| 1 | /*************************************************************************** |
| 2 | * Copyright (C) 2008 by Gerd v. Egidy and Reinhard Pfau * |
| 3 | * gve@intra2net.com * |
| 4 | * * |
| 5 | * This library is free software; you can redistribute it and/or modify * |
| 6 | * it under the terms of the GNU Lesser General Public License version * |
| 7 | * 2.1 as published by the Free Software Foundation. * |
| 8 | * * |
| 9 | * This library is distributed in the hope that it will be useful, * |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of * |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
| 12 | * GNU Lesser General Public License for more details. * |
| 13 | * * |
| 14 | * You should have received a copy of the GNU Lesser General Public * |
| 15 | * License along with this program; if not, write to the * |
| 16 | * Free Software Foundation, Inc., * |
| 17 | * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * |
| 18 | ***************************************************************************/ |
| 19 | #ifndef __LIBT2N_CLIENT_WRAPPER |
| 20 | #define __LIBT2N_CLIENT_WRAPPER |
| 21 | |
| 22 | #include <functional> |
| 23 | |
| 24 | #include <boost/config.hpp> |
| 25 | #include <boost/bind.hpp> |
| 26 | #include <boost/function.hpp> |
| 27 | #include <boost/preprocessor.hpp> |
| 28 | |
| 29 | #include <client.hxx> |
| 30 | #include <command_client.hxx> |
| 31 | |
| 32 | #ifndef T2N_SINGLETON_WRAPPER_MAX_ARGS |
| 33 | #define T2N_SINGLETON_WRAPPER_MAX_ARGS 9 |
| 34 | #endif |
| 35 | |
| 36 | namespace libt2n |
| 37 | { |
| 38 | |
| 39 | /** @brief provide access to client_connection singletons and call-handling function |
| 40 | |
| 41 | This is an abstact base class for use with T2nSingletonWrapper. It provides access |
| 42 | to the singleton-client_connection and offers a handle-method which is used for |
| 43 | every call to a method on a t2n-server. |
| 44 | */ |
| 45 | class ConnectionWrapper |
| 46 | { |
| 47 | private: |
| 48 | long long command_timeout_usec; |
| 49 | long long hello_timeout_usec; |
| 50 | |
| 51 | protected: |
| 52 | log_level_values log_level; |
| 53 | std::ostream *logstream; |
| 54 | void set_logging_on_connection(client_connection& c); |
| 55 | |
| 56 | public: |
| 57 | ConnectionWrapper() |
| 58 | : log_level(none), logstream(NULL), |
| 59 | command_timeout_usec(command_client::command_timeout_usec_default), |
| 60 | hello_timeout_usec(command_client::hello_timeout_usec_default) |
| 61 | { } |
| 62 | |
| 63 | virtual ~ConnectionWrapper() |
| 64 | { } |
| 65 | |
| 66 | /** @brief return active connection, create new one if not existing |
| 67 | |
| 68 | Return a pointer to an active client_connection. Use detail-data |
| 69 | stored within the derived class to create a new connection if needed, |
| 70 | otherwise return an alredy active connection. The derived class has |
| 71 | to take care of destroying the connection when not needed anymore. |
| 72 | */ |
| 73 | virtual client_connection* get_connection()=0; |
| 74 | |
| 75 | /** @brief this function is called on every execution of a method on a server |
| 76 | |
| 77 | @param stubBase pointer to the command_client executing the call |
| 78 | @param f boost::function object containing the method to call and all parameters |
| 79 | @retval true if the call was successful and the original return-value of the called function can be used |
| 80 | false if T2nSingletonWrapper has to create a return-value with the default-constructor |
| 81 | |
| 82 | T2nSingletonWrapper will call this function on every execution of a server-side |
| 83 | method. This version will just call the function without any special treatment. |
| 84 | You can overload this function to implement different error handling strategies. |
| 85 | */ |
| 86 | virtual bool handle(command_client* stubBase, boost::function< void() > f) |
| 87 | { |
| 88 | f(); |
| 89 | return true; |
| 90 | } |
| 91 | |
| 92 | long long get_command_timeout_usec(void) |
| 93 | { return command_timeout_usec; } |
| 94 | |
| 95 | void set_command_timeout_usec(long long _command_timeout_usec) |
