doc: add stream/promises pipeline and finished to doc

PR-URL: #45832 Fixes: #45821 Reviewed-By: Paolo Insogna <[email protected]> Reviewed-By: Antoine du Hamel <[email protected]>
nodejs · Jan 1, 2023 · b93a967 · b93a967
1 parent 5de08ef
commit b93a967
Showing 1 changed file with 227 additions and 107 deletions.
diff --git a/doc/api/stream.md b/doc/api/stream.md
@@ -59,6 +59,227 @@ functions for streams that return `Promise` objects rather than using
 callbacks. The API is accessible via `require('node:stream/promises')`
 or `require('node:stream').promises`.
 
+### `stream.pipeline(source[, ...transforms], destination[, options])`
+
+### `stream.pipeline(streams[, options])`
+
+<!-- YAML
+added: v15.0.0
+-->
+
+* `streams` {Stream\[]|Iterable\[]|AsyncIterable\[]|Function\[]}
+* `source` {Stream|Iterable|AsyncIterable|Function}
+  * Returns: {Promise|AsyncIterable}
+* `...transforms` {Stream|Function}
+  * `source` {AsyncIterable}
+  * Returns: {Promise|AsyncIterable}
+* `destination` {Stream|Function}
+  * `source` {AsyncIterable}
+  * Returns: {Promise|AsyncIterable}
+* `options` {Object}
+  * `signal` {AbortSignal}
+  * `end` {boolean}
+* Returns: {Promise} Fulfills when the pipeline is complete.
+
+```cjs
+const { pipeline } = require('node:stream/promises');
+const fs = require('node:fs');
+const zlib = require('node:zlib');
+
+async function run() {
+  await pipeline(
+    fs.createReadStream('archive.tar'),
+    zlib.createGzip(),
+    fs.createWriteStream('archive.tar.gz'),
+  );
+  console.log('Pipeline succeeded.');
+}
+
+run().catch(console.error);
+```
+
+```mjs
+import { pipeline } from 'node:stream/promises';
+import { createReadStream, createWriteStream } from 'node:fs';
+import { createGzip } from 'node:zlib';
+
+await pipeline(
+  createReadStream('archive.tar'),
+  createGzip(),
+  createWriteStream('archive.tar.gz'),
+);
+console.log('Pipeline succeeded.');
+```
+
+To use an `AbortSignal`, pass it inside an options object, as the last argument.
+When the signal is aborted, `destroy` will be called on the underlying pipeline,
+with an `AbortError`.
+
+```cjs
+const { pipeline } = require('node:stream/promises');
+const fs = require('node:fs');
+const zlib = require('node:zlib');
+
+async function run() {
+  const ac = new AbortController();
+  const signal = ac.signal;
+
+  setImmediate(() => ac.abort());
+  await pipeline(
+    fs.createReadStream('archive.tar'),
+    zlib.createGzip(),
+    fs.createWriteStream('archive.tar.gz'),
+    { signal },
+  );
+}
+
+run().catch(console.error); // AbortError
+```
+
+```mjs
+import { pipeline } from 'node:stream/promises';
+import { createReadStream, createWriteStream } from 'node:fs';
+import { createGzip } from 'node:zlib';
+
+const ac = new AbortController();
+const { signal } = ac;
+setImmediate(() => ac.abort());
+try {
+  await pipeline(
+    createReadStream('archive.tar'),
+    createGzip(),
+    createWriteStream('archive.tar.gz'),
+    { signal },
+  );
+} catch (err) {
+  console.error(err); // AbortError
+}
+```
+
+The `pipeline` API also supports async generators:
+
+```cjs
+const { pipeline } = require('node:stream/promises');
+const fs = require('node:fs');
+
+async function run() {
+  await pipeline(
+    fs.createReadStream('lowercase.txt'),
+    async function* (source, { signal }) {
+      source.setEncoding('utf8');  // Work with strings rather than `Buffer`s.
+      for await (const chunk of source) {
+        yield await processChunk(chunk, { signal });
+      }
+    },
+    fs.createWriteStream('uppercase.txt'),
+  );
+  console.log('Pipeline succeeded.');
+}
+
+run().catch(console.error);
+```
+
+```mjs
+import { pipeline } from 'node:stream/promises';
+import { createReadStream, createWriteStream } from 'node:fs';
+
+await pipeline(
+  createReadStream('lowercase.txt'),
+  async function* (source, { signal }) {
+    source.setEncoding('utf8');  // Work with strings rather than `Buffer`s.
+    for await (const chunk of source) {
+      yield await processChunk(chunk, { signal });
+    }
+  },
+  createWriteStream('uppercase.txt'),
+);
+console.log('Pipeline succeeded.');
+```
+
+Remember to handle the `signal` argument passed into the async generator.
+Especially in the case where the async generator is the source for the
+pipeline (i.e. first argument) or the pipeline will never complete.
+
+```cjs
+const { pipeline } = require('node:stream/promises');
+const fs = require('node:fs');
+
+async function run() {
+  await pipeline(
+    async function* ({ signal }) {
+      await someLongRunningfn({ signal });
+      yield 'asd';
+    },
+    fs.createWriteStream('uppercase.txt'),
+  );
+  console.log('Pipeline succeeded.');
+}
+
+run().catch(console.error);
+```
+
+```mjs
+import { pipeline } from 'node:stream/promises';
+import fs from 'node:fs';
+await pipeline(
+  async function* ({ signal }) {
+    await someLongRunningfn({ signal });
+    yield 'asd';
+  },
+  fs.createWriteStream('uppercase.txt'),
+);
+console.log('Pipeline succeeded.');
+```
+
+The `pipeline` API provides [callback version][stream-pipeline]:
+
+### `stream.finished(stream[, options])`
+
+<!-- YAML
+added: v15.0.0
+-->
+
+* `stream` {Stream}
+* `options` {Object}
+  * `error` {boolean|undefined}
+  * `readable` {boolean|undefined}
+  * `writable` {boolean|undefined}
+  * `signal`: {AbortSignal|undefined}
+* Returns: {Promise} Fulfills when the stream is no
+  longer readable or writable.
+
+```cjs
+const { finished } = require('node:stream/promises');
+const fs = require('node:fs');
+
+const rs = fs.createReadStream('archive.tar');
+
+async function run() {
+  await finished(rs);
+  console.log('Stream is done reading.');
+}
+
+run().catch(console.error);
+rs.resume(); // Drain the stream.
+```
+
+```mjs
+import { finished } from 'node:stream/promises';
+import { createReadStream } from 'node:fs';
+
+const rs = createReadStream('archive.tar');
+
+async function run() {
+  await finished(rs);
+  console.log('Stream is done reading.');
+}
+
+run().catch(console.error);
+rs.resume(); // Drain the stream.
+```
+
+The `finished` API provides [callback version][stream-finished]:
+
 ### Object mode
 
