STL stl_alloc.h

# // Comment By:  凝霜

# // E-mail:      mdl2009@vip.qq.com

# // Blog:        http://blog.csdn.net/mdl13412

#

# // 特别说明: SGI STL的allocator在我的编译环境下不使用内存池

# //          而其内存池不进行内存释放操作, 其释放时机为程序退出或者stack unwinding

# //          由操作系统保证内存的回收

#

# /*

#  * 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

# // SUN编译器对private限制过多, 需要开放权限

# #else

# #  define __PRIVATE private

# #endif

#

# // 为了保证兼容性, 对于不支持模板类静态成员的情况, 使用malloc()进行内存分配

# #ifdef __STL_STATIC_TEMPLATE_MEMBER_BUG

# #  define __USE_MALLOC

# #endif

#

# // 实现了一些标准的node allocator

# // 但是不同于C++标准或者STL原始STL标准

# // 这些allocator没有封装不同指针类型

# // 事实上我们假定只有一种指针理性

# // allocation primitives意在分配不大于原始STL allocator分配的独立的对象

#

# #if 0

# #   include <new>

# #   define __THROW_BAD_ALLOC throw bad_alloc

# #elif !defined(__THROW_BAD_ALLOC)

# #   include <iostream.h>

# #   define __THROW_BAD_ALLOC cerr << "out of memory" << endl; exit()

# #endif

#

# #ifndef __ALLOC

# #   define __ALLOC alloc

# #endif

# #ifdef __STL_WIN32THREADS

# #   include <windows.h>

# #endif

#

# #include <stddef.h>

# #include <stdlib.h>

# #include <string.h>

# #include <assert.h>

# #ifndef __RESTRICT

# #  define __RESTRICT

# #endif

#

# // 多线程支持

# // __STL_PTHREADS       // GCC编译器

# // _NOTHREADS           // 不支持多线程

# // __STL_SGI_THREADS    // SGI机器专用

# // __STL_WIN32THREADS   // MSVC编译器

# #if !defined(__STL_PTHREADS) && !defined(_NOTHREADS) \

#  && !defined(__STL_SGI_THREADS) && !defined(__STL_WIN32THREADS)

# #   define _NOTHREADS

# #endif

#

# # ifdef __STL_PTHREADS

#     // POSIX Threads

#     // This is dubious, since this is likely to be a high contention

#     // lock.   Performance may not be adequate.

# #   include <pthread.h>

# #   define __NODE_ALLOCATOR_LOCK \

#         if (threads) pthread_mutex_lock(&__node_allocator_lock)

# #   define __NODE_ALLOCATOR_UNLOCK \

#         if (threads) pthread_mutex_unlock(&__node_allocator_lock)

# #   define __NODE_ALLOCATOR_THREADS true

# #   define __VOLATILE volatile  // Needed at -O3 on SGI

# # endif

# # ifdef __STL_WIN32THREADS

#     // The lock needs to be initialized by constructing an allocator

#     // objects of the right type.  We do that here explicitly for alloc.

# #   define __NODE_ALLOCATOR_LOCK \

#         EnterCriticalSection(&__node_allocator_lock)

# #   define __NODE_ALLOCATOR_UNLOCK \

#         LeaveCriticalSection(&__node_allocator_lock)

# #   define __NODE_ALLOCATOR_THREADS true

# #   define __VOLATILE volatile  // may not be needed

# # endif /* WIN32THREADS */

# # ifdef __STL_SGI_THREADS

#     // This should work without threads, with sproc threads, or with

#     // pthreads.  It is suboptimal in all cases.

#     // It is unlikely to even compile on nonSGI machines.

#

#     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) \

#                 { __lock(&__node_allocator_lock); }

# #   define __NODE_ALLOCATOR_UNLOCK if (threads && __us_rsthread_malloc) \

#                 { __unlock(&__node_allocator_lock); }

# #   define __NODE_ALLOCATOR_THREADS true

# #   define __VOLATILE volatile  // Needed at -O3 on SGI

# # endif

# # ifdef _NOTHREADS

# //  Thread-unsafe

# #   define __NODE_ALLOCATOR_LOCK

# #   define __NODE_ALLOCATOR_UNLOCK

# #   define __NODE_ALLOCATOR_THREADS false

# #   define __VOLATILE

# # 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)() = ;

#     // g++ 2.7.2 does not handle static template data members.