| 96 | { command_timeout_usec=_command_timeout_usec; } |
| 97 | |
| 98 | long long get_hello_timeout_usec(void) |
| 99 | { return hello_timeout_usec; } |
| 100 | |
| 101 | void set_hello_timeout_usec(long long _hello_timeout_usec) |
| 102 | { hello_timeout_usec=_hello_timeout_usec; } |
| 103 | |
| 104 | virtual void set_logging(std::ostream *_logstream, log_level_values _log_level); |
| 105 | |
| 106 | std::ostream* get_logstream(log_level_values level); |
| 107 | }; |
| 108 | |
| 109 | // contains the internal stuff needed for T2nWrapper |
| 110 | namespace detail |
| 111 | { |
| 112 | |
| 113 | template< typename T > |
| 114 | struct TypeWrap |
| 115 | { |
| 116 | typedef T type; |
| 117 | }; |
| 118 | |
| 119 | template< > |
| 120 | struct TypeWrap< void > |
| 121 | { |
| 122 | typedef int type; |
| 123 | }; |
| 124 | |
| 125 | template< typename R > |
| 126 | struct Call |
| 127 | { |
| 128 | typedef boost::function< R() > FuncType; |
| 129 | |
| 130 | FuncType function; |
| 131 | R& result; |
| 132 | |
| 133 | Call( FuncType f, R& res ) : function(f), result( res ) {} |
| 134 | |
| 135 | void operator()() |
| 136 | { |
| 137 | result= function(); |
| 138 | } |
| 139 | }; |
| 140 | |
| 141 | template< > |
| 142 | struct Call<void> |
| 143 | { |
| 144 | typedef boost::function< void() > FuncType; |
| 145 | typedef TypeWrap< void >::type ResultType; |
| 146 | |
| 147 | FuncType function; |
| 148 | ResultType& result; |
| 149 | |
| 150 | Call( FuncType f, ResultType& res ) : function(f), result( res ) {} |
| 151 | |
| 152 | void operator()() |
| 153 | { |
| 154 | function(); |
| 155 | result= ResultType(); |
| 156 | } |
| 157 | }; |
| 158 | } // eo namespace detail |
| 159 | |
| 160 | class T2nSingletonWrapperMessages |
| 161 | { |
| 162 | protected: |
| 163 | static const char* NotInitializedMessage; |
| 164 | }; |
| 165 | |
| 166 | /** @brief wrap calls to server-side-functions with different error-handling strategies |
| 167 | |
| 168 | Template class to access a process-wide singleton server-connection and to wrap all |
| 169 | calls using this connection with an error-handling strategy (e.g. to reconnect when |
| 170 | the connection broke). The source looks very complicated due to heavy use of templates, |
| 171 | look at the 3rd codegen example to see how to use it. |
| 172 | |
| 173 | @par Example |
| 174 | Calling remote methods is usually done via t2n_exec, this saves you from always |
| 175 | specifying which T2nSingletonWrapper-template to use when calling T2nSingletonWrapper::exec |
| 176 | @code |
| 177 | t2n_exec(&cmd_group_t2nexample_client::testfunc)("the answer is %d",42) |
| 178 | @endcode |
| 179 | */ |
| 180 | template< class Client > |
| 181 | class T2nSingletonWrapper : public T2nSingletonWrapperMessages |
| 182 | { |
| 183 | private: |
| 184 | std::auto_ptr<Client> Stub; |
| 185 | |
| 186 | static std::auto_ptr<T2nSingletonWrapper> SingletonObject; |
| 187 | static std::auto_ptr<ConnectionWrapper> WrappedConnection; |
| 188 | |
| 189 | /// @cond |
| 190 | // create a prep-method for each possible number of parameters |
| 191 | #define _GEN_ARG(z,n,d) Arg ## n arg ##n |
| 192 | #define _GEN_PREP(z,n,d) \ |
| 193 | template< typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 194 | static boost::function< R(Client*) > prep \ |
| 195 | ( \ |
| 196 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 197 | BOOST_PP_COMMA_IF(n) \ |
| 198 | BOOST_PP_ENUM( n, _GEN_ARG, ~ ) \ |
| 199 | ) \ |
| 200 | { \ |
| 201 | return boost::bind< R > \ |
| 202 | ( \ |
| 203 | f, _1 BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,arg) \ |
| 204 | ); \ |
| 205 | } // eo prep |
| 206 | |
| 207 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1) , _GEN_PREP, ~ ) |
| 208 | |
| 209 | #undef _GEN_PREP |
| 210 | #undef _GEN_ARG |
| 211 | /// @endcond |
| 212 | |
| 213 | T2nSingletonWrapper(std::auto_ptr<Client> stub) |
| 214 | { |
| 215 | Stub=stub; |
| 216 | } |
| 217 | |
| 218 | static void init() |
| 219 | { |
| 220 | if (WrappedConnection.get() == NULL) |
| 221 | throw std::logic_error(NotInitializedMessage); |
