modified structure

api/include/opentelemetry/metrics/async_instruments.h

@@ -8,69 +8,79 @@ namespace metrics
 {
 
 template <class T>
-class ValueObserver : public AsynchronousInstrument<T>
+class ValueObserver : virtual public AsynchronousInstrument<T>
 {
-
+    
 public:
-  ValueObserver() = default;
-
-  ValueObserver(nostd::string_view name,
-                   nostd::string_view description,
-                   nostd::string_view unit,
-                   bool enabled,
-                   void (*callback)(ObserverResult<T>))
-  {}
-
-  /*
-   * Updates the instruments aggregator with the new value. The labels should
-   * contain the keys and values to be associated with this value.
-   *
-   * @param value is the numerical representation of the metric being captured
-   * @param labels the set of labels, as key-value pairs
-   */
-  virtual void observe(T value, const trace::KeyValueIterable &labels) {}
+    ValueObserver() = default;
+
+    ValueObserver(nostd::string_view name,
+                  nostd::string_view description,
+                  nostd::string_view unit,
+                  bool enabled,
+                  void (*callback)(ObserverResult<T>))
+    {}
+
+    /*
+     * Updates the instruments aggregator with the new value. The labels should
+     * contain the keys and values to be associated with this value.
+     *
+     * @param value is the numerical representation of the metric being captured
+     * @param labels the set of labels, as key-value pairs
+     */
+    virtual void observe(T value, const trace::KeyValueIterable &labels) override = 0;
+
+    /**
+     * Captures data by activating the callback function associated with the
+     * instrument and storing its return value.  Callbacks for asynchronous
+     * instruments are defined during construction.
+     *
+     * @param none
+     * @return none
+     */
+    virtual void run () override = 0;
+
 };
 
 template <class T>
-class SumObserver : public AsynchronousInstrument<T>
+class SumObserver : virtual public AsynchronousInstrument<T>
 {
-
+    
 public:
-  SumObserver() = default;
-
-  SumObserver(nostd::string_view name,
-                 nostd::string_view description,
-                 nostd::string_view unit,
-                 bool enabled,
-                 void (*callback)(ObserverResult<T>))
-  {}
-
-  /*
-   * Add adds the value to the counter's sum. The labels should contain
-   * the keys and values to be associated with this value.  Counters only     * accept positive
-   * valued updates.
-   *
-   * @param value is the numerical representation of the metric being captured
-   * @param labels the set of labels, as key-value pairs
-   */
-  virtual void observe(T value, const trace::KeyValueIterable &labels) {}
+    SumObserver() = default;
+
+    SumObserver(nostd::string_view name,
+                nostd::string_view description,
+                nostd::string_view unit,
+                bool enabled,
+                void (*callback)(ObserverResult<T>))
+    {}
+
+
+    virtual void observe(T value, const trace::KeyValueIterable &labels) override = 0;
+
+    virtual void run() override = 0;
+
 };
 
 template <class T>
-class UpDownSumObserver : public AsynchronousInstrument<T>
+class UpDownSumObserver : virtual public AsynchronousInstrument<T>
 {
-
+    
 public:
-  UpDownSumObserver() = default;
-
-  UpDownSumObserver(nostd::string_view name,
-                       nostd::string_view description,
-                       nostd::string_view unit,
-                       bool enabled,
-                       void (*callback)(ObserverResult<T>))
-  {}
-
-  virtual void observe(int value, const trace::KeyValueIterable &labels) {}
+    UpDownSumObserver() = default;
+
+    UpDownSumObserver(nostd::string_view name,
+                      nostd::string_view description,
+                      nostd::string_view unit,
+                      bool enabled,
+                      void (*callback)(ObserverResult<T>))
+    {}
+
+    virtual void observe(T value, const trace::KeyValueIterable &labels) override = 0;
+
+    virtual void run() override = 0;
+
 };
 
 }  // namespace metrics