {
+	const mergedStream = MERGED_STREAMS.get(destinationStream);
+	mergedStream.add(sourceStream);
+	return mergedStream;
+};
+
+const cleanupMergedStreamsMap = async destinationStream => {
+	try {
+		await finished(destinationStream, {cleanup: true, readable: false, writable: true});
+	} catch {}
+
+	MERGED_STREAMS.delete(destinationStream);
+};
+
+const MERGED_STREAMS = new WeakMap();
+
+// Number of listeners set up on `sourceStream` by each `sourceStream.pipe(destinationStream)`
+// Those are added by `merge-streams`
+const SOURCE_LISTENERS_PER_PIPE = 2;
+// Number of listeners set up on `destinationStream` by each `sourceStream.pipe(destinationStream)`
+// Those are added by `finished()` in `cleanupMergedStreamsMap()`
+const DESTINATION_LISTENERS_PER_PIPE = 1;