Make HTTP headers use a growing buffer, not a fixed-size 8K one.

sdk/lib/io/http_impl.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 const int _OUTGOING_BUFFER_SIZE = 8 * 1024;
 
 typedef void _BytesConsumer(List<int> bytes);
 
@@ skipping 556 matching lines @@
     if (_deadlineTimer != null) _deadlineTimer.cancel();
     _deadline = d;
 
     if (_deadline == null) return;
     _deadlineTimer = new Timer(_deadline, () {
       _httpRequest._httpConnection.destroy();
     });
   }
 
   void _writeHeader() {
-    Uint8List buffer = new Uint8List(_OUTGOING_BUFFER_SIZE);
-    int offset = 0;
-
-    void write(List<int> bytes) {
-      int len = bytes.length;
-      for (int i = 0; i < len; i++) {
-        buffer[offset + i] = bytes[i];
-      }
-      offset += len;
-    }
+    BytesBuilder buffer = new _CopyingBytesBuilder(_OUTGOING_BUFFER_SIZE);
 
     // Write status line.
     if (headers.protocolVersion == "1.1") {
-      write(_Const.HTTP11);
+      buffer.add(_Const.HTTP11);
     } else {
-      write(_Const.HTTP10);
+      buffer.add(_Const.HTTP10);
     }
-    buffer[offset++] = _CharCode.SP;
-    write(statusCode.toString().codeUnits);
-    buffer[offset++] = _CharCode.SP;
-    write(reasonPhrase.codeUnits);
-    buffer[offset++] = _CharCode.CR;
-    buffer[offset++] = _CharCode.LF;
+    buffer.addByte(_CharCode.SP);
+    buffer.add(statusCode.toString().codeUnits);
+    buffer.addByte(_CharCode.SP);
+    buffer.add(reasonPhrase.codeUnits);
+    buffer.addByte(_CharCode.CR);
+    buffer.addByte(_CharCode.LF);
 
     var session = _httpRequest._session;
     if (session != null && !session._destroyed) {
       // Mark as not new.
       session._isNew = false;
       // Make sure we only send the current session id.
       bool found = false;
       for (int i = 0; i < cookies.length; i++) {
         if (cookies[i].name.toUpperCase() == _DART_SESSION_ID) {
           cookies[i]
@@ skipping 13 matching lines @@
     // Add all the cookies set to the headers.
     if (_cookies != null) {
       _cookies.forEach((cookie) {
         headers.add(HttpHeaders.SET_COOKIE, cookie);
       });
     }
 
     headers._finalize();
 
     // Write headers.
-    offset = headers._write(buffer, offset);

[Søren Gjesse, 2017/01/05 14:22:12]

Is headers._write still used?

[Lasse Reichstein Nielsen, 2017/01/13 06:22:59]

There is another implementation of _writeHeaders, so I fixed that one too, then
_write could be removed.

-    buffer[offset++] = _CharCode.CR;
-    buffer[offset++] = _CharCode.LF;
-    _outgoing.setHeader(buffer, offset);
+    headers._build(buffer);
+    buffer.addByte(_CharCode.CR);
+    buffer.addByte(_CharCode.LF);
+    Uint8List headerBytes = buffer.takeBytes();
+    _outgoing.setHeader(headerBytes, headerBytes.length);
   }
 
   String _findReasonPhrase(int statusCode) {
     if (_reasonPhrase != null) {
       return _reasonPhrase;
     }
 
     switch (statusCode) {
       case HttpStatus.CONTINUE: return "Continue";
       case HttpStatus.SWITCHING_PROTOCOLS: return "Switching Protocols";
@@ skipping 506 matching lines @@
     if (future != null) {
       return _closeFuture = future.whenComplete(finalize);
     }
     return _closeFuture = finalize();
   }
 
   Future<Socket> get done => _doneCompleter.future;
 
   void setHeader(List<int> data, int length) {
     assert(_length == 0);
-    assert(data.length == _OUTGOING_BUFFER_SIZE);
     _buffer = data;
     _length = length;
   }
 
   void set gzip(bool value) {
     _gzip = value;
     if (_gzip) {
       _gzipBuffer = new Uint8List(_OUTGOING_BUFFER_SIZE);
       assert(_gzipSink == null);
       _gzipSink = new ZLibEncoder(gzip: true)
@@ skipping 1717 matching lines @@
   const _RedirectInfo(this.statusCode, this.method, this.location);
 }
 
 String _getHttpVersion() {
   var version = Platform.version;
   // Only include major and minor version numbers.
   int index = version.indexOf('.', version.indexOf('.') + 1);
   version = version.substring(0, index);
   return 'Dart/$version (dart:io)';
 }