stl_alloc.h

eVC stl 方便大家在evc中使用stl 帮助程序员更方便的编程。

/*
 * Copyright (c) 1996-1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */

#ifndef __SGI_STL_INTERNAL_ALLOC_H
#define __SGI_STL_INTERNAL_ALLOC_H

#ifdef __SUNPRO_CC
#  define __PRIVATE public
   // Extra access restrictions prevent us from really making some things
   // private.
#else
#  define __PRIVATE private
#endif

#ifdef __STL_STATIC_TEMPLATE_MEMBER_BUG
#  define __USE_MALLOC
#endif


// This implements some standard node allocators.  These are
// NOT the same as the allocators in the C++ draft standard or in
// in the original STL.  They do not encapsulate different pointer
// types; indeed we assume that there is only one pointer type.
// The allocation primitives are intended to allocate individual objects,
// not larger arenas as with the original STL allocators.

#ifndef __THROW_BAD_ALLOC
# ifndef UNDER_CE
#  if defined(__STL_NO_BAD_ALLOC) || !defined(__STL_USE_EXCEPTIONS)
#    include <stdio.h>
#    include <stdlib.h>
#    define __THROW_BAD_ALLOC fprintf(stderr, "out of memory\n"); exit(1)
#  else /* Standard conforming out-of-memory handling */
#    include <new>
#    define __THROW_BAD_ALLOC throw std::bad_alloc()
#  endif
# endif /* UNDER_CE */
#endif

#ifndef UNDER_CE
#include <stddef.h>
#else
#include <wce_defs.h>
#endif /* UNDER_CE */
#include <stdlib.h>
#include <string.h>
#ifndef UNDER_CE
#include <assert.h>
#endif
#ifndef __RESTRICT
#  define __RESTRICT
#endif

#ifdef __STL_THREADS
# include <stl_threads.h>
# define __NODE_ALLOCATOR_THREADS true
# ifdef __STL_SGI_THREADS
  // We test whether threads are in use before locking.
  // Perhaps this should be moved into stl_threads.h, but that
  // probably makes it harder to avoid the procedure call when
  // it isn't needed.
    extern "C" {
      extern int __us_rsthread_malloc;
    }
	// The above is copied from malloc.h.  Including <malloc.h>
	// would be cleaner but fails with certain levels of standard
	// conformance.
#   define __NODE_ALLOCATOR_LOCK if (threads && __us_rsthread_malloc) \
                { _S_node_allocator_lock._M_acquire_lock(); }
#   define __NODE_ALLOCATOR_UNLOCK if (threads && __us_rsthread_malloc) \
                { _S_node_allocator_lock._M_release_lock(); }
# else /* !__STL_SGI_THREADS */
#   define __NODE_ALLOCATOR_LOCK \
        { if (threads) _S_node_allocator_lock._M_acquire_lock(); }
#   define __NODE_ALLOCATOR_UNLOCK \
        { if (threads) _S_node_allocator_lock._M_release_lock(); }
# endif
#else
//  Thread-unsafe
#   define __NODE_ALLOCATOR_LOCK
#   define __NODE_ALLOCATOR_UNLOCK
#   define __NODE_ALLOCATOR_THREADS false
#endif

__STL_BEGIN_NAMESPACE

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1174
#endif

// Malloc-based allocator.  Typically slower than default alloc below.
// Typically thread-safe and more storage efficient.
#ifdef __STL_STATIC_TEMPLATE_MEMBER_BUG
# ifdef __DECLARE_GLOBALS_HERE
    void (* __malloc_alloc_oom_handler)() = 0;
    // g++ 2.7.2 does not handle static template data members.
# else
    extern void (* __malloc_alloc_oom_handler)();
# endif
#endif

template <int __inst>
class __malloc_alloc_template {

private:

  static void* _S_oom_malloc(size_t);
  static void* _S_oom_realloc(void*, size_t);

#ifndef __STL_STATIC_TEMPLATE_MEMBER_BUG
  static void (* __malloc_alloc_oom_handler)();
#endif

public:

  static void* allocate(size_t __n)
  {
    void* __result = malloc(__n);
    if (0 == __result) __result = _S_oom_malloc(__n);
    return __result;
  }

  static void deallocate(void* __p, size_t /* __n */)
  {
    free(__p);
  }

  static void* reallocate(void* __p, size_t /* old_sz */, size_t __new_sz)
  {
    void* __result = realloc(__p, __new_sz);
    if (0 == __result) __result = _S_oom_realloc(__p, __new_sz);
    return __result;
  }

  static void (* __set_malloc_handler(void (*__f)()))()
  {
    void (* __old)() = __malloc_alloc_oom_handler;
    __malloc_alloc_oom_handler = __f;
    return(__old);
  }

};

