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Summary 0022545: Improved exception handling
Revision 2011-11-25 14:50 by szy
Description RLN contribution.
Detailed description:
      - Exception objects (Standard_Failure ancestors) are now
defined/implemented using macros (see Standard_DefineException>
        in a way similar to defining handles. This enables creating user-defined
exceptions without CDL.
        Note that as preprocessor does not allow to insert preprocessor
instructions (starting with #) into macro definitions, it is impossible to
define macros #<object_type>_Raise_if(). Therefore their generation is
kept within CDL extractor as previously. The user does not really need to do
this - he may rely on No_Exceptions macro. CPPExt_Template.edl must be copied to
$WOKHOME/lib for CDL extractor to take effect.
      - Standard_Failure has Throw() non-virtual and ancestros does not have it
anymore (implementation was the same).

   OSD_signal_WNT.cxx
      - OSD::SetSignal() now always sets signal handlers, exception handlers and
structured exception (SE) translators. This >
        to deal correctly in case if user's code is compiled with /EHs or /EHa.
UseSETranslation() are removed,
        as redundant. See detailed documentation in OSD_signal_WNT.cxx on
OSD::SetSignal().
      - very detailed documentation for OSD::Setsignal() in Doygen format is now
in this file.
      - removed static variables that set signals only once to enable calling
::SetSignal() for other threads or even
        within the same thread if the user switched handlers before
      - mutexes are used to control multi-threading.

     - TODO:
             - Minimize signal handling by OSD_Signal.cxx to SIGSEGV and SIGFPE.
On Unix it currently processes
               all (or almost all) signals (e.g. SIGHUP) by exiting. There is no
value add to that. It's better to be
               done by user apps.
               OCC should only handle those which it can survive after, if at
all it must do anything. OCC classes may
               or maynot be provided for convenience but should not be set in
the OCC itself.
             - OSD_signal.cxx - if possible, get rid of sigaction() and replace
with signal() and and other more
               advanced staff. We just need to map signals to C++ exceptions, so
let's not make code more complex than neede>
               can simplify the OSD API and remove. If possible, minimize
implementation discrepancies between OSes.
             - On SGI - remove use of env variable TRAP_FPE and replace with
function handle_sigfpes() (as this is more
               reliable) - see SGI doc
(http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0530&db=man&fname=/usr/s> [^]
             - minimize exposing OSD API by removing SegvHandler(), WntHandler()
and others and keep SetSignal() only.
               Alternative approach is instead expose functions which map to OCC
exceptions and document them, so that
               the user can reuse them in his own handlers.
             - rename OSD::SetSignal() with SetHandlers() as it not only sets
signal handlers but exceptions also.
             - removed message box and call to a debugger. This is an ugly way
and only pollutes the code. Moreover call
               to Debugger does really work on modern Windows (debugger is still
ironically called due some failure within
               OSD_signal_WNT.cxx). In reality debugger can be attached to the
process. Moreover, CSF_DEBUG_MODE was
               seemingly never tested - the message box could not display for
FPE signals (because _fpreset() and
               _clearfp() were not called before it). In the ultimate case this
code can be moved to some DRAW function
               as an example of how to implement own signal handling.
             - add additional boolean argument Reenforce into OSD::SetSignal()
that would not redefine already set user's
               defined handlers. In this case, OSD_Pipeline should call
OSD::SetSignal(aFloatingSignal=true,
               aReenforce=false) and would not reset user's handlers if they
were redefined by user in the main thread
Revision 2011-10-21 16:38 by bugmaster
Description RLN Detailed description:
      - Exception objects (Standard_Failure ancestors) are now
defined/implemented using macros (see Standard_DefineException>
        in a way similar to defining handles. This enables creating user-defined
exceptions without CDL.
        Note that as preprocessor does not allow to insert preprocessor
instructions (starting with #) into macro definitions, it is impossible to
define macros #<object_type>_Raise_if(). Therefore their generation is
kept within CDL extractor as previously. The user does not really need to do
this - he may rely on No_Exceptions macro. CPPExt_Template.edl must be copied to
$WOKHOME/lib for CDL extractor to take effect.
      - Standard_Failure has Throw() non-virtual and ancestros does not have it
anymore (implementation was the same).

   OSD_signal_WNT.cxx
      - OSD::SetSignal() now always sets signal handlers, exception handlers and
structured exception (SE) translators. This >
        to deal correctly in case if user's code is compiled with /EHs or /EHa.
UseSETranslation() are removed,
        as redundant. See detailed documentation in OSD_signal_WNT.cxx on
OSD::SetSignal().
      - very detailed documentation for OSD::Setsignal() in Doygen format is now
in this file.
      - removed static variables that set signals only once to enable calling
::SetSignal() for other threads or even
        within the same thread if the user switched handlers before
      - mutexes are used to control multi-threading.

