00001 00002 // -*- mode: c++; c-basic-offset:4 -*- 00003 00004 // This file is part of libdap, A C++ implementation of the OPeNDAP Data 00005 // Access Protocol. 00006 00007 // Copyright (c) 2002,2003 OPeNDAP, Inc. 00008 // Author: James Gallagher <jgallagher@opendap.org> 00009 // 00010 // This library is free software; you can redistribute it and/or 00011 // modify it under the terms of the GNU Lesser General Public 00012 // License as published by the Free Software Foundation; either 00013 // version 2.1 of the License, or (at your option) any later version. 00014 // 00015 // This library is distributed in the hope that it will be useful, 00016 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00018 // Lesser General Public License for more details. 00019 // 00020 // You should have received a copy of the GNU Lesser General Public 00021 // License along with this library; if not, write to the Free Software 00022 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 00023 // 00024 // You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112. 00025 00026 #ifndef signal_handler_h 00027 #define signal_handler_h 00028 00029 #include <signal.h> 00030 00031 #include "EventHandler.h" 00032 #include "InternalErr.h" 00033 00034 typedef void Sigfunc(int); // Plauger, 1992 00035 00063 class SignalHandler 00064 { 00065 private: 00066 // Ensure we're a Singleton. 00067 SignalHandler() 00068 {} 00069 00070 // Singleton pointer. 00071 static SignalHandler *d_instance; 00072 00073 // Table of pointers to instances of EventHandlers. Since EventHandler is 00074 // abstract, the pointers will actually reference instances that are 00075 // children of EventHandler. NSIG is defined in signal.h but this may be 00076 // a portability issue. 00077 static EventHandler *d_signal_handlers[NSIG]; 00078 00079 // This array holds the old signal handlers. Once the handler in 00080 // d_signal_handler[signum] is run, look here to see what the original 00081 // action was. This is important since libdap++ is often embedded in code 00082 // that already has a non-default signal handler for things like SIGINT. 00083 static Sigfunc *d_old_handlers[NSIG]; 00084 00085 // Entry point adapter installed into sigaction(). This must be static 00086 // method (or a regular C-function) to conform to sigaction's interface. 00087 // this is the part of SignalHandler that uses the Adapter pattern. 00088 static void dispatcher(int signum); 00089 00090 // Delete the global instance. Call this with atexit(). 00091 static void delete_instance(); 00092 00093 // Call this using pthread_once() to ensure there's only one instance 00094 // when running in a MT world. 00095 static void initialize_instance(); 00096 00097 friend class SignalHandlerTest; 00098 friend class HTTPCacheTest; 00099 00100 public: 00101 static SignalHandler *instance(); 00102 00104 virtual ~SignalHandler() 00105 {} 00106 00107 EventHandler *register_handler(int signum, EventHandler *eh, 00108 bool override = false); 00109 00110 EventHandler *remove_handler(int signum); 00111 }; 00112 00113 #endif // signal_handler_h