// malloc_alloc out-of-memory handling

#ifndef __STL_STATIC_TEMPLATE_MEMBER_BUG
template <int __inst>
void (* __malloc_alloc_template<__inst>::__malloc_alloc_oom_handler)() = 0;
#endif

template <int __inst>
void*
__malloc_alloc_template<__inst>::_S_oom_malloc(size_t __n)
{
    void (* __my_malloc_handler)();
    void* __result;

    for (;;) {
        __my_malloc_handler = __malloc_alloc_oom_handler;
        if (0 == __my_malloc_handler) { __THROW_BAD_ALLOC; }
        (*__my_malloc_handler)();
        __result = malloc(__n);
        if (__result) return(__result);
    }
}

template <int __inst>
void* __malloc_alloc_template<__inst>::_S_oom_realloc(void* __p, size_t __n)
{
    void (* __my_malloc_handler)();
    void* __result;

    for (;;) {
        __my_malloc_handler = __malloc_alloc_oom_handler;
        if (0 == __my_malloc_handler) { __THROW_BAD_ALLOC; }
        (*__my_malloc_handler)();
        __result = realloc(__p, __n);
        if (__result) return(__result);
    }
}

typedef __malloc_alloc_template<0> malloc_alloc;

template<class _Tp, class _Alloc>
class simple_alloc {

public:
    static _Tp* allocate(size_t __n)
      { return 0 == __n ? 0 : (_Tp*) _Alloc::allocate(__n * sizeof (_Tp)); }
    static _Tp* allocate(void)
      { return (_Tp*) _Alloc::allocate(sizeof (_Tp)); }
    static void deallocate(_Tp* __p, size_t __n)
      { if (0 != __n) _Alloc::deallocate(__p, __n * sizeof (_Tp)); }
    static void deallocate(_Tp* __p)
      { _Alloc::deallocate(__p, sizeof (_Tp)); }
};

// Allocator adaptor to check size arguments for debugging.
// Reports errors using assert.  Checking can be disabled with
// NDEBUG, but it's far better to just use the underlying allocator
// instead when no checking is desired.
// There is some evidence that this can confuse Purify.
template <class _Alloc>
class debug_alloc {

private:

  enum {_S_extra = 8};  // Size of space used to store size.  Note
                        // that this must be large enough to preserve
                        // alignment.

public:

  static void* allocate(size_t __n)
  {
    char* __result = (char*)_Alloc::allocate(__n + (int) _S_extra);
    *(size_t*)__result = __n;
    return __result + (int) _S_extra;
  }

  static void deallocate(void* __p, size_t __n)
  {
    char* __real_p = (char*)__p - (int) _S_extra;
    assert(*(size_t*)__real_p == __n);
    _Alloc::deallocate(__real_p, __n + (int) _S_extra);
  }

  static void* reallocate(void* __p, size_t __old_sz, size_t __new_sz)
  {
    char* __real_p = (char*)__p - (int) _S_extra;
    assert(*(size_t*)__real_p == __old_sz);
    char* __result = (char*)
      _Alloc::reallocate(__real_p, __old_sz + (int) _S_extra,
                                   __new_sz + (int) _S_extra);
    *(size_t*)__result = __new_sz;
    return __result + (int) _S_extra;
  }

};


# ifdef __USE_MALLOC

typedef malloc_alloc alloc;
typedef malloc_alloc single_client_alloc;

# else


// Default node allocator.
// With a reasonable compiler, this should be roughly as fast as the
// original STL class-specific allocators, but with less fragmentation.
// Default_alloc_template parameters are experimental and MAY
// DISAPPEAR in the future.  Clients should just use alloc for now.
//
// Important implementation properties:
// 1. If the client request an object of size > _MAX_BYTES, the resulting
//    object will be obtained directly from malloc.
// 2. In all other cases, we allocate an object of size exactly
//    _S_round_up(requested_size).  Thus the client has enough size
//    information that we can return the object to the proper free list
//    without permanently losing part of the object.
//

// The first template parameter specifies whether more than one thread
// may use this allocator.  It is safe to allocate an object from
// one instance of a default_alloc and deallocate it with another
// one.  This effectively transfers its ownership to the second one.
// This may have undesirable effects on reference locality.
// The second parameter is unreferenced and serves only to allow the
// creation of multiple default_alloc instances.
// Node that containers built on different allocator instances have
// different types, limiting the utility of this approach.

