IndexPool (struct)

The IndexPool is an helper class for the management of array data, where free indices can be reused (re-allocated). For performance applications, using contiguous (array) storage of multiple elements improves speed by both minimizing heap allocation calls and by making a better use of CPU memory cache. This class helps to write such custom allocators.

注釈

IndexPool only helps to allocate/reuse data cells (indices), however it doesn’t hold the stored data per say (would need C++ -like templates to do that).

IndexPool IndexPool IndexPool 

/*
** Example: IndexPool
*/

require Math, Containers;

struct Mat44Allocator {
  Mat44 matrices[];
  IndexPool indexPool;
};

inline UInt32 Mat44Allocator.allocate!() {
  UInt32 index;
  if( this.indexPool.getFreeIndex(index) )
    this.matrices.resize( this.indexPool.getIndexEnd() );
  return index;
}

inline Mat44Allocator.free!( UInt32 index ) {
  this.indexPool.unusedIndex(index);
}

operator entry(){

  Mat44Allocator mat44s;

  UInt32 first = mat44s.allocate();
  mat44s.matrices[first].setTranslation( Vec3(1,0,0) );

  UInt32 second = mat44s.allocate();
  mat44s.matrices[second].setTranslation( Vec3(2,0,0) );

  //Free the 1st allocated one, we no longer need it
  mat44s.free(first);

  report( mat44s.indexPool.getNumUsed() + " used out of " + mat44s.indexPool.getIndexEnd() );

  //Allocate a 3rd one, which should reuse the free 1st entry
  UInt32 third = mat44s.allocate();
  mat44s.matrices[third].setTranslation( Vec3(3,0,0) );

  report( mat44s.indexPool.getNumUsed() + " used out of " + mat44s.indexPool.getIndexEnd() );
}

/*
** Output:

1 used out of 2
2 used out of 2

*/

Methods

  IndexPool ( in IndexPool other )
  IndexPool ()
Boolean allAllocated ? ()
Boolean allFree ? ()
IndexPool clone ? ()
Boolean getFreeIndex ! ( out UInt32 index )
UInt32 getIndexEnd ? ()
Size getNumUsed ? ()
  reset ! ()
  setAllAsUnused ! ( in Boolean entry0IsReserved )
  unusedIndex ! ( in UInt32 index )

Methods in detail

IndexPool ( in IndexPool other )

copy constructor

IndexPool ()

default constructor

Boolean IndexPool.allAllocated? ()

returns true if all indices are in use

Boolean IndexPool.allFree? ()

returns true if no indices are in use

IndexPool IndexPool.clone? ()

clone method

Boolean IndexPool.getFreeIndex! ( out UInt32 index )

UInt32 IndexPool.getIndexEnd? ()

returns the last index

Size IndexPool.getNumUsed? ()

returns the number of used indices

IndexPool.reset! ()

resets the contents of the IndexPool

IndexPool.setAllAsUnused! ( in Boolean entry0IsReserved )

frees all indices, but optionally keeps the first one

IndexPool.unusedIndex! ( in UInt32 index )

pushes an unused index on the stack