QGrpc{Channel,Call}Options: Support incremental updates via addMetadata

Currently we only provide `setMetadata(~)` as a way for users to
supply their metadata. However, certain code paths would benefit from
having an `add` functionality as well, without requiring the user to
create a temporary object.

[ChangeLog][GRPC][QGrpc*Options] Added support for incrementally adding
metadata via `addMetadata()`.

Change-Id: Ibc5d721850745df5f171b9126b595ca9c6b0c319
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>

src/grpc/qgrpccalloptions.cpp

@@ -256,6 +256,22 @@ QGrpcCallOptions::setMetadata(std::initializer_list<std::pair<QByteArray, QByteA
     return setMetadata(QMultiHash<QByteArray, QByteArray>(list));
 }
 
+/*!
+    \include qgrpccommonoptions.cpp add-metadata
+
+    \include qgrpccalloptions.cpp merge-md-note
+    \l{QGrpcChannelOptions::addMetadata()}
+*/
+QGrpcCallOptions &QGrpcCallOptions::addMetadata(QByteArray key, QByteArray value)
+{
+    if (d_ptr->metadata(QtGrpc::MultiValue).contains(key, value))
+        return *this;
+    d_ptr.detach();
+    Q_D(QGrpcCallOptions);
+    d->addMetadata(std::move(key), std::move(value));
+    return *this;
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 /*!
     \since 6.8

src/grpc/qgrpccalloptions.h

@@ -62,6 +62,7 @@ public:
     Q_GRPC_EXPORT QGrpcCallOptions &setMetadata(QMultiHash<QByteArray, QByteArray> &&metadata);
     Q_GRPC_EXPORT QGrpcCallOptions &
     setMetadata(std::initializer_list<std::pair<QByteArray, QByteArray>> list);
+    Q_GRPC_EXPORT QGrpcCallOptions &addMetadata(QByteArray key, QByteArray value);
 
 private:
     QExplicitlySharedDataPointer<QGrpcCallOptionsPrivate> d_ptr;

src/grpc/qgrpcchanneloptions.cpp

@@ -265,6 +265,22 @@ QGrpcChannelOptions::setMetadata(std::initializer_list<std::pair<QByteArray, QBy
     return setMetadata(QMultiHash<QByteArray, QByteArray>(list));
 }
 
+/*!
+    \include qgrpccommonoptions.cpp add-metadata
+
+    \include qgrpcchanneloptions.cpp merge-md-note
+    \l{QGrpcCallOptions::addMetadata()}
+*/
+QGrpcChannelOptions &QGrpcChannelOptions::addMetadata(QByteArray key, QByteArray value)
+{
+    if (d_ptr->metadata(QtGrpc::MultiValue).contains(key, value))
+        return *this;
+    d_ptr.detach();
+    Q_D(QGrpcChannelOptions);
+    d->addMetadata(std::move(key), std::move(value));
+    return *this;
+}
+
 /*!
     \since 6.8
 

src/grpc/qgrpcchanneloptions.h

@@ -68,6 +68,7 @@ public:
     Q_GRPC_EXPORT QGrpcChannelOptions &setMetadata(QMultiHash<QByteArray, QByteArray> &&metadata);
     Q_GRPC_EXPORT QGrpcChannelOptions &
     setMetadata(std::initializer_list<std::pair<QByteArray, QByteArray>> list);
+    Q_GRPC_EXPORT QGrpcChannelOptions &addMetadata(QByteArray key, QByteArray value);
 
     [[nodiscard]] Q_GRPC_EXPORT QGrpcSerializationFormat serializationFormat() const;
     Q_GRPC_EXPORT QGrpcChannelOptions &

src/grpc/qgrpccommonoptions.cpp

@@ -137,4 +137,24 @@ void QGrpcCommonOptions::setMetadata(QMultiHash<QByteArray, QByteArray> &&md)
 #endif
 }
 
+/*!
+//! [add-metadata]
+    \since 6.10
+
+    Adds \a key and \a value to the \l metadata if the exact pair is not already contained.
+    The same key may appear multiple times with different values.
+
+    \sa {metadata(QtGrpc::MultiValueTag)}{metadata()} {setMetadata(const
+    QMultiHash<QByteArray, QByteArray>&)}{setMetadata()}
+//! [add-metadata]
+*/
+void QGrpcCommonOptions::addMetadata(QByteArray &&key, QByteArray &&value)
+{
+#if QT_DEPRECATED_SINCE(6, 13)
+    if (m_deprecatedQHashRefUsed)
+        m_metadata.insertOrAssign(key, value);
+#endif
+    m_metadataMulti.emplace(std::move(key), std::move(value));
+}
+
 QT_END_NAMESPACE

src/grpc/qgrpccommonoptions_p.h

@@ -46,6 +46,7 @@ public:
     QMultiHash<QByteArray, QByteArray> metadata(QtGrpc::MultiValueTag /*tag*/) &&;
     void setMetadata(const QMultiHash<QByteArray, QByteArray> &md);
     void setMetadata(QMultiHash<QByteArray, QByteArray> &&md);
+    void addMetadata(QByteArray &&key, QByteArray &&value);
 
 private:
     std::optional<std::chrono::milliseconds> m_timeout;

tests/auto/grpc/shared/grpccommonoptions.h

@@ -210,6 +210,14 @@ QT_WARNING_POP
         T o4;
         o4.setMetadata(list);
         QCOMPARE_EQ(o4.metadata(QtGrpc::MultiValue), data);
+
+        // addMetadata
+        T o5 = T{}.addMetadata("keyA", "valA1").addMetadata("keyA", "valA2");
+        auto o5Detach = o5;
+        QByteArray k = "keyB", v = "valB";
+        o5.addMetadata(k, v);
+        QCOMPARE_EQ(o5.metadata(QtGrpc::MultiValue), data);
+        QCOMPARE_NE(o5.metadata(QtGrpc::MultiValue), o5Detach.metadata(QtGrpc::MultiValue));
     }
     void propertyDeadline() const
     {