Re: [osg-users] [vpb] a bug in vpb
Hi Chen,
The changes to the code you've made change what it does and starts
mixing iterators from two different containers (that aren't event the
same type), so you've almost certainly broken the code.
It's a while since I wrote this particular code so exactly what it
does and how it's used escapes me right now - I'll need to do a wider
code review to uncover this. I really don't know whether there is a
bug here or not, lowering the amount of memory your system has
available will eventually introduce memory errors at some point - but
that would happen for almost all apps, a memory itself doesn't not
indicate a bug in the code that end up crashing at.
Could you please post a stack trace so we can analyse the issue
further, as well as info on exactly which VPB apps you are using, OS,
how much memory you set, etc.
Robert.
On Wed, Jun 10, 2009 at 4:20 AM, wind509459...@qq.com wrote:
Hi,
Robert, when i set my machine's virtual memory to a lower value for some
test related to vpb, thousands of image files as input, then vpb jumps into
this error:
//system.cpp, Line 305,
void eraseFrom(System::DatasetMap datasetMap)
{
for(TimeIteratorMap::iterator itr = _timeIteratorMap.begin();
itr != _timeIteratorMap.end();
++itr)
{
datasetMap.erase(itr-second);
}
}
Evidently, the iterator was used incorrectly. So i changed it:
void eraseFrom(System::DatasetMap datasetMap)
{
for(TimeIteratorMap::iterator itr = _timeIteratorMap.begin();
itr != _timeIteratorMap.end();)
{
itr = datasetMap.erase(itr-second);
}
}
Then it works. My version is r973. Hope to correct it in later version.
Xuex, Chen
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Re: [osg-users] [vpb] a bug in vpb
Hi Chen,
I think the problem is also not using the iterator in the style that the
iterator algorithm was originally intended. I have used your style as it hides
the iterator declation when the for loop goes out of scope, but I think the
expected usage was more along the lines of:
{
iterator iter = map.begin();
while( iter != map.end() )
iter = map.erase( ... );
}
PhilT
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Re: [osg-users] [vpb] a bug in vpb
Hi,
It seems that the return value of erase() are different in Windows and
Unix/Linux. I've done some work in my previous projects like:
for ( DataMap::iterator itr=map.begin(); itr!=map.end(); )
{
DataMap::iterator old_itr = itr;
itr++;
map.erase( old_itr );
}
That's because itr = map.erase(itr) is not compilable with some gcc
versions.
My shame for not studying into the vpb source code yet. :)
Wang Rui
2009/6/10 phili...@ntlworld.com
Hi Chen,
I think the problem is also not using the iterator in the style that the
iterator algorithm was originally intended. I have used your style as it
hides the iterator declation when the for loop goes out of scope, but I
think the expected usage was more along the lines of:
{
iterator iter = map.begin();
while( iter != map.end() )
iter = map.erase( ... );
}
PhilT
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Re: [osg-users] [vpb] a bug in vpb
On 10.06.2009 15:45 Uhr, Wang Rui wrote:
It seems that the return value of erase() are different in Windows and
Unix/Linux. I've done some work in my previous projects like:
for ( DataMap::iterator itr=map.begin(); itr!=map.end(); )
{
DataMap::iterator old_itr = itr;
itr++;
map.erase( old_itr );
}
That's because itr = map.erase(itr) is not compilable with some gcc
versions.
I don't believe this is the problem. The 'it = container.erase(it)' construct
is correct.
However, in this case (from VPB):
for(TimeIteratorMap::iterator itr = _timeIteratorMap.begin();
itr != _timeIteratorMap.end();
++itr)
{
datasetMap.erase(itr-second);
}
the iterator 'itr' is for TimeIteratorMap whereas the erase is on 'datasetMap'
and
'datasetMap.erase(...)' would logically return a DatasetMap::iterator which (thankfully)
cannot be assigned to a TimeIteratorMap::iterator, not even under Windows.
