Add API support for optional arguments

.travis.yml

@@ -30,7 +30,6 @@ script:
  - 'which build-wrapper-linux-x86-64 && build-wrapper-linux-x86-64 --out-dir bw-output make -j 2 || make -j 2'
  - set -o pipefail
  - tests/run-parallel-tests.sh tests/all_tests
- - "tests/api 2>&1 | grep -vE 'callback result 9|remote_calc->add. 4, 5 .: 9|set callback|] \\.$'"
  - tests/hmac_test 2>&1 | cat
  - tests/ecc_test README.md 2>&1 | cat
  - 'find CMakeFiles/fc.dir -type d | while read d; do gcov -o "$d" "${d/CMakeFiles*.dir/./}"/*.cpp; done >/dev/null'

include/fc/api.hpp

@@ -13,13 +13,91 @@
 #endif
 
 namespace fc {
-  struct identity_member { 
+  namespace detail {
+    /// This metafunction determines whether its template argument is an instantiation of fc::optional
+    template<typename T> struct is_optional : public std::false_type {};
+    template<typename T> struct is_optional<fc::optional<T>> : public std::true_type {};
+    /// This metafunction determines whether all of its template arguments are instantiations of fc::optional
+    template<typename... Ts> struct all_optionals;
+    template<> struct all_optionals<> : public std::true_type {};
+    template<typename T, typename... Ts> struct all_optionals<T, Ts...> : public std::false_type {};
+    template<typename T, typename... Ts> struct all_optionals<fc::optional<T>, Ts...> : public all_optionals<Ts...> {};
+
+    /// A wrapper of std::function allowing callers to omit the last several arguments if those arguments are
+    /// fc::optional types. i.e. given a function taking (int, double, bool, fc::optional<string>, fc::optional<char>),
+    /// whereas normally the last two arguments must be provided, this template allows them to be omitted.
+    /// Note that this only applies to trailing optional arguments, i.e. given a callable taking
+    /// (fc::optional<int>, int, fc::optional<int>), only the last argument can be omitted.
+    ///
+    /// A discussion of how exactly this works is available here:
+    /// https://github.com/bitshares/bitshares-fc/pull/126#issuecomment-490566060
+    template<typename R, typename... Parameters>
+    struct optionals_callable : public std::function<R(Parameters...)> {
+       using std::function<R(Parameters...)>::operator();
+
+       template<typename... CutList>
+       struct short_pack {};
+       /// This metafunction removes the first several types from a variadic parameter pack of types.
+       /// The first parameter is the number of arguments to remove from the beginning of the pack.
+       /// All subsequent parameters are types in the list to be cut
+       /// The result pack_cutter<...>::type is a short_pack<RemainingTypes>
+       template<unsigned RemoveCount, typename... Types>
+       struct pack_cutter;
+       template<unsigned RemoveCount, typename, typename... Types>
+       struct pack_cutter_impl;
+       template<typename... Types>
+       struct pack_cutter_impl<0, void, Types...> {
+           static_assert(all_optionals<Types...>::value, "All omitted arguments must correspond to optional parameters.");
+           using type = short_pack<Types...>;
+       };
+       template<unsigned RemoveCount, typename T, typename... Types>
+       struct pack_cutter_impl<RemoveCount, std::enable_if_t<RemoveCount != 0>, T, Types...>
+               : public pack_cutter_impl<RemoveCount - 1, void, Types...> {};
+       template<unsigned RemoveCount, typename... Types>
+       struct pack_cutter : public pack_cutter_impl<RemoveCount, void, Types...> {};
+       template<unsigned RemoveCount, typename... Types>
+       using pack_cutter_t = typename pack_cutter<RemoveCount, Types...>::type;
+
+       template<typename F, typename... OptionalTypes>
+       R call_function(F&& f, short_pack<OptionalTypes...>) {
+           return f(OptionalTypes()...);
+       }
+
+       /// Overload the function call operator, enabled if the caller provides fewer arguments than there are parameters.
+       /// Pads out the provided arguments with default-constructed optionals, checking that they are indeed optional types
+       template<class... Args>
+       std::enable_if_t<sizeof...(Args) < sizeof...(Parameters), R> operator()(Args... args) {
+           // Partially apply with the arguments provided
+           auto partial_function = [this, &args...](auto&&... rest) {
+               return (*this)(std::forward<decltype(args)>(args)..., std::move(rest)...);
+           };
+           // Cut the provided arguments' types out of the Parameters list, and store the rest in a dummy type
+           pack_cutter_t<sizeof...(Args), std::decay_t<Parameters>...> dummy;
+           // Pass the partially applied function and the dummy type to another function which can deduce the optional
+           // types and call the function with default instantiations of those types
+           return call_function(std::move(partial_function), dummy);
+       }
+    };
+  }
+
+  // This is no longer used and probably no longer can be used without generalizing the infrastructure around it, but I
+  // kept it because it is informative.
+//  struct identity_member {
+//       template<typename R, typename C, typename P, typename... Args>
+//       static std::function<R(Args...)> functor( P&& p, R (C::*mem_func)(Args...) );
+//       template<typename R, typename C, typename P, typename... Args>
+//       static std::function<R(Args...)> functor( P&& p, R (C::*mem_func)(Args...)const );
+//  };
+  /// Used as the Transform template parameter for APIs, this type has two main purposes: first, it reads the argument
+  /// list and return type of a method into template parameters; and second, it uses those types in conjunction with the
+  /// optionals_callable template above to create a function pointer which supports optional arguments.
+  struct identity_member_with_optionals {
        template<typename R, typename C, typename P, typename... Args>
-       static std::function<R(Args...)> functor( P&& p, R (C::*mem_func)(Args...) );
+       static detail::optionals_callable<R, Args...> functor( P&& p, R (C::*mem_func)(Args...) );
        template<typename R, typename C, typename P, typename... Args>
-       static std::function<R(Args...)> functor( P&& p, R (C::*mem_func)(Args...)const );
+       static detail::optionals_callable<R, Args...> functor( P&& p, R (C::*mem_func)(Args...)const );
   };
-   
+
   template< typename Interface, typename Transform  >
   struct vtable  : public std::enable_shared_from_this<vtable<Interface,Transform>> 
   { private: vtable(); };
@@ -57,13 +135,13 @@ namespace fc {
 
