# // Comment By: 凝霜
# // E-mail: [email protected]
# // 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(1)
# #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)() = 0;
# // 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 (0 == 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 (0 == 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)() = 0;
# #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 (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>::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);
# }
# }
#
# // 这个版本的STL并没有使用non-type模板参数
# typedef __malloc_alloc_template<0> 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 0 == n? 0 : (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 (0 != 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 = 8}; // 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 = 8};
# enum {__MAX_BYTES = 128};
# 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 = 8};
# enum {__MAX_BYTES = 128};
# 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-1) & ~(__ALIGN - 1));
# }
# __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[1]; /* 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-1)/__ALIGN - 1);
# }
#
# // 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 == 0) {
# 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, 0> alloc;
# typedef __default_alloc_template<false, 0> 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 = 2 * total_bytes + ROUND_UP(heap_size >> 4);
# // 将剩余的内存分配给指定的free_list[FREELIST_INDEX(bytes_left)]
# if (bytes_left > 0) {
# 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 (0 == 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 (0 != 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 = 0; // 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 = 20;
# 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 (1 == 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 = 1; ; i++) {
# current_obj = next_obj;
# next_obj = (obj *)((char *)next_obj + n);
# if (nobjs - 1 == i) {
# current_obj -> free_list_link = 0;
# 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 = 0;
#
# #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 = 30; // spin cycles if we suspect uniprocessor
# const unsigned high_spin_max = 1000; // spin cycles for multiprocessor
# static unsigned spin_max = low_spin_max;
# unsigned my_spin_max;
# static unsigned last_spins = 0;
# unsigned my_last_spins;
# static struct timespec ts = {0, 1000};
# unsigned junk;
# # define __ALLOC_PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk
# int i;
#
# if (!__test_and_set((unsigned long *)lock, 1)) {
# return;
# }
# my_spin_max = spin_max;
# my_last_spins = last_spins;
# for (i = 0; i < my_spin_max; i++) {
# if (i < my_last_spins/2 || *lock) {
# __ALLOC_PAUSE;
# continue;
# }
# if (!__test_and_set((unsigned long *)lock, 1)) {
# // 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, 1)) {
# return;
# }
# nanosleep(&ts, 0);
# }
# }
#
# template <bool threads, int inst>
# inline void
# __default_alloc_template<threads, inst>::__unlock(volatile unsigned long *lock)
# {
# # if defined(__GNUC__) && __mips >= 3
# asm("sync");
# *lock = 0;
# # elif __mips >= 3 && (defined (_ABIN32) || defined(_ABI64))
# __lock_release(lock);
# # else
# *lock = 0;
# // 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 = 0;
# // 内存池结束位置
# template <bool threads, int inst>
# char *__default_alloc_template<threads, inst>::end_free = 0;
#
# template <bool threads, int inst>
# size_t __default_alloc_template<threads, inst>::heap_size = 0;
# // 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
# ] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };
# // 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:
时间： 2024-10-14 03:20:31