stream: remove defaultEncoding of ReadableState

The defaultEncoding of ReadableState can not be set by any API.

Use new Buffer()'s default encoding should be more reasonable.

lib/_stream_readable.js

@@ -52,11 +52,6 @@ function ReadableState(options, stream) {
   this.emittedReadable = false;
   this.readableListening = 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.
-  this.defaultEncoding = options.defaultEncoding || 'utf8';
-
   // when piping, we only care about 'readable' events that happen
   // after read()ing all the bytes and not getting any pushback.
   this.ranOut = false;
@@ -69,6 +64,7 @@ function ReadableState(options, stream) {
 
   this.decoder = null;
   this.encoding = null;
+
   if (options.encoding) {
     if (!StringDecoder)
       StringDecoder = require('string_decoder').StringDecoder;
@@ -102,11 +98,8 @@ Readable.prototype.push = function(chunk, encoding) {
   var state = this._readableState;
 
   if (!state.objectMode && typeof chunk === 'string') {
-    encoding = encoding || state.defaultEncoding;
-    if (encoding !== state.encoding) {
-      chunk = new Buffer(chunk, encoding);
-      encoding = '';
-    }
+    chunk = new Buffer(chunk, encoding);
+    encoding = '';
   }
 
   return readableAddChunk(this, state, chunk, encoding, false);

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

@@ -30,6 +30,63 @@ const Transform = require('stream').Transform;
   });
 })();
 
+(function() {
+  const readable = new Readable({
+    read: function(n) {
+      var i = this._index++;
+      if (i > this._max)
+        this.push(null);
+      else
+        this.push('中文', 'utf8');
+    }
+  });
+
+  readable._max = 5;
+  readable._index = 1;
+
+  var total = 0;
+  readable.setEncoding('utf8');
+  readable.on('data', function(chunk) {
+    total += Buffer.byteLength(chunk);
+  });
+
+  readable.on('end', function() {
+    assert.equal(total, readable.bytesRead);
+    assert.equal(30, readable.bytesRead);
+  });
+})();
+
+(function() {
+  // complex case
+  const readable = new Readable({
+    read: function(n) {
+      var i = this._index++;
+      if (i === 3)
+        this.push(null);
+      else if (i === 1) {
+        this.push(new Buffer([0xe4, 0xb8, 0xad, 0xe6, 0x96])); // 5 bytes
+      } else if (i === 2) {
+        this.push('中文'); // 6 bytes
+      }
+    }
+  });
+
+  readable._index = 1;
+
+  var total = 0;
+  readable.setEncoding('utf8');
+  readable.on('data', function(chunk) {
+    console.log(chunk);
+    total += Buffer.byteLength(chunk);
+    console.log(Buffer.byteLength(chunk));
+  });
+
+  readable.on('end', function() {
+    assert.equal(11, readable.bytesRead);
+    assert.equal(total, readable.bytesRead);
+  });
+})();
+
 (function() {
   const readable = new Readable({
     read: function(n) {