ref.h

大型并行量子化学软件；支持密度泛函（DFT）。可以进行各种量子化学计算。支持CHARMM并行计算。非常具有应用价值。

//
// ref.h --- definitions of the reference counting classes
//
// Copyright (C) 1996 Limit Point Systems, Inc.
//
// Author: Curtis Janssen <[e-mail]>
// Maintainer: LPS
//
// This file is part of the SC Toolkit.
//
// The SC Toolkit is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// The SC Toolkit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
//
// The U.S. Government is granted a limited license as per AL 91-7.
//

//   This is the main include file for the reference counting classes.
// This includes two other files: reftmpl.h and refmacr.h.  The
// former is a template declaration for the reference counted classes
// and the latter is generated from the former by a perl script and
// provides CPP macros that declare reference counting classes.
//
//   The behaviour of the package can be modified with the following five
// macros, each of which should be undefined, 0, or 1:
//
// REF_CHECK_STACK:  If this is 1 referenced objects are checked to see if they
// reside on the stack, in which case storage for the object is not managed,
// if management is enabled.  This feature can be confused by multiple threads
// and memory checking libraries.
//
// REF_MANAGE:  If this is 1 the manage and unmanage members are enabled.
//
// REF_CHECK_MAX_NREF:  If this is 1 the reference count is checked before
// it is incremented to make sure it isn't too big.
//
// REF_CHECK_MIN_NREF:  If this is 1 the reference count is checked before
// it is decremented to make sure it isn't already zero.
//
// REF_USE_LOCKS:  If this is 1 then critical regions are locked before they
// are entered.  This prevents erroneous behavior when multiple threads
// share reference counted objects.  This will slow down certain operations,
// so it should be set to 0 if your application does not need to be thread
// safe.
//
// If a macro is undefined, then the behaviour is architecture
// dependent--usually, the macro will be set to 1 in this case.
// For maximum efficiency and for normal operation after the program is
// debugged, compile with all of the above macros defined to zero.
// This can also be done with -DREF_OPTIMIZE.
//
//   An include file can be used to set these options as well.  This has
// the advantage that dependency checking will force an automatic
// recompile of all affected files if the options change.  The file
// <scconfig.h> will be include if -DHAVE_CONFIG_H is specified.
//
//   Note that all source code that uses references must be compiled with
// the same value REF_MANAGE.  Changing this can change the storage layout
// and the interpretation of the reference count data.


#ifdef __GNUC__
#pragma interface
#endif

#ifndef _util_ref_ref_h
#define _util_ref_ref_h

#include <iostream>
#include <stdlib.h>
#include <limits.h>

#include <util/ref/identity.h>

#ifdef HAVE_CONFIG_H
#include <scconfig.h>
#endif

#ifdef REF_OPTIMIZE
#ifndef REF_CHECK_STACK
# define REF_CHECK_STACK   0
#endif
#ifndef REF_MANAGE
# define REF_MANAGE        0
#endif
#ifndef REF_CHECK_MAX_NREF
# define REF_CHECK_MAX_NREF 0
#endif
#ifndef REF_CHECK_MIN_NREF
# define REF_CHECK_MIN_NREF 0
#endif
#endif

#ifdef SUNMOS
#ifndef REF_CHECK_STACK
#define REF_CHECK_STACK 0
#endif
#else
#ifndef REF_CHECK_STACK
#define REF_CHECK_STACK 0
#endif
#endif

#ifndef REF_MANAGE
#define REF_MANAGE 1
#endif

#ifndef REF_CHECK_MAX_NREF
#define REF_CHECK_MAX_NREF 1
#endif

#ifndef REF_CHECK_MIN_NREF
#define REF_CHECK_MIN_NREF 1
#endif

#ifndef REF_USE_LOCKS
#  if HAVE_STHREAD || HAVE_CREATETHREAD || HAVE_PTHREAD
#    define REF_USE_LOCKS 1
#  endif
#endif