# # else

#     extern void (* __malloc_alloc_oom_handler)();

# # endif

# #endif

#

# // 一级配置器

# template <int inst>

# class __malloc_alloc_template

# {

# private:

#     // 用于在设置了__malloc_alloc_oom_handler情况下循环分配内存,

#     // 直到成功分配

#     static void *oom_malloc(size_t);

#     static void *oom_realloc(void *, size_t);

#

#     // 如果编译器支持模板类静态成员, 则使用错误处理函数, 类似C++的set_new_handler()

#     // 默认值为0, 如果不设置, 则内存分配失败时直接__THROW_BAD_ALLOC

# #ifndef __STL_STATIC_TEMPLATE_MEMBER_BUG

#     static void (* __malloc_alloc_oom_handler)();

# #endif

#

# public:

#     // 分配指定大小的内存(size_t n)， 如果分配失败, 则进入循环分配阶段

#     // 循环分配前提是要保证正确设置了__malloc_alloc_oom_handler

#     static void * allocate(size_t n)

#     {

#         void *result = malloc(n);

#         if ( == result) result = oom_malloc(n);

#         return result;

#     }

#

#     // 后面的size_t是为了兼容operator delele

#     static void deallocate(void *p, size_t /* n */)

#     { free(p); }

#

#     // 重新分配内存大小, 第二个参数是为了兼容operator new

#     static void * reallocate(void *p, size_t /* old_sz */, size_t new_sz)

#     {

#         void * result = realloc(p, new_sz);

#         if ( == result) result = oom_realloc(p, new_sz);

#         return result;

#     }

#

#     // 设置错误处理函数, 返回原来的函数指针

#     // 不属于C++标准规定的接口

#     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)() = ;

# #endif

#

# // 如果设置了__malloc_alloc_oom_handler, 则首先执行错误处理函数, 然后循环分配直到成功

# // 如果未设置__malloc_alloc_oom_handler, __THROW_BAD_ALLOC

# template <int inst>

# void * __malloc_alloc_template<inst>::oom_malloc(size_t n)

# {

#     void (* my_malloc_handler)();

#     void *result;

#

#     for (;;) {

#         my_malloc_handler = __malloc_alloc_oom_handler;

#         if ( == my_malloc_handler) { __THROW_BAD_ALLOC; }

#         (*my_malloc_handler)();

#         result = malloc(n);

#         if (result) return(result);

#     }

# }

#

# template <int inst>

# void * __malloc_alloc_template<inst>::oom_realloc(void *p, size_t n)

# {

#     void (* my_malloc_handler)();

#     void *result;

#

#     for (;;) {

#         my_malloc_handler = __malloc_alloc_oom_handler;

#         if ( == my_malloc_handler) { __THROW_BAD_ALLOC; }

#         (*my_malloc_handler)();

#         result = realloc(p, n);

#         if (result) return(result);

#     }

# }

#

# // 这个版本的STL并没有使用non-type模板参数

# typedef __malloc_alloc_template<> malloc_alloc;

#

# // 这个类中的接口其实就是STL标准中的allocator的接口

# // 实际上所有的SGI STL都使用这个进行内存配置

# // 例如: stl_vector.h中

# // template <class T, class Alloc = alloc>

# // class vector

# // {

# //      ...

# // protected:

# //      typedef simple_alloc<value_type, Alloc> data_allocator;

# //      ...

# //};

# template<class T, class Alloc>

# class simple_alloc

# {

# public:

#     static T *allocate(size_t n)

#                 { return  == n?  : (T*) Alloc::allocate(n * sizeof (T)); }

#     static T *allocate(void)

#                 { return (T*) Alloc::allocate(sizeof (T)); }

#     static void deallocate(T *p, size_t n)

#                 { if ( != n) Alloc::deallocate(p, n * sizeof (T)); }

#     static void deallocate(T *p)

#                 { Alloc::deallocate(p, sizeof (T)); }

# };

#

# // 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 {extra = };       // Size of space used to store size.  Note

#                             // that this must be large enough to preserve

#                             // alignment.

#

# public:

#

#     // extra 保证不会分配为0的内存空间, 而且要保证内存对齐

#     // 把分配内存的最前面设置成n的大小, 用于后面校验

#     // 内存对齐的作用就是保护前面extra大小的数据不被修改

#     static void * allocate(size_t n)

#     {

#         char *result = (char *)Alloc::allocate(n + extra);

#         *(size_t *)result = n;

#         return result + extra;

#     }

#

#     // 如果*(size_t *)real_p != n则肯定发生向前越界

#     static void deallocate(void *p, size_t n)

#     {

#         char * real_p = (char *)p - extra;

#         assert(*(size_t *)real_p == n);

#         Alloc::deallocate(real_p, n + extra);

#     }

#

#     static void * reallocate(void *p, size_t old_sz, size_t new_sz)

#     {

#         char * real_p = (char *)p - extra;

#         assert(*(size_t *)real_p == old_sz);

#         char * result = (char *)

#                       Alloc::reallocate(real_p, old_sz + extra, new_sz + extra);

#         *(size_t *)result = new_sz;

#         return result + extra;

#     }

# };

#

# # ifdef __USE_MALLOC

#

# typedef malloc_alloc alloc;

# typedef malloc_alloc single_client_alloc;

#

# # else

#

# // 默认的node allocator

# // 如果有合适的编译器, 速度上与原始的STL class-specific allocators大致等价

# // 但是具有产生更少内存碎片的优点

# // Default_alloc_template参数是用于实验性质的, 在未来可能会消失

# // 客户只能在当下使用alloc

# //

# // 重要的实现属性:

# // 1. 如果客户请求一个size > __MAX_BYTE的对象, 则直接使用malloc()分配

# // 2. 对于其它情况下, 我们将请求对象的大小按照内存对齐向上舍入ROUND_UP(requested_size)

# // TODO: 待翻译

# // 2. In all other cases, we allocate an object of size exactly

# //    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.

# //

#

# // 第一个模板参数指定是否有多于一个线程使用本allocator

# // 在一个default_alloc实例中分配对象, 在另一个deallocate实例中释放对象, 是安全的

# // 这有效的转换其所有权到另一个对象

# // 这可能导致对我们引用的区域产生不良影响

# // 第二个模板参数仅仅用于创建多个default_alloc实例

# // 不同容器使用不同allocator实例创建的node拥有不同类型, 这限制了此方法的通用性

#

# // Sun C++ compiler需要在类外定义这些枚举

# #ifdef __SUNPRO_CC

# // breaks if we make these template class members:

#   enum {__ALIGN = };

#   enum {__MAX_BYTES = };

#   enum {__NFREELISTS = __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.

# # ifndef __SUNPRO_CC

#     enum {__ALIGN = };

#     enum {__MAX_BYTES = };

#     enum {__NFREELISTS = __MAX_BYTES/__ALIGN};

# # endif

#     // 向上舍入操作

#     // 解释一下, __ALIGN - 1指明的是实际内存对齐的粒度

#     // 例如__ALIGN = 8时, 我们只需要7就可以实际表示8个数(0~7)

#     // 那么~(__ALIGN - 1)就是进行舍入的粒度

#     // 我们将(bytes) + __ALIGN-1)就是先进行进位, 然后截断

#     // 这就保证了我是向上舍入的

#     // 例如byte = 100, __ALIGN = 8的情况

#     // ~(__ALIGN - 1) = (1 000)B

#     // ((bytes) + __ALIGN-1) = (1 101 011)B

#     // (((bytes) + __ALIGN-1) & ~(__ALIGN - 1)) = (1 101 000 )B = (104)D

#     // 104 / 8 = 13, 这就实现了向上舍入

#     // 对于byte刚好满足内存对齐的情况下, 结果保持byte大小不变

#     // 记得《Hacker's Delight》上面有相关的计算

#     // 这个表达式与下面给出的等价

#     // ((((bytes) + _ALIGN - 1) * _ALIGN) / _ALIGN)

#     // 但是SGI STL使用的方法效率非常高

#     static size_t ROUND_UP(size_t bytes)

#     {

#         return (((bytes) + __ALIGN-) & ~(__ALIGN - ));

#     }

# __PRIVATE:

#     // 管理内存链表用

#     // 为了尽最大可能减少内存的使用, 这里使用一个union

#     // 如果使用第一个成员, 则指向另一个相同的union obj

#     // 而如果使用第二个成员, 则指向实际的内存区域

#     // 这样就实现了链表结点只使用一个指针的大小空间, 却能同时做索引和指向内存区域

#     // 这个技巧性非常强, 值得学习

#     union obj

#     {

#         union obj * free_list_link;

#         char client_data[];    /* The client sees this.        */

#     };

# private:

# # ifdef __SUNPRO_CC

#     static obj * __VOLATILE free_list[];

#         // Specifying a size results in duplicate def for 4.1

# # else

#     // 这里分配的free_list为16

#     // 对应的内存链容量分别为8, 16, 32 ... 128

#     static obj * __VOLATILE free_list[__NFREELISTS];

# # endif

#     // 根据待待分配的空间大小, 在free_list中选择合适的大小

#     static  size_t FREELIST_INDEX(size_t bytes)

#     {

#         return (((bytes) + __ALIGN-)/__ALIGN - );

#     }

#

#   // Returns an object of size n, and optionally adds to size n free list.

#   static void *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 *chunk_alloc(size_t size, int &nobjs);

#

#   // 内存池

#   static char *start_free;      // 内存池起始点

#   static char *end_free;        // 内存池结束点

#   static size_t heap_size;      // 已经在堆上分配的空间大小

#

# // 下面三个条件编译给多线程条件下使用的锁提供必要支持

# # ifdef __STL_SGI_THREADS

#     static volatile unsigned long __node_allocator_lock;

#     static void __lock(volatile unsigned long *);

#     static inline void __unlock(volatile unsigned long *);

# # endif

#

# # ifdef __STL_PTHREADS

#     static pthread_mutex_t __node_allocator_lock;

# # endif

#

# # ifdef __STL_WIN32THREADS

#     static CRITICAL_SECTION __node_allocator_lock;

#     static bool __node_allocator_lock_initialized;

#

#   public:

#     __default_alloc_template() {

#     // This assumes the first constructor is called before threads

#     // are started.

#         if (!__node_allocator_lock_initialized) {

#             InitializeCriticalSection(&__node_allocator_lock);

#             __node_allocator_lock_initialized = true;

#         }

#     }

#   private:

# # endif

#

#     // 用于多线程环境下锁定操作用

#     class lock

#     {

#     public:

#         lock() { __NODE_ALLOCATOR_LOCK; }

#         ~lock() { __NODE_ALLOCATOR_UNLOCK; }

#     };

#     friend class lock;

#

# public:

#   /* n must be > 0      */

#   static void * allocate(size_t n)

#   {

#     obj * __VOLATILE * my_free_list;

#     obj * __RESTRICT result;

#

#     // 如果待分配对象大于__MAX_BYTES, 使用一级配置器分配

#     if (n > (size_t) __MAX_BYTES) {

#         return(malloc_alloc::allocate(n));

#     }

#     my_free_list = free_list + 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

#     result = *my_free_list;

#     // 如果是第一次使用这个容量的链表, 则分配此链表需要的内存

#     // 如果不是, 则判断内存吃容量, 不够则分配

#     if (result == ) {

#         void *r = refill(ROUND_UP(n));

#         return r;

#     }

#     *my_free_list = result -> free_list_link;

#     return (result);

#   };

#

#   /* p may not be 0 */

#   static void deallocate(void *p, size_t n)

#   {

#     obj *q = (obj *)p;

#     obj * __VOLATILE * my_free_list;

#

#     // 对于大于__MAX_BYTES的对象, 因为采用的是一级配置器分配, 所以同样使用一级配置器释放

#     if (n > (size_t) __MAX_BYTES) {

#         malloc_alloc::deallocate(p, n);

#         return;

#     }

#     