tinydir_open_sorted is really slow under windows

[Jean-Philippe Jodoin]

I have a folder of 8000 images in it. If I call tinydir_open_sorted on it's path, it will take as long as 2 minutes to retrieve the full list of file. I am under MSVC 2010 under windows 7 x64. Profiling shows 99.9% of the time spent in an unknown method. If I use tinydir_open instead and I sort the file myself using a vector and std::sort, the result will take much less than a second to return.

I think the problem is with the use of realloc, that must constantly allocate new block of memory compare to a std::vector that might handle the reallocation much better.

Here's the C++ version that run much faster (to compare with tinydir_open_sorted)
std::vectorstd::string dirList
tinydir_open(&dir, dirPath.c_str());
while (dir.has_next)
{
tinydir_file file;
tinydir_readfile(&dir, &file);
if(!file.is_dir)
dirList.push_back(std::string(file.name));
tinydir_next(&dir);
}

tinydir_close(&dir);
std::sort(dirList.begin(), dirList.end());
return dirList;

[Jean-Philippe Jodoin]

I think a good solution would be to count the number of file before and calling the allocation one time instead.

[Cong]

Yes you are right the realloc is the most likely culprit. The current implementation is very inefficient as it reallocs every time the size grows. I think simply changing to a doubling of capacity will make it fast enough.

[Jean-Philippe Jodoin]

Yeah. That would most likely be a good enough improvement.

[Cong]

I've decided to count the number of files beforehand; I tested on a folder with 10000 subfolders and this seemed the fastest:

Times in seconds
Previous: 78.579
Doubling realloc: 0.04
Counting: 0.019

Thanks for raising this issue!