QNetworkReply::setReadBufferSize fix for threaded http

Added the setReadBufferSize functionallity again by limiting the
amount that the delegate read from the channel. Each time that data is
fetched from the reply buffer, we communicate back to the thread so
that more data can be fetched.

Task-number: QTBUG-25327
Change-Id: I2f9950196e64acd09bc8da50c1116f2c9deacad4
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/network/access/qhttpnetworkreply.cpp

@@ -206,6 +206,19 @@ QByteArray QHttpNetworkReply::readAll()
     return d->responseData.readAll();
 }
 
+QByteArray QHttpNetworkReply::read(qint64 amount)
+{
+    Q_D(QHttpNetworkReply);
+    return d->responseData.read(amount);
+}
+
+
+qint64 QHttpNetworkReply::sizeNextBlock()
+{
+    Q_D(QHttpNetworkReply);
+    return d->responseData.sizeNextBlock();
+}
+
 void QHttpNetworkReply::setDownstreamLimited(bool dsl)
 {
     Q_D(QHttpNetworkReply);
@@ -213,6 +226,12 @@ void QHttpNetworkReply::setDownstreamLimited(bool dsl)
     d->connection->d_func()->readMoreLater(this);
 }
 
+void QHttpNetworkReply::setReadBufferSize(qint64 size)
+{
+    Q_D(QHttpNetworkReply);
+    d->readBufferMaxSize = size;
+}
+
 bool QHttpNetworkReply::supportsUserProvidedDownloadBuffer()
 {
     Q_D(QHttpNetworkReply);
@@ -258,7 +277,7 @@ QHttpNetworkReplyPrivate::QHttpNetworkReplyPrivate(const QUrl &newUrl)
       connectionCloseEnabled(true),
       forceConnectionCloseEnabled(false),
       lastChunkRead(false),
-      currentChunkSize(0), currentChunkRead(0), connection(0),
+      currentChunkSize(0), currentChunkRead(0), readBufferMaxSize(0), connection(0),
       autoDecompress(false), responseData(), requestIsPrepared(false)
       ,pipeliningUsed(false), downstreamLimited(false)
       ,userProvidedDownloadBuffer(0)
@@ -598,6 +617,10 @@ qint64 QHttpNetworkReplyPrivate::readBodyFast(QAbstractSocket *socket, QByteData
 {
 
     qint64 toBeRead = qMin(socket->bytesAvailable(), bodyLength - contentRead);
+    if (readBufferMaxSize)
+        toBeRead = qMin(toBeRead, readBufferMaxSize);
+
+
     QByteArray bd;
     bd.resize(toBeRead);
     qint64 haveRead = socket->read(bd.data(), toBeRead);
@@ -698,6 +721,9 @@ qint64 QHttpNetworkReplyPrivate::readReplyBodyRaw(QAbstractSocket *socket, QByte
 
     int toBeRead = qMin<qint64>(128*1024, qMin<qint64>(size, socket->bytesAvailable()));
 
+    if (readBufferMaxSize)
+        toBeRead = qMin<qint64>(toBeRead, readBufferMaxSize);
+
     while (toBeRead > 0) {
         QByteArray byteData;
         byteData.resize(toBeRead);
@@ -723,6 +749,10 @@ qint64 QHttpNetworkReplyPrivate::readReplyBodyChunked(QAbstractSocket *socket, Q
 {
     qint64 bytes = 0;
     while (socket->bytesAvailable()) {
+
+        if (readBufferMaxSize && (bytes > readBufferMaxSize))
+            break;
+
         if (!lastChunkRead && currentChunkRead >= currentChunkSize) {
             // For the first chunk and when we're done with a chunk
             currentChunkSize = 0;

src/network/access/qhttpnetworkreply_p.h

@@ -120,7 +120,10 @@ public:
     bool readAnyAvailable() const;
     QByteArray readAny();
     QByteArray readAll();
+    QByteArray read(qint64 amount);
+    qint64 sizeNextBlock();
     void setDownstreamLimited(bool t);
+    void setReadBufferSize(qint64 size);
 
     bool supportsUserProvidedDownloadBuffer();
     void setUserProvidedDownloadBuffer(char*);
@@ -220,6 +223,7 @@ public:
     bool lastChunkRead;
     qint64 currentChunkSize;
     qint64 currentChunkRead;
+    qint64 readBufferMaxSize;
     QPointer<QHttpNetworkConnection> connection;
     QPointer<QHttpNetworkConnectionChannel> connectionChannel;
 

src/network/access/qhttpthreaddelegate.cpp

@@ -194,6 +194,8 @@ QHttpThreadDelegate::QHttpThreadDelegate(QObject *parent) :
     QObject(parent)
     , ssl(false)
     , downloadBufferMaximumSize(0)
+    , readBufferMaxSize(0)
+    , bytesEmitted(0)
     , pendingDownloadData(0)
     , pendingDownloadProgress(0)
     , synchronous(false)
@@ -349,15 +351,58 @@ void QHttpThreadDelegate::abortRequest()
     }
 }
 
