Signal.cpp

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00001 /*
00002  * This program is free software; you can redistribute it and/or modify
00003  * it under the terms of the GNU General Public License as published by
00004  * the Free Software Foundation; either version 3 of the License, or
00005  * (at your option) any later version.
00006  *
00007  * Written (W) 1999-2009 Soeren Sonnenburg
00008  * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society
00009  */
00010 
00011 #include <shogun/lib/config.h>
00012 
00013 #ifndef WIN32
00014 
00015 #include <stdlib.h>
00016 #include <signal.h>
00017 #include <string.h>
00018 
00019 #include <shogun/io/SGIO.h>
00020 #include <shogun/lib/Signal.h>
00021 
00022 using namespace shogun;
00023 
00024 int CSignal::signals[NUMTRAPPEDSIGS]={SIGINT, SIGURG};
00025 struct sigaction CSignal::oldsigaction[NUMTRAPPEDSIGS];
00026 bool CSignal::active=false;
00027 bool CSignal::cancel_computation=false;
00028 bool CSignal::cancel_immediately=false;
00029 
00030 CSignal::CSignal()
00031 : CSGObject()
00032 {
00033 }
00034 
00035 CSignal::~CSignal()
00036 {
00037     if (!unset_handler())
00038         SG_PRINT("error uninitalizing signal handler\n");
00039 }
00040 
00041 void CSignal::handler(int signal)
00042 {
00043     if (signal == SIGINT)
00044     {
00045         SG_SPRINT("\nImmediately return to prompt / Prematurely finish computations / Do nothing (I/P/D)? ");
00046         char answer=fgetc(stdin);
00047 
00048         if (answer == 'I')
00049         {
00050             unset_handler();
00051             set_cancel(true);
00052             if (sg_print_error)
00053                 sg_print_error(stdout, "sg stopped by SIGINT\n");
00054         }
00055         else if (answer == 'P')
00056             set_cancel();
00057         else
00058             SG_SPRINT("Continuing...\n");
00059     }
00060     else if (signal == SIGURG)
00061         set_cancel();
00062     else
00063         SG_SPRINT("unknown signal %d received\n", signal);
00064 }
00065 
00066 bool CSignal::set_handler()
00067 {
00068     if (!active)
00069     {
00070         struct sigaction act;
00071         sigset_t st;
00072 
00073         sigemptyset(&st);
00074         for (int32_t i=0; i<NUMTRAPPEDSIGS; i++)
00075             sigaddset(&st, signals[i]);
00076 
00077 #ifndef __INTERIX
00078         act.sa_sigaction=NULL; //just in case
00079 #endif
00080         act.sa_handler=CSignal::handler;
00081         act.sa_mask = st;
00082         act.sa_flags = 0;
00083 
00084         for (int32_t i=0; i<NUMTRAPPEDSIGS; i++)
00085         {
00086             if (sigaction(signals[i], &act, &oldsigaction[i]))
00087             {
00088                 SG_SPRINT("Error trapping signals!\n");
00089                 for (int32_t j=i-1; j>=0; j--)
00090                     sigaction(signals[i], &oldsigaction[i], NULL);
00091 
00092                 clear();
00093                 return false;
00094             }
00095         }
00096 
00097         active=true;
00098         return true;
00099     }
00100     else
00101         return false;
00102 }
00103 
00104 bool CSignal::unset_handler()
00105 {
00106     if (active)
00107     {
00108         bool result=true;
00109 
00110         for (int32_t i=0; i<NUMTRAPPEDSIGS; i++)
00111         {
00112             if (sigaction(signals[i], &oldsigaction[i], NULL))
00113             {
00114                 SG_SPRINT("error uninitalizing signal handler for signal %d\n", signals[i]);
00115                 result=false;
00116             }
00117         }
00118 
00119         if (result)
00120             clear();
00121 
00122         return result;
00123     }
00124     else
00125         return false;
00126 }
00127 
00128 void CSignal::clear_cancel()
00129 {
00130     cancel_computation=false;
00131     cancel_immediately=false;
00132 }
00133 
00134 void CSignal::set_cancel(bool immediately)
00135 {
00136     cancel_computation=true;
00137 
00138     if (immediately)
00139         cancel_immediately=true;
00140 }
00141 
00142 void CSignal::clear()
00143 {
00144     clear_cancel();
00145     active=false;
00146     memset(&CSignal::oldsigaction, 0, sizeof(CSignal::oldsigaction));
00147 }
00148 #endif //WIN32
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