QNAM HTTP: Do zero-copy for small HTTP replies by default

Task-Number: QTBUG-19046

Change-Id: I34bf432c81d94787524124b7d110a00305a660c1
Reviewed-on: http://codereview.qt.nokia.com/1516
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Martin Petersson <Martin.Petersson@nokia.com>
Reviewed-by: Peter Hartmann <peter.hartmann@nokia.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/src/network/access/qnetworkreplyhttpimpl.cpp b/src/network/access/qnetworkreplyhttpimpl.cpp
index df0a32dd6c..52cbaae5e0 100644
--- a/src/network/access/qnetworkreplyhttpimpl.cpp
+++ b/src/network/access/qnetworkreplyhttpimpl.cpp
@@ -777,8 +777,16 @@ void QNetworkReplyHttpImplPrivate::postRequest()
 
     if (!synchronous) {
         // Tell our zerocopy policy to the delegate
-        delegate->downloadBufferMaximumSize =
-                request.attribute(QNetworkRequest::MaximumDownloadBufferSizeAttribute).toLongLong();
+        QVariant downloadBufferMaximumSizeAttribute = request.attribute(QNetworkRequest::MaximumDownloadBufferSizeAttribute);
+        if (downloadBufferMaximumSizeAttribute.isValid()) {
+            delegate->downloadBufferMaximumSize = downloadBufferMaximumSizeAttribute.toLongLong();
+        } else {
+            // If there is no MaximumDownloadBufferSizeAttribute set (which is for the majority
+            // of QNetworkRequest) then we can assume we'll do it anyway for small HTTP replies.
+            // This helps with performance and memory fragmentation.
+            delegate->downloadBufferMaximumSize = 128*1024;
+        }
+
 
         // These atomic integers are used for signal compression
         delegate->pendingDownloadData = pendingDownloadDataEmissions;