src/hoard/src/heaplayers/experimental/fifofreelist.h

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/* -*- C++ -*- */

#ifndef _FIFOFREELIST_H_
#define _FIFOFREELIST_H_

#include <assert.h>

#ifdef NDEBUG
#define IFDEBUG(x)
#else
#define IFDEBUG(x) x
#endif


template <class SuperHeap>
class FIFOFreelistHeap : public SuperHeap {
public:
  
  FIFOFreelistHeap (void)
          IFDEBUG(:     nObjects (0))
  {
          head.next = &tail;
          tail.next = &tail;
          assert (isEmpty());
  }

  ~FIFOFreelistHeap (void)
  {
        // printf ("Adios free list.\n");
    // Delete everything on the free list.
    freeObject * ptr = head.next;
    while (ptr != &tail) {
      void * oldptr = ptr;
      ptr = ptr->next;
      SuperHeap::free (oldptr);
    }
  }

  inline void * malloc (size_t sz) {
        assert (isValid());
    // Check the free list first.
    freeObject * ptr = head.next;
    if (ptr == &tail) {
          assert (nObjects == 0);
          assert (isEmpty());
      ptr = (freeObject *) SuperHeap::malloc (sz);
    } else {
          assert (nObjects > 0);
          head.next = ptr->next;
          if (head.next == &tail) {
                  tail.next = &tail;
          }
          IFDEBUG (nObjects--);
    }
        assert (isValid());
    return (void *) ptr;
  }
  
  inline void free (void * ptr) {
        assert (isValid());
    // Add this object to the free list.
        assert (ptr != NULL);
        IFDEBUG (nObjects++);
        freeObject * p = (freeObject *) ptr;
    p->next = &tail;
        tail.next->next = p;
        tail.next = p;
        if (head.next == &tail) {
                head.next = p;
        }
        assert (!isEmpty());
        assert (isValid());
  }

private:

        int isValid (void) {
                // Make sure every object is the right size.
                freeObject * ptr = head.next;
                if (ptr != &tail) {
                        size_t sz = SuperHeap::getSize(ptr);
                        while (ptr != &tail) {
                          void * oldptr = ptr;
                          ptr = ptr->next;
                          assert (SuperHeap::getSize(oldptr) >= sz);
                        }
                }
                return 1;
        }

  int isEmpty (void) {
        return (head.next == &tail);
  }

  class freeObject {
  public:
        freeObject * prev;
    freeObject * next;
  };

  freeObject head, tail;
  IFDEBUG (int nObjects);
};

#endif