Add more fine grained counters (#683)

Fixes #665

src/rpc/Counters.h

@@ -36,14 +36,23 @@ class Counters
     {
         std::uint64_t started = 0u;
         std::uint64_t finished = 0u;
+        std::uint64_t failed = 0u;
         std::uint64_t errored = 0u;
         std::uint64_t forwarded = 0u;
+        std::uint64_t failedForward = 0u;
         std::uint64_t duration = 0u;
     };
 
     mutable std::mutex mutex_;
     std::unordered_map<std::string, MethodInfo> methodInfo_;
 
+    // counters that don't carry RPC method information
+    std::atomic_uint64_t tooBusyCounter_;
+    std::atomic_uint64_t notReadyCounter_;
+    std::atomic_uint64_t badSyntaxCounter_;
+    std::atomic_uint64_t unknownCommandCounter_;
+    std::atomic_uint64_t internalErrorCounter_;
+
     std::reference_wrapper<const WorkQueue> workQueue_;
 
 public:
@@ -55,6 +64,9 @@ public:
         return Counters{wq};
     }
 
+    void
+    rpcFailed(std::string const& method);
+
     void
     rpcErrored(std::string const& method);
 
@@ -64,6 +76,24 @@ public:
     void
     rpcForwarded(std::string const& method);
 
+    void
+    rpcFailedToForward(std::string const& method);
+
+    void
+    onTooBusy();
+
+    void
+    onNotReady();
+
+    void
+    onBadSyntax();
+
+    void
+    onUnknownCommand();
+
+    void
+    onInternalError();
+
     boost::json::object
     report() const;
 };