[postgis-users] Update on GEOS Integration

[Doug_Newcomb at fws.gov]

Paul,
      Thanks !

Doug Newcomb



                                                                                                                                               
                      Paul Ramsey                                                                                                              
                      <pramsey at refractions.net>                  To:      PostGIS Users Discussion <postgis-users at postgis.refractions.net>     
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                      postgis-users-bounces at postgis.refr         Subject: [postgis-users] Update on GEOS Integration                           
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                      06/01/2003 02:56 PM                                                                                                      
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We appear to have found a viable workaround to the exception handling
problems described on this list a couple weeks ago.

- The problem was a manifestation of the parent postgres process not
being able to intelligently handle signals raised by the dynamically
linked GEOS library. Specifically, the GEOS library would raise C++
exceptions which the parent postgres process would interpret as
SIGABORT. The postgres process would then terminate before the exception
could be passed on to a piece of code which could handle it.
- The solution turned out to be relatively simple. Dynamically linking
the postgres server with libstdc++, the standard C++ library. Since
everyone currently installing and using PostGIS is either (a) building
thier own postgresql or (b) using a binary provided with PostGIS support
built in by someone else, this build-time solution should be easily
applicable. From a compilation point of view, all that changes is the
invocation of 'configure' when building postgresql. "LDFLAGS=-lstdc++
./configure --your --options --here" will pre-set the linker flags to
include the C++ library, and everything else will procede as normal.

The extremely brave can experiment using the postgis cvs and geos cvs
versions. No bug reports please at this time, only bug fixes, as we
still have not done any due diligence on this code and are time
constrained at the moment.

Thanks all,
Paul


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