 All streams created by Node.js APIs operate exclusively on strings and `Buffer`
@@ -2447,22 +2668,7 @@ Especially useful in error handling scenarios where a stream is destroyed
 prematurely (like an aborted HTTP request), and will not emit `'end'`
 or `'finish'`.
 
-The `finished` API provides promise version:
-
-```js
-const { finished } = require('node:stream/promises');
-const fs = require('node:fs');
-
-const rs = fs.createReadStream('archive.tar');
-
-async function run() {
-  await finished(rs);
-  console.log('Stream is done reading.');
-}
-
-run().catch(console.error);
-rs.resume(); // Drain the stream.
-```
+The `finished` API provides [promise version][stream-finished-promise].
 
 `stream.finished()` leaves dangling event listeners (in particular
 `'error'`, `'end'`, `'finish'` and `'close'`) after `callback` has been
@@ -2542,97 +2748,7 @@ pipeline(
 );
 ```
 
-The `pipeline` API provides a promise version, which can also
-receive an options argument as the last parameter with a
-`signal` {AbortSignal} property. When the signal is aborted,
-`destroy` will be called on the underlying pipeline, with an
-`AbortError`.
-
-```js
-const { pipeline } = require('node:stream/promises');
-const fs = require('node:fs');
-const zlib = require('node:zlib');
-
-async function run() {
-  await pipeline(
-    fs.createReadStream('archive.tar'),
-    zlib.createGzip(),
-    fs.createWriteStream('archive.tar.gz'),
-  );
-  console.log('Pipeline succeeded.');
-}
-
-run().catch(console.error);
-```
-
-To use an `AbortSignal`, pass it inside an options object,
-as the last argument:
-
-```js
-const { pipeline } = require('node:stream/promises');
-const fs = require('node:fs');
-const zlib = require('node:zlib');
-
-async function run() {
-  const ac = new AbortController();
-  const signal = ac.signal;
-
-  setTimeout(() => ac.abort(), 1);
-  await pipeline(
-    fs.createReadStream('archive.tar'),
-    zlib.createGzip(),
-    fs.createWriteStream('archive.tar.gz'),
-    { signal },
-  );
-}
-
-run().catch(console.error); // AbortError
-```
-
-The `pipeline` API also supports async generators:
-
-```js
-const { pipeline } = require('node:stream/promises');
-const fs = require('node:fs');
-
-async function run() {
-  await pipeline(
-    fs.createReadStream('lowercase.txt'),
-    async function* (source, { signal }) {
-      source.setEncoding('utf8');  // Work with strings rather than `Buffer`s.
-      for await (const chunk of source) {
-        yield await processChunk(chunk, { signal });
-      }
-    },
-    fs.createWriteStream('uppercase.txt'),
-  );
-  console.log('Pipeline succeeded.');
-}
-
-run().catch(console.error);
-```
-
-Remember to handle the `signal` argument passed into the async generator.
-Especially in the case where the async generator is the source for the
-pipeline (i.e. first argument) or the pipeline will never complete.
-
-```js
-const { pipeline } = require('node:stream/promises');
-const fs = require('node:fs');
-
-async function run() {
-  await pipeline(
-    async function* ({ signal }) {
-      await someLongRunningfn({ signal });
-      yield 'asd';
-    },
-    fs.createWriteStream('uppercase.txt'),
-  );
-  console.log('Pipeline succeeded.');
-}
-
-run().catch(console.error);
-```
+The `pipeline` API provides a [promise version][stream-pipeline-promise].
 
 `stream.pipeline()` will call `stream.destroy(err)` on all streams except:
 
@@ -4566,7 +4682,11 @@ contain multi-byte characters.
 [stream-_write]: #writable_writechunk-encoding-callback
 [stream-_writev]: #writable_writevchunks-callback
 [stream-end]: #writableendchunk-encoding-callback
+[stream-finished]: #streamfinishedstream-options-callback
+[stream-finished-promise]: #streamfinishedstream-options
 [stream-pause]: #readablepause
+[stream-pipeline]: #streampipelinesource-transforms-destination-callback
+[stream-pipeline-promise]: #streampipelinesource-transforms-destination-options
 [stream-push]: #readablepushchunk-encoding
 [stream-read]: #readablereadsize
 [stream-resume]: #readableresume