| 222 | |
| 223 | std::auto_ptr<Client> stub(new Client(WrappedConnection->get_connection(), |
| 224 | WrappedConnection->get_command_timeout_usec(), |
| 225 | WrappedConnection->get_hello_timeout_usec())); |
| 226 | |
| 227 | SingletonObject=std::auto_ptr<T2nSingletonWrapper>(new T2nSingletonWrapper(stub)); |
| 228 | } |
| 229 | |
| 230 | template< typename R > |
| 231 | static |
| 232 | typename detail::TypeWrap<R>::type real_exec( boost::function< R(Client*) > f) |
| 233 | { |
| 234 | ensure_singleton_there(); |
| 235 | |
| 236 | typename detail::TypeWrap<R>::type result; |
| 237 | |
| 238 | // bind our Client-object and the local result |
| 239 | detail::Call<R> call( boost::bind( f, SingletonObject->Stub.get()), result ); |
| 240 | |
| 241 | // let the wrapper-handler call the fully-bound function |
| 242 | if (!WrappedConnection->handle(SingletonObject->Stub.get(),call)) |
| 243 | { |
| 244 | // create an result with default-constructor if the handler could not |
| 245 | // successfully do a call but no exception occured |
| 246 | result=typename detail::TypeWrap<R>::type(); |
| 247 | } |
| 248 | return result; |
| 249 | } |
| 250 | |
| 251 | public: |
| 252 | |
| 253 | /** @brief tell the wrapper which connection to use |
| 254 | @param wrappedConnection the connection to establish when needed |
| 255 | */ |
| 256 | static void set_connection(std::auto_ptr<ConnectionWrapper> wrappedConnection) |
| 257 | { |
| 258 | WrappedConnection=wrappedConnection; |
| 259 | |
| 260 | // reset the singleton to NULL because the singleton must be constructed with current WrappedConnection |
| 261 | if (SingletonObject.get() != NULL) |
| 262 | SingletonObject.reset(); |
| 263 | } |
| 264 | |
| 265 | /// return a pointer to the ConnectionWrapper currently in use |
| 266 | static ConnectionWrapper* get_connection_wrapper(void) |
| 267 | { return WrappedConnection.get(); } |
| 268 | |
| 269 | /// manually establish the connection without actually executing a call |
| 270 | static void ensure_singleton_there(void) |
| 271 | { |
| 272 | if (SingletonObject.get() == NULL) |
| 273 | init(); |
| 274 | } |
| 275 | |
| 276 | /// @cond |
| 277 | // create an exec-method for each possible number of parameters |
| 278 | #define _GEN_PLACEHOLDER(z,n,d) BOOST_PP_CAT(_,BOOST_PP_ADD(n,1)) |
| 279 | #define _GEN_EXEC(z,n,d) \ |
| 280 | template< typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 281 | static boost::function< R( BOOST_PP_ENUM_PARAMS(n,Arg) ) > exec \ |
| 282 | ( \ |
| 283 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 284 | ) \ |
| 285 | { \ |
| 286 | boost::function<R(Client*)>(*p)(R(Client::*)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 287 | BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg)) \ |
| 288 | = &T2nSingletonWrapper::template prep<R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg) >; \ |
| 289 | return boost::bind \ |
| 290 | ( \ |
| 291 | T2nSingletonWrapper::template real_exec<R>, \ |
| 292 | boost::bind( p, f BOOST_PP_COMMA_IF(n) \ |
| 293 | BOOST_PP_ENUM(n, _GEN_PLACEHOLDER, ~ ) ) \ |
| 294 | ); \ |
| 295 | } // eo exec |
| 296 | |
| 297 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1), _GEN_EXEC, ~ ) |
| 298 | |
| 299 | #undef _GEN_EXEC |
| 300 | #undef _GEN_PLACEHOLDER |
| 301 | /// @endcond |
| 302 | |
| 303 | }; |
| 304 | |
| 305 | /// @cond |
| 306 | // create an t2n_exec-method for each possible number of parameters |
| 307 | #define _GEN_EXEC(z,n,d) \ |
| 308 | template< class Client, typename R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \ |
| 309 | static boost::function< R( BOOST_PP_ENUM_PARAMS(n,Arg) ) > t2n_exec \ |
| 310 | ( \ |
| 311 | R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \ |
| 312 | ) \ |
| 313 | { \ |
| 314 | return T2nSingletonWrapper<Client>::exec(f); \ |
| 315 | } // eo exec |
| 316 | |
| 317 | BOOST_PP_REPEAT( BOOST_PP_ADD(T2N_SINGLETON_WRAPPER_MAX_ARGS,1), _GEN_EXEC, ~ ) |
| 318 | |
| 319 | #undef _GEN_EXEC |
| 320 | #undef _GEN_PLACEHOLDER |
| 321 | /// @endcond |
| 322 | |
| 323 | } |
| 324 | #endif |