netgen/libsrc/core/localheap.hpp

#ifndef NETGEN_CORE_LOCALHEAP_HPP
#define NETGEN_CORE_LOCALHEAP_HPP

/**************************************************************************/
/* File:   localheap.hpp                                                  */
/* Author: Joachim Schoeberl                                              */
/* Date:   19. Apr. 2000                                                  */
/**************************************************************************/

#include <cstdlib>

#include "exception.hpp"
#include "ngcore_api.hpp"
#include "utils.hpp"

namespace ngcore
{

class Allocator
{
public:
  virtual ~Allocator() {}
  virtual void * Alloc (size_t size)
  {
    return new char[size];
  }
  virtual void Delete(void* p)
  {
    delete (char*) p;
  }
  virtual void ArrayDelete(void* p)
  {
      delete [] (char*) p;
  }
};
static Allocator global_alloc;

/**
   Exception on heap overflow.
   Thrown by allocation on LocalHeap.
*/
class NGCORE_API LocalHeapOverflow : public Exception
{
public:
  LocalHeapOverflow (size_t size);
  virtual ~LocalHeapOverflow ();
};



/**
   Optimized memory handler.
   One block of data is organized as stack memory. 
   One can allocate memory out of it. This increases the stack pointer.
   With \Ref{CleanUp}, the pointer is reset to the beginning or to a
   specific position. 
*/
class LocalHeap : public Allocator
{
  char * data;
  char * next;
  char * p;
  size_t totsize;
public:
  bool owner;
  const char * name;

#if defined(__MIC__) || defined (__AVX512F__)
  enum { ALIGN = 64 };
#else
  enum { ALIGN = 32 };
#endif  

public:
  /// Allocate one block of size asize.
  NGCORE_API LocalHeap (size_t asize, 
                            const char * aname = "noname",
                            bool mult_by_threads = false);

  /// Use provided memory for the LocalHeap
  NETGEN_INLINE LocalHeap (char * adata, size_t asize, 
                    const char  * aname = "noname") throw ()
  {
    totsize = asize;
    data = adata;
    next = data + totsize;
    owner = 0;
    // p = data;
    name = aname;
    CleanUp();
  }

  /*
  /// Use provided memory for the LocalHeap
  NETGEN_INLINE LocalHeap (const LocalHeap & lh2)
    : data(lh2.data), p(lh2.p), totsize(lh2.totsize), owner(false),
      name(lh2.name)
  {
    next = data + totsize;
  }
  */
  NETGEN_INLINE LocalHeap (const LocalHeap & lh2) = delete;

  NETGEN_INLINE LocalHeap (LocalHeap && lh2)
    : data(lh2.data), p(lh2.p), totsize(lh2.totsize), owner(lh2.owner),
      name(lh2.name)
  {
    next = data + totsize;
    lh2.owner = false;
  }
  
  NETGEN_INLINE LocalHeap Borrow() 
  {
    return LocalHeap (p, Available());
  }


  NETGEN_INLINE LocalHeap & operator= (LocalHeap && lh2)
  {
    if (owner)
      delete [] data;
    
    data = lh2.data;
    p = lh2.p;
    totsize = lh2.totsize;
    owner = lh2.owner;
    name = lh2.name;

    next = data + totsize;
    lh2.owner = false;
    return *this;
  }

  NETGEN_INLINE LocalHeap ()
    : data(nullptr), next(nullptr), p(nullptr), totsize(0), owner(false) { ; }


  /// free memory
  virtual ~LocalHeap ()
  {
    if (owner)
      delete [] data;
  }

  /// delete all memory on local heap
  NETGEN_INLINE void CleanUp() throw ()
  {
    p = data;
    // p += (16 - (long(p) & 15) );
    p += (ALIGN - (size_t(p) & (ALIGN-1) ) );
  }

  /// returns heap-pointer
  NETGEN_INLINE void * GetPointer () throw ()
  {
    return p;
  }

