Add implementation for signal handling. Use generic signal handler in…

… DDG4 for controlled shutdown on CTRL-C. Add test DDG4_SIGINT_handler in examples/DDG4

DDCore/include/DD4hep/SignalHandler.h

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+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+#ifndef DD4HEP_DDCORE_SIGNALHANDLER_H
+#define DD4HEP_DDCORE_SIGNALHANDLER_H
+
+/// System include files
+#include <csignal>
+#include <memory>
+
+/// Namespace for the AIDA detector description toolkit
+namespace dd4hep {
+
+  /// Interruptsback interface class with argument
+  /**
+   *  \author  M.Frank
+   *  \version 1.0
+   *  \ingroup DD4HEP_CORE
+   */
+  class  SignalHandler  {
+  public:
+    /// User signal handler definition
+    typedef bool (*signal_handler_t)(void* user_context, int signal);
+    /// Internal implementation class
+    class implementation;
+
+  public:
+    /// Default constructor
+    SignalHandler();
+    /// Default destructor
+    virtual ~SignalHandler();
+    /// (Re-)apply registered interrupt handlers to override potentially later registrations by other libraries
+    void applyHandlers();
+    /// Specialized handler for any signal
+    bool registerHandler(int sig_num, void* param, signal_handler_t handler);
+  };
+}      // End namespace dd4hep
+#endif // DD4HEP_DDCORE_SIGNALHANDLER_H

