QNAM - maintain a weak reference to the QNetworkSession

When handling signals from the session, a pointer is needed.
Also the QNetworkReplyImpl needs to access the manager's session.
So, the manager should have a strong and weak reference.
The strong reference is held during connection establishment.
The weak reference is held all the time, though it will become
null when the session is destroyed in idle.
The non static member function getNetworkSession() is used to
create strong references from the weak reference where required.

Task-number: ou1cimx#1004278
Change-Id: I4b5b36b1d996b98e659d993969006c61b4440c15
Reviewed-by: Martin Petersson <Martin.Petersson@nokia.com>
(backported from commit bae1613c4c3d8c38b90ed2ba5c1b149e1bc87987)

4 files changed, 49 insertions, 31 deletions

diff --git a/src/network/access/qnetworkaccessbackend.cpp b/src/network/access/qnetworkaccessbackend.cpp
index db2243c..41b0b4e 100644
--- a/src/network/access/qnetworkaccessbackend.cpp
+++ b/src/network/access/qnetworkaccessbackend.cpp
@@ -370,13 +370,14 @@ bool QNetworkAccessBackend::start()
 {
 #ifndef QT_NO_BEARERMANAGEMENT
     // For bearer, check if session start is required
-    if (manager->networkSession) {
+    QSharedPointer<QNetworkSession> networkSession(manager->getNetworkSession());
+    if (networkSession) {
         // session required
-        if (manager->networkSession->isOpen() &&
-            manager->networkSession->state() == QNetworkSession::Connected) {
+        if (networkSession->isOpen() &&
+            networkSession->state() == QNetworkSession::Connected) {
             // Session is already open and ready to use.
             // copy network session down to the backend
-            setProperty("_q_networksession", QVariant::fromValue(manager->networkSession));
+            setProperty("_q_networksession", QVariant::fromValue(networkSession));
         } else {
             // Session not ready, but can skip for loopback connections
 
@@ -399,7 +400,7 @@ bool QNetworkAccessBackend::start()
 #ifndef QT_NO_BEARERMANAGEMENT
     // Get the proxy settings from the network session (in the case of service networks,
     // the proxy settings change depending which AP was activated)
-    QNetworkSession *session = manager->networkSession.data();
+    QNetworkSession *session = networkSession.data();
     QNetworkConfiguration config;
     if (session) {
         QNetworkConfigurationManager configManager;
diff --git a/src/network/access/qnetworkaccessmanager.cpp b/src/network/access/qnetworkaccessmanager.cpp
index 768c135..92ece46 100644
--- a/src/network/access/qnetworkaccessmanager.cpp
+++ b/src/network/access/qnetworkaccessmanager.cpp
@@ -772,8 +772,9 @@ QNetworkConfiguration QNetworkAccessManager::configuration() const
 {
     Q_D(const QNetworkAccessManager);
 
-    if (d->networkSession)
-        return d->networkSession->configuration();
+    QSharedPointer<QNetworkSession> session(d->getNetworkSession());
+    if (session)
+        return session->configuration();
     else
         return QNetworkConfiguration();
 }
@@ -797,11 +798,12 @@ QNetworkConfiguration QNetworkAccessManager::activeConfiguration() const
 {
     Q_D(const QNetworkAccessManager);
 
-    if (d->networkSession) {
+    QSharedPointer<QNetworkSession> networkSession(d->getNetworkSession());
+    if (networkSession) {
         QNetworkConfigurationManager manager;
 
         return manager.configurationFromIdentifier(
-            d->networkSession->sessionProperty(QLatin1String("ActiveConfiguration")).toString());
+            networkSession->sessionProperty(QLatin1String("ActiveConfiguration")).toString());
     } else {
         return QNetworkConfiguration();
     }
@@ -836,7 +838,8 @@ QNetworkAccessManager::NetworkAccessibility QNetworkAccessManager::networkAccess
 {
     Q_D(const QNetworkAccessManager);
 
-    if (d->networkSession) {
+    QSharedPointer<QNetworkSession> networkSession(d->getNetworkSession());
+    if (networkSession) {
         // d->online holds online/offline state of this network session.
         if (d->online)
             return d->networkAccessible;
@@ -848,6 +851,13 @@ QNetworkAccessManager::NetworkAccessibility QNetworkAccessManager::networkAccess
     }
 }
 
