stream: error once

doc/api/stream.md

@@ -281,6 +281,9 @@ The stream is not closed when the `'error'` event is emitted unless the
 [`autoDestroy`][writable-new] option was set to `true` when creating the
 stream.
 
+After `'error'`, no further events other than `'close'` *should* be emitted
+(including `'error'` events).
+
 ##### Event: 'finish'
 <!-- YAML
 added: v0.9.4

lib/_stream_readable.js

@@ -117,6 +117,9 @@ function ReadableState(options, stream, isDuplex) {
   this.resumeScheduled = false;
   this.paused = true;
 
+  // True if the error was already emitted and should not be thrown again
+  this.errorEmitted = false;
+
   // Should close be emitted on destroy. Defaults to true.
   this.emitClose = options.emitClose !== false;
 

lib/internal/streams/destroy.js

@@ -1,22 +1,37 @@
 'use strict';
 
+function needError(stream, err) {
+  if (!err) {
+    return false;
+  }
+
+  const r = stream._readableState;
+  const w = stream._writableState;
+
+  if ((w && w.errorEmitted) || (r && r.errorEmitted)) {
+    return false;
+  }
+
+  if (w) {
+    w.errorEmitted = true;
+  }
+  if (r) {
+    r.errorEmitted = true;
+  }
+
+  return true;
+}
+
 // Undocumented cb() API, needed for core, not for public API
 function destroy(err, cb) {
-  const readableDestroyed = this._readableState &&
-    this._readableState.destroyed;
-  const writableDestroyed = this._writableState &&
-    this._writableState.destroyed;
+  const r = this._readableState;
+  const w = this._writableState;
 
-  if (readableDestroyed || writableDestroyed) {
+  if ((w && w.destroyed) || (r && r.destroyed)) {
     if (cb) {
       cb(err);
-    } else if (err) {
-      if (!this._writableState) {
-        process.nextTick(emitErrorNT, this, err);
-      } else if (!this._writableState.errorEmitted) {
-        this._writableState.errorEmitted = true;
-        process.nextTick(emitErrorNT, this, err);
-      }
+    } else if (needError(this, err)) {
+      process.nextTick(emitErrorNT, this, err);
     }
 
     return this;
@@ -25,28 +40,19 @@ function destroy(err, cb) {
   // We set destroyed to true before firing error callbacks in order
   // to make it re-entrance safe in case destroy() is called within callbacks
 
-  if (this._readableState) {
-    this._readableState.destroyed = true;
+  if (w) {
+    w.destroyed = true;
   }
-
-  // If this is a duplex stream mark the writable part as destroyed as well
-  if (this._writableState) {
-    this._writableState.destroyed = true;
+  if (r) {
+    r.destroyed = true;
   }
 
   this._destroy(err || null, (err) => {
-    if (!cb && err) {
-      if (!this._writableState) {
-        process.nextTick(emitErrorAndCloseNT, this, err);
-      } else if (!this._writableState.errorEmitted) {
-        this._writableState.errorEmitted = true;
-        process.nextTick(emitErrorAndCloseNT, this, err);
-      } else {
-        process.nextTick(emitCloseNT, this);
-      }
-    } else if (cb) {
+    if (cb) {
       process.nextTick(emitCloseNT, this);
       cb(err);
+    } else if (needError(this, err)) {
+      process.nextTick(emitErrorAndCloseNT, this, err);
     } else {
       process.nextTick(emitCloseNT, this);
     }
@@ -61,29 +67,36 @@ function emitErrorAndCloseNT(self, err) {
 }
 
 function emitCloseNT(self) {
-  if (self._writableState && !self._writableState.emitClose)
+  const r = self._readableState;
+  const w = self._writableState;
+
+  if (w && !w.emitClose)
     return;
-  if (self._readableState && !self._readableState.emitClose)
+  if (r && !r.emitClose)
     return;
   self.emit('close');
 }
 
 function undestroy() {
-  if (this._readableState) {
-    this._readableState.destroyed = false;
-    this._readableState.reading = false;
-    this._readableState.ended = false;
-    this._readableState.endEmitted = false;
+  const r = this._readableState;
+  const w = this._writableState;
+
+  if (r) {
+    r.destroyed = false;
+    r.reading = false;
+    r.ended = false;
+    r.endEmitted = false;
+    r.errorEmitted = false;
   }
 
-  if (this._writableState) {
-    this._writableState.destroyed = false;
-    this._writableState.ended = false;
-    this._writableState.ending = false;
-    this._writableState.finalCalled = false;
-    this._writableState.prefinished = false;
-    this._writableState.finished = false;
-    this._writableState.errorEmitted = false;
+  if (w) {
+    w.destroyed = false;
+    w.ended = false;
+    w.ending = false;
+    w.finalCalled = false;
+    w.prefinished = false;
+    w.finished = false;
+    w.errorEmitted = false;
   }
 }
 
@@ -98,17 +111,13 @@ function errorOrDestroy(stream, err) {
   // the error to be emitted nextTick. In a future
   // semver major update we should change the default to this.
 
