QNAM: More zerocopy changes

The zerocopy download buffer is now QSharedPointer<char>
instead of the QSharedPointer to QVarLengthArray<char>.
This will be a bit leaner to handle by QML and QtWebKit
and does not tie us to a QVLA that much.
Also fix some bugs related to signal emissions and the
return value of bytesAvailable(). Now the behaviour should be
the same if a zerocopy buffer is used or not.

Reviewed-by: Peter Hartmann
Reviewed-by: Thiago Macieira

3 files changed, 30 insertions, 23 deletions

diff --git a/src/network/access/qhttpnetworkconnectionchannel.cpp b/src/network/access/qhttpnetworkconnectionchannel.cpp
index e39f9ed..617602d 100644
--- a/src/network/access/qhttpnetworkconnectionchannel.cpp
+++ b/src/network/access/qhttpnetworkconnectionchannel.cpp
@@ -427,7 +427,8 @@ void QHttpNetworkConnectionChannel::_q_receiveReply()
                replyPrivate->totalProgress += haveRead;
 
                // the user will get notified of it via progress signal
-               emit reply->dataReadProgress(replyPrivate->totalProgress, replyPrivate->bodyLength);
+               if (haveRead > 0)
+                   emit reply->dataReadProgress(replyPrivate->totalProgress, replyPrivate->bodyLength);
            } else if (!replyPrivate->isChunked() && !replyPrivate->autoDecompress
                  && replyPrivate->bodyLength > 0) {
                  // bulk files like images should fulfill these properties and
diff --git a/src/network/access/qnetworkreplyimpl.cpp b/src/network/access/qnetworkreplyimpl.cpp
index 3a629cf..2dbd21c 100644
--- a/src/network/access/qnetworkreplyimpl.cpp
+++ b/src/network/access/qnetworkreplyimpl.cpp
@@ -49,16 +49,12 @@
 #include "QtNetwork/qnetworksession.h"
 #include "qnetworkaccesshttpbackend_p.h"
 #include "qnetworkaccessmanager_p.h"
-#include <QVarLengthArray>
 
 #include <QtCore/QCoreApplication>
 
 QT_BEGIN_NAMESPACE
-typedef QSharedPointer<QVarLengthArray<char, 0> > QVarLengthArraySharedPointer;
-QT_END_NAMESPACE
-Q_DECLARE_METATYPE(QVarLengthArraySharedPointer)
 
-QT_BEGIN_NAMESPACE
+Q_DECLARE_METATYPE(QSharedPointer<char>)
 
 inline QNetworkReplyImplPrivate::QNetworkReplyImplPrivate()
     : backend(0), outgoingData(0), outgoingDataBuffer(0),
@@ -69,7 +65,9 @@ inline QNetworkReplyImplPrivate::QNetworkReplyImplPrivate()
       httpStatusCode(0),
       state(Idle)
       , downloadBuffer(0)
-      , downloadBufferPosition(0)
+      , downloadBufferReadPosition(0)
+      , downloadBufferCurrentSize(0)
+      , downloadBufferMaximumSize(0)
 {
 }
 
@@ -603,6 +601,11 @@ void QNetworkReplyImplPrivate::appendDownstreamData(const QByteArray &data)
     qFatal("QNetworkReplyImplPrivate::appendDownstreamData not implemented");
 }
 
+static void downloadBufferDeleter(char *ptr)
+{
+    delete[] ptr;
+}
+
 char* QNetworkReplyImplPrivate::getDownloadBuffer(qint64 size)
 {
     Q_Q(QNetworkReplyImpl);
@@ -611,12 +614,12 @@ char* QNetworkReplyImplPrivate::getDownloadBuffer(qint64 size)
     if (!downloadBuffer) {
         QVariant bufferAllocationPolicy = request.attribute(QNetworkRequest::MaximumDownloadBufferSizeAttribute);
         if (bufferAllocationPolicy.isValid() && bufferAllocationPolicy.toLongLong() >= size) {
-            downloadBufferArray = QSharedPointer<QVarLengthArray<char, 0> >(new QVarLengthArray<char, 0>());
-            downloadBufferArray->reserve(size);
-
-            downloadBuffer = downloadBufferArray->data();
+            downloadBufferCurrentSize = 0;
+            downloadBufferMaximumSize = size;
+            downloadBuffer = new char[downloadBufferMaximumSize]; // throws if allocation fails
+            downloadBufferPointer = QSharedPointer<char>(downloadBuffer, downloadBufferDeleter);
 