         // defined in api_connection.hpp
         template< typename T >
-        api<T, identity_member> as();
+        api<T, identity_member_with_optionals> as();
   };
   typedef std::shared_ptr< api_base > api_ptr;
 
   class api_connection;
 
-  template<typename Interface, typename Transform = identity_member >
+  template<typename Interface, typename Transform = identity_member_with_optionals >
   class api : public api_base {
     public:
       typedef vtable<Interface,Transform> vtable_type;

include/fc/network/http/websocket.hpp

@@ -50,8 +50,12 @@ namespace fc { namespace http {
          void on_connection( const on_connection_handler& handler);
          void listen( uint16_t port );
          void listen( const fc::ip::endpoint& ep );
+         uint16_t get_listening_port();
          void start_accept();
 
+         void stop_listening();
+         void close();
+
       private:
          friend class detail::websocket_server_impl;
          std::unique_ptr<detail::websocket_server_impl> my;
@@ -83,6 +87,9 @@ namespace fc { namespace http {
 
          websocket_connection_ptr connect( const std::string& uri );
          websocket_connection_ptr secure_connect( const std::string& uri );
+
+         void close();
+         void synchronous_close();
       private:
          std::unique_ptr<detail::websocket_client_impl> my;
          std::unique_ptr<detail::websocket_tls_client_impl> smy;

