doc: further fix async iterator example

Further fixes an issue with the async iterator example where an incorrect assumption was made in regards that drain or error is always invoked after !write(). Fixes: #31365 PR-URL: #31367 Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: Luigi Pinca <[email protected]>
nodejs · Feb 17, 2020 · 729b961 · 729b961
1 parent 15b24b7
commit 729b961
Showing 1 changed file with 12 additions and 2 deletions.
diff --git a/doc/api/stream.md b/doc/api/stream.md
@@ -2644,12 +2644,22 @@ const finished = util.promisify(stream.finished);
 
 const writable = fs.createWriteStream('./file');
 
+function drain(writable) {
+  if (writable.destroyed) {
+    return Promise.reject(new Error('premature close'));
+  }
+  return Promise.race([
+    once(writable, 'drain'),
+    once(writable, 'close')
+      .then(() => Promise.reject(new Error('premature close')))
+  ]);
+}
+
 async function pump(iterable, writable) {
   for await (const chunk of iterable) {
     // Handle backpressure on write().
     if (!writable.write(chunk)) {
-      if (writable.destroyed) return;
-      await once(writable, 'drain');
+      await drain(writable);
     }
   }
   writable.end();