DDCore/src/SignalHandler.cpp

@@ -0,0 +1,308 @@
+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+
+// Framework include files
+#include <DD4hep/Printout.h>
+#include <DD4hep/SignalHandler.h>
+
+#include <map>
+#include <string>
+#include <vector>
+#include <iostream>
+#include <unistd.h>
+#include <execinfo.h>
+
+using namespace dd4hep;
+
+using signal_handler_t = SignalHandler::signal_handler_t;
+
+namespace {
+  static bool s_exit_handler_print  = true;
+  static bool s_exit_handler_active = false;
+  static bool s_exit_handler_backtrace = false;
+  static bool s_exit_handler_sleep_on_fatal = false;
+
+  template<class T> union func_cast   {
+    void* ptr;
+    T     fun;
+    explicit func_cast(T t) { fun = t; }
+    explicit func_cast(void* t) { ptr = t; }
+  };
+}
+
+/**@class SignalHandler::implementation
+ *
+ * Small class to manipulate default signal handling
+ *
+ * \author M.Frank
+ */
+class SignalHandler::implementation {
+protected:
+  struct sig_entry_t  {
+    void* user_context { nullptr };
+    signal_handler_t user_handler { nullptr };
+  };
+  struct sig_handler_t  {
+    std::string name { };
+    struct sigaction old_action { };
+    struct sigaction handler_action { };
+    std::vector<sig_entry_t> user_handlers { };
+  };
+
+public:
+  typedef std::map<int, sig_handler_t> SigMap;
+  SigMap  m_map;
+
+public:
+  /// Default constructor
+  implementation();
+  /// Default destructor
+  ~implementation();
+  /// Singleton accessor
+  static implementation& instance();
+  /// Initialize the exit handler. Subscribe to default signals
+  void init();
+  /// Install handler for a single signal
+  void install(int num, const std::string& name, struct sigaction& action);
+  /// Subscribe to a given signal with a user context and a user handler. The context MUST be unique!
+  int subscribe(int signum, void* user_context, signal_handler_t handler);
+  /// Unsubscribe from a given signal with a user context identifier
+  int unsubscribe(int signum, void* user_context);
+  /// Create simple backtrace
+  void back_trace(int /* signum */);
+  /// Static handler callback for system signal handler
+  static void handler(int signum, siginfo_t *info,void * );
+};
+
+/// Default constructor
+SignalHandler::implementation::implementation()  {
+}
+
+/// Default destructor
+SignalHandler::implementation::~implementation()  {
+}
+
+/// Singleton accessor
+SignalHandler::implementation& SignalHandler::implementation::instance()  {
+  static std::unique_ptr<implementation> imp;
+  if ( !imp )  {
+    imp = std::make_unique<implementation>();
+  }
+  return *imp;
+}
+
+/// Initialize the exit handler. Subscribe to default signals
+void SignalHandler::implementation::init()  {
+  struct sigaction new_action;
+  sigemptyset(&new_action.sa_mask);
+  new_action.sa_handler   = 0;
+  new_action.sa_sigaction = handler;
+  new_action.sa_flags     = SA_SIGINFO;
+
+  install(SIGILL,  "SIGILL",  new_action);
+  install(SIGINT,  "SIGINT",  new_action);
+  install(SIGTERM, "SIGTERM", new_action);
+  install(SIGHUP,  "SIGHUP",  new_action);
+
+  install(SIGQUIT, "SIGQUIT", new_action);
+  install(SIGBUS,  "SIGBUS",  new_action);
+  install(SIGXCPU, "SIGXCPU", new_action);
+  sigaddset(&new_action.sa_mask,SIGSEGV);
+  sigaddset(&new_action.sa_mask,SIGABRT);
+  sigaddset(&new_action.sa_mask,SIGFPE);
+  install(SIGABRT, "SIGABRT", new_action);
+  install(SIGFPE,  "SIGFPE",  new_action);
+  install(SIGSEGV, "SIGSEGV", new_action);
+}
+
+/// Subscribe to a given signal with a user context and a user handler. The context MUST be unique!
+int SignalHandler::implementation::subscribe(int signum, void* user_context, signal_handler_t user_handler)   {
+  if ( m_map.empty() )  {
+    this->init();
+  }
+  auto ihandler = m_map.find(signum);
+  if ( ihandler == m_map.end() )   {
+    char text[32];
+    struct sigaction new_action;
+    sigemptyset(&new_action.sa_mask);
+    new_action.sa_handler   = 0;
+    new_action.sa_sigaction = SignalHandler::implementation::handler;
+    new_action.sa_flags     = SA_SIGINFO;
+    ::snprintf(text, sizeof(text),"%08X",signum);
+    install(signum, text, new_action);
+    ihandler = m_map.find(signum);
+  }
+  if ( ihandler != m_map.end() )   { // Should always be true
+    sig_entry_t entry {user_context, user_handler};
+    ihandler->second.user_handlers.emplace_back(entry);
+    return 1;
+  }
+  return 0;
+}
+
+/// Unsubscribe from a given signal with a user context identifier
+int SignalHandler::implementation::unsubscribe(int signum, void* user_context)   {
+  auto ihandler = m_map.find(signum);
+  if ( ihandler != m_map.end() )   {
+    auto & handlers = ihandler->second.user_handlers;
+    for( auto it = handlers.begin(); it != handlers.end(); ++it )   {
+      if ( it->user_context == user_context )   {
+	handlers.erase(it);
+	return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/// Create simple backtrace
+void SignalHandler::implementation::back_trace(int /* signum */) {
+  if ( s_exit_handler_backtrace )   {
+    void *bt[256];
+    char text[512];
+    int bt_size = ::backtrace(bt, sizeof(bt) / sizeof(void *));
