Switch to insitu parsing for ZMQ-JSON; GetBlocksFast reads 13%+ faster

src/rpc/daemon_handler.cpp

@@ -906,13 +906,13 @@ namespace rpc
     return true;
   }
 
-  epee::byte_slice DaemonHandler::handle(const std::string& request)
+  epee::byte_slice DaemonHandler::handle(std::string&& request)
   {
     MDEBUG("Handling RPC request: " << request);
 
     try
     {
-      FullMessage req_full(request, true);
+      FullMessage req_full(std::move(request), true);
 
       const std::string request_type = req_full.getRequestType();
       const auto matched_handler = std::lower_bound(std::begin(handlers), std::end(handlers), request_type);

src/rpc/daemon_handler.h

@@ -133,7 +133,7 @@ class DaemonHandler : public RpcHandler
 
     void handle(const GetOutputDistribution::Request& req, GetOutputDistribution::Response& res);
 
-    epee::byte_slice handle(const std::string& request) override final;
+    epee::byte_slice handle(std::string&& request) override final;
 
   private:
 

src/rpc/message.cpp

@@ -79,9 +79,12 @@ void Message::fromJson(const rapidjson::Value& val)
   GET_FROM_JSON_OBJECT(val, rpc_version, rpc_version);
 }
 
-FullMessage::FullMessage(const std::string& json_string, bool request)
+FullMessage::FullMessage(std::string&& json_string, bool request)
+  : contents(std::move(json_string)), doc()
 {
-  doc.Parse(json_string.c_str());
+  /* Insitu parsing does not copy data from `contents` to DOM,
+     accelerating string heavy content. */
+  doc.ParseInsitu(std::addressof(contents[0]));
   if (doc.HasParseError() || !doc.IsObject())
   {
     throw cryptonote::json::PARSE_FAIL();

src/rpc/message.h

@@ -72,9 +72,7 @@ namespace rpc
     public:
       ~FullMessage() { }
 
-      FullMessage(FullMessage&& rhs) noexcept : doc(std::move(rhs.doc)) { }
+      FullMessage(std::string&& json_string, bool request=false);
-
-      FullMessage(const std::string& json_string, bool request=false);
 
       std::string getRequestType() const;
 
@@ -91,10 +89,13 @@ namespace rpc
     private:
 
       FullMessage() = default;
+      FullMessage(const FullMessage&) = delete;
+      FullMessage& operator=(const FullMessage&) = delete;
 
       FullMessage(const std::string& request, Message* message);
       FullMessage(Message* message);
 
+      std::string contents;
       rapidjson::Document doc;
   };
 

src/rpc/rpc_handler.h

@@ -55,7 +55,7 @@ class RpcHandler
     RpcHandler() { }
     virtual ~RpcHandler() { }
 
-    virtual epee::byte_slice handle(const std::string& request) = 0;
+    virtual epee::byte_slice handle(std::string&& request) = 0;
 
     static boost::optional<output_distribution_data>
       get_output_distribution(const std::function<bool(uint64_t, uint64_t, uint64_t, uint64_t&, std::vector<uint64_t>&, uint64_t&)> &f, uint64_t amount, uint64_t from_height, uint64_t to_height, const std::function<crypto::hash(uint64_t)> &get_hash, bool cumulative, uint64_t blockchain_height);

src/rpc/zmq_server.cpp

@@ -158,9 +158,9 @@ void ZmqServer::serve()
 
       if (!pub || sockets[2].revents)
       {
-        const std::string message = MONERO_UNWRAP(net::zmq::receive(rep.get(), read_flags));
+        std::string message = MONERO_UNWRAP(net::zmq::receive(rep.get(), read_flags));
         MDEBUG("Received RPC request: \"" << message << "\"");
-        epee::byte_slice response = handler.handle(message);
+        epee::byte_slice response = handler.handle(std::move(message));
 
         const boost::string_ref response_view{reinterpret_cast<const char*>(response.data()), response.size()};
         MDEBUG("Sending RPC reply: \"" << response_view << "\"");