my_free_list = free_list + FREELIST_INDEX(n);

#     // acquire lock

# #       ifndef _NOTHREADS

#         /*REFERENCED*/

#         lock lock_instance;

# #       endif /* _NOTHREADS */

#     q -> 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, > alloc;

# typedef __default_alloc_template<false, > single_client_alloc;

#

# // 每次分配一大块内存, 防止多次分配小内存块带来的内存碎片

# // 进行分配操作时, 根据具体环境决定是否加锁

# // 我们假定要分配的内存满足内存对齐要求

# template <bool threads, int inst>

# char*

# __default_alloc_template<threads, inst>::chunk_alloc(size_t size, int& nobjs)

# {

#     char * result;

#     size_t total_bytes = size * nobjs;

#     size_t bytes_left = end_free - start_free;  // 计算内存池剩余容量

#

#     // 如果内存池中剩余内存>=需要分配的内内存, 返回start_free指向的内存块,

#     // 并且重新设置内存池起始点

#     if (bytes_left >= total_bytes) {

#         result = start_free;

#         start_free += total_bytes;

#         return(result);

#     }

#     // 如果内存吃中剩余的容量不够分配, 但是能至少分配一个节点时,

#     // 返回所能分配的最多的节点, 返回start_free指向的内存块

#     // 并且重新设置内存池起始点

#     else if (bytes_left >= size) {

#         nobjs = bytes_left/size;

#         total_bytes = size * nobjs;

#         result = start_free;

#         start_free += total_bytes;

#         return(result);

#     }

#     // 内存池剩余内存连一个节点也不够分配

#     else {

#         size_t bytes_to_get =  * total_bytes + ROUND_UP(heap_size >> );

#         // 将剩余的内存分配给指定的free_list[FREELIST_INDEX(bytes_left)]

#         if (bytes_left > ) {

#             obj * __VOLATILE * my_free_list =

#                         free_list + FREELIST_INDEX(bytes_left);

#

#             ((obj *)start_free) -> free_list_link = *my_free_list;

#             *my_free_list = (obj *)start_free;

#         }

#         start_free = (char *)malloc(bytes_to_get);

#         // 分配失败, 搜索原来已经分配的内存块, 看是否有大于等于当前请求的内存块

#         if ( == start_free) {

#             int i;

#             obj * __VOLATILE * my_free_list, *p;

#             // Try to make do with what we have.  That can't

#             // hurt.  We do not try smaller requests, since that tends

#             // to result in disaster on multi-process machines.

#             for (i = size; i <= __MAX_BYTES; i += __ALIGN) {

#                 my_free_list = free_list + FREELIST_INDEX(i);

#                 p = *my_free_list;

#                 // 找到了一个, 将其加入内存池中

#                 if ( != p) {

#                     *my_free_list = p -> free_list_link;

#                     start_free = (char *)p;

#                     end_free = start_free + i;

#                     // 内存池更新完毕, 重新分配需要的内存

#                     return(chunk_alloc(size, nobjs));

#                     // Any leftover piece will eventually make it to the

#                     // right free list.

#                 }

#             }

#

#             // 再次失败, 直接调用一级配置器分配, 期待异常处理函数能提供帮助

#             // 不过在我看来, 内存分配失败进行其它尝试已经没什么意义了,

#             // 最好直接log, 然后让程序崩溃

#         end_free = ;   // In case of exception.

