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: I08a246f4e7fbfdb8d58f4c5982ed0c9fa474f560
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>

9 files changed, 123 insertions, 6 deletions

diff --git a/src/network/access/qhttpnetworkreply.cpp b/src/network/access/qhttpnetworkreply.cpp
index acd4b55d8f..e52aa806cb 100644
--- a/src/network/access/qhttpnetworkreply.cpp
+++ b/src/network/access/qhttpnetworkreply.cpp
@@ -201,6 +201,18 @@ 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);
@@ -208,6 +220,12 @@ 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);
@@ -253,7 +271,7 @@ QHttpNetworkReplyPrivate::QHttpNetworkReplyPrivate(const QUrl &newUrl)
       connectionCloseEnabled(true),
       forceConnectionCloseEnabled(false),
       lastChunkRead(false),
-      currentChunkSize(0), currentChunkRead(0), connection(0), initInflate(false),
+      currentChunkSize(0), currentChunkRead(0), readBufferMaxSize(0), connection(0), initInflate(false),
       autoDecompress(false), responseData(), requestIsPrepared(false)
       ,pipeliningUsed(false), downstreamLimited(false)
       ,userProvidedDownloadBuffer(0)
@@ -699,6 +717,8 @@ 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);
@@ -746,6 +766,8 @@ qint64 QHttpNetworkReplyPrivate::readReplyBodyRaw(QAbstractSocket *socket, QByte
     Q_ASSERT(out);
 
     int toBeRead = qMin<qint64>(128*1024, qMin<qint64>(size, socket->bytesAvailable()));
+    if (readBufferMaxSize)
+        toBeRead = qMin<qint64>(toBeRead, readBufferMaxSize);
 
     while (toBeRead > 0) {
         QByteArray byteData;
@@ -772,6 +794,10 @@ 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;
diff --git a/src/network/access/qhttpnetworkreply_p.h b/src/network/access/qhttpnetworkreply_p.h
index 92b29cef0d..032dccb44b 100644
--- a/src/network/access/qhttpnetworkreply_p.h
+++ b/src/network/access/qhttpnetworkreply_p.h
@@ -128,7 +128,10 @@ 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*);
@@ -236,6 +239,7 @@ public:
     bool lastChunkRead;
     qint64 currentChunkSize;
     qint64 currentChunkRead;
+    qint64 readBufferMaxSize;
     QPointer<QHttpNetworkConnection> connection;
     QPointer<QHttpNetworkConnectionChannel> connectionChannel;
     bool initInflate;
diff --git a/src/network/access/qhttpthreaddelegate.cpp b/src/network/access/qhttpthreaddelegate.cpp
index 698ca2d127..d1203731cd 100644
--- a/src/network/access/qhttpthreaddelegate.cpp
+++ b/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 +351,57 @@ void QHttpThreadDelegate::abortRequest()
     }
 }
 
+void QHttpThreadDelegate::readBufferSizeChanged(qint64 size)
+{
+#ifdef QHTTPTHREADDELEGATE_DEBUG
+    qDebug() << "QHttpThreadDelegate::readBufferSizeChanged() size " << size;
+#endif
+    if (httpReply) {
+        httpReply->setDownstreamLimited(true);
+        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());
+        }
     }
 }
 
diff --git a/src/network/access/qhttpthreaddelegate_p.h b/src/network/access/qhttpthreaddelegate_p.h
index e43f38a7ae..c105ca2d01 100644
--- a/src/network/access/qhttpthreaddelegate_p.h
+++ b/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 +147,8 @@ 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:
diff --git a/src/network/access/qnetworkaccessbackend.cpp b/src/network/access/qnetworkaccessbackend.cpp
index 2869232e9a..db2243c6d0 100644
--- a/src/network/access/qnetworkaccessbackend.cpp
+++ b/src/network/access/qnetworkaccessbackend.cpp
@@ -164,6 +164,18 @@ void QNetworkAccessBackend::setDownstreamLimited(bool b)
     // do nothing
 }
 
