Stub NameOwnerChanged signal support

NameOwnerChanged signals will be used within fan control to configure
set speed events for when services providing parameters to the fan
control application have unexpectedly terminated.

Change-Id: I04f3c7ca2842732e33dc94b0280ad4483f7f1286
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

2 files changed, 87 insertions, 0 deletions

diff --git a/control/functor.hpp b/control/functor.hpp
index daaa1b7..1f3e4d8 100644
--- a/control/functor.hpp
+++ b/control/functor.hpp
@@ -251,6 +251,75 @@ auto objectSignal(const char* path,
                                 std::forward<U>(handler));
 }
 
+/**
+ * @struct Name Owner Changed
+ * @brief A match filter functor for Dbus name owner changed signals
+ *
+ * @tparam U - The type of the handler
+ */
+template <typename U>
+struct NameOwnerChanged
+{
+    NameOwnerChanged() = delete;
+    ~NameOwnerChanged() = default;
+    NameOwnerChanged(const NameOwnerChanged&) = default;
+    NameOwnerChanged& operator=(const NameOwnerChanged&) = default;
+    NameOwnerChanged(NameOwnerChanged&&) = default;
+    NameOwnerChanged& operator=(NameOwnerChanged&&) = default;
+    NameOwnerChanged(const char* path,
+                     const char* iface,
+                     U&& handler) :
+        _path(path),
+        _iface(iface),
+        _handler(std::forward<U>(handler)) { }
+
+    /** @brief Run signal handler function
+     *
+     * Extract the name owner from the NameOwnerChanged
+     * message (or read the name owner when the message is null)
+     * and run the handler function.
+     */
+    void operator()(sdbusplus::bus::bus& bus,
+                    sdbusplus::message::message& msg,
+                    Zone& zone) const
+    {
+        if (msg)
+        {
+            // TODO Handle NameOwnerChanged signals
+        }
+        else
+        {
+            // TODO Initialize NameOwnerChanged data store with service names
+        }
+    }
+
+private:
+    const char* _path;
+    const char* _iface;
+    U _handler;
+};
+
+/**
+ * @brief Used to process a Dbus name owner changed signal event
+ *
+ * @param[in] path - Object path
+ * @param[in] iface - Object interface
+ * @param[in] handler - Handler function to perform
+ *
+ * @tparam U - The type of the handler
+ *
+ * @return - The NameOwnerChanged signal struct
+ */
+template <typename U>
+auto ownerSignal(const char* path,
+                 const char* iface,
+                 U&& handler)
+{
+    return NameOwnerChanged<U>(path,
+                               iface,
+                               std::forward<U>(handler));
+}
+
 } // namespace control
 } // namespace fan
 } // namespace phosphor
diff --git a/control/handlers.hpp b/control/handlers.hpp
index 79c299b..3f42d3c 100644
--- a/control/handlers.hpp
+++ b/control/handlers.hpp
@@ -30,6 +30,24 @@ auto setProperty(const char* path, const char* interface, const char* property)
     };
 }
 
+/**
+ * @brief A handler function to set/update service name owner state
+ * @details Sets or updates service name owner state used by a group where
+ * a service name without an owner represents the service no longer exists
+ *
+ * @param[in] group - Group associated with a service
+ *
+ * @return Lambda function
+ *     A lambda function to set/update the service name owner state
+ */
+auto setService(Group&& group)
+{
+    return [group = std::move(group)](auto& zone, auto& name, bool hasOwner)
+    {
+        // TODO Update service name owner state list of a group
+    };
+}
+
 } // namespace handler
 } // namespace control
 } // namespace fan