12345qiupeng
/
gtsam
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add comments

release/4.3a0
Fan Jiang 2020-06-24 16:25:46 -04:00
parent 7d7475b881
commit 6dbd7c243a
2 changed files with 24 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
gtsam/base/make_shared.h
View File

@ -26,16 +26,28 @@
#include <type_traits>
namespace gtsam {
/// An shorthand alias for accessing the ::type inside std::enable_if that can be used in a template directly
template<bool B, class T = void>
using enable_if_t = typename std::enable_if<B, T>::type;
}
namespace gtsam {
/** Add our own `make_shared` as a layer of wrapping on `boost::make_shared`
/**
* Add our own `make_shared` as a layer of wrapping on `boost::make_shared`
* This solves the problem with the stock `make_shared` that custom alignment is not respected, causing SEGFAULTs
* at runtime, which is notoriously hard to debug.
*
* Explanation
* ===============
* The template `needs_eigen_aligned_allocator<T>::value` will evaluate to `std::true_type` if the type alias
* `_eigen_aligned_allocator_trait = void` is present in a class, which is automatically added by the
* `GTSAM_MAKE_ALIGNED_OPERATOR_NEW` macro.
*
* This function declaration will only be taken when the above condition is true, so if some object does not need to
* be aligned, `gtsam::make_shared` will fall back to the next definition, which is a simple wrapper for
* `boost::make_shared`.
*
* @tparam T The type of object being constructed
* @tparam Args Type of the arguments of the constructor
* @param args Arguments of the constructor

12
gtsam/base/types.h
View File

@ -238,8 +238,18 @@ namespace gtsam {
/**
* A SFINAE trait to mark classes that need special alignment.
*
* This is required to make boost::make_shared and etc respect alignment, which is essential for the Python
* wrappers to work properly.
*
* Explanation
* =============
* When a GTSAM type is not declared with the type alias `_eigen_aligned_allocator_trait = void`, the first template
* will be taken so `needs_eigen_aligned_allocator` will be resolved to `std::false_type`.
*
* Otherwise, it will resolve to the second template, which will be resolved to `std::true_type`.
*
* Please refer to `gtsam/base/make_shared.h` for an example.
*/
template<typename, typename = void_t<>>
struct needs_eigen_aligned_allocator : std::false_type {
@ -253,7 +263,7 @@ namespace gtsam {
/**
* This marks a GTSAM object to require alignment. With this macro an object will automatically be allocated in aligned
* memory when one uses `gtsam::make_shared`. It reduces future misalignment problems that is hard to debug.
* See https://eigen.tuxfamily.org/dox/group__DenseMatrixManipulation__Alignement.html for details
* See https://eigen.tuxfamily.org/dox/group__DenseMatrixManipulation__Alignement.html for detailed explanation.
*/
#define GTSAM_MAKE_ALIGNED_OPERATOR_NEW \
EIGEN_MAKE_ALIGNED_OPERATOR_NEW \