stream: finished callback for closed streams

Previously finished(stream, cb) would not invoke the callback
for streams that have already finished, ended or errored
before being passed to finished(stream, cb).

PR-URL: https://github.com/nodejs/node/pull/31509
Refs: https://github.com/nodejs/node/pull/31508
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/_stream_readable.js

@@ -148,6 +148,9 @@ function ReadableState(options, stream, isDuplex) {
   // Indicates whether the stream has errored.
   this.errored = false;
 
+  // Indicates whether the stream has finished destroying.
+  this.closed = false;
+
   // Crypto is kind of old and crusty.  Historically, its default string
   // encoding is 'binary' so we have to make this configurable.
   // Everything else in the universe uses 'utf8', though.

lib/_stream_writable.js

@@ -175,6 +175,9 @@ function WritableState(options, stream, isDuplex) {
   // is disabled we need a way to tell whether the stream has failed.
   this.errored = false;
 
+  // Indicates whether the stream has finished destroying.
+  this.closed = false;
+
   // Count buffered requests
   this.bufferedRequestCount = 0;
 

lib/internal/streams/async_iterator.js

@@ -67,16 +67,6 @@ function finish(self, err) {
   return new Promise((resolve, reject) => {
     const stream = self[kStream];
 
-    // TODO(ronag): Remove this check once finished() handles
-    // already ended and/or destroyed streams.
-    const ended = stream.destroyed || stream.readableEnded ||
-      (stream._readableState && stream._readableState.endEmitted);
-
-    if (ended) {
-      resolve(createIterResult(undefined, true));
-      return;
-    }
-
     finished(stream, (err) => {
       if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
         reject(err);

lib/internal/streams/destroy.js

@@ -48,6 +48,13 @@ function destroy(err, cb) {
       }
     }
 
+    if (w) {
+      w.closed = true;
+    }
+    if (r) {
+      r.closed = true;
+    }
+
     if (cb) {
       // Invoke callback before scheduling emitClose so that callback
       // can schedule before.
@@ -101,6 +108,7 @@ function undestroy() {
   const w = this._writableState;
 
   if (r) {
+    r.closed = false;
     r.destroyed = false;
     r.errored = false;
     r.reading = false;
@@ -110,6 +118,7 @@ function undestroy() {
   }
 
   if (w) {
+    w.closed = false;
     w.destroyed = false;
     w.errored = false;
     w.ended = false;

lib/internal/streams/end-of-stream.js

@@ -32,6 +32,8 @@ function isWritableFinished(stream) {
   return wState.finished || (wState.ended && wState.length === 0);
 }
 
+function nop() {}
+
 function eos(stream, opts, callback) {
   if (arguments.length === 2) {
     callback = opts;
@@ -52,12 +54,15 @@ function eos(stream, opts, callback) {
   let writable = opts.writable ||
     (opts.writable !== false && isWritable(stream));
 
+  const wState = stream._writableState;
+  const rState = stream._readableState;
+
   const onlegacyfinish = () => {
     if (!stream.writable) onfinish();
   };
 
   let writableFinished = stream.writableFinished ||
-    (stream._writableState && stream._writableState.finished);
+    (rState && rState.finished);
   const onfinish = () => {
     writable = false;
     writableFinished = true;
@@ -65,7 +70,7 @@ function eos(stream, opts, callback) {
   };
 
   let readableEnded = stream.readableEnded ||
-    (stream._readableState && stream._readableState.endEmitted);
+    (rState && rState.endEmitted);
   const onend = () => {
     readable = false;
     readableEnded = true;
@@ -79,7 +84,7 @@ function eos(stream, opts, callback) {
   const onclose = () => {
     let err;
     if (readable && !readableEnded) {
-      if (!stream._readableState || !stream._readableState.ended)
+      if (!rState || !rState.ended)
         err = new ERR_STREAM_PREMATURE_CLOSE();
       return callback.call(stream, err);
     }
@@ -99,7 +104,7 @@ function eos(stream, opts, callback) {
     stream.on('abort', onclose);
     if (stream.req) onrequest();
     else stream.on('request', onrequest);
-  } else if (writable && !stream._writableState) { // legacy streams
+  } else if (writable && !wState) { // legacy streams
     stream.on('end', onlegacyfinish);
     stream.on('close', onlegacyfinish);
   }
@@ -114,7 +119,24 @@ function eos(stream, opts, callback) {
   if (opts.error !== false) stream.on('error', onerror);
   stream.on('close', onclose);
 
