// Copyright (C) 2003 Davis E. King (davis@dlib.net) // License: Boost Software License See LICENSE.txt for the full license. #undef DLIB_SERVER_KERNEL_ABSTRACT_ #ifdef DLIB_SERVER_KERNEL_ABSTRACT_ #include "../threads/threads_kernel_abstract.h" #include "../sockets/sockets_kernel_abstract.h" #include namespace dlib { class server { /*! INITIAL VALUE get_listening_ip() == "" get_listening_port() == 0 is_running() == false get_max_connections() == 1000 get_graceful_close_timeout() == 500 CALLBACK FUNCTIONS on_connect(): To use this object inherit from it and define the pure virtual function on_connect. Inside this function is where you will handle each new connection. Note that the connection object passed to on_connect() should NOT be closed, just let the function end and it will be gracefully closed for you. Also note that each call to on_connect() is run in its own thread. Also note that on_connect() should NOT throw any exceptions, all exceptions must be dealt with inside on_connect() and cannot be allowed to leave. on_listening_port_assigned(): This function is called to let the client know that the operating system has assigned a port number to the listening port. This happens if a port number of zero was given. Note that this function does not need to be defined. If you don't care then don't define it and it will do nothing. Note also that this function is NOT called in its own thread. Thus, making it block might hang the server. WHAT THIS OBJECT REPRESENTS This object represents a server that listens on a port and spawns new threads to handle each new connection. Note that the clear() function does not return until all calls to on_connect() have finished and the start() function has been shutdown. Also note that when clear() is called all open connection objects will be shutdown(). A note about get_max_connections(): when the maximum number of connections has been reached accept() will simply not be called until the number of open connections drops below get_max_connections(). This means connections will just wait to be serviced, rather than being outright refused. THREAD SAFETY All member functions are thread-safe. !*/ public: server( ); /*! ensures - #*this is properly initialized throws - std::bad_alloc - dlib::thread_error !*/ virtual ~server( ); /*! requires - is not called from any of server's callbacks ensures - all resources associated with *this have been released !*/ void clear( ); /*! requires - is not called from any of server's callbacks ensures - #*this has its initial value - all open connection objects passed to on_connect() are shutdown() - blocks until all calls to on_connect() have finished - blocks until the start() function has released all its resources throws - std::bad_alloc if this exception is thrown then the server object is unusable until clear() is called and succeeds !*/ void start ( ); /*! requires - is_running() == false ensures - starts listening on the port and ip specified by get_listening_ip() and #get_listening_port() for new connections. - if (get_listening_port() == 0) then - a port to listen on will be automatically selected - #get_listening_port() == the selected port being used - if (get_listening_ip() == "" ) then - all local IPs will be listened on - blocks until clear() is called or an error occurs throws - dlib::socket_error start() will throw this exception if there is some problem binding ports and/or starting the server or if there is a problem accepting new connections while it's running. If this happens then - All open connection objects passed to on_connect() are shutdown() and the exception will not be thrown until all on_connect() calls have terminated. - The server will be cleared and returned to its initial value. - dlib::thread_error start() will throw this exception if there is a problem creating new threads. Or it may throw this exception if there is a problem creating threading objects. If this happens then - All open connection objects passed to on_connect() are shutdown() and the exception will not be thrown until all on_connect() calls have terminated. - The server will be cleared and returned to its initial value. - std::bad_alloc start() may throw this exception and if it does then the object will be unusable until clear() is called and succeeds !*/ void start_async ( ); /*! ensures - starts listening on the port and ip specified by get_listening_ip() and #get_listening_port() for new connections. - if (get_listening_port() == 0) then - a port to listen on will be automatically selected - #get_listening_port() == the selected port being used - if (get_listening_ip() == "" ) then - all local IPs will be listened on - does NOT block. That is, this function will return right away and the server will run on a background thread until clear() or this object's destructor is called (or until some kind of fatal error occurs). - if an error occurs in the background thread while the server is running then it will shut itself down, set is_running() to false, and log the error to a dlib::logger object. - calling start_async() on a running server has no effect. throws - dlib::socket_error start_async() will throw this exception if there is some problem binding ports and/or starting the server. If this happens then - The server will be cleared and returned to its initial value. !*/ bool is_running ( ) const; /*! ensures - returns true if start() is running - returns false if start() is not running or has released all its resources and is about to terminate throws - std::bad_alloc !*/ int get_max_connections ( ) const; /*! ensures - returns the maximum number of connections the server will accept at a time. - returns 0 if the server will accept any number of connections throws - std::bad_alloc !*/ const std::string get_listening_ip ( ) const; /*! ensures - returns the local ip to listen for new connections on - returns "" if ALL local ips are to be listened on throws - std::bad_alloc !*/ int get_listening_port ( ) const; /*! ensures - returns the local port number to listen for new connections on - returns 0 if the local port number has not yet been set throws - std::bad_alloc !*/ void set_listening_port ( int port ); /*! requires - port >= 0 - is_running() == false ensures - #get_listening_port() == port throws - std::bad_alloc !*/ void set_listening_ip ( const std::string& ip ); /*! requires - is_ip_address(ip) == true or ip == "" - is_running() == false ensures - #get_listening_ip() == ip throws - std::bad_alloc !*/ void set_max_connections ( int max ); /*! requires - max >= 0 ensures - #get_max_connections() == max throws - std::bad_alloc !*/ void set_graceful_close_timeout ( unsigned long timeout ); /*! ensures - #get_graceful_close_timeout() == timeout !*/ unsigned long get_graceful_close_timeout ( ) const; /*! ensures - When on_connect() terminates, it will close the connection using close_gracefully(). This is done so that any data still in the operating system's output buffers gets a chance to be properly transmitted to the remote host. Part of this involves waiting for the remote host to close their end of the connection. Therefore, get_graceful_close_timeout() returns the timeout, in milliseconds, that we wait for the remote host to close their end of the connection. This is the timeout value given to close_gracefully(). !*/ private: virtual void on_connect ( connection& new_connection )=0; /*! requires - on_connect() is run in its own thread - is_running() == true - the number of current connections < get_max_connection() - new_connection == the new connection to the server which is to be serviced by this call to on_connect() ensures - when new_connection is shutdown() on_connect() will terminate - this function will not call clear() throws - does not throw any exceptions !*/ // do nothing by default virtual void on_listening_port_assigned ( ) {} /*! requires - is called if a listening port of zero was specified and an actual port number has just been assigned to the server ensures - this function will not block - this function will not call clear() throws - does not throw any exceptions !*/ // restricted functions server(server&); // copy constructor server& operator=(server&); // assignment operator }; } #endif // DLIB_SERVER_KERNEL_ABSTRACT_