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Public Member Functions | Static Public Member Functions | Static Private Member Functions
ASSA::SigHandlers Class Reference

#include <SigHandlers.h>

Inheritance diagram for ASSA::SigHandlers:
ASSA::SigHandler

List of all members.

Public Member Functions

virtual int install (int signum_, EventHandler *new_hand_, SigAction *new_disp_=0, EventHandler **old_hand_=0, SigAction *old_disp_=0)
 Register EventHandler with dispatching system.
virtual int remove (int signum_, EventHandler *eh_, SigAction *new_disp_=0, SigAction *old_disp_=0)
 Remove EventHandler from the list of registered handler for signum_.
- Public Member Functions inherited from ASSA::SigHandler
virtual ~SigHandler ()
 No-op virtual destructor.
EventHandlerhandler (int signum_, EventHandler *new_)
 Set new event handler for signal signum_ and return an existing one.
EventHandlerhandler (int signum_)
 Retrieve current event handler for signum_.

Static Public Member Functions

static void sighandlers_dispatcher (int signum_)
 A wrapper around static SigHandlers::dispatch().

Static Private Member Functions

static void dispatch (int signum_)
 The heart of SigHandlers class - this callback function is really registered with OS to catch all of the signals for which event handler has been installed.

Additional Inherited Members

- Protected Member Functions inherited from ASSA::SigHandler
int in_range (int signum_)
 Check that signum_ is in valid range.

Detailed Description

Definition at line 55 of file SigHandlers.h.


Member Function Documentation

void SigHandlers::dispatch ( int  signum_)
staticprivate

The heart of SigHandlers class - this callback function is really registered with OS to catch all of the signals for which event handler has been installed.

Appropriate EventHandler(s) are then notified.

Reimplemented from ASSA::SigHandler.

Definition at line 237 of file SigHandlers.cpp.

References ASSA::SigHandlersList::begin(), ASSA::SigHandlersList::end(), ASSA::SigHandlersList::erase(), ASSA::EventHandler::handle_signal(), ASSA::SigHandlersList::instance(), ASSA::SIGHAND, and trace_with_mask.

Referenced by sighandlers_dispatcher().

{
trace_with_mask("SigHandlers::dispatch", SIGHAND);
/*---
For every element in the set that holds all EventHandlers for
given signum, call its respective handle_signal() member function.
---*/
/*--- save errno ---*/
int errno_saved = errno;
SigHandlersList& handlist = *(SigHandlersList::instance(signum_));
for (it=handlist.begin(); it != handlist.end(); it++) {
ehp = *it;
if (ehp->handle_signal (signum_) == -1) {
/*---
this event handler reported error when handling
signum - remove it from the set
---*/
handlist.erase (it);
}
}
/*--- restore errno ---*/
errno = errno_saved;
}
int SigHandlers::install ( int  signum_,
EventHandler new_hand_,
SigAction new_disp_ = 0,
EventHandler **  old_hand_ = 0,
SigAction old_disp_ = 0 
)
virtual

Register EventHandler with dispatching system.

Parameters:
signum_(In ) Signal number.
new_hand_(In ) Pointer to new event handler to install.
new_disp_(In=0 ) New disposition to use to handle signal.
old_hand_(Out=0) Placeholder for old event handler.
old_disp_(Out=0) Placeholder for old disposition.
Returns:
0 on success; -1 on error.

Reimplemented from ASSA::SigHandler.

Definition at line 36 of file SigHandlers.cpp.

References ASSA::ASSAERR, ASSA::SigHandlersList::cfunc_handler(), DL, EL, ASSA::SigHandlersList::erase(), ASSA::SigAction::handler(), ASSA::SigHandler::in_range(), ASSA::SigHandlersList::insert(), ASSA::SigHandlersList::instance(), ASSA::SigAction::register_action(), ASSA::SigAction::retrieve_action(), ASSA::SigHandlersList::seen_cfunc_handler(), ASSA::SIGHAND, sighandlers_dispatcher(), ASSA::SigHandlersList::size(), and trace_with_mask.

Referenced by ASSA::GenServer::init().

