ACE_Sig_Handler Class Reference

This is the main dispatcher of signals for ACE. It improves the existing UNIX signal handling mechanism by allowing C++ objects to handle signals in a way that avoids the use of global/static variables and functions. More...

#include <Sig_Handler.h>

Inheritance diagram for ACE_Sig_Handler:
Inheritance graph
[legend]
Collaboration diagram for ACE_Sig_Handler:
Collaboration graph
[legend]

List of all members.

Public Member Functions

 ACE_Sig_Handler (void)
 Default constructor.
virtual ~ACE_Sig_Handler (void)
 Destructor.
virtual int register_handler (int signum, ACE_Event_Handler *new_sh, ACE_Sig_Action *new_disp=0, ACE_Event_Handler **old_sh=0, ACE_Sig_Action *old_disp=0)
virtual int remove_handler (int signum, ACE_Sig_Action *new_disp=0, ACE_Sig_Action *old_disp=0, int sigkey=-1)
virtual ACE_Event_Handler * handler (int signum)
 Return the ACE_Sig_Handler associated with signum.
virtual ACE_Event_Handler * handler (int signum, ACE_Event_Handler *)
void dump (void) const
 Dump the state of an object.

Static Public Member Functions

static int sig_pending (void)
 True if there is a pending signal.
static void sig_pending (int)
 Reset the value of <sig_pending_> so that no signal is pending.
static void dispatch (int, siginfo_t *, ucontext_t *)

Public Attributes

 ACE_ALLOC_HOOK_DECLARE
 Declare the dynamic allocation hooks.

Static Protected Member Functions

static ACE_Event_Handler * handler_i (int signum, ACE_Event_Handler *)
static int register_handler_i (int signum, ACE_Event_Handler *new_sh, ACE_Sig_Action *new_disp=0, ACE_Event_Handler **old_sh=0, ACE_Sig_Action *old_disp=0)
static int in_range (int signum)
 Check whether the SIGNUM is within the legal range of signals.

Static Protected Attributes

static sig_atomic_t sig_pending_ = 0
 Keeps track of whether a signal is pending.

Static Private Attributes

static ACE_Event_Handler * signal_handlers_ [ACE_NSIG]

Detailed Description

This is the main dispatcher of signals for ACE. It improves the existing UNIX signal handling mechanism by allowing C++ objects to handle signals in a way that avoids the use of global/static variables and functions.

Using this class a program can register an ACE_Event_Handler with the ACE_Sig_Handler in order to handle a designated signum. When a signal occurs that corresponds to this signum, the handle_signal method of the registered ACE_Event_Handler is invoked automatically.

Definition at line 43 of file Sig_Handler.h.

Constructor & Destructor Documentation

ACE_Sig_Handler::ACE_Sig_Handler ( void   ) 

Default constructor.

Definition at line 6 of file Sig_Handler.inl.

00007 {
00008 }

ACE_Sig_Handler::~ACE_Sig_Handler ( void   )  [virtual]

Destructor.

Definition at line 55 of file Sig_Handler.cpp.

00056 {
00057 }

Member Function Documentation

void ACE_Sig_Handler::dispatch ( int  signum,
siginfo_t *  siginfo,
ucontext_t *  ucontext 
) [static]

Callback routine registered with sigaction(2) that dispatches the <handle_signal> method of the appropriate pre-registered ACE_Event_Handler.

Reimplemented in ACE_Sig_Handlers.

Definition at line 231 of file Sig_Handler.cpp.

00234 {
00235   ACE_TRACE ("ACE_Sig_Handler::dispatch");
00236 
00237   // Save/restore errno.
00238   ACE_Errno_Guard error (errno);
00239 
00240   // We can't use the <sig_pending> call here because that acquires
00241   // the lock, which is non-portable...
00242   ACE_Sig_Handler::sig_pending_ = 1;
00243 
00244   // Darn well better be in range since the OS dispatched this...
00245   ACE_ASSERT (ACE_Sig_Handler::in_range (signum));
00246 
00247   ACE_Event_Handler *eh = ACE_Sig_Handler::signal_handlers_[signum];
00248 
00249   if (eh != 0)
00250     {
00251       if (eh->handle_signal (signum, siginfo, ucontext) == -1)
00252         {
00253           // Define the default disposition.
00254           ACE_Sig_Action sa ((ACE_SignalHandler) SIG_DFL, (sigset_t *) 0);
00255 
00256           ACE_Sig_Handler::signal_handlers_[signum] = 0;
00257 
00258           // Remove the current disposition by registering the default
00259           // disposition.
00260           sa.register_action (signum);
00261 
00262           // Allow the event handler to close down if necessary.
00263           eh->handle_close (ACE_INVALID_HANDLE,
00264                             ACE_Event_Handler::SIGNAL_MASK);
00265         }
00266 #if defined (ACE_WIN32)
00267       else
00268         // Win32 is weird in the sense that it resets the signal
00269         // disposition to SIG_DFL after a signal handler is
00270         // dispatched.  Therefore, to workaround this "feature" we
00271         // must re-register the <ACE_Event_Handler> with <signum>
00272         // explicitly.
00273         ACE_Sig_Handler::register_handler_i (signum,
00274                                              eh);
00275 #endif /* ACE_WIN32*/
00276     }
00277 }