     - TODO:
             - Minimize signal handling by OSD_Signal.cxx to SIGSEGV and SIGFPE.
On Unix it currently processes
               all (or almost all) signals (e.g. SIGHUP) by exiting. There is no
value add to that. It's better to be
               done by user apps.
               OCC should only handle those which it can survive after, if at
all it must do anything. OCC classes may
               or maynot be provided for convenience but should not be set in
the OCC itself.
             - OSD_signal.cxx - if possible, get rid of sigaction() and replace
with signal() and and other more
               advanced staff. We just need to map signals to C++ exceptions, so
let's not make code more complex than neede>
               can simplify the OSD API and remove. If possible, minimize
implementation discrepancies between OSes.
             - On SGI - remove use of env variable TRAP_FPE and replace with
function handle_sigfpes() (as this is more
               reliable) - see SGI doc
(http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0530&db=man&fname=/usr/s> [^]
             - minimize exposing OSD API by removing SegvHandler(), WntHandler()
and others and keep SetSignal() only.
               Alternative approach is instead expose functions which map to OCC
exceptions and document them, so that
               the user can reuse them in his own handlers.
             - rename OSD::SetSignal() with SetHandlers() as it not only sets
signal handlers but exceptions also.
             - removed message box and call to a debugger. This is an ugly way
and only pollutes the code. Moreover call
               to Debugger does really work on modern Windows (debugger is still
ironically called due some failure within
               OSD_signal_WNT.cxx). In reality debugger can be attached to the
process. Moreover, CSF_DEBUG_MODE was
               seemingly never tested - the message box could not display for
FPE signals (because _fpreset() and
               _clearfp() were not called before it). In the ultimate case this
code can be moved to some DRAW function
               as an example of how to implement own signal handling.
             - add additional boolean argument Reenforce into OSD::SetSignal()
that would not redefine already set user's
               defined handlers. In this case, OSD_Pipeline should call
OSD::SetSignal(aFloatingSignal=true,
               aReenforce=false) and would not reset user's handlers if they
were redefined by user in the main thread
Revision 2011-06-27 13:11 by bugmaster
Description RLN Detailed description:
      - Exception objects (Standard_Failure ancestors) are now
defined/implemented using macros (see Standard_DefineException>
        in a way similar to defining handles. This enables creating user-defined
exceptions without CDL.
        Note that as preprocessor does not allow to insert preprocessor
instructions (starting with #) into macro definitions, it is impossible to
define macros #<object_type>_Raise_if(). Therefore their generation is
kept within CDL extractor as previously. The user does not really need to do
this - he may rely on No_Exceptions macro. CPPExt_Template.edl must be copied to
$WOKHOME/lib for CDL extractor to take effect.
      - Standard_Failure has Throw() non-virtual and ancestros does not have it
anymore (implementation was the same).

   OSD_signal_WNT.cxx
      - OSD::SetSignal() now always sets signal handlers, exception handlers and
structured exception (SE) translators. This >
        to deal correctly in case if user's code is compiled with /EHs or /EHa.
UseSETranslation() are removed,
        as redundant. See detailed documentation in OSD_signal_WNT.cxx on
OSD::SetSignal().
      - very detailed documentation for OSD::Setsignal() in Doygen format is now
in this file.
      - removed static variables that set signals only once to enable calling
::SetSignal() for other threads or even
        within the same thread if the user switched handlers before
      - mutexes are used to control multi-threading.

     - TODO:
             - Minimize signal handling by OSD_Signal.cxx to SIGSEGV and SIGFPE.
On Unix it currently processes
               all (or almost all) signals (e.g. SIGHUP) by exiting. There is no
value add to that. It's better to be
               done by user apps.
               OCC should only handle those which it can survive after, if at
all it must do anything. OCC classes may
               or maynot be provided for convenience but should not be set in
the OCC itself.
             - OSD_signal.cxx - if possible, get rid of sigaction() and replace
with signal() and and other more
               advanced staff. We just need to map signals to C++ exceptions, so
let's not make code more complex than neede>
               can simplify the OSD API and remove. If possible, minimize
implementation discrepancies between OSes.
             - On SGI - remove use of env variable TRAP_FPE and replace with
function handle_sigfpes() (as this is more
               reliable) - see SGI doc
(http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0530&db=man&fname=/usr/s> [^]
             - minimize exposing OSD API by removing SegvHandler(), WntHandler()
and others and keep SetSignal() only.
               Alternative approach is instead expose functions which map to OCC
exceptions and document them, so that
               the user can reuse them in his own handlers.
             - rename OSD::SetSignal() with SetHandlers() as it not only sets
signal handlers but exceptions also.
             - removed message box and call to a debugger. This is an ugly way
and only pollutes the code. Moreover call
               to Debugger does really work on modern Windows (debugger is still
ironically called due some failure within
               OSD_signal_WNT.cxx). In reality debugger can be attached to the
process. Moreover, CSF_DEBUG_MODE was
               seemingly never tested - the message box could not display for
FPE signals (because _fpreset() and
               _clearfp() were not called before it). In the ultimate case this
code can be moved to some DRAW function
               as an example of how to implement own signal handling.
             - add additional boolean argument Reenforce into OSD::SetSignal()
that would not redefine already set user's
               defined handlers. In this case, OSD_Pipeline should call
OSD::SetSignal(aFloatingSignal=true,
               aReenforce=false) and would not reset user's handlers if they
were redefined by user in the main thread


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