{
/*
Retrieve current signal disposition. If 3rd party handler has
already been istalled, make CFUNC_Handler out of it, and put it in
the list with id=0.
Add new_hand_ to the list. Has global sighandlers_dispatcher not
been installed yet, install it too.
*/
trace_with_mask("SigHandlers::install()", SIGHAND);
if (!in_range(signum_) == -1) {
EL((ASSAERR,"in_range (%s) failed\n",signum_));
return -1;
}
CFUNC_Handler* cfhp = NULL;
SigHandlersList* handlist = NULL;
handlist = SigHandlersList::instance(signum_);
/*--- Retrieve current signal disposition ---*/
cd.retrieve_action(signum_);
/*
Check whether 3rd party software has already installed
signal handler.
*/
cd.handler() != SIG_IGN &&
cd.handler() != SIG_DFL )
{
/*
Looks like some other code got ahead of me and installed C-function
signal handler. Make a note of it.
Create EventHandler to hold 3rd party handler. This handler will be
deleted only by SigHandlers::remove (NULL), when application demanded
to remove all of the handlers.
*/
DL((SIGHAND,"Detected 3rd party \"C\" handler!\n"));
cfhp = new CFUNC_Handler (cd.handler ());
handlist->cfunc_handler (cfhp);
/*
Insert 3rd party handler in list of handlers
for this signal.
*/
DL((SIGHAND,"Adding 3rd party \"C\" handler\n"));
if ( handlist->insert (cfhp) == false ) {
EL((ASSAERR, "Failed to insert "\
"c_func_handler for signum %d\n", signum_));
delete (cfhp);
handlist->cfunc_handler (0);
return -1;
}
DL((SIGHAND,"Set size: %d\n", handlist->size () ));
}
/*--- Add new_hand_ to the list of handlers for signum_. ---*/
DL((SIGHAND,"Adding EventHandler to the list\n"));
if (handlist->insert (new_hand_) == false) {
/*---
I failed to install new handler and might have already
added 3rd party CFUNC_Handler to the list without altering
disposition - if that's true, clean up the list.
---*/
EL((ASSAERR,"failed to add new_hand_ to handlers list\n"));
if (handlist->seen_cfunc_handler () &&
handlist->size() == 1)
{
handlist->erase ();
handlist->cfunc_handler (0);
}
return -1;
}
DL((SIGHAND,"Set size: %d\n", handlist->size () ));
/*--- Has sighandlers_dispatcher been already installed? ---*/
return 0;
}
DL((SIGHAND,"Installing 'sighandlers_dispatcher'\n"));
/*
Installing new disposition; if user forgot to give me one
then default will be used.
*/
SigAction sa ((C_SIG_HANDLER) SIG_DFL);
if (new_disp_ == 0) {
new_disp_ = &sa;
}
if (new_disp_->register_action (signum_, old_disp_) == -1) {
/*---
I failed to install sighandlers_dispatcher. Up to this
point, if application had conventional C handler installed,
it still remains active. Handlers list built so far is
meaningless - get rid of it. ---*/
EL((ASSAERR,"register_action() error\n"));
if (handlist->seen_cfunc_handler ()) {
handlist->erase ();
handlist->cfunc_handler (0);
delete cfhp;
}
handlist->erase (new_hand_);
return -1;
}
return 0;
}
int SigHandlers::remove ( int  signum_,
EventHandler eh_,
SigAction new_disp_ = 0,
SigAction old_disp_ = 0 
)
virtual

Remove EventHandler from the list of registered handler for signum_.

If eh_ is NULL, then all EventHandler(s) will be removed from the list, and object will go back to passive mode in which no signal handling is done via SigHandlers class dispatcher. If new_disp_ is omitted, SIG_DFL will be used instead.

Parameters:
signum_(In ) Signal number.
eh_(In ) Event handler to remove.
new_disp_(In=0 ) New disposition to use to handle signal.
old_disp_(Out=0) Placeholder for old disposition.
Returns:
0 on success; -1 on error.

Reimplemented from ASSA::SigHandler.

Definition at line 167 of file SigHandlers.cpp.

References ASSA::ASSAERR, ASSA::SigHandlersList::cfunc_handler(), DL, EL, ASSA::SigHandlersList::end(), ASSA::SigHandlersList::erase(), ASSA::SigHandlersList::find(), ASSA::CFUNC_Handler::handler(), ASSA::SigAction::handler(), ASSA::SigHandler::in_range(), ASSA::SigHandlersList::instance(), ASSA::SigAction::register_action(), ASSA::SigHandlersList::seen_cfunc_handler(), ASSA::SIGHAND, ASSA::SigHandlersList::size(), and trace_with_mask.

{
trace_with_mask("SigHandlers::remove()", SIGHAND);
if (in_range (signum_)) {
EL((ASSAERR, "singum_ %d is out of range\n", signum_));
return -1;
}
CFUNC_Handler* Cfhp = NULL; // pointer to C-function event handler
EventHandler* ehp = NULL; // pointer to current event handler
SigHandlersList& handlist = *(SigHandlersList::instance(signum_));
if (eh_ == NULL) {
DL((SIGHAND,"Erasing the entire set\n"));
/*--- Erase an entire list. ---*/
handlist.erase ();
DL((SIGHAND,"Set size: %d\n", handlist.size ()));
}
else {
/*
Note: I cannot do erasure in the same loop for following reason:
According to Stroustrup (Section 17.4.1.7):
"After erase(), the iterator cannot be used again because
the element to which it pointed is no longer there."
According to STL Tutorial and Ref. Guide:
"The erase function invalidates all iterators to all
positions past the point of erasure."
That's why here we first take care of id recycling and heap memory
deallocation, and only then clean() the map all at once.
*/
if ((it = handlist.find (eh_)) != handlist.end ()) {
DL((SIGHAND,"Removing EventHandler\n"));
ehp = (*it);
handlist.erase (it);
}
DL((SIGHAND,"Set size: %d\n", handlist.size () ));
}
/*--- If set is not empty, we're done ---*/
if (handlist.size ()) return 0;
/* If map was emptied out, install new disposition
with the 3rd party "C" function handler, if we had it.
*/
SigAction null_sa;
if (new_disp_ == 0) new_disp_ = &null_sa;
DL((SIGHAND,"Handlers List is empty\n"));
if (handlist.seen_cfunc_handler ()) {
/*--- Put 3rd party handler into disposition ---*/
DL((SIGHAND,"Reinstalling \"C\" handler\n"));
Cfhp = handlist.cfunc_handler (0);
new_disp_->handler (Cfhp->handler ());
delete Cfhp;
}
/*--- Install new disposition ---*/
return new_disp_->register_action (signum_, old_disp_);
}
void SigHandlers::sighandlers_dispatcher ( int  signum_)
static

A wrapper around static SigHandlers::dispatch().

It is needed for the purpose of differentiation it with other signal handlers that might be installed by user's code.

Parameters:
signum_Dispatch event handlers for this signal.

Definition at line 26 of file SigHandlers.cpp.

References dispatch(), DL, ASSA::SIGHAND, and trace_with_mask.

Referenced by install().

{
trace_with_mask("SigHandlers::sighandlers_dispatch", SIGHAND);
DL((SIGHAND,"==> Recevied signal # %d\n", signum_));
dispatch (signum_);
}

The documentation for this class was generated from the following files: