QNI: Add API to check if connection is metered

This may be a useful factor in deciding whether or not you should
perform communications over the network which are not purely essential.
For example, if you have a logging mechanism you can delay uploading
them until you are no longer on a metered network.

Task-number: QTBUG-91024
Change-Id: I19d32f031a3893512dc440914133678004987fb1
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

3 files changed, 39 insertions, 0 deletions

diff --git a/src/network/kernel/qnetworkinformation.cpp b/src/network/kernel/qnetworkinformation.cpp
index 5d889ac574..034a277b3c 100644
--- a/src/network/kernel/qnetworkinformation.cpp
+++ b/src/network/kernel/qnetworkinformation.cpp
@@ -457,6 +457,11 @@ QNetworkInformationBackendFactory::~QNetworkInformationBackendFactory()
         property will provide useful results. Otherwise it will always return
         \c{TransportMedium::Unknown}.
         See also QNetworkInformation::TransportMedium.
+
+    \value Metered
+        If the plugin supports this feature then the \c isMetered
+        property will provide useful results. Otherwise it will always return
+        \c{false}.
 */
 
 /*!
@@ -520,6 +525,8 @@ QNetworkInformation::QNetworkInformation(QNetworkInformationBackend *backend)
             &QNetworkInformation::isBehindCaptivePortalChanged);
     connect(backend, &QNetworkInformationBackend::transportMediumChanged, this,
             &QNetworkInformation::transportMediumChanged);
+    connect(backend, &QNetworkInformationBackend::isMeteredChanged, this,
+           &QNetworkInformation::isMeteredChanged);
 }
 
 /*!
@@ -580,6 +587,22 @@ QNetworkInformation::TransportMedium QNetworkInformation::transportMedium() cons
 }
 
 /*!
+    \property QNetworkInformation::isMetered
+    \brief Check if the current connection is metered
+    \since 6.3
+
+    This property returns whether the current connection is (known to be)
+    metered or not. You can use this as a guiding factor to decide whether your
+    application should perform certain network requests or uploads.
+    For instance, you may not want to upload logs or diagnostics while this
+    property is \c true.
+*/
+bool QNetworkInformation::isMetered() const
+{
+    return d_func()->backend->isMetered();
+}
+
+/*!
     Returns the name of the currently loaded backend.
 */
 QString QNetworkInformation::backendName() const
diff --git a/src/network/kernel/qnetworkinformation.h b/src/network/kernel/qnetworkinformation.h
index e280894fef..9b09fcee98 100644
--- a/src/network/kernel/qnetworkinformation.h
+++ b/src/network/kernel/qnetworkinformation.h
@@ -58,6 +58,7 @@ class Q_NETWORK_EXPORT QNetworkInformation : public QObject
     Q_PROPERTY(bool isBehindCaptivePortal READ isBehindCaptivePortal
                NOTIFY isBehindCaptivePortalChanged)
     Q_PROPERTY(TransportMedium transportMedium READ transportMedium NOTIFY transportMediumChanged)
+    Q_PROPERTY(bool isMetered READ isMetered NOTIFY isMeteredChanged)
 public:
     enum class Reachability {
         Unknown,
@@ -81,6 +82,7 @@ public:
         Reachability = 0x1,
         CaptivePortal = 0x2,
         TransportMedium = 0x4,
+        Metered = 0x8,
     };
     Q_DECLARE_FLAGS(Features, Feature)
     Q_FLAG(Features)
@@ -91,6 +93,8 @@ public:
 
     TransportMedium transportMedium() const;
 
+    bool isMetered() const;
+
     QString backendName() const;
 
     bool supports(Features features) const;
@@ -106,6 +110,7 @@ Q_SIGNALS:
     void reachabilityChanged(Reachability newReachability);
     void isBehindCaptivePortalChanged(bool state);
     void transportMediumChanged(TransportMedium current);
+    void isMeteredChanged(bool isMetered);
 
 private:
     friend struct QNetworkInformationDeleter;
diff --git a/src/network/kernel/qnetworkinformation_p.h b/src/network/kernel/qnetworkinformation_p.h
index 3493de3b44..36084b8e44 100644
--- a/src/network/kernel/qnetworkinformation_p.h
+++ b/src/network/kernel/qnetworkinformation_p.h
@@ -87,11 +87,13 @@ public:
     Reachability reachability() const { return m_reachability; }
     bool behindCaptivePortal() const { return m_behindCaptivePortal; }
     TransportMedium transportMedium() const { return m_transportMedium; }
+    bool isMetered() const { return m_metered; }
 
 Q_SIGNALS:
     void reachabilityChanged(Reachability reachability);
     void behindCaptivePortalChanged(bool behindPortal);
     void transportMediumChanged(TransportMedium medium);
+    void isMeteredChanged(bool isMetered);
 
 protected:
     void setReachability(QNetworkInformation::Reachability reachability)
@@ -118,10 +120,19 @@ protected:
         }
     }
 
+    void setMetered(bool isMetered)
+    {
+        if (m_metered != isMetered) {
+            m_metered = isMetered;
+            emit isMeteredChanged(isMetered);
+        }
+    }
+
 private:
     Reachability m_reachability = Reachability::Unknown;
     TransportMedium m_transportMedium = TransportMedium::Unknown;
     bool m_behindCaptivePortal = false;
+    bool m_metered = false;
 
     Q_DISABLE_COPY_MOVE(QNetworkInformationBackend)
     friend class QNetworkInformation;