| 1 | /* |
| 2 | Copyright (C) 2006 by Intra2net AG - Gerd v. Egidy |
| 3 | |
| 4 | The software in this package is distributed under the GNU General |
| 5 | Public License version 2 (with a special exception described below). |
| 6 | |
| 7 | A copy of GNU General Public License (GPL) is included in this distribution, |
| 8 | in the file COPYING.GPL. |
| 9 | |
| 10 | As a special exception, if other files instantiate templates or use macros |
| 11 | or inline functions from this file, or you compile this file and link it |
| 12 | with other works to produce a work based on this file, this file |
| 13 | does not by itself cause the resulting work to be covered |
| 14 | by the GNU General Public License. |
| 15 | |
| 16 | However the source code for this file must still be made available |
| 17 | in accordance with section (3) of the GNU General Public License. |
| 18 | |
| 19 | This exception does not invalidate any other reasons why a work based |
| 20 | on this file might be covered by the GNU General Public License. |
| 21 | */ |
| 22 | #ifndef __LIBT2N_CLIENT_WRAPPER |
| 23 | #define __LIBT2N_CLIENT_WRAPPER |
| 24 | |
| 25 | #include <functional> |
| 26 | |
| 27 | #include <boost/config.hpp> |
| 28 | #include <boost/bind.hpp> |
| 29 | #include <boost/function.hpp> |
| 30 | #include <boost/preprocessor.hpp> |
| 31 | |
| 32 | #include <client.hxx> |
| 33 | #include <command_client.hxx> |
| 34 | |
| 35 | #ifndef T2N_SINGLETON_WRAPPER_MAX_ARGS |
| 36 | #define T2N_SINGLETON_WRAPPER_MAX_ARGS 9 |
| 37 | #endif |
| 38 | |
| 39 | namespace libt2n |
| 40 | { |
| 41 | |
| 42 | /** @brief provide access to client_connection singletons and call-handling function |
| 43 | |
| 44 | This is an abstact base class for use with T2nSingletonWrapper. It provides access |
| 45 | to the singleton-client_connection and offers a handle-method which is used for |
| 46 | every call to a method on a t2n-server. |
| 47 | */ |
| 48 | class ConnectionWrapper |
| 49 | { |
| 50 | private: |
| 51 | long long command_timeout_usec; |
| 52 | long long hello_timeout_usec; |
| 53 | |
| 54 | protected: |
| 55 | log_level_values log_level; |
| 56 | std::ostream *logstream; |
| 57 | void set_logging_on_connection(client_connection& c); |
| 58 | |
| 59 | public: |
| 60 | ConnectionWrapper() |
| 61 | : log_level(none), logstream(NULL), |
| 62 | command_timeout_usec(command_client::command_timeout_usec_default), |
| 63 | hello_timeout_usec(command_client::hello_timeout_usec_default) |
| 64 | { } |
| 65 | |
| 66 | virtual ~ConnectionWrapper() |
| 67 | { } |
| 68 | |
| 69 | /** @brief return active connection, create new one if not existing |
| 70 | |
| 71 | Return a pointer to an active client_connection. Use detail-data |
| 72 | stored within the derived class to create a new connection if needed, |
| 73 | otherwise return an alredy active connection. The derived class has |
| 74 | to take care of destroying the connection when not needed anymore. |
| 75 | */ |
| 76 | virtual client_connection* get_connection()=0; |
| 77 | |
| 78 | /** @brief this function is called on every execution of a method on a server |
| 79 | |
| 80 | @param stubBase pointer to the command_client executing the call |
| 81 | @param f boost::function object containing the method to call and all parameters |
| 82 | @retval true if the call was successful and the original return-value of the called function can be used |
| 83 | false if T2nSingletonWrapper has to create a return-value with the default-constructor |
| 84 | |
| 85 | T2nSingletonWrapper will call this function on every execution of a server-side |
| 86 | method. This version will just call the function without any special treatment. |
| 87 | You can overload this function to implement different error handling strategies. |
| 88 | */ |
| 89 | virtual bool handle(command_client* stubBase, boost::function< void() > f) |
| 90 | { |
| 91 | f(); |
| 92 | return true; |
| 93 | } |
| 94 | |
| 95 | long long get_command_timeout_usec(void) |
| 96 | { return command_timeout_usec; } |
| 97 | |
| 98 | void set_command_timeout_usec(long long _command_timeout_usec) |