+  const closed = (wState && wState.closed) || (rState && rState.closed) ||
+    (wState && wState.errorEmitted) || (rState && rState.errorEmitted) ||
+    (wState && wState.finished) || (rState && rState.endEmitted) ||
+    (rState && stream.req && stream.aborted);
+
+  if (closed) {
+    // TODO(ronag): Re-throw error if errorEmitted?
+    // TODO(ronag): Throw premature close as if finished was called?
+    // before being closed? i.e. if closed but not errored, ended or finished.
+    // TODO(ronag): Throw some kind of error? Does it make sense
+    // to call finished() on a "finished" stream?
+    process.nextTick(() => {
+      callback();
+    });
+  }
+
   return function() {
+    callback = nop;
     stream.removeListener('aborted', onclose);
     stream.removeListener('complete', onfinish);
     stream.removeListener('abort', onclose);

test/parallel/test-stream-finished.js

@@ -215,3 +215,120 @@ const { promisify } = require('util');
   w.end('asd');
   w.destroy();
 }
+
+function testClosed(factory) {
+  {
+    // If already destroyed but finished is cancelled in same tick
+    // don't invoke the callback,
+
+    const s = factory();
+    s.destroy();
+    const dispose = finished(s, common.mustNotCall());
+    dispose();
+  }
+
+  {
+    // If already destroyed invoked callback.
+
+    const s = factory();
+    s.destroy();
+    finished(s, common.mustCall());
+  }
+
+  {
+    // Don't invoke until destroy has completed.
+
+    let destroyed = false;
+    const s = factory({
+      destroy(err, cb) {
+        setImmediate(() => {
+          destroyed = true;
+          cb();
+        });
+      }
+    });
+    s.destroy();
+    finished(s, common.mustCall(() => {
+      assert.strictEqual(destroyed, true);
+    }));
+  }
+
+  {
+    // Invoke callback even if close is inhibited.
+
+    const s = factory({
+      emitClose: false,
+      destroy(err, cb) {
+        cb();
+        finished(s, common.mustCall());
+      }
+    });
+    s.destroy();
+  }
+
+  {
+    // Invoke with deep async.
+
+    const s = factory({
+      destroy(err, cb) {
+        setImmediate(() => {
+          cb();
+          setImmediate(() => {
+            finished(s, common.mustCall());
+          });
+        });
+      }
+    });
+    s.destroy();
+  }
+}
+
+testClosed((opts) => new Readable({ ...opts }));
+testClosed((opts) => new Writable({ write() {}, ...opts }));
+
+{
+  const w = new Writable({
+    write(chunk, encoding, cb) {
+      cb();
+    },
+    autoDestroy: false
+  });
+  w.end('asd');
+  process.nextTick(() => {
+    finished(w, common.mustCall());
+  });
+}
+
+{
+  const w = new Writable({
+    write(chunk, encoding, cb) {
+      cb(new Error());
+    },
+    autoDestroy: false
+  });
+  w.write('asd');
+  w.on('error', common.mustCall(() => {
+    finished(w, common.mustCall());
+  }));
+}
+
+
+{
+  const r = new Readable({
+    autoDestroy: false
+  });
+  r.push(null);
+  r.resume();
+  r.on('end', common.mustCall(() => {
+    finished(r, common.mustCall());
+  }));
+}
+
+{
+  const rs = fs.createReadStream(__filename, { autoClose: false });
+  rs.resume();
+  rs.on('close', common.mustNotCall());
+  rs.on('end', common.mustCall(() => {
+    finished(rs, common.mustCall());
+  }));
+}