+QSharedPointer<QNetworkSession> QNetworkAccessManagerPrivate::getNetworkSession() const
+{
+    if (networkSessionStrongRef)
+        return networkSessionStrongRef;
+    return networkSessionWeakRef.toStrongRef();
+}
+
 #endif // QT_NO_BEARERMANAGEMENT
 
 /*!
@@ -937,7 +947,7 @@ QNetworkReply *QNetworkAccessManager::createRequest(QNetworkAccessManager::Opera
         return new QDisabledNetworkReply(this, req, op);
     }
 
-    if (!d->networkSession && (d->initializeSession || !d->networkConfiguration.isEmpty())) {
+    if (!d->networkSessionStrongRef && (d->initializeSession || !d->networkConfiguration.isEmpty())) {
         QNetworkConfigurationManager manager;
         if (!d->networkConfiguration.isEmpty()) {
             d->createSession(manager.configurationFromIdentifier(d->networkConfiguration));
@@ -1015,8 +1025,8 @@ void QNetworkAccessManagerPrivate::_q_replyFinished()
     // It will not be destroyed immediately, but rather when the connection cache is flushed
     // after 2 minutes.
     activeReplyCount--;
-    if (networkSession && activeReplyCount == 0)
-        networkSession.clear();
+    if (networkSessionStrongRef && activeReplyCount == 0)
+        networkSessionStrongRef.clear();
 #endif
 }
 
@@ -1178,25 +1188,29 @@ void QNetworkAccessManagerPrivate::createSession(const QNetworkConfiguration &co
 
     initializeSession = false;
 
+    //resurrect weak ref if possible
+    networkSessionStrongRef = networkSessionWeakRef.toStrongRef();
+
     QSharedPointer<QNetworkSession> newSession;
     if (config.isValid())
         newSession = QSharedNetworkSessionManager::getSession(config);
 
-    if (networkSession) {
+    if (networkSessionStrongRef) {
         //do nothing if new and old session are the same
-        if (networkSession == newSession)
+        if (networkSessionStrongRef == newSession)
             return;
         //disconnect from old session
-        QObject::disconnect(networkSession.data(), SIGNAL(opened()), q, SIGNAL(networkSessionConnected()));
-        QObject::disconnect(networkSession.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()));
-        QObject::disconnect(networkSession.data(), SIGNAL(stateChanged(QNetworkSession::State)),
+        QObject::disconnect(networkSessionStrongRef.data(), SIGNAL(opened()), q, SIGNAL(networkSessionConnected()));
+        QObject::disconnect(networkSessionStrongRef.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()));
+        QObject::disconnect(networkSessionStrongRef.data(), SIGNAL(stateChanged(QNetworkSession::State)),
             q, SLOT(_q_networkSessionStateChanged(QNetworkSession::State)));
     }
 
     //switch to new session (null if config was invalid)
-    networkSession = newSession;
+    networkSessionStrongRef = newSession;
+    networkSessionWeakRef = networkSessionStrongRef.toWeakRef();
 
-    if (!networkSession) {
+    if (!networkSessionStrongRef) {
         online = false;
 
         if (networkAccessible == QNetworkAccessManager::NotAccessible)
@@ -1208,18 +1222,19 @@ void QNetworkAccessManagerPrivate::createSession(const QNetworkConfiguration &co
     }
 
     //connect to new session
-    QObject::connect(networkSession.data(), SIGNAL(opened()), q, SIGNAL(networkSessionConnected()), Qt::QueuedConnection);
+    QObject::connect(networkSessionStrongRef.data(), SIGNAL(opened()), q, SIGNAL(networkSessionConnected()), Qt::QueuedConnection);
     //QueuedConnection is used to avoid deleting the networkSession inside its closed signal
-    QObject::connect(networkSession.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()), Qt::QueuedConnection);
-    QObject::connect(networkSession.data(), SIGNAL(stateChanged(QNetworkSession::State)),
+    QObject::connect(networkSessionStrongRef.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()), Qt::QueuedConnection);
+    QObject::connect(networkSessionStrongRef.data(), SIGNAL(stateChanged(QNetworkSession::State)),
                      q, SLOT(_q_networkSessionStateChanged(QNetworkSession::State)), Qt::QueuedConnection);
 