| 99 | { command_timeout_usec=_command_timeout_usec; } |
| 100 | |
| 101 | long long get_hello_timeout_usec(void) |
| 102 | { return hello_timeout_usec; } |
| 103 | |
| 104 | void set_hello_timeout_usec(long long _hello_timeout_usec) |
| 105 | { hello_timeout_usec=_hello_timeout_usec; } |
| 106 | |
| 107 | virtual void set_logging(std::ostream *_logstream, log_level_values _log_level); |
| 108 | |
| 109 | std::ostream* get_logstream(log_level_values level); |
| 110 | }; |
| 111 | |
| 112 | // contains the internal stuff needed for T2nWrapper |
| 113 | namespace detail |
| 114 | { |
| 115 | |
| 116 | template< typename T > |
| 117 | struct TypeWrap |
| 118 | { |
| 119 | typedef T type; |
| 120 | }; |
| 121 | |
| 122 | template< > |
| 123 | struct TypeWrap< void > |
| 124 | { |
| 125 | typedef int type; |
| 126 | }; |
| 127 | |
| 128 | template< typename R > |
| 129 | struct Call |
| 130 | { |
| 131 | typedef boost::function< R() > FuncType; |
| 132 | |
| 133 | FuncType function; |
| 134 | R& result; |
| 135 | |
| 136 | Call( FuncType f, R& res ) : function(f), result( res ) {} |
| 137 | |
| 138 | void operator()() |
| 139 | { |
| 140 | result= function(); |
| 141 | } |
| 142 | }; |
| 143 | |
| 144 | template< > |
| 145 | struct Call<void> |
| 146 | { |
| 147 | typedef boost::function< void() > FuncType; |
| 148 | typedef TypeWrap< void >::type ResultType; |
| 149 | |
| 150 | FuncType function; |
| 151 | ResultType& result; |
| 152 | |
| 153 | Call( FuncType f, ResultType& res ) : function(f), result( res ) {} |
| 154 | |
| 155 | void operator()() |
| 156 | { |
| 157 | function(); |
| 158 | result= ResultType(); |
| 159 | } |
| 160 | }; |
| 161 | } // eo namespace detail |
| 162 | |
| 163 | class T2nSingletonWrapperMessages |
| 164 | { |
| 165 | protected: |
| 166 | static const char* NotInitializedMessage; |
| 167 | }; |
| 168 | |
| 169 | /** @brief wrap calls to server-side-functions with different error-handling strategies |
| 170 | |
| 171 | Template class to access a process-wide singleton server-connection and to wrap all |
| 172 | calls using this connection with an error-handling strategy (e.g. to reconnect when |
| 173 | the connection broke). The source looks very complicated due to heavy use of templates, |
| 174 | look at the 3rd codegen example to see how to use it. |
| 175 | |
| 176 | @par Example |
| 177 | Calling remote methods is usually done via t2n_exec, this saves you from always |
| 178 | specifying which T2nSingletonWrapper-template to use when calling T2nSingletonWrapper::exec |
| 179 | @code |
| 180 | t2n_exec(&cmd_group_t2nexample_client::testfunc)("the answer is %d",42) |
| 181 | @endcode |
| 182 | */ |
| 183 | template< class Client > |
| 184 | class T2nSingletonWrapper : public T2nSingletonWrapperMessages |
| 185 | { |
| 186 | private: |
| 187 | std::auto_ptr<Client> Stub; |
| 188 | |
| 189 | static std::auto_ptr<T2nSingletonWrapper> SingletonObject; |
| 190 | static std::auto_ptr<ConnectionWrapper> WrappedConnection; |
| 191 | |
| 192 | /// @cond |
| 193 | // create a prep-method for each possible number of parameters |
| 194 | #define _GEN_ARG(z,n,d) Arg ## n arg ##n |
| 195 | #define _GEN_PREP(z,n,d) \ |
| 196 | template< typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 197 | static boost::function< R(Client*) > prep \ |
| 198 | ( \ |
| 199 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 200 | BOOST_PP_COMMA_IF(n) \ |
| 201 | BOOST_PP_ENUM( n, _GEN_ARG, ~ ) \ |
| 202 | ) \ |
| 203 | { \ |
| 204 | return boost::bind< R > \ |
| 205 | ( \ |
| 206 | f, _1 BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,arg) \ |
| 207 | ); \ |
| 208 | } // eo prep |
| 209 | |
| 210 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1) , _GEN_PREP, ~ ) |
| 211 | |
| 212 | #undef _GEN_PREP |
| 213 | #undef _GEN_ARG |
| 214 | /// @endcond |
| 215 | |
| 216 | T2nSingletonWrapper(std::auto_ptr<Client> stub) |
| 217 | { |
| 218 | Stub=stub; |
| 219 | } |
| 220 | |
| 221 | static void init() |
| 222 | { |
| 223 | if (WrappedConnection.get() == NULL) |
