QNetworkAccessManager: HTTP download performance improvements

Better usage of move semantics with implicit sharing to avoid
detaching (=malloc/memcpy). Also some other improvements.
Download performance improvement is around 20% according
to the httpDownloadPerformance autotest.

Reviewed-by: Thiago Macieira

1 files changed, 8 insertions, 3 deletions

diff --git a/src/network/access/qnetworkaccesshttpbackend.cpp b/src/network/access/qnetworkaccesshttpbackend.cpp
index db84e58..9c36026 100644
--- a/src/network/access/qnetworkaccesshttpbackend.cpp
+++ b/src/network/access/qnetworkaccesshttpbackend.cpp
@@ -653,10 +653,15 @@ void QNetworkAccessHttpBackend::readFromHttp()
     // this is not a critical thing since it is already in the
     // memory anyway
 
-    while (httpReply->bytesAvailable() != 0 && nextDownstreamBlockSize() != 0) {
-        const QByteArray data = httpReply->readAny();
-        writeDownstreamData(data);
+    QByteDataBuffer list;
+
+    while (httpReply->bytesAvailable() != 0 && nextDownstreamBlockSize() != 0 && nextDownstreamBlockSize() > list.byteAmount()) {
+        QByteArray data = httpReply->readAny();
+        list.append(data);
     }
+
+    if (!list.isEmpty())
+      writeDownstreamData(list);
 }
 
 void QNetworkAccessHttpBackend::replyFinished()