-    _q_networkSessionStateChanged(networkSession->state());
+    _q_networkSessionStateChanged(networkSessionStrongRef->state());
 }
 
 void QNetworkAccessManagerPrivate::_q_networkSessionClosed()
 {
     Q_Q(QNetworkAccessManager);
+    QSharedPointer<QNetworkSession> networkSession(getNetworkSession());
     if (networkSession) {
         networkConfiguration = networkSession->configuration().identifier();
 
@@ -1228,7 +1243,8 @@ void QNetworkAccessManagerPrivate::_q_networkSessionClosed()
         QObject::disconnect(networkSession.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()));
         QObject::disconnect(networkSession.data(), SIGNAL(stateChanged(QNetworkSession::State)),
             q, SLOT(_q_networkSessionStateChanged(QNetworkSession::State)));
-        networkSession.clear();
+        networkSessionStrongRef.clear();
+        networkSessionWeakRef.clear();
     }
 }
 
diff --git a/src/network/access/qnetworkaccessmanager_p.h b/src/network/access/qnetworkaccessmanager_p.h
index ddacf68..8d03c37 100644
--- a/src/network/access/qnetworkaccessmanager_p.h
+++ b/src/network/access/qnetworkaccessmanager_p.h
@@ -78,7 +78,6 @@ public:
           proxyFactory(0),
 #endif
 #ifndef QT_NO_BEARERMANAGEMENT
-          networkSession(0),
           lastSessionState(QNetworkSession::Invalid),
           networkAccessible(QNetworkAccessManager::Accessible),
           activeReplyCount(0),
@@ -113,6 +112,7 @@ public:
 
 #ifndef QT_NO_BEARERMANAGEMENT
     void createSession(const QNetworkConfiguration &config);
+    QSharedPointer<QNetworkSession> getNetworkSession() const;
 
     void _q_networkSessionClosed();
     void _q_networkSessionNewConfigurationActivated();
@@ -137,7 +137,8 @@ public:
 #endif
 
 #ifndef QT_NO_BEARERMANAGEMENT
-    QSharedPointer<QNetworkSession> networkSession;
+    QSharedPointer<QNetworkSession> networkSessionStrongRef;
+    QWeakPointer<QNetworkSession> networkSessionWeakRef;
     QNetworkSession::State lastSessionState;
     QString networkConfiguration;
     QNetworkAccessManager::NetworkAccessibility networkAccessible;
diff --git a/src/network/access/qnetworkreplyimpl.cpp b/src/network/access/qnetworkreplyimpl.cpp
index b0e81e9..6f885d1 100644
--- a/src/network/access/qnetworkreplyimpl.cpp
+++ b/src/network/access/qnetworkreplyimpl.cpp
@@ -97,12 +97,12 @@ void QNetworkReplyImplPrivate::_q_startOperation()
         // state changes.
         state = WaitingForSession;
 
-        QNetworkSession *session = manager->d_func()->networkSession.data();
+        QSharedPointer<QNetworkSession> session(manager->d_func()->getNetworkSession());
 
         if (session) {
             Q_Q(QNetworkReplyImpl);
 
-            QObject::connect(session, SIGNAL(error(QNetworkSession::SessionError)),
+            QObject::connect(session.data(), SIGNAL(error(QNetworkSession::SessionError)),
                              q, SLOT(_q_networkSessionFailed()), Qt::QueuedConnection);
 
             if (!session->isOpen())
@@ -268,7 +268,7 @@ void QNetworkReplyImplPrivate::_q_networkSessionConnected()
     if (manager.isNull())
         return;
 
-    QNetworkSession *session = manager->d_func()->networkSession.data();
+    QSharedPointer<QNetworkSession> session = manager->d_func()->getNetworkSession();
     if (!session)
         return;
 
@@ -746,7 +746,7 @@ void QNetworkReplyImplPrivate::finished()
 
     if (!manager.isNull()) {
 #ifndef QT_NO_BEARERMANAGEMENT
-        QNetworkSession *session = manager->d_func()->networkSession.data();
+        QSharedPointer<QNetworkSession> session (manager->d_func()->getNetworkSession());
         if (session && session->state() == QNetworkSession::Roaming &&
             state == Working && errorCode != QNetworkReply::OperationCanceledError) {
             // only content with a known size will fail with a temporary network failure error