void ACE_Sig_Handler::dump ( void   )  const

Dump the state of an object.

Reimplemented in ACE_Sig_Handlers.

Definition at line 60 of file Sig_Handler.cpp.

00061 {
00062 #if defined (ACE_HAS_DUMP)
00063   ACE_TRACE ("ACE_Sig_Handler::dump");
00064 #endif /* ACE_HAS_DUMP */
00065 }

ACE_Event_Handler * ACE_Sig_Handler::handler ( int  signum,
ACE_Event_Handler *  new_sh 
) [virtual]

Set a new ACE_Event_Handler that is associated with signum. Return the existing handler.

Reimplemented in ACE_Sig_Handlers.

Definition at line 123 of file Sig_Handler.cpp.

00125 {
00126   ACE_TRACE ("ACE_Sig_Handler::handler");
00127   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00128     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00129       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00130     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00131 
00132   return ACE_Sig_Handler::handler_i (signum, new_sh);
00133 }

ACE_Event_Handler * ACE_Sig_Handler::handler ( int  signum  )  [virtual]

Return the ACE_Sig_Handler associated with signum.

Reimplemented in ACE_Sig_Handlers.

Definition at line 91 of file Sig_Handler.cpp.

00092 {
00093   ACE_TRACE ("ACE_Sig_Handler::handler");
00094   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00095     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00096       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00097     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00098 
00099   if (ACE_Sig_Handler::in_range (signum))
00100     return ACE_Sig_Handler::signal_handlers_[signum];
00101   else
00102     return 0;
00103 }

ACE_Event_Handler * ACE_Sig_Handler::handler_i ( int  signum,
ACE_Event_Handler *  new_sh 
) [static, protected]

Set a new ACE_Event_Handler that is associated with signum. Return the existing handler. Does not acquire any locks so that it can be called from a signal handler, such as <dispatch>.

Definition at line 106 of file Sig_Handler.cpp.

00108 {
00109   ACE_TRACE ("ACE_Sig_Handler::handler_i");
00110 
00111   if (ACE_Sig_Handler::in_range (signum))
00112     {
00113       ACE_Event_Handler *sh = ACE_Sig_Handler::signal_handlers_[signum];
00114 
00115       ACE_Sig_Handler::signal_handlers_[signum] = new_sh;
00116       return sh;
00117     }
00118   else
00119     return 0;
00120 }

int ACE_Sig_Handler::in_range ( int  signum  )  [static, protected]

Check whether the SIGNUM is within the legal range of signals.

Definition at line 11 of file Sig_Handler.inl.

00012 {
00013   ACE_TRACE ("ACE_Sig_Handler::in_range");
00014   return signum > 0 && signum < ACE_NSIG;
00015 }

int ACE_Sig_Handler::register_handler ( int  signum,
ACE_Event_Handler *  new_sh,
ACE_Sig_Action *  new_disp = 0,
ACE_Event_Handler **  old_sh = 0,
ACE_Sig_Action *  old_disp = 0 
) [virtual]

Add a new ACE_Event_Handler and a new sigaction associated with signum. Passes back the existing ACE_Event_Handler and its sigaction if pointers are non-zero. Returns -1 on failure and >= 0 on success.

Reimplemented in ACE_Sig_Handlers.

Definition at line 178 of file Sig_Handler.cpp.