#ifndef REF_ALWAYS_USE_LOCKS
#  define REF_ALWAYS_USE_LOCKS 1
#endif

#if REF_CHECK_STACK
#include <unistd.h>
#ifndef HAVE_SBRK_DEC
extern "C" void * sbrk(ssize_t);
#endif
#define DO_REF_CHECK_STACK(p) (((void*) (p) > sbrk(0)) && (p)->managed())
#else // REF_CHECK_STACK
#define DO_REF_CHECK_STACK(p) (0)
#endif // REF_CHECK_STACK

#if REF_MANAGE
#define DO_REF_UNMANAGE(p) ((p)->unmanage())
#else // REF_MANAGE
#define DO_REF_UNMANAGE(p)
#endif // REF_MANAGE

#if REF_USE_LOCKS
#define __REF_LOCK__(p) p->lock_ptr()
#define __REF_UNLOCK__(p) p->unlock_ptr()
#if REF_ALWAYS_USE_LOCKS
#define __REF_INITLOCK__() use_locks(true)
#else
#define __REF_INITLOCK__() ref_lock_ = 0xff
#endif
#else
#define __REF_LOCK__(p)
#define __REF_UNLOCK__(p)
#define __REF_INITLOCK__()
#endif

namespace sc {

typedef unsigned long refcount_t;

/** The base class for all reference counted objects.  If multiple
    inheritance is used, RefCount must be virtually inherited from,
    otherwise references to invalid memory will likely result.

    Reference counting information is usually maintained by smart
    pointer classes Ref, however this mechanism can be
    supplemented or replaced by directly using the public
    interface to RefCount.

    The unmanage() member is only needed for special cases where memory
    management must be turned off.  For example, if a reference counted
    object is created on the stack, memory management mechanisms based on
    reference counting must be prohibited from deleting it.  The unmanage()
    member accomplishes this, but a better solution would be to allocate
    the object on the heap with new and let a smart pointer manage the
    memory for the object.

    When using a debugger to look at reference counted objects the count is
    maintained in the _reference_count_ member.  However, this member is
    encoded so that memory overwrites can be sometimes detected.  Thus,
    interpretation of _reference_count_ is not always straightforward.

*/

class RefCount: public Identity {
  private:
#if REF_MANAGE
#  define REF_MAX_NREF (UINT_MAX - 1)
#  define REF_MANAGED_CODE UINT_MAX
#else
#  define REF_MAX_NREF UINT_MAX
#endif
    unsigned int _reference_count_;
#if REF_USE_LOCKS
    unsigned char ref_lock_;
#endif

    void error(const char*) const;
    void too_many_refs() const;
    void not_enough_refs() const;
  protected:
    RefCount(): _reference_count_(0) {
        __REF_INITLOCK__();
        //std::cout << "ref_lock_ = " << (int) ref_lock_ << std::endl;
      }
    RefCount(const RefCount&): _reference_count_(0) {
        __REF_INITLOCK__();
        //std::cout << "ref_lock_ = " << (int) ref_lock_ << std::endl;
      }

    // Assigment should not overwrite the reference count.
    RefCount& operator=(const RefCount&) { return *this; }
  public:
    virtual ~RefCount();

    /// Lock this object.
    int lock_ptr() const;
    /// Unlock this object.
    int unlock_ptr() const;

    /// start and stop using locks on this object
    void use_locks(bool inVal);

    /// Return the reference count.
    refcount_t nreference() const {
#       if REF_MANAGE
        if (!managed()) return 1;
#       endif
        return _reference_count_;
      }

    /// Increment the reference count and return the new count.
    refcount_t reference() {
#       if REF_MANAGE
        if (!managed()) return 1;
#       endif
        __REF_LOCK__(this);
#       if REF_CHECK_MAX_NREF
        if (_reference_count_ >= REF_MAX_NREF) too_many_refs();
#       endif
        _reference_count_++;
        refcount_t r = _reference_count_;
        __REF_UNLOCK__(this);
        return r;
      }

    /// Decrement the reference count and return the new count.
    refcount_t dereference() {
#       if REF_MANAGE