-            q->setAttribute(QNetworkRequest::DownloadBufferAttribute, qVariantFromValue<QSharedPointer<QVarLengthArray<char, 0> > > (downloadBufferArray));
+            q->setAttribute(QNetworkRequest::DownloadBufferAttribute, qVariantFromValue<QSharedPointer<char> > (downloadBufferPointer));
         }
     }
 
@@ -644,12 +647,12 @@ void QNetworkReplyImplPrivate::appendDownstreamDataDownloadBuffer(qint64 bytesRe
     bytesDownloaded = bytesReceived;
     lastBytesDownloaded = bytesReceived;
 
-    // Update the array so our user (e.g. QtWebKit) knows the real size
-    if (bytesReceived > 0)
-        downloadBufferArray->resize(bytesReceived);
+    downloadBufferCurrentSize = bytesReceived;
 
     emit q->downloadProgress(bytesDownloaded, bytesTotal);
-    emit q->readyRead();
+    // Only emit readyRead when actual data is there
+    if (bytesDownloaded > 0)
+        emit q->readyRead();
 }
 
 void QNetworkReplyImplPrivate::finished()
@@ -846,7 +849,7 @@ qint64 QNetworkReplyImpl::bytesAvailable() const
     // Special case for the "zero copy" download buffer
     Q_D(const QNetworkReplyImpl);
     if (d->downloadBuffer) {
-        qint64 maxAvail = d->downloadBufferArray->size() - d->downloadBufferPosition;
+        qint64 maxAvail = d->downloadBufferCurrentSize - d->downloadBufferReadPosition;
         return QNetworkReply::bytesAvailable() + maxAvail;
     }
 
@@ -907,12 +910,12 @@ qint64 QNetworkReplyImpl::readData(char *data, qint64 maxlen)
 
     // Special case code if we have the "zero copy" download buffer
     if (d->downloadBuffer) {
-        qint64 maxAvail = qMin<qint64>(d->downloadBufferArray->size() - d->downloadBufferPosition, maxlen);
+        qint64 maxAvail = qMin<qint64>(d->downloadBufferCurrentSize - d->downloadBufferReadPosition, maxlen);
         if (maxAvail == 0)
             return d->state == QNetworkReplyImplPrivate::Finished ? -1 : 0;
         // FIXME what about "Aborted" state?
-        qMemCopy(data, d->downloadBuffer + d->downloadBufferPosition, maxAvail);
-        d->downloadBufferPosition += maxAvail;
+        qMemCopy(data, d->downloadBuffer + d->downloadBufferReadPosition, maxAvail);
+        d->downloadBufferReadPosition += maxAvail;
         return maxAvail;
     }
 
diff --git a/src/network/access/qnetworkreplyimpl_p.h b/src/network/access/qnetworkreplyimpl_p.h
index 2cb3082..e944601 100644
--- a/src/network/access/qnetworkreplyimpl_p.h
+++ b/src/network/access/qnetworkreplyimpl_p.h
@@ -62,7 +62,7 @@
 #include "QtCore/qbuffer.h"
 #include "private/qringbuffer_p.h"
 #include "private/qbytedata_p.h"
-#include <QVarLengthArray>
+#include <QSharedPointer>
 
 QT_BEGIN_NAMESPACE
 
@@ -206,9 +206,12 @@ public:
     State state;
 
     // only used when the "zero copy" style is used. Else readBuffer is used.
-    QSharedPointer< QVarLengthArray<char, 0> > downloadBufferArray;
+    // Please note that the whole "zero copy" download buffer API is private right now. Do not use it.
+    qint64 downloadBufferReadPosition;
+    qint64 downloadBufferCurrentSize;
+    qint64 downloadBufferMaximumSize;
+    QSharedPointer<char> downloadBufferPointer;
     char* downloadBuffer;
-    qint64 downloadBufferPosition;
 
     Q_DECLARE_PUBLIC(QNetworkReplyImpl)
 };