00183 {
00184   ACE_TRACE ("ACE_Sig_Handler::register_handler");
00185   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00186     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00187       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00188     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00189 
00190   return ACE_Sig_Handler::register_handler_i (signum,
00191                                               new_sh,
00192                                               new_disp,
00193                                               old_sh,
00194                                               old_disp);
00195 }

int ACE_Sig_Handler::register_handler_i ( int  signum,
ACE_Event_Handler *  new_sh,
ACE_Sig_Action *  new_disp = 0,
ACE_Event_Handler **  old_sh = 0,
ACE_Sig_Action *  old_disp = 0 
) [static, protected]

This implementation method is called by <register_handler> and dispatch. It doesn't do any locking so that it can be called within a signal handler, such as dispatch. It adds a new ACE_Event_Handler and a new sigaction associated with signum. Passes back the existing ACE_Event_Handler and its sigaction if pointers are non-zero. Returns -1 on failure and >= 0 on success.

Definition at line 140 of file Sig_Handler.cpp.

00145 {
00146   ACE_TRACE ("ACE_Sig_Handler::register_handler_i");
00147 
00148   if (ACE_Sig_Handler::in_range (signum))
00149     {
00150       ACE_Sig_Action sa; // Define a "null" action.
00151       ACE_Event_Handler *sh = ACE_Sig_Handler::handler_i (signum, new_sh);
00152 
00153       // Return a pointer to the old <ACE_Sig_Handler> if the user
00154       // asks for this.
00155       if (old_sh != 0)
00156         *old_sh = sh;
00157 
00158       // Make sure that <new_disp> points to a valid location if the
00159       // user doesn't care...
00160       if (new_disp == 0)
00161         new_disp = &sa;
00162 
00163       new_disp->handler (ace_signal_handler_dispatcher);
00164 #if !defined (ACE_HAS_LYNXOS4_SIGNALS)
00165       new_disp->flags (new_disp->flags () | SA_SIGINFO);
00166 #endif /* ACE_HAS_LYNXOS4_SIGNALS */
00167       return new_disp->register_action (signum, old_disp);
00168     }
00169   else
00170     return -1;
00171 }

int ACE_Sig_Handler::remove_handler ( int  signum,
ACE_Sig_Action *  new_disp = 0,
ACE_Sig_Action *  old_disp = 0,
int  sigkey = -1 
) [virtual]

Remove the ACE_Event_Handler currently associated with signum. sigkey is ignored in this implementation since there is only one instance of a signal handler. Install the new disposition (if given) and return the previous disposition (if desired by the caller). Returns 0 on success and -1 if signum is invalid.

Reimplemented in ACE_Sig_Handlers.

Definition at line 200 of file Sig_Handler.cpp.

00204 {
00205   ACE_TRACE ("ACE_Sig_Handler::remove_handler");
00206   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00207     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00208       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00209     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00210 
00211   if (ACE_Sig_Handler::in_range (signum))
00212     {
00213       ACE_Sig_Action sa (SIG_DFL, (sigset_t *) 0); // Define the default disposition.
00214 
00215       if (new_disp == 0)
00216         new_disp = &sa;
00217 
00218       ACE_Sig_Handler::signal_handlers_[signum] = 0;
00219 
00220       // Register either the new disposition or restore the default.
00221       return new_disp->register_action (signum, old_disp);
00222     }
00223 
00224     return -1;
00225 }

void ACE_Sig_Handler::sig_pending ( int  pending  )  [static]

Reset the value of <sig_pending_> so that no signal is pending.

Definition at line 79 of file Sig_Handler.cpp.

00080 {
00081   ACE_TRACE ("ACE_Sig_Handler::sig_pending");
00082 
00083   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00084           ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00085           (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00086           ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00087   ACE_Sig_Handler::sig_pending_ = pending;
00088 }

int ACE_Sig_Handler::sig_pending ( void   )  [static]

True if there is a pending signal.

Definition at line 68 of file Sig_Handler.cpp.

00069 {
00070   ACE_TRACE ("ACE_Sig_Handler::sig_pending");
00071   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00072           ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00073           (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00074           ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00075   return ACE_Sig_Handler::sig_pending_ != 0;
00076 }

Member Data Documentation

ACE_Sig_Handler::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

Reimplemented in ACE_Sig_Handlers.

Definition at line 106 of file Sig_Handler.h.

sig_atomic_t ACE_Sig_Handler::sig_pending_ = 0 [static, protected]

Keeps track of whether a signal is pending.

Definition at line 138 of file Sig_Handler.h.

ACE_Event_Handler * ACE_Sig_Handler::signal_handlers_ [static, private]

Array used to store one user-defined Event_Handler for every signal.

Definition at line 143 of file Sig_Handler.h.

The documentation for this class was generated from the following files:
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines
Generated on Sat Nov 21 23:18:08 2009 for ACE by  doxygen 1.6.1