-  const rState = stream._readableState;
-  const wState = stream._writableState;
+  const r = stream._readableState;
+  const w = stream._writableState;
 
-  if ((rState && rState.autoDestroy) || (wState && wState.autoDestroy)) {
+  if ((r && r.autoDestroy) || (w && w.autoDestroy))
     stream.destroy(err);
-  } else {
-    if (wState) {
-      wState.errorEmitted = true;
-    }
+  else if (needError(stream, err))
     stream.emit('error', err);
-  }
 }
 
 

test/parallel/test-net-connect-buffer.js

@@ -69,12 +69,14 @@ tcp.listen(0, common.mustCall(function() {
     [],
     {}
   ].forEach((value) => {
-    common.expectsError(() => socket.write(value), {
+    // We need to check the callback since 'error' will only
+    // be emitted once per instance.
+    socket.write(value, common.expectsError({
       code: 'ERR_INVALID_ARG_TYPE',
       type: TypeError,
       message: 'The "chunk" argument must be one of type string or Buffer. ' +
                `Received type ${typeof value}`
-    });
+    }));
   });
 
   // Write a string that contains a multi-byte character sequence to test that

test/parallel/test-stream-error-once.js

@@ -0,0 +1,19 @@
+'use strict';
+const common = require('../common');
+const { Writable, Readable } = require('stream');
+
+{
+  const writable = new Writable();
+  writable.on('error', common.mustCall());
+  writable.end();
+  writable.write('h');
+  writable.write('h');
+}
+
+{
+  const readable = new Readable();
+  readable.on('error', common.mustCall());
+  readable.push(null);
+  readable.push('h');
+  readable.push('h');
+}

test/parallel/test-stream-readable-invalid-chunk.js

@@ -3,17 +3,32 @@
 const common = require('../common');
 const stream = require('stream');
 
-const readable = new stream.Readable({
-  read: () => {}
-});
-
-function checkError(fn) {
-  common.expectsError(fn, {
+function testPushArg(val) {
+  const readable = new stream.Readable({
+    read: () => {}
+  });
+  readable.on('error', common.expectsError({
     code: 'ERR_INVALID_ARG_TYPE',
     type: TypeError
+  }));
+  readable.push(val);
+}
+
+testPushArg([]);
+testPushArg({});
+testPushArg(0);
+
+function testUnshiftArg(val) {
+  const readable = new stream.Readable({
+    read: () => {}
   });
+  readable.on('error', common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    type: TypeError
+  }));
+  readable.unshift(val);
 }
 
-checkError(() => readable.push([]));
-checkError(() => readable.push({}));
-checkError(() => readable.push(0));
+testUnshiftArg([]);
+testUnshiftArg({});
+testUnshiftArg(0);

test/parallel/test-stream-readable-unshift.js

@@ -112,23 +112,6 @@ const { Readable } = require('stream');
 
 }
 
-{
-  // Check that error is thrown for invalid chunks
-
-  const readable = new Readable({ read() {} });
-  function checkError(fn) {
-    common.expectsError(fn, {
-      code: 'ERR_INVALID_ARG_TYPE',
-      type: TypeError
-    });
-  }
-
-  checkError(() => readable.unshift([]));
-  checkError(() => readable.unshift({}));
-  checkError(() => readable.unshift(0));
-
-}
-
 {
   // Check that ObjectMode works
   const readable = new Readable({ objectMode: true, read() {} });

test/parallel/test-stream-unshift-read-race.js

@@ -86,13 +86,7 @@ w._write = function(chunk, encoding, cb) {
 };
 
 r.on('end', common.mustCall(function() {
-  common.expectsError(function() {
-    r.unshift(Buffer.allocUnsafe(1));
-  }, {
-    code: 'ERR_STREAM_UNSHIFT_AFTER_END_EVENT',
-    type: Error,
-    message: 'stream.unshift() after end event'
-  });
+  r.unshift(Buffer.allocUnsafe(1));
   w.end();
 }));
 

test/parallel/test-stream2-writable.js

@@ -410,10 +410,7 @@ const helloWorldBuffer = Buffer.from('hello world');
   w._final = common.mustCall(function(cb) {
     cb(new Error('test'));
   });
-  w._write = function(chunk, e, cb) {
-    process.nextTick(cb);
-  };
-  w.once('error', common.mustCall((err) => {
+  w.on('error', common.mustCall((err) => {
     assert.strictEqual(w._writableState.errorEmitted, true);
     assert.strictEqual(err.message, 'test');
     w.on('error', common.mustNotCall());