Faster Vector list... how?

Helper

On 20/04/2015 at 06:35, xxxxxxxx wrote:

Just out of curiosity, why should I never use new[] and delete[]?
Because it is all too easy to make a mistake and produce memory-leak.

  
Vector* point_list = new Vector[n_elements];  
//do some work here  
delete point_list; // this is wrong

  
Vector* point_list = new Vector[n_elements];  
//do some work here  
if(well_done) return true;  
//do more work here  
delete[] point_list; // this will be not called

I would also avoid naked/manual delete in almost all cases.

Xcode 6 will try to use SSE3 per default, how well this really work is of course other question.
Handmade SIMD code can be faster but also much more complicated and error-prone.
So it makes sense to some library optimized for this.

If you want to do it multithreading in hard and not comfortable way then try to use C4DThread form C4D API

Remo

Helper

On 20/04/2015 at 06:39, xxxxxxxx wrote:

Well, my code is well behaved (I don't leave inbetween the new[] and delete[]) but I see your point. I will change to BaseArrays
I'm still using XCode 5.0.3
Will XCode 6.x create more optimized code?

I have to see how that C4DThread stuff is. I'm not a professional programmer so, it may be too much for me

Helper

On 20/04/2015 at 07:08, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Well, my code is well behaved (I don't leave inbetween the new[] and delete[]) but I see your point. I will change to BaseArrays
I'm still using XCode 5.0.3
Will XCode 6.x create more optimized code?

I have to see how that C4DThread stuff is. I'm not a professional programmer so, it may be too much for me

Xcode 6 (6.2/6.3) has a variety of options going from no optimizations up to aggressive optimizations (which can include link time optimizations). There are similar options for Xcode 5 (but not the aggressive optimizations option).

The used vector ops are determined by the code generation settings in Xcode and are by default SSE 3 in the current SDK (as any supported machine has it included). If you enable new vector ops (e.g. AVX) you might gain speed (depending on your problem), but reduce the amount of machines that can run your plugin.

Regarding multithreading: Understand your single-threaded performance bottlenecks and optimize them before start digging into multithreading. It's a different playground - a lot to learn and lot of things that can go wrong

Best regards,

Wilfried

Helper

On 20/04/2015 at 07:14, xxxxxxxx wrote:

Thank you for all the answers.
I will check out the optimization of the code.
And I prefer to have my code running in more types of machines

Helper

On 20/04/2015 at 15:54, xxxxxxxx wrote:

How does one use, say, BaseArray with my_spline->GetPoints()? Do you simply cast or does one need to copy the Vector* array into the BaseArray? What exactly? You guys continue to tout this stuff but where are the extensive usage examples? Even these types are well hidden in the API docs. And they are not used in the cinema4dsdk examples. One reason that I don't use them is there is no exemplification of their usage.

Helper

On 20/04/2015 at 16:10, xxxxxxxx wrote:

Well, that is an excellent question, Robert.
I would also like to know that.

Helper

On 20/04/2015 at 17:02, xxxxxxxx wrote:

I'd use STL, std::vector can handle all of this, fast, cache friendly, I think I use it 99% of the time.

Helper

On 20/04/2015 at 17:16, xxxxxxxx wrote:

The problem with the STL is that is utilizes Exceptions and the C4D SDK does not. If an exception is thrown you must be assured to capture and handle all of them or the code will unwind back to C4DMain (and crash). As the docs say:

"Do not use external libraries (e.g STL or BOOST) unless absolutely necessary."

and

"C++ exceptions and RTTI will not be used in any of our projects unless external libraries require it (also RTTI operators typeid and dynamic_cast cannot be used)."

You can use them but be aware of the caveats.

ETA: I see that the "Plugin Code Style Guide" does mention the use of BaseArray et al in a basic sense. It would be nice to know more about using these classes with the built-in pointer arrays (such as Vector and CPolygon arrays).

Helper

On 20/04/2015 at 18:26, xxxxxxxx wrote:

I think you can compile with exceptions turned off? at least this is doable in visual studio, not sure about xcode.

Helper

On 20/04/2015 at 18:38, xxxxxxxx wrote:

I am pretty certain that doing so causes the compiler to complain since they are needed. Been there, tried that. Maybe there are ways to circumvent it, but if you disable "Handle Exceptions" in a project, it typically errors on the build if there are exceptions in the code.

Helper

On 20/04/2015 at 19:46, xxxxxxxx wrote:

oh, I wasn't aware of this "I guess I'm learning more about exceptions everyday "

I don't want to jump over the thread with my questions now, but I'm curious about 2 things:
1- I'm using a dll which uses STL very heavily , is this safe?
2- any suggestion of STL like containers library that doesn't use exceptions? "I didn't try Boost yet but I don't know if it uses exceptions or not".

Helper

On 21/04/2015 at 00:47, xxxxxxxx wrote:

Originally posted by xxxxxxxx

How does one use, say, BaseArray with my_spline->GetPoints()? Do you simply cast or does one need to copy the Vector* array into the BaseArray? What exactly? You guys continue to tout this stuff but where are the extensive usage examples? Even these types are well hidden in the API docs. And they are not used in the cinema4dsdk examples. One reason that I don't use them is there is no exemplification of their usage.

If you look at my reply you'll see that I recommended using the BaseArray instead of the manual array Rui used in his first example.

You'll have to use the pointers/manual freeing as long as we keep the API compatible (and it took some efforts to keep the changes you had to apply to your plugin code minimal - compared to what changed internally in recent years).

Keeping the API compatible for a very wide range of plugins however won't be possible till infinity (if you look in the past there have been bigger changes like going from float to double in the scene format that broke API compatibility).

Therefore my advice is: Avoid manual arrays in your code (whenever possible), make yourself familiar with the BaseArray (and it's derivations), understand the usefulness of C++ 11 move semantics and spend some time with iterators.

Regarding examples in the SDK: Searching for "BaseArray" reveals 13 occurrencies in the R16 SDK
- activeobject.cpp
- arraytutorial.cpp
- edgecuttool.cpp
- gl_test_object.cpp
- memstat.cpp
- menutest.pp
- misctest.cpp
- movecopyconstructors.cpp
- paintundo.h
- pgp.cpp
- sculptbrushmultistamp.cpp
- sculptmodifier.cpp
- snaptool.cpp

Best regards,

Wilfried

Helper

On 21/04/2015 at 06:16, xxxxxxxx wrote:

Originally posted by xxxxxxxx

oh, I wasn't aware of this "I guess I'm learning more about exceptions everyday "

I don't want to jump over the thread with my questions now, but I'm curious about 2 things:
1- I'm using a dll which uses STL very heavily , is this safe?
2- any suggestion of STL like containers library that doesn't use exceptions? "I didn't try Boost yet but I don't know if it uses exceptions or not".

1.: Not it is not really safe. If you disable exceptions and STL try to throw one then you plugin will simple CRASH.
AFAIK std::vector will throw exception only on memory errors.
This is not that likely on 64bit system, but still possible.

2.: Well the first chose would be c4d_misc::BaseArray and Co.
Boost is based on STL and of course uses exceptions.

About GetPoints() and other such functions.
Most of them return pointer to memory that you do not Own so you do not need BaseArrayfor this. BaseArrayis need for arrays that you Own and responsible to free.

In other cases you can use RAII types like AutoGeFree from "ge_autoptr.h" header file.

Remo

Helper

On 23/04/2015 at 14:56, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Well, my code is well behaved (I don't leave inbetween the new[] and delete[]) but I see your point.

How can you be sure about this ?

http://bromeon.ch/articles/raii.html

Remo

Helper

On 24/04/2015 at 01:46, xxxxxxxx wrote:

Because all my returns checks are performed before the creation of the arrays. In between the creation and deletion, there are no returns.
So, I'm pretty sure there are no arrays left hanging.
But, in the future, I will use BaseArray

Helper

On 24/04/2015 at 02:31, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Originally posted by xxxxxxxx

oh, I wasn't aware of this "I guess I'm learning more about exceptions everyday "

I don't want to jump over the thread with my questions now, but I'm curious about 2 things:
1- I'm using a dll which uses STL very heavily , is this safe?
2- any suggestion of STL like containers library that doesn't use exceptions? "I didn't try Boost yet but I don't know if it uses exceptions or not".

1.: Not it is not really safe. If you disable exceptions and STL try to throw one then you plugin will simple CRASH.
AFAIK std::vector will throw exception only on memory errors.
This is not that likely on 64bit system, but still possible.

2.: Well the first chose would be c4d_misc::BaseArray and Co.
Boost is based on STL and of course uses exceptions.

About GetPoints() and other such functions.
Most of them return pointer to memory that you do not Own so you do not need BaseArrayfor this. BaseArrayis need for arrays that you Own and responsible to free.

In other cases you can use RAII types like AutoGeFree from "ge_autoptr.h" header file.

Remo

Also, you will have problems if you write to the std::vector in two different modules as they are
(especially in a C4D plugin) likely to use a different memory allocator. If you append to the vector
in your C4D plugin so that new memory must be (re-allocated) but the vector becomes destroyed in
DLL, it will most likely crash.

-Niklas