+    size_t len = ::snprintf(text, sizeof(text), "\n[INFO] (ExitSignalHandler) %s\n",
+			    "---------------------- Backtrace ----------------------\n");
+    text[sizeof(text)-2] = '\n';
+    text[sizeof(text)-1] = 0;
+    ::write(STDERR_FILENO, text, len);
+    len = ::snprintf(text, sizeof(text), "[INFO] Number of elements in backtrace: %d\n", bt_size);
+    text[sizeof(text)-2] = '\n';
+    text[sizeof(text)-1] = 0;
+    ::write(STDERR_FILENO, text, len);
+    ::backtrace_symbols_fd(bt, bt_size, STDERR_FILENO);
+    for (int i = 0; i < bt_size; i++) {
+      len = ::snprintf(text,sizeof(text),"[INFO] (SignalHandler) %02d --> %p\n", i, bt[i]);
+      text[sizeof(text)-2] = '\n';
+      text[sizeof(text)-1] = 0;
+      ::write(STDERR_FILENO, text, len);
+    }
+  }
+}
+
+/// Install handler for a single signal
+void SignalHandler::implementation::install(int num, const std::string& name, struct sigaction& action) {
+  auto& action_entry = m_map[num];
+  int res = ::sigaction (num, &action, &action_entry.old_action);
+  if ( res != 0 ) {
+    char text[512];
+    auto len = ::snprintf(text,sizeof(text),"Failed to install exit handler for %s", name.c_str());
+    text[sizeof(text)-2] = '\n';
+    text[sizeof(text)-1] = 0;
+    ::write(STDERR_FILENO, text, len);
+    return;
+  }
+  action_entry.handler_action = action;
+  action_entry.name = name;
+}
+
+/// Static handler callback for system signal handler
+void SignalHandler::implementation::handler(int signum, siginfo_t *info, void *ptr) {
+  SigMap& m = instance().m_map;
+  SigMap::iterator iter_handler = m.find(signum);
+  s_exit_handler_active = true;
+  if ( iter_handler != m.end() ) {
+    __sighandler_t hdlr = iter_handler->second.old_action.sa_handler;
+    func_cast<void (*)(int)> dsc0(hdlr);
+    func_cast<void (*)(int,siginfo_t*, void*)> dsc(dsc0.ptr);
+
+    if ( s_exit_handler_print ) {{
+	char text[512];
+	size_t len = ::snprintf(text,sizeof(text),
+				"[FATAL] (SignalHandler) Handle signal: %d [%s] Old action:%p Mem:%p Code:%08X\n",
+				signum,iter_handler->second.name.c_str(),dsc.ptr,info->si_addr,info->si_code);
+	text[sizeof(text)-2] = '\n';
+	text[sizeof(text)-1] = 0;
+	::write(STDERR_FILENO,text,len);
+	// Debugging hack, if enabled (default: NO)
+	if ( s_exit_handler_sleep_on_fatal )  {
+	  bool _s_sleep = true;
+	  len = ::snprintf(text,sizeof(text),
+			   "[FATAL] (SignalHandler) Sleeping for debugging.... %s\n",
+			   _s_sleep ? "YES" : "NO");
+	  text[sizeof(text)-2] = '\n';
+	  text[sizeof(text)-1] = 0;
+	  ::write(STDERR_FILENO,text,len);
+	  while ( _s_sleep ) ::usleep(100000);
+	}
+      }
+      if ( !iter_handler->second.user_handlers.empty() )    {
+	auto& handlers = iter_handler->second.user_handlers;
+	for( auto ih = handlers.rbegin(); ih != handlers.rend(); ++ih )   {
+	  if ( ih->user_handler )  {
+	    bool ret = (*(ih->user_handler))(ih->user_context, signum);
+	    if ( ret )   {
+	      return;
+	    }
+	    // Otherwise continue signal processing and eventually call default handlers
+	  }
+	  // No handler fired: call previously registered signal handler
+	  auto& entry = iter_handler->second.old_action;
+	  if ( entry.sa_handler )
+	    (*entry.sa_handler)(signum);
+	  else if ( entry.sa_sigaction )
+	    (*entry.sa_sigaction)(signum, info, ptr);
+	}
+      }
+      if ( signum == SIGSEGV || signum == SIGBUS || signum == SIGILL || signum == SIGABRT )  {
+	instance().back_trace(signum);
+      }
+      else if ( info->si_signo == SIGSEGV || info->si_signo == SIGBUS || info->si_signo == SIGILL || info->si_signo == SIGABRT )  {
+	instance().back_trace(info->si_signo);
+      }
+    }
+    if ( signum == SIGINT || signum == SIGHUP || signum == SIGFPE || signum == SIGPIPE ) {
+      if ( dsc.fun && (dsc0.fun != SIG_IGN) )
+	dsc.fun(signum, info, ptr);
+      else if ( signum == SIGHUP )
+	::_exit(signum);
+    }
+    else if ( signum == SIGSEGV && hdlr && hdlr != SIG_IGN && hdlr != SIG_DFL ) {
+      ::_exit(0);
+    }
+    else if ( hdlr && hdlr != SIG_IGN && dsc.fun )  {
+      dsc.fun(signum, info, ptr);
+    }
+    else if ( hdlr == SIG_DFL ) {
+      ::_exit(0);
+    }
+  }
+  s_exit_handler_active = false;
+}
+
+/// Default constructor
+SignalHandler::SignalHandler()
+{
+}
+
+/// Default destructor
+SignalHandler::~SignalHandler()  {
+}
+
+/// (Re-)apply registered interrupt handlers to override potentially later registrations by other libraries
+void SignalHandler::applyHandlers()  {
+  auto& imp = implementation::instance();
+  struct sigaction old_action { };
+  printout(INFO, "SignalHandler", "++ Re-apply signal handlers");
+  for( const auto& e : imp.m_map )  {
+    ::sigaction (e.first, &e.second.handler_action, &old_action);
+    printout(DEBUG, "SignalHandler",
+	     "++ Re-apply signal handler for %-10s [%3ld entries]",
+	     e.second.name.c_str(), e.second.user_handlers.size());
+  }
+}
+
+/// Install handler for any signal
+bool SignalHandler::registerHandler(int sig_num, void* param, signal_handler_t handler)  {
+  return implementation::instance().subscribe(sig_num, param, handler) == 1;
+}