Cheers,
/ulrich
2009/6/10 phili...@ntlworld.com mailto:phili...@ntlworld.com
I think the problem is also not using the iterator in the style that
the iterator algorithm was originally intended. I have used your
style as it hides the iterator declation when the for loop goes out
of scope, but I think the expected usage was more along the lines of:
{
iterator iter = map.begin();
while( iter != map.end() )
iter = map.erase( ... );
}
PhilT
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Re: [osg-users] [vpb] a bug in vpb
Hi Ulrich, You're right that what you (and Robert) note is an error (i.e. assigning an iterator from one container to an iterator from another container). But... I don't believe this is the problem. The 'it = container.erase(it)' construct is correct. It seems that according to the standard, it is, but some (many?) versions of gcc don't support it (perhaps it was added late in the standardization process or whatever). I've run across the same problem as Wang Rui - map::erase(iterator) returns void on some common compilers. So it's not portable code (by gcc's fault but still...). J-S -- __ Jean-Sebastien Guayjean-sebastien.g...@cm-labs.com http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] [vpb] a bug in vpb
Jean-Sébastien Guay wrote: Hi Ulrich, You're right that what you (and Robert) note is an error (i.e. assigning an iterator from one container to an iterator from another container). But... I don't believe this is the problem. The 'it = container.erase(it)' construct is correct. It seems that according to the standard, it is, but some (many?) versions of gcc don't support it (perhaps it was added late in the standardization process or whatever). I've run across the same problem as Wang Rui - map::erase(iterator) returns void on some common compilers. So it's not portable code (by gcc's fault but still...). According to the spec I have here (ISO C++ 1998 draft) std::map::erase(it) should return void (and same for std::set). Only for sequential containers (vector, list, deque) is an iterator returned in case of erase()ing. Makes sense too, as associative containers are usually not implemented as a simple list of elements, so returning the next item after the one just erased could be tricky. Regards, Paul ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] [vpb] a bug in vpb
Hi J-S, On 10.06.2009 16:23 Uhr, Jean-Sébastien Guay wrote: But... I don't believe this is the problem. The 'it = container.erase(it)' construct is correct. It seems that according to the standard, it is, but some (many?) versions of gcc don't support it (perhaps it was added late in the standardization process or whatever). I've run across the same problem as Wang Rui - map::erase(iterator) returns void on some common compilers. So it's not portable code (by gcc's fault but still...). It seems that std::map::erase doesn't actually return an iterator at all, at least according to http://www.cplusplus.com/reference/stl/map/erase/ I'm not across any of that code but in my experience it can be dangerous to hold on to iterators for a length of time since they may become invalid with insert/erase. This shouldn't be the case for maps though... /ulrich ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] [vpb] a bug in vpb
Paul Melis wrote: Jean-Sébastien Guay wrote: Hi Ulrich, You're right that what you (and Robert) note is an error (i.e. assigning an iterator from one container to an iterator from another container). But... I don't believe this is the problem. The 'it = container.erase(it)' construct is correct. It seems that according to the standard, it is, but some (many?) versions of gcc don't support it (perhaps it was added late in the standardization process or whatever). I've run across the same problem as Wang Rui - map::erase(iterator) returns void on some common compilers. So it's not portable code (by gcc's fault but still...). According to the spec I have here (ISO C++ 1998 draft) std::map::erase(it) should return void (and same for std::set). Only for sequential containers (vector, list, deque) is an iterator returned in case of erase()ing. Makes sense too, as associative containers are usually not implemented as a simple list of elements, so returning the next item after the one just erased could be tricky. Interestingly, the c0x draft I could find indeed lists std::map::erase(it) (and for set as well) as returning an interator. Paul ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] [vpb] a bug in vpb
Hi Paul, According to the spec I have here (ISO C++ 1998 draft) std::map::erase(it) should return void (and same for std::set). The version I have is dated October 2008. Here's a link: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2798.pdf From here: http://www.open-std.org/JTC1/SC22/WG21/ See page 838: iterator erase(const_iterator position); size_type erase(const key_type x); iterator erase(const_iterator first, const_iterator last); So yeah, it was probably added later. Anyways, the result is that some (all? I'm not sure) versions of gcc don't support the version that return an iterator, and return void instead. VC++ does. Does this mark the first time VC++ is more up-to-date than gcc with regards to standards? :-) J-S -- __ Jean-Sebastien Guayjean-sebastien.g...@cm-labs.com http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] [vpb] a bug in vpb
Hey, Jean-Sébastien Guay wrote: According to the spec I have here (ISO C++ 1998 draft) std::map::erase(it) should return void (and same for std::set). The version I have is dated October 2008. Here's a link: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2798.pdf From here: http://www.open-std.org/JTC1/SC22/WG21/ See page 838: iterator erase(const_iterator position); size_type erase(const key_type x); iterator erase(const_iterator first, const_iterator last); So yeah, it was probably added later. The inconsistency in void - iterator return type seems to have been marked as defect (DR 130) shortly after the previous C++ spec was published in 1998. DR 130 is dated March 1990: http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#130 The DR proposes to change erase() from returning void to returning an iterator. Anyways, the result is that some (all? I'm not sure) versions of gcc don't support the version that return an iterator, and return void instead. VC++ does. Does this mark the first time VC++ is more up-to-date than gcc with regards to standards? :-) From what I can find about this is that Dinkumware STL (which is what VS is using) has chosen to return iterators for erase(). I guess you could say that any conforming code using erase() must ignore the return value, as it is prescribed to be void. An STL implementation that differs in return type will also work with conforming code, as the result value is ignored anyway. So perhaps it is code using Dinkumware STL (VS) that expects an iterator as result value that is non-conforming... Paul ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] [vpb] a bug in vpb
Hi,
Robert, when i set my machine's virtual memory to a lower value for some test
related to vpb, thousands of image files as input, then vpb jumps into this
error:
//system.cpp, Line 305,
void eraseFrom(System::DatasetMap datasetMap)
{
for(TimeIteratorMap::iterator itr = _timeIteratorMap.begin();
itr != _timeIteratorMap.end();
++itr)
{
datasetMap.erase(itr-second);
}
}
Evidently, the iterator was used incorrectly. So i changed it:
void eraseFrom(System::DatasetMap datasetMap)
{
for(TimeIteratorMap::iterator itr = _timeIteratorMap.begin();
itr != _timeIteratorMap.end();)
{
itr = datasetMap.erase(itr-second);
}
}
Then it works. My version is r973. Hope to correct it in later version.
Xuex, Chen___
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