parallel_buffered_sort Function

Arranges the elements in a specified range into a nondescending order, or according to an ordering criterion specified by a binary predicate, in parallel. This function is semantically similar to std::sort in that it is a compare-based, unstable, in-place sort except that it needs O(n) additional space, and requires default initialization for the elements being sorted.

template<
   typename _Random_iterator
>
inline void parallel_buffered_sort(
   const _Random_iterator &_Begin,
   const _Random_iterator &_End
);

template<
   typename _Allocator,
   typename _Random_iterator
>
inline void parallel_buffered_sort(
   const _Random_iterator &_Begin,
   const _Random_iterator &_End
);

template<
   typename _Allocator,
   typename _Random_iterator
>
inline void parallel_buffered_sort(
   const _Allocator& _Alloc,
   const _Random_iterator &_Begin,
   const _Random_iterator &_End
);

template<
   typename _Random_iterator,
   typename _Function
>
inline void parallel_buffered_sort(
   const _Random_iterator &_Begin,
   const _Random_iterator &_End,
   const _Function &_Func,
   const size_t _Chunk_size = 2048
);

template<
   typename _Allocator,
   typename _Random_iterator,
   typename _Function
>
inline void parallel_buffered_sort(
   const _Random_iterator &_Begin,
   const _Random_iterator &_End,
   const _Function &_Func,
   const size_t _Chunk_size = 2048
);

template<
   typename _Allocator,
   typename _Random_iterator,
   typename _Function
>
inline void parallel_buffered_sort(
   const _Allocator& _Alloc,
   const _Random_iterator &_Begin,
   const _Random_iterator &_End,
   const _Function &_Func,
   const size_t _Chunk_size = 2048
);

Parameters

• _Random_iterator
  The iterator type of the input range.

• _Allocator
  The type of an STL compatible memory allocator.

• _Function
  The type of the binary comparator.

• _Begin
  A random-access iterator addressing the position of the first element in the range to be sorted.

• _End
  A random-access iterator addressing the position one past the final element in the range to be sorted.

• _Alloc
  An instance of an STL compatible memory allocator.

• _Func
  A user-defined predicate function object that defines the comparison criterion to be satisfied by successive elements in the ordering. A binary predicate takes two arguments and returns true when satisfied and false when not satisfied. This comparator function must impose a strict weak ordering on pairs of elements from the sequence.

• _Chunk_size
  The mimimum size of a chunk that will be split into two for parallel execution.

Remarks

All overloads require n * sizeof(T) additional space, where n is the number of elements to be sorted, and T is the element type. In most cases parallel_buffered_sort will show an improvement in performance over parallel_sort, and you should use it over parallel_sort if you have the memory available.

If you do not supply a binary comparator std::less is used as the default, which requires the element type to provide the operator operator<().

If you do not supply an allocator type or instance, the STL memory allocator std::allocator<T> is used to allocate the buffer.

The algorithm divides the input range into two chunks and successively divides each chunk into two sub-chunks for execution in parallel. The optional argument _Chunk_size can be used to indicate to the algorithm that it should handles chunks of size < _Chunk_size serially.

Requirements

Header: ppl.h

Namespace: concurrency

See Also

Reference

concurrency Namespace