[ruby-core:39471] Re: File.realpath behavior questions

On Sat, Sep 10, 2011 at 9:23 PM, KOSAKI Motohiro
<[e-mail]> wrote:
> Hello,
>
> 2011/9/11 Luis Lavena <[e-mail]>:
>>
>> This means: build absolute path, expand if required, combine with
>> GetFileAttributesEx to check for existance.
>>
>> Would this approach be acceptable?
>
> I have no strong opinion. But I have a little curious. Why do you want
> to avoid several stat()? unix platform also use such a bit expensive chec=
k
> and now works.
>

So far, from my initial digging.

The problem is that current winnt_stat() (a wrapper around the
expected stat() implementation) is considerable slow compared to POSIX
counterpart:

* It performs a globbing operating (FindFirstFile) to determine if the
file exist and retrieve the attributes (which then is FindClose to
release the handle)

* It obtains a directory handle if these attributes match the one of a
directory (another handle that is obtained using FindFirstFile
globbing operation using open_dir_handle)

* It performs several translations of the results (to conform unixism)
and allocate several times memory registered in the GC
(rb_alloc_tmp_buffer) which is expensive.

These operations result in a slow stat() implementation.
--=20
Luis Lavena
AREA 17
-
Perfection in design is achieved not when there is nothing more to add,
but rather when there is nothing more to take away.
Antoine de Saint-Exup=E9ry