include/fc/rpc/api_connection.hpp

@@ -33,7 +33,9 @@ namespace fc {
       template<typename R, typename Arg0, typename ... Args>
       std::function<R(Args...)> bind_first_arg( const std::function<R(Arg0,Args...)>& f, Arg0 a0 )
       {
-         return [=]( Args... args ) { return f( a0, args... ); };
+         // Capture a0 this way because of a {compiler,fc,???} bug that causes optional<bool>() to be incorrectly
+         // captured as optional<bool>(false).
+         return [f, a0 = std::decay_t<Arg0>(a0)]( Args... args ) { return f( a0, args... ); };
       }
       template<typename R>
       R call_generic( const std::function<R()>& f, variants::const_iterator a0, variants::const_iterator e, uint32_t max_depth = 1 )
@@ -44,9 +46,11 @@ namespace fc {
       template<typename R, typename Arg0, typename ... Args>
       R call_generic( const std::function<R(Arg0,Args...)>& f, variants::const_iterator a0, variants::const_iterator e, uint32_t max_depth )
       {
-         FC_ASSERT( a0 != e );
+         bool optional_args = all_optionals<std::decay_t<Arg0>, std::decay_t<Args>...>::value;
+         FC_ASSERT( a0 != e || optional_args );
          FC_ASSERT( max_depth > 0, "Recursion depth exceeded!" );
-         return call_generic<R,Args...>( bind_first_arg<R,Arg0,Args...>( f, a0->as< typename std::decay<Arg0>::type >( max_depth - 1 ) ), a0+1, e, max_depth - 1 );
+         auto arg = (a0 == e)? std::decay_t<Arg0>() : a0->as<std::decay_t<Arg0>>(max_depth - 1);
+         return call_generic<R,Args...>( bind_first_arg<R,Arg0,Args...>( f, arg ), a0+1, e, max_depth - 1 );
       }
 
       template<typename R, typename ... Args>
@@ -137,7 +141,9 @@ namespace fc {
          template<typename R, typename Arg0, typename ... Args>
          std::function<R(Args...)> bind_first_arg( const std::function<R(Arg0,Args...)>& f, Arg0 a0 )const
          {
-            return [=]( Args... args ) { return f( a0, args... ); };
+            // Capture a0 this way because of a {compiler,fc,???} bug that causes optional<bool>() to be incorrectly
+            // captured as optional<bool>(false).
+            return [f, a0 = std::decay_t<Arg0>(a0)]( Args... args ) { return f( a0, args... ); };
          }
 
          template<typename R>
@@ -172,9 +178,11 @@ namespace fc {
          template<typename R, typename Arg0, typename ... Args>
          R call_generic( const std::function<R(Arg0,Args...)>& f, variants::const_iterator a0, variants::const_iterator e, uint32_t max_depth )
          {
-            FC_ASSERT( a0 != e, "too few arguments passed to method" );
+            bool optional_args = detail::all_optionals<std::decay_t<Arg0>, std::decay_t<Args>...>::value;
+            FC_ASSERT( a0 != e || optional_args, "too few arguments passed to method" );
             FC_ASSERT( max_depth > 0, "Recursion depth exceeded!" );
-            return  call_generic<R,Args...>( this->bind_first_arg<R,Arg0,Args...>( f, a0->as< typename std::decay<Arg0>::type >( max_depth - 1 ) ), a0+1, e, max_depth - 1 );
+            auto arg = (a0 == e)? std::decay_t<Arg0>() : a0->as<std::decay_t<Arg0>>(max_depth - 1);
+            return  call_generic<R,Args...>( this->bind_first_arg<R,Arg0,Args...>( f, arg ), a0+1, e, max_depth - 1 );
          }
 
          struct api_visitor

src/network/http/websocket.cpp

@@ -214,7 +214,6 @@ namespace fc { namespace http {
                        auto current_con = _connections.find(hdl);
                        assert( current_con != _connections.end() );
                        wdump(("server")(msg->get_payload()));
-                       //std::cerr<<"recv: "<<msg->get_payload()<<"\n";
                        auto payload = msg->get_payload();
                        std::shared_ptr<websocket_connection> con = current_con->second;
                        ++_pending_messages;
@@ -290,7 +289,7 @@ namespace fc { namespace http {
                if( _server.is_listening() )
                   _server.stop_listening();
 