#             start_free = (char *)malloc_alloc::allocate(bytes_to_get);

#         }

#         heap_size += bytes_to_get;

#         end_free = start_free + bytes_to_get;

#         // 内存池更新完毕, 重新分配需要的内存

#         return(chunk_alloc(size, nobjs));

#     }

# }

#

#

# // 返回一个大小为n的对象, 并且加入到free_list[FREELIST_INDEX(n)]

# // 进行分配操作时, 根据具体环境决定是否加锁

# // 我们假定要分配的内存满足内存对齐要求

# template <bool threads, int inst>

# void* __default_alloc_template<threads, inst>::refill(size_t n)

# {

#     int nobjs = ;

#     char * chunk = chunk_alloc(n, nobjs);

#     obj * __VOLATILE * my_free_list;

#     obj * result;

#     obj * current_obj, * next_obj;

#     int i;

#

#     // 如果内存池仅仅只够分配一个对象的空间, 直接返回即可

#     if ( == nobjs) return(chunk);

#

#     // 内存池能分配更多的空间

#     my_free_list = free_list + FREELIST_INDEX(n);

#

#     // 在chunk的空间中建立free_list

#       result = (obj *)chunk;

#       *my_free_list = next_obj = (obj *)(chunk + n);

#       for (i = ; ; i++) {

#         current_obj = next_obj;

#         next_obj = (obj *)((char *)next_obj + n);

#         if (nobjs -  == i) {

#             current_obj -> free_list_link = ;

#             break;

#         } else {

#             current_obj -> free_list_link = next_obj;

#         }

#       }

#     return(result);

# }

#

# template <bool threads, int inst>

# void*

# __default_alloc_template<threads, inst>::reallocate(void *p,

#                                                     size_t old_sz,

#                                                     size_t new_sz)

# {

#     void * result;

#     size_t copy_sz;

#

#     // 如果old_size和new_size均大于__MAX_BYTES, 则直接调用realloc()

#     // 因为这部分内存不是经过内存池分配的

#     if (old_sz > (size_t) __MAX_BYTES && new_sz > (size_t) __MAX_BYTES) {

#         return(realloc(p, new_sz));

#     }

#     // 如果ROUND_UP(old_sz) == ROUND_UP(new_sz), 内存大小没变化, 不进行重新分配

#     if (ROUND_UP(old_sz) == ROUND_UP(new_sz)) return(p);

#     // 进行重新分配并拷贝数据

#     result = allocate(new_sz);

#     copy_sz = new_sz > old_sz? old_sz : new_sz;

#     memcpy(result, p, copy_sz);

#     deallocate(p, old_sz);

#     return(result);

# }

#

# #ifdef __STL_PTHREADS

#     template <bool threads, int inst>

#     pthread_mutex_t

#     __default_alloc_template<threads, inst>::__node_allocator_lock

#         = PTHREAD_MUTEX_INITIALIZER;

# #endif

#

# #ifdef __STL_WIN32THREADS

#     template <bool threads, int inst> CRITICAL_SECTION

#     __default_alloc_template<threads, inst>::__node_allocator_lock;

#

#     template <bool threads, int inst> bool

#     __default_alloc_template<threads, inst>::__node_allocator_lock_initialized

#     = false;

# #endif

#

# #ifdef __STL_SGI_THREADS

# __STL_END_NAMESPACE

# #include <mutex.h>

# #include <time.h>

# __STL_BEGIN_NAMESPACE

# // Somewhat generic lock implementations.  We need only test-and-set

# // and some way to sleep.  These should work with both SGI pthreads

# // and sproc threads.  They may be useful on other systems.

# template <bool threads, int inst>

# volatile unsigned long

# __default_alloc_template<threads, inst>::__node_allocator_lock = ;

#

# #if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64)) || defined(__GNUC__)

# #   define __test_and_set(l,v) test_and_set(l,v)

# #endif

#

# template <bool threads, int inst>

# void

# __default_alloc_template<threads, inst>::__lock(volatile unsigned long *lock)

# {

#     const unsigned low_spin_max = ;  // spin cycles if we suspect uniprocessor

#     const unsigned high_spin_max = ; // spin cycles for multiprocessor

#     static unsigned spin_max = low_spin_max;

#     unsigned my_spin_max;

#     static unsigned last_spins = ;

#     unsigned my_last_spins;

#     static struct timespec ts = {, };

#     unsigned junk;

# #   define __ALLOC_PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk

#     int i;

#

#     if (!