+void QHttpThreadDelegate::readBufferSizeChanged(qint64 size)
+{
+#ifdef QHTTPTHREADDELEGATE_DEBUG
+    qDebug() << "QHttpThreadDelegate::readBufferSizeChanged() size " << size;
+#endif
+    if (httpReply) {
+        httpReply->setDownstreamLimited(size > 0);
+        httpReply->setReadBufferSize(size);
+        readBufferMaxSize = size;
+    }
+}
+
+void QHttpThreadDelegate::readBufferFreed(qint64 size)
+{
+    if (readBufferMaxSize) {
+        bytesEmitted -= size;
+
+        QMetaObject::invokeMethod(this, "readyReadSlot", Qt::QueuedConnection);
+    }
+}
+
 void QHttpThreadDelegate::readyReadSlot()
 {
     // Don't do in zerocopy case
     if (!downloadBuffer.isNull())
         return;
 
-    while (httpReply->readAnyAvailable()) {
-        pendingDownloadData->fetchAndAddRelease(1);
-        emit downloadData(httpReply->readAny());
+    if (readBufferMaxSize) {
+        if (bytesEmitted < readBufferMaxSize) {
+            qint64 sizeEmitted = 0;
+            while (httpReply->readAnyAvailable() && (sizeEmitted < (readBufferMaxSize-bytesEmitted))) {
+                if (httpReply->sizeNextBlock() > (readBufferMaxSize-bytesEmitted)) {
+                    sizeEmitted = readBufferMaxSize-bytesEmitted;
+                    bytesEmitted += sizeEmitted;
+                    pendingDownloadData->fetchAndAddRelease(1);
+                    emit downloadData(httpReply->read(sizeEmitted));
+                } else {
+                    sizeEmitted = httpReply->sizeNextBlock();
+                    bytesEmitted += sizeEmitted;
+                    pendingDownloadData->fetchAndAddRelease(1);
+                    emit downloadData(httpReply->readAny());
+                }
+            }
+        } else {
+            // We need to wait until we empty data from the read buffer in the reply.
+        }
+
+    } else {
+        while (httpReply->readAnyAvailable()) {
+            pendingDownloadData->fetchAndAddRelease(1);
+            emit downloadData(httpReply->readAny());
+        }
     }
 }
 

src/network/access/qhttpthreaddelegate_p.h

@@ -93,6 +93,8 @@ public:
 #endif
     QHttpNetworkRequest httpRequest;
     qint64 downloadBufferMaximumSize;
+    qint64 readBufferMaxSize;
+    qint64 bytesEmitted;
     // From backend, modified by us for signal compression
     QSharedPointer<QAtomicInt> pendingDownloadData;
     QSharedPointer<QAtomicInt> pendingDownloadProgress;
@@ -145,6 +147,9 @@ public slots:
     // This are called via QueuedConnection from user thread
     void startRequest();
     void abortRequest();
+    void readBufferSizeChanged(qint64 size);
+    void readBufferFreed(qint64 size);
+
     // This is called with a BlockingQueuedConnection from user thread
     void startRequestSynchronously();
 protected slots:

src/network/access/qnetworkreplyhttpimpl.cpp

@@ -357,17 +357,22 @@ qint64 QNetworkReplyHttpImpl::readData(char* data, qint64 maxlen)
     if (maxlen == 1) {
         // optimization for getChar()
         *data = d->downloadMultiBuffer.getChar();
+        if (readBufferSize())
+            emit readBufferFreed(1);
         return 1;
     }
 
     maxlen = qMin<qint64>(maxlen, d->downloadMultiBuffer.byteAmount());
-    return d->downloadMultiBuffer.read(data, maxlen);
+    qint64 bytesRead = d->downloadMultiBuffer.read(data, maxlen);
+    if (readBufferSize())
+        emit readBufferFreed(bytesRead);
+    return bytesRead;
 }
 
 void QNetworkReplyHttpImpl::setReadBufferSize(qint64 size)
 {
-    Q_UNUSED(size);
-    // FIXME, unsupported right now
+    QNetworkReply::setReadBufferSize(size);
+    emit readBufferSizeChanged(size);
     return;
 }
 
@@ -839,6 +844,10 @@ void QNetworkReplyHttpImplPrivate::postRequest()
         QObject::connect(q, SIGNAL(startHttpRequest()), delegate, SLOT(startRequest()));
         QObject::connect(q, SIGNAL(abortHttpRequest()), delegate, SLOT(abortRequest()));
 
+        // To throttle the connection.
+        QObject::connect(q, SIGNAL(readBufferSizeChanged(qint64)), delegate, SLOT(readBufferSizeChanged(qint64)));
+        QObject::connect(q, SIGNAL(readBufferFreed(qint64)), delegate, SLOT(readBufferFreed(qint64)));
+
         if (uploadByteDevice) {
             QNonContiguousByteDeviceThreadForwardImpl *forwardUploadDevice =
                     new QNonContiguousByteDeviceThreadForwardImpl(uploadByteDevice->atEnd(), uploadByteDevice->size());

src/network/access/qnetworkreplyhttpimpl_p.h

@@ -139,6 +139,8 @@ signals:
     // To HTTP thread:
     void startHttpRequest();
     void abortHttpRequest();
+    void readBufferSizeChanged(qint64 size);
+    void readBufferFreed(qint64 size);
 
     void startHttpRequestSynchronously();