#if defined(__SUNPRO_CC) || defined(__GNUC__)
// breaks if we make these template class members:
  enum {_ALIGN = 8};
  enum {_MAX_BYTES = 128};
  enum {_NFREELISTS = 16}; // _MAX_BYTES/_ALIGN
#endif

template <bool threads, int inst>
class __default_alloc_template {

private:
  // Really we should use static const int x = N
  // instead of enum { x = N }, but few compilers accept the former.
#if ! (defined(__SUNPRO_CC) || defined(__GNUC__))
    enum {_ALIGN = 8};
    enum {_MAX_BYTES = 128};
    enum {_NFREELISTS = 16}; // _MAX_BYTES/_ALIGN
# endif
  static size_t
  _S_round_up(size_t __bytes) 
    { return (((__bytes) + (size_t) _ALIGN-1) & ~((size_t) _ALIGN - 1)); }

__PRIVATE:
  union _Obj {
        union _Obj* _M_free_list_link;
        char _M_client_data[1];    /* The client sees this.        */
  };
private:
# if defined(__SUNPRO_CC) || defined(__GNUC__) || defined(__HP_aCC)
    static _Obj* __STL_VOLATILE _S_free_list[]; 
        // Specifying a size results in duplicate def for 4.1
# else
    static _Obj* __STL_VOLATILE _S_free_list[_NFREELISTS]; 
# endif
  static  size_t _S_freelist_index(size_t __bytes) {
        return (((__bytes) + (size_t)_ALIGN-1)/(size_t)_ALIGN - 1);
  }

  // Returns an object of size __n, and optionally adds to size __n free list.
  static void* _S_refill(size_t __n);
  // Allocates a chunk for nobjs of size size.  nobjs may be reduced
  // if it is inconvenient to allocate the requested number.
  static char* _S_chunk_alloc(size_t __size, int& __nobjs);

  // Chunk allocation state.
  static char* _S_start_free;
  static char* _S_end_free;
  static size_t _S_heap_size;

# ifdef __STL_THREADS
    static _STL_mutex_lock _S_node_allocator_lock;
# endif

    // It would be nice to use _STL_auto_lock here.  But we
    // don't need the NULL check.  And we do need a test whether
    // threads have actually been started.
    class _Lock;
    friend class _Lock;
    class _Lock {
        public:
            _Lock() { __NODE_ALLOCATOR_LOCK; }
            ~_Lock() { __NODE_ALLOCATOR_UNLOCK; }
    };

public:

  /* __n must be > 0      */
  static void* allocate(size_t __n)
  {
    void* __ret = 0;

    if (__n > (size_t) _MAX_BYTES) {
      __ret = malloc_alloc::allocate(__n);
    }
    else {
      _Obj* __STL_VOLATILE* __my_free_list
          = _S_free_list + _S_freelist_index(__n);
      // Acquire the lock here with a constructor call.
      // This ensures that it is released in exit or during stack
      // unwinding.
#     ifndef _NOTHREADS
      /*REFERENCED*/
      _Lock __lock_instance;
#     endif
      _Obj* __RESTRICT __result = *__my_free_list;
      if (__result == 0)
        __ret = _S_refill(_S_round_up(__n));
      else {
        *__my_free_list = __result -> _M_free_list_link;
        __ret = __result;
      }
    }

    return __ret;
  };

  /* __p may not be 0 */
  static void deallocate(void* __p, size_t __n)
  {
    if (__n > (size_t) _MAX_BYTES)
      malloc_alloc::deallocate(__p, __n);
    else {
      _Obj* __STL_VOLATILE*  __my_free_list
          = _S_free_list + _S_freelist_index(__n);
      _Obj* __q = (_Obj*)__p;

      // acquire lock
#       ifndef _NOTHREADS
      /*REFERENCED*/
      _Lock __lock_instance;
#       endif /* _NOTHREADS */
      __q -> _M_free_list_link = *__my_free_list;
      *__my_free_list = __q;
      // lock is released here
    }
  }

  static void* reallocate(void* __p, size_t __old_sz, size_t __new_sz);

} ;

typedef __default_alloc_template<__NODE_ALLOCATOR_THREADS, 0> alloc;
typedef __default_alloc_template<false, 0> single_client_alloc;

template <bool __threads, int __inst>
inline bool operator==(const __default_alloc_template<__threads, __inst>&,
                       const __default_alloc_template<__threads, __inst>&)
{
  return true;
}

# ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER
template <bool __threads, int __inst>
inline bool operator!=(const __default_alloc_template<__threads, __inst>&,
                       const __default_alloc_template<__threads, __inst>&)
{
  return false;
}
# endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */



/* We allocate memory in large chunks in order to avoid fragmenting     */
/* the malloc heap too much.                                            */
/* We assume that size is properly aligned.                             */
/* We hold the allocation lock.                                         */
template <bool __threads, int __inst>
char*
__default_alloc_template<__threads, __inst>::_S_chunk_alloc(size_t __size, 
                                                            int& __nobjs)
{
    char* __result;
    size_t __total_bytes = __size * __nobjs;
    size_t __bytes_left = _S_end_free - _S_start_free;

    if (__bytes_left >= __total_bytes) {
        __result = _S_start_free;
        _S_start_free += __total_bytes;
        return(__result);
    } else if (__bytes_left >= __size) {
        __nobjs = (int)(__bytes_left/__size);
        __total_bytes = __size * __nobjs;
        __result = _S_start_free;
        _S_start_free += __total_bytes;
        return(__result);