  /// deletes memory back to heap-pointer
  NETGEN_INLINE void CleanUp (void * addr) throw ()
  {
    p = (char*)addr;
  }

  /// allocates size bytes of memory from local heap
  void * Alloc (size_t size) final // throw (LocalHeapOverflow)
  {
    char * oldp = p;
  
    // 16 byte alignment
    size += (ALIGN - size % ALIGN);
    p += size;

    // if ( size_t(p - data) >= totsize )
#ifndef FULLSPEED
    if (likely(p >= next))
        ThrowException();
#endif
      return oldp;
    }

    /// allocates size objects of type T on local heap
    template <typename T>
    T * Alloc (size_t size) // throw (LocalHeapOverflow)
    {
      char * oldp = p;
      size *= sizeof (T);

      // 16 byte alignment
      size += (ALIGN - size % ALIGN);
      p += size;

#ifndef FULLSPEED
      if (likely(p >= next))
	ThrowException();
#endif

      return reinterpret_cast<T*> (oldp);
    }

  virtual void Delete(void* /* p */) {}

  virtual void ArrayDelete(void* /* p */) {}
  private: 
    ///
#ifndef __CUDA_ARCH__
    [[noreturn]] NGCORE_API void ThrowException(); 
#else
    NETGEN_INLINE void ThrowException() { ; }
#endif

  public:
    /// free memory (dummy function)
  NETGEN_INLINE void Free (void * /* data */) throw () 
    {
      ;
    }

    /// available memory on LocalHeap
    NETGEN_INLINE size_t Available () const throw () { return (totsize - (p-data)); }

    /// Split free memory on heap into pieces for each thread
    NGCORE_API LocalHeap Split () const;

    /// Split free memory on heap into pieces
    NETGEN_INLINE LocalHeap Split (int partnr, int nparts) const
    {
      int pieces = nparts;
      int i = partnr;

      size_t freemem = totsize - (p - data);
      size_t size_of_piece = freemem / pieces;
      return LocalHeap (p + i * size_of_piece, size_of_piece, name);
    }


    NETGEN_INLINE void ClearValues ()
    {
      for (size_t i = 0; i < totsize; i++) data[i] = 47;
    }

    NETGEN_INLINE size_t UsedSize ()
    {
      for (size_t i = totsize-1; i != 0; i--)
        if (data[i] != 47) return i;
      return 0;
    }
  };



  /**
     Optimized memory handler.
     Provides static memory for the local heap. The template argument specifies the size in number of chars.
  */
  template <int S>
  class LocalHeapMem : public LocalHeap
  {
    char mem[S];
  public:
    NETGEN_INLINE LocalHeapMem (const char * aname) throw () : LocalHeap (mem, S, aname) { ; }
  };








  /**
     A reset for the heap-pointer of a LocalHeap..
     The constructor stores the heap-pointer, the constructor at the end of the regions resets the heap-pointer.
  */
  class HeapReset
  {
    LocalHeap & lh;
    void * pointer;
  public:
    ///
    NETGEN_INLINE HeapReset (LocalHeap & alh) 
      : lh(alh), pointer (alh.GetPointer()) { ; }
    
    ///
    NETGEN_INLINE ~HeapReset () 
    {
      lh.CleanUp (pointer);
    }
  };

}



NETGEN_INLINE void * operator new (size_t size, ngcore::Allocator & alloc)  
{
  return alloc.Alloc(size);
}

NETGEN_INLINE void * operator new [] (size_t size, ngcore::Allocator & alloc)  
{
  return alloc.Alloc(size);
}


NETGEN_INLINE void operator delete (void * p, ngcore::Allocator & lh)  
{
  lh.Delete(p);
}

NETGEN_INLINE void operator delete [] (void * p, ngcore::Allocator & lh)  
{
  lh.ArrayDelete(p);
}



#endif // NETGEN_CORE_LOCALHEAP_HPP