| 224 | throw std::logic_error(NotInitializedMessage); |
| 225 | |
| 226 | std::auto_ptr<Client> stub(new Client(WrappedConnection->get_connection(), |
| 227 | WrappedConnection->get_command_timeout_usec(), |
| 228 | WrappedConnection->get_hello_timeout_usec())); |
| 229 | |
| 230 | SingletonObject=std::auto_ptr<T2nSingletonWrapper>(new T2nSingletonWrapper(stub)); |
| 231 | } |
| 232 | |
| 233 | template< typename R > |
| 234 | static |
| 235 | typename detail::TypeWrap<R>::type real_exec( boost::function< R(Client*) > f) |
| 236 | { |
| 237 | ensure_singleton_there(); |
| 238 | |
| 239 | typename detail::TypeWrap<R>::type result; |
| 240 | |
| 241 | // bind our Client-object and the local result |
| 242 | detail::Call<R> call( boost::bind( f, SingletonObject->Stub.get()), result ); |
| 243 | |
| 244 | // let the wrapper-handler call the fully-bound function |
| 245 | if (!WrappedConnection->handle(SingletonObject->Stub.get(),call)) |
| 246 | { |
| 247 | // create an result with default-constructor if the handler could not |
| 248 | // successfully do a call but no exception occured |
| 249 | result=typename detail::TypeWrap<R>::type(); |
| 250 | } |
| 251 | return result; |
| 252 | } |
| 253 | |
| 254 | public: |
| 255 | |
| 256 | /** @brief tell the wrapper which connection to use |
| 257 | @param wrappedConnection the connection to establish when needed |
| 258 | */ |
| 259 | static void set_connection(std::auto_ptr<ConnectionWrapper> wrappedConnection) |
| 260 | { |
| 261 | WrappedConnection=wrappedConnection; |
| 262 | |
| 263 | // reset the singleton to NULL because the singleton must be constructed with current WrappedConnection |
| 264 | if (SingletonObject.get() != NULL) |
| 265 | SingletonObject.reset(); |
| 266 | } |
| 267 | |
| 268 | /// return a pointer to the ConnectionWrapper currently in use |
| 269 | static ConnectionWrapper* get_connection_wrapper(void) |
| 270 | { return WrappedConnection.get(); } |
| 271 | |
| 272 | /// manually establish the connection without actually executing a call |
| 273 | static void ensure_singleton_there(void) |
| 274 | { |
| 275 | if (SingletonObject.get() == NULL) |
| 276 | init(); |
| 277 | } |
| 278 | |
| 279 | /// @cond |
| 280 | // create an exec-method for each possible number of parameters |
| 281 | #define _GEN_PLACEHOLDER(z,n,d) BOOST_PP_CAT(_,BOOST_PP_ADD(n,1)) |
| 282 | #define _GEN_EXEC(z,n,d) \ |
| 283 | template< typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 284 | static boost::function< R( BOOST_PP_ENUM_PARAMS(n,Arg) ) > exec \ |
| 285 | ( \ |
| 286 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 287 | ) \ |
| 288 | { \ |
| 289 | boost::function<R(Client*)>(*p)(R(Client::*)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 290 | BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg)) \ |
| 291 | = &T2nSingletonWrapper::template prep<R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg) >; \ |
| 292 | return boost::bind \ |
| 293 | ( \ |
| 294 | T2nSingletonWrapper::template real_exec<R>, \ |
| 295 | boost::bind( p, f BOOST_PP_COMMA_IF(n) \ |
| 296 | BOOST_PP_ENUM(n, _GEN_PLACEHOLDER, ~ ) ) \ |
| 297 | ); \ |
| 298 | } // eo exec |
| 299 | |
| 300 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1), _GEN_EXEC, ~ ) |
| 301 | |
| 302 | #undef _GEN_EXEC |
| 303 | #undef _GEN_PLACEHOLDER |
| 304 | /// @endcond |
| 305 | |
| 306 | }; |
| 307 | |
| 308 | /// @cond |
| 309 | // create an t2n_exec-method for each possible number of parameters |
| 310 | #define _GEN_EXEC(z,n,d) \ |
| 311 | template< class Client, typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 312 | static boost::function< R( BOOST_PP_ENUM_PARAMS(n,Arg) ) > t2n_exec \ |
| 313 | ( \ |
| 314 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 315 | ) \ |
| 316 | { \ |
| 317 | return T2nSingletonWrapper<Client>::exec(f); \ |
| 318 | } // eo exec |
| 319 | |
| 320 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1), _GEN_EXEC, ~ ) |
| 321 | |
| 322 | #undef _GEN_EXEC |
| 323 | #undef _GEN_PLACEHOLDER |
| 324 | /// @endcond |
| 325 | |
| 326 | } |
| 327 | #endif |