-               if( _connections.size() )
+               if ( _connections.size() )
                   _closed = new fc::promise<void>();
 
                auto cpy_con = _connections;
@@ -431,6 +430,7 @@ namespace fc { namespace http {
 
       typedef websocket_client_type::connection_ptr  websocket_client_connection_type;
       typedef websocket_tls_client_type::connection_ptr  websocket_tls_client_connection_type;
+      using websocketpp::connection_hdl;
 
       class websocket_client_impl
       {
@@ -484,6 +484,7 @@ namespace fc { namespace http {
             websocket_client_type              _client;
             websocket_connection_ptr           _connection;
             std::string                        _uri;
+            fc::optional<connection_hdl>       _hdl;
       };
 
 
@@ -625,13 +626,29 @@ namespace fc { namespace http {
    }
    void websocket_server::listen( const fc::ip::endpoint& ep )
    {
-      my->_server.listen( boost::asio::ip::tcp::endpoint( boost::asio::ip::address_v4(uint32_t(ep.get_address())),ep.port()) );
+       my->_server.listen( boost::asio::ip::tcp::endpoint( boost::asio::ip::address_v4(uint32_t(ep.get_address())),ep.port()) );
+   }
+
+   uint16_t websocket_server::get_listening_port()
+   {
+       websocketpp::lib::asio::error_code ec;
+       return my->_server.get_local_endpoint(ec).port();
    }
 
    void websocket_server::start_accept() {
-      my->_server.start_accept();
+       my->_server.start_accept();
+   }
+
+   void websocket_server::stop_listening()
+   {
+       my->_server.stop_listening();
    }
 
+   void websocket_server::close()
+   {
+       for (auto& connection : my->_connections)
+           my->_server.close(connection.first, websocketpp::close::status::normal, "Goodbye");
+   }
 
 
 
@@ -678,6 +695,7 @@ namespace fc { namespace http {
        my->_connected = fc::promise<void>::ptr( new fc::promise<void>("websocket::connect") );
 
        my->_client.set_open_handler( [=]( websocketpp::connection_hdl hdl ){
+          my->_hdl = hdl;
           auto con =  my->_client.get_con_from_hdl(hdl);
           my->_connection = std::make_shared<detail::websocket_connection_impl<detail::websocket_client_connection_type>>( con );
           my->_closed = fc::promise<void>::ptr( new fc::promise<void>("websocket::closed") );
@@ -717,7 +735,20 @@ namespace fc { namespace http {
        smy->_client.connect(con);
        smy->_connected->wait();
        return smy->_connection;
-   } FC_CAPTURE_AND_RETHROW( (uri) ) }
+       } FC_CAPTURE_AND_RETHROW( (uri) ) }
+
+   void websocket_client::close()
+   {
+       if (my->_hdl)
+           my->_client.close(*my->_hdl, websocketpp::close::status::normal, "Goodbye");
+   }
+
+   void websocket_client::synchronous_close()
+   {
+       close();
+       if (my->_closed)
+          my->_closed->wait();
+   }
 
    websocket_connection_ptr websocket_tls_client::connect( const std::string& uri )
    { try {

tests/CMakeLists.txt

@@ -1,7 +1,3 @@
-
-add_executable( api api.cpp )
-target_link_libraries( api fc )
-
 if( ECC_IMPL STREQUAL secp256k1 )
     add_executable( blind all_tests.cpp crypto/blind.cpp )
     target_link_libraries( blind fc )
@@ -55,5 +51,6 @@ add_executable( all_tests all_tests.cpp
                           utf8_test.cpp
                           variant_test.cpp
                           logging_tests.cpp
+                          api_tests.cpp
                           )
 target_link_libraries( all_tests fc )