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:

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Collaboration diagram for ACE_Sig_Handler:

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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 228 of file Sig_Handler.cpp.

00231 {
00232   ACE_TRACE ("ACE_Sig_Handler::dispatch");
00233 
00234   // Save/restore errno.
00235   ACE_Errno_Guard error (errno);
00236 
00237   // We can't use the <sig_pending> call here because that acquires
00238   // the lock, which is non-portable...
00239   ACE_Sig_Handler::sig_pending_ = 1;
00240 
00241   // Darn well better be in range since the OS dispatched this...
00242   ACE_ASSERT (ACE_Sig_Handler::in_range (signum));
00243 
00244   ACE_Event_Handler *eh = ACE_Sig_Handler::signal_handlers_[signum];
00245 
00246   if (eh != 0)
00247     {
00248       if (eh->handle_signal (signum, siginfo, ucontext) == -1)
00249         {
00250           // Define the default disposition.
00251           ACE_Sig_Action sa ((ACE_SignalHandler) SIG_DFL, (sigset_t *) 0);
00252 
00253           ACE_Sig_Handler::signal_handlers_[signum] = 0;
00254 
00255           // Remove the current disposition by registering the default
00256           // disposition.
00257           sa.register_action (signum);
00258 
00259           // Allow the event handler to close down if necessary.
00260           eh->handle_close (ACE_INVALID_HANDLE,
00261                             ACE_Event_Handler::SIGNAL_MASK);
00262         }
00263 #if defined (ACE_WIN32)
00264       else
00265         // Win32 is weird in the sense that it resets the signal
00266         // disposition to SIG_DFL after a signal handler is
00267         // dispatched.  Therefore, to workaround this "feature" we
00268         // must re-register the <ACE_Event_Handler> with <signum>
00269         // explicitly.
00270         ACE_Sig_Handler::register_handler_i (signum,
00271                                              eh);
00272 #endif /* ACE_WIN32*/
00273     }
00274 }

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 175 of file Sig_Handler.cpp.

00180 {
00181   ACE_TRACE ("ACE_Sig_Handler::register_handler");
00182   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00183     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00184       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00185     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00186 
00187   return ACE_Sig_Handler::register_handler_i (signum,
00188                                               new_sh,
00189                                               new_disp,
00190                                               old_sh,
00191                                               old_disp);
00192 }

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       return new_disp->register_action (signum, old_disp);
00165     }
00166   else
00167     return -1;
00168 }

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 197 of file Sig_Handler.cpp.

00201 {
00202   ACE_TRACE ("ACE_Sig_Handler::remove_handler");
00203   ACE_MT (ACE_Recursive_Thread_Mutex *lock =
00204     ACE_Managed_Object<ACE_Recursive_Thread_Mutex>::get_preallocated_object
00205       (ACE_Object_Manager::ACE_SIG_HANDLER_LOCK);
00206     ACE_Guard<ACE_Recursive_Thread_Mutex> m (*lock));
00207 
00208   if (ACE_Sig_Handler::in_range (signum))
00209     {
00210       ACE_Sig_Action sa (SIG_DFL, (sigset_t *) 0); // Define the default disposition.
00211 
00212       if (new_disp == 0)
00213         new_disp = &sa;
00214 
00215       ACE_Sig_Handler::signal_handlers_[signum] = 0;
00216 
00217       // Register either the new disposition or restore the default.
00218       return new_disp->register_action (signum, old_disp);
00219     }
00220 
00221     return -1;
00222 }

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 }