stream: cleanup and fix Readable.wrap

Cleans up Readable.wrap and also ensures destroy
is called for certain events.

PR-URL: #34204
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/_stream_readable.js

@@ -26,6 +26,7 @@ const {
   NumberIsInteger,
   NumberIsNaN,
   ObjectDefineProperties,
+  ObjectKeys,
   ObjectSetPrototypeOf,
   Set,
   SymbolAsyncIterator,
@@ -1007,83 +1008,49 @@ function flow(stream) {
 // This is *not* part of the readable stream interface.
 // It is an ugly unfortunate mess of history.
 Readable.prototype.wrap = function(stream) {
-  const state = this._readableState;
   let paused = false;
 
-  stream.on('end', () => {
-    debug('wrapped end');
-    if (state.decoder && !state.ended) {
-      const chunk = state.decoder.end();
-      if (chunk && chunk.length)
-        this.push(chunk);
-    }
-
-    this.push(null);
-  });
+  // TODO (ronag): Should this.destroy(err) emit
+  // 'error' on the wrapped stream? Would require
+  // a static factory method, e.g. Readable.wrap(stream).
 
   stream.on('data', (chunk) => {
-    debug('wrapped data');
-    if (state.decoder)
-      chunk = state.decoder.write(chunk);
-
-    // Don't skip over falsy values in objectMode.
-    if (state.objectMode && (chunk === null || chunk === undefined))
-      return;
-    else if (!state.objectMode && (!chunk || !chunk.length))
-      return;
-
-    const ret = this.push(chunk);
-    if (!ret) {
+    if (!this.push(chunk) && stream.pause) {
       paused = true;
       stream.pause();
     }
   });
 
-  // Proxy all the other methods. Important when wrapping filters and duplexes.
-  for (const i in stream) {
-    if (this[i] === undefined && typeof stream[i] === 'function') {
-      this[i] = function methodWrap(method) {
-        return function methodWrapReturnFunction() {
-          return stream[method].apply(stream, arguments);
-        };
-      }(i);
-    }
-  }
+  stream.on('end', () => {
+    this.push(null);
+  });
 
   stream.on('error', (err) => {
     errorOrDestroy(this, err);
   });
 
   stream.on('close', () => {
-    // TODO(ronag): Update readable state?
-    this.emit('close');
+    this.destroy();
   });
 
   stream.on('destroy', () => {
-    // TODO(ronag): this.destroy()?
-    this.emit('destroy');
+    this.destroy();
   });
 
-  stream.on('pause', () => {
-    // TODO(ronag): this.pause()?
-    this.emit('pause');
-  });
-
-  stream.on('resume', () => {
-    // TODO(ronag): this.resume()?
-    this.emit('resume');
-  });
-
-  // When we try to consume some more bytes, simply unpause the
-  // underlying stream.
-  this._read = (n) => {
-    debug('wrapped _read', n);
-    if (paused) {
+  this._read = () => {
+    if (paused && stream.resume) {
       paused = false;
       stream.resume();
     }
   };
 
+  // Proxy all the other methods. Important when wrapping filters and duplexes.
+  for (const i of ObjectKeys(stream)) {
+    if (this[i] === undefined && typeof stream[i] === 'function') {
+      this[i] = stream[i].bind(stream);
+    }
+  }
+
   return this;
 };
 

test/parallel/test-stream2-readable-wrap-destroy.js

@@ -0,0 +1,27 @@
+'use strict';
+const common = require('../common');
+
+const Readable = require('_stream_readable');
+const EE = require('events').EventEmitter;
+
+const oldStream = new EE();
+oldStream.pause = () => {};
+oldStream.resume = () => {};
+
+{
+  new Readable({
+    autoDestroy: false,
+    destroy: common.mustCall()
+  })
+    .wrap(oldStream);
+  oldStream.emit('destroy');
+}
+
+{
+  new Readable({
+    autoDestroy: false,
+    destroy: common.mustCall()
+  })
+    .wrap(oldStream);
+  oldStream.emit('close');
+}

test/parallel/test-stream2-readable-wrap.js

@@ -44,6 +44,16 @@ function runTest(highWaterMark, objectMode, produce) {
     flow();
   };
 
+  // Make sure pause is only emitted once.
+  let pausing = false;
+  r.on('pause', () => {
+    assert.strictEqual(pausing, false);
+    pausing = true;
+    process.nextTick(() => {
+      pausing = false;
+    });
+  });
+
   let flowing;
   let chunks = 10;
   let oldEnded = false;