+void QNetworkAccessBackend::setReadBufferSize(qint64 size)
+{
+    Q_UNUSED(size);
+    // do nothing
+}
+
+void QNetworkAccessBackend::emitReadBufferFreed(qint64 size)
+{
+    Q_UNUSED(size);
+    // do nothing
+}
+
 void QNetworkAccessBackend::copyFinished(QIODevice *)
 {
     // do nothing
diff --git a/src/network/access/qnetworkaccessbackend_p.h b/src/network/access/qnetworkaccessbackend_p.h
index f9563da4a7..cc3df80999 100644
--- a/src/network/access/qnetworkaccessbackend_p.h
+++ b/src/network/access/qnetworkaccessbackend_p.h
@@ -116,6 +116,8 @@ public:
     // slot-like:
     virtual void downstreamReadyWrite();
     virtual void setDownstreamLimited(bool b);
+    virtual void setReadBufferSize(qint64 size);
+    virtual void emitReadBufferFreed(qint64 size);
     virtual void copyFinished(QIODevice *);
     virtual void ignoreSslErrors();
     virtual void ignoreSslErrors(const QList<QSslError> &errors);
diff --git a/src/network/access/qnetworkaccesshttpbackend.cpp b/src/network/access/qnetworkaccesshttpbackend.cpp
index db2b83ed83..0b2af93a85 100644
--- a/src/network/access/qnetworkaccesshttpbackend.cpp
+++ b/src/network/access/qnetworkaccesshttpbackend.cpp
@@ -598,6 +598,10 @@ void QNetworkAccessHttpBackend::postRequest()
         connect(this, SIGNAL(startHttpRequest()), delegate, SLOT(startRequest()));
         connect(this, SIGNAL(abortHttpRequest()), delegate, SLOT(abortRequest()));
 
+        // To throttle the connection.
+        QObject::connect(this, SIGNAL(readBufferSizeChanged(qint64)), delegate, SLOT(readBufferSizeChanged(qint64)));
+        QObject::connect(this, SIGNAL(readBufferFreed(qint64)), delegate, SLOT(readBufferFreed(qint64)));
+
         if (uploadByteDevice) {
             QNonContiguousByteDeviceThreadForwardImpl *forwardUploadDevice =
                     new QNonContiguousByteDeviceThreadForwardImpl(uploadByteDevice->atEnd(), uploadByteDevice->size());
@@ -705,6 +709,16 @@ void QNetworkAccessHttpBackend::setDownstreamLimited(bool b)
     // The task to fix this is QTBUG-15065
 }
 
+void QNetworkAccessHttpBackend::setReadBufferSize(qint64 size)
+{
+    emit readBufferSizeChanged(size);
+}
+
+void QNetworkAccessHttpBackend::emitReadBufferFreed(qint64 size)
+{
+    emit readBufferFreed(size);
+}
+
 void QNetworkAccessHttpBackend::replyDownloadData(QByteArray d)
 {
     int pendingSignals = (int)pendingDownloadDataEmissions->fetchAndAddAcquire(-1) - 1;
diff --git a/src/network/access/qnetworkaccesshttpbackend_p.h b/src/network/access/qnetworkaccesshttpbackend_p.h
index 273b7ee1c4..c5c20736ff 100644
--- a/src/network/access/qnetworkaccesshttpbackend_p.h
+++ b/src/network/access/qnetworkaccesshttpbackend_p.h
@@ -84,6 +84,8 @@ public:
 
     virtual void downstreamReadyWrite();
     virtual void setDownstreamLimited(bool b);
+    virtual void setReadBufferSize(qint64 size);
+    virtual void emitReadBufferFreed(qint64 size);
 
     virtual void copyFinished(QIODevice *);
 #ifndef QT_NO_OPENSSL
@@ -105,6 +107,8 @@ signals:
     // To HTTP thread:
     void startHttpRequest();
     void abortHttpRequest();
+    void readBufferSizeChanged(qint64 size);
+    void readBufferFreed(qint64 size);
 
     void startHttpRequestSynchronously();
 
diff --git a/src/network/access/qnetworkreplyimpl.cpp b/src/network/access/qnetworkreplyimpl.cpp
index a94bb0f41d..b0e81e910f 100644
--- a/src/network/access/qnetworkreplyimpl.cpp
+++ b/src/network/access/qnetworkreplyimpl.cpp
@@ -946,8 +946,10 @@ void QNetworkReplyImpl::setReadBufferSize(qint64 size)
 
     QNetworkReply::setReadBufferSize(size);
 
-    if (d->backend)
+    if (d->backend) {
         d->backend->setDownstreamLimited(d->readBufferMaxSize > 0);
+        d->backend->setReadBufferSize(size);
+    }
 }
 
 #ifndef QT_NO_OPENSSL
@@ -1009,11 +1011,16 @@ qint64 QNetworkReplyImpl::readData(char *data, qint64 maxlen)
     if (maxlen == 1) {
         // optimization for getChar()
         *data = d->readBuffer.getChar();
+        if (d->backend && readBufferSize())
+            d->backend->emitReadBufferFreed(1);
         return 1;
     }
 
     maxlen = qMin<qint64>(maxlen, d->readBuffer.byteAmount());
-    return d->readBuffer.read(data, maxlen);
+    qint64 bytesRead = d->readBuffer.read(data, maxlen);
+    if (d->backend && readBufferSize())
+        d->backend->emitReadBufferFreed(bytesRead);
+    return bytesRead;
 }
 
 /*!