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

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index a965afa43fe2f18dc4ce986a393e02a64429dd15..40d909d0283213ab071218b464f464e1553833d7 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -574,29 +574,20 @@ class _HttpResponse extends _HttpOutboundMessage<HttpResponse>
   }
 
   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) {
@@ -630,10 +621,11 @@ class _HttpResponse extends _HttpOutboundMessage<HttpResponse>
     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) {
@@ -1160,7 +1152,6 @@ class _HttpOutgoing implements StreamConsumer<List<int>> {
 
   void setHeader(List<int> data, int length) {
     assert(_length == 0);
-    assert(data.length == _OUTGOING_BUFFER_SIZE);
     _buffer = data;
     _length = length;
   }