OS_Memory.h
这个文件主要提供了内存分配的安全的宏定义和内存分配静态类。
ACE的内存宏定义
ACE_HAS_NEW_NOTHROW宏定义了是否使用new的异常抛出
POINTER,CONSTRUCTOR,RET_VAL
用法：ACE_*(指针，类型，失败返回值)
# if defined (ACE_HAS_NEW_NOTHROW)
# define ACE_NEW_RETURN(POINTER,CONSTRUCTOR,RET_VAL)
do { POINTER = new (ACE_nothrow) CONSTRUCTOR;
if (POINTER == 0) { errno = ENOMEM; return RET_VAL; }
} while (0)
# define ACE_NEW(POINTER,CONSTRUCTOR)
do { POINTER = new(ACE_nothrow) CONSTRUCTOR;
if (POINTER == 0) { errno = ENOMEM; return; }
} while (0)
# define ACE_NEW_NORETURN(POINTER,CONSTRUCTOR)
do { POINTER = new(ACE_nothrow) CONSTRUCTOR;
if (POINTER == 0) { errno = ENOMEM; }
} while (0)
# else
# define ACE_NEW_RETURN(POINTER,CONSTRUCTOR,RET_VAL)
do { try { POINTER = new CONSTRUCTOR; }
catch (ACE_bad_alloc) { errno = ENOMEM; POINTER = 0; return RET_VAL; }
} while (0)
# define ACE_NEW(POINTER,CONSTRUCTOR)
do { try { POINTER = new CONSTRUCTOR; }
catch (ACE_bad_alloc) { errno = ENOMEM; POINTER = 0; return; }
} while (0)
# define ACE_NEW_NORETURN(POINTER,CONSTRUCTOR)
do { try { POINTER = new CONSTRUCTOR; }
catch (ACE_bad_alloc) { errno = ENOMEM; POINTER = 0; }
} while (0)
# endif /* ACE_HAS_NEW_NOTHROW */
#else /* ACE_NEW_THROWS_EXCEPTIONS */
很明显使用NEW的抛出宏定义里使用到do{}while{} 语句和异常处理try{}catch{}的，保证分配内存的正确性。鼓励使用内存分配宏定义。在抛出的new的异常ACE_bad_alloc的定义如下：
// =========================================================================
// ACE_NEW macros
//
// A useful abstraction for expressions involving operator new since
// we can change memory allocation error handling policies (e.g.,
// depending on whether ANSI/ISO exception handling semantics are
// being used).
// =========================================================================
#if defined (ACE_NEW_THROWS_EXCEPTIONS)
// Since new() throws exceptions, we need a way to avoid passing
// exceptions past the call to new because ACE counts on having a 0
// return value for a failed allocation. Some compilers offer the
// new (nothrow) version, which does exactly what we want. Others
// do not. For those that do not, this sets up what exception is thrown,
// and then below we'll do a try/catch around the new to catch it and
// return a 0 pointer instead.
// 定义的惠普aCC编译器和各个版本
# if defined (__HP_aCC)
// I know this works for HP aC++... if <stdexcept> is used, it
// introduces other stuff that breaks things, like <memory>, which
// screws up auto_ptr.
# include /**/ <new>
// _HP_aCC was first defined at aC++ 03.13 on HP-UX 11. Prior to that
// (03.10 and before) a failed new threw bad_alloc. After that (03.13
// and above) the exception thrown is dependent on the below settings.
# if (HPUX_VERS >= 1100)
# if ((__HP_aCC < 32500 && !defined (RWSTD_NO_NAMESPACE)) ||
defined (ACE_USES_STD_NAMESPACE_FOR_STDCPP_LIB))
# define ACE_bad_alloc std::bad_alloc
# define ACE_nothrow std::nothrow
# define ACE_nothrow_t std::nothrow_t
# else
# define ACE_bad_alloc bad_alloc
# define ACE_nothrow nothrow
# define ACE_nothrow_t nothrow_t
# endif /* __HP_aCC */
# elif ((__HP_aCC < 12500 && !defined (RWSTD_NO_NAMESPACE)) ||
defined (ACE_USES_STD_NAMESPACE_FOR_STDCPP_LIB))
# define ACE_bad_alloc std::bad_alloc
# define ACE_nothrow std::nothrow
# define ACE_nothrow_t std::nothrow_t
# else
# define ACE_bad_alloc bad_alloc
# define ACE_nothrow nothrow
# define ACE_nothrow_t nothrow_t
# endif /* HPUX_VERS < 1100 */
# define ACE_throw_bad_alloc throw ACE_bad_alloc ()
// Sun的编译器和版本
# elif defined (__SUNPRO_CC)
# if (__SUNPRO_CC < 0x500) || (__SUNPRO_CC_COMPAT == 4)
# include /**/ <exception.h>
// Note: we catch ::xalloc rather than just xalloc because of
// a name clash with unsafe_ios::xalloc()
# define ACE_bad_alloc ::xalloc
# define ACE_throw_bad_alloc throw ACE_bad_alloc ("no more memory")
# else
# include /**/ <new>
# define ACE_bad_alloc std::bad_alloc
# define ACE_throw_bad_alloc throw ACE_bad_alloc ()
# endif /* __SUNPRO_CC < 0x500 */
// Borland的编译器或者使用标准名字空间的C++库
# elif defined (__BORLANDC__) || defined (ACE_USES_STD_NAMESPACE_FOR_STDCPP_LIB)
# include /**/ <new>
# define ACE_bad_alloc std::bad_alloc
# define ACE_throw_bad_alloc throw ACE_bad_alloc ()
# else
// 缺省的时候的编译器
# include /**/ <new>
# define ACE_bad_alloc bad_alloc
# define ACE_throw_bad_alloc throw ACE_bad_alloc ()
# endif /* __HP_aCC */
# define ACE_throw_bad_alloc
void* gcc_will_complain_if_literal_0_is_returned = 0;
return gcc_will_complain_if_literal_0_is_returned
另外一个是内存分配类ACE_OS_Memory，比较简单与C风格的内存分配函数类似。
class ACE_OS_Export ACE_OS_Memory
{
public:
// = A set of wrappers for memory managment.
static void *sbrk (int brk);
static void *calloc (size_t elements, size_t sizeof_elements);
static void *malloc (size_t);
static void *realloc (void *, size_t);
static void free (void *);
};
