Report RPC counts in server_info (#72)

src/rpc/Counters.h

@@ -0,0 +1,53 @@
+#ifndef RPC_COUNTERS_H
+#define RPC_COUNTERS_H
+
+#include <chrono>
+#include <cstdint>
+#include <string>
+#include <shared_mutex>
+#include <boost/json.hpp>
+
+namespace RPC
+{
+
+class Counters
+{
+private:
+    struct MethodInfo
+    {
+        MethodInfo() = default;
+
+        std::atomic_uint started{0};
+        std::atomic_uint finished{0};
+        std::atomic_uint errored{0};
+        std::atomic_uint forwarded{0};
+        std::atomic_uint duration{0};
+    };
+    
+    void
+    initializeCounter(std::string const& method);
+
+    std::shared_mutex mutex_;
+    std::unordered_map<std::string, MethodInfo> methodInfo_;
+
+public: 
+    Counters() = default;
+
+    void
+    rpcErrored(std::string const& method);
+
+    void
+    rpcComplete(
+        std::string const& method,
+        std::chrono::microseconds const& rpcDuration);
+
+    void
+    rpcForwarded(std::string const& method);
+
+    boost::json::object
+    report();
+};
+
+} // namespace RPCs
+
+#endif // RPC_COUNTERS_H