__test_and_set((unsigned long *)lock, )) {

#         return;

#     }

#     my_spin_max = spin_max;

#     my_last_spins = last_spins;

#     for (i = ; i < my_spin_max; i++) {

#         if (i < my_last_spins/ || *lock) {

#             __ALLOC_PAUSE;

#             continue;

#         }

#         if (!__test_and_set((unsigned long *)lock, )) {

#             // got it!

#             // Spinning worked.  Thus we're probably not being scheduled

#             // against the other process with which we were contending.

#             // Thus it makes sense to spin longer the next time.

#             last_spins = i;

#             spin_max = high_spin_max;

#             return;

#         }

#     }

#     // We are probably being scheduled against the other process.  Sleep.

#     spin_max = low_spin_max;

#     for (;;) {

#         if (!__test_and_set((unsigned long *)lock, )) {

#             return;

#         }

#         nanosleep(&ts, );

#     }

# }

#

# template <bool threads, int inst>

# inline void

# __default_alloc_template<threads, inst>::__unlock(volatile unsigned long *lock)

# {

# #   if defined(__GNUC__) && __mips >=

#         asm("sync");

#         *lock = ;

# #   elif __mips >=  && (defined (_ABIN32) || defined(_ABI64))

#         __lock_release(lock);

# #   else

#         *lock = ;

#         // This is not sufficient on many multiprocessors, since

#         // writes to protected variables and the lock may be reordered.

# #   endif

# }

# #endif

#

# // 内存池起始位置

# template <bool threads, int inst>

# char *__default_alloc_template<threads, inst>::start_free = ;

# // 内存池结束位置

# template <bool threads, int inst>

# char *__default_alloc_template<threads, inst>::end_free = ;

#

# template <bool threads, int inst>

# size_t __default_alloc_template<threads, inst>::heap_size = ;

# // 内存池容量索引数组

# template <bool threads, int inst>

# __default_alloc_template<threads, inst>::obj * __VOLATILE

# __default_alloc_template<threads, inst> ::free_list[

# # ifdef __SUNPRO_CC

#     __NFREELISTS

# # else

#     __default_alloc_template<threads, inst>::__NFREELISTS

# # endif

# ] = {, , , , , , , , , , , , , , , , };

# // The 16 zeros are necessary to make version 4.1 of the SunPro

# // compiler happy.  Otherwise it appears to allocate too little

# // space for the array.

#

# # ifdef __STL_WIN32THREADS

#   // Create one to get critical section initialized.

#   // We do this onece per file, but only the first constructor

#   // does anything.

#   static alloc __node_allocator_dummy_instance;

# # endif

#

# #endif /* ! __USE_MALLOC */

#

# #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)

# #pragma reset woff 1174

# #endif

#

# __STL_END_NAMESPACE

#

# #undef __PRIVATE

#

# #endif /* __SGI_STL_INTERNAL_ALLOC_H */

#

# // Local Variables:

# // mode:C++

# // End:
巴特西

STL stl_alloc.h

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