Re: [RFC/PATCH v2 1/1] cygwin: Add fast_lstat() and fast_fstat() functions
- From
Mark Levedahl <mlevedahl@gmail.com>
- Date
- Jul 14, 2013, 16:15 UTC
- Message-ID
- <51E2CE97.2040900@gmail.com>
- In-Reply-To
- <51DDC2AF.9010504@ramsay1.demon.co.uk>
On 07/10/2013 04:23 PM, Ramsay Jones wrote:
Show 17 quoted lines
> Commit adbc0b6b ("cygwin: Use native Win32 API for stat", 30-09-2008)
> added a Win32 specific implementation of the stat functions. In order
> to handle absolute paths, cygwin mount points and symbolic links, this
> implementation may fall back on the standard cygwin l/stat() functions.
> Also, the choice of cygwin or Win32 functions is made lazily (by the
> first call(s) to l/stat) based on the state of some config variables.
>
> Unfortunately, this "schizophrenic stat" implementation has been the
> source of many problems ever since. For example, see commits 7faee6b8,
> 79748439, 452993c2, 085479e7, b8a97333, 924aaf3e, 05bab3ea and 0117c2f0.
>
> In order to limit the adverse effects caused by this implementation,
> we provide a new "fast stat" interface, which allows us to use this
> only for interactions with the index (i.e. the cached stat data).
>
> Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
> ---I've tested this on Cygwin 1.7 on WIndows 7 , comparing to the results using your prior patch (removing the Cygwin specific lstat entirely) and get the same results with both, so this seems ok from me.
My comparison point was created by reverting your current patch from pu, then reapplying your earlier patch on top, so the only difference was which approach was used to address the stat functions.
Caveats: 1) I don't find any speed improvement of the current patch over the previous one (the tests actually ran faster with the earlier patch, though the difference was less than 1%). 2) I still question this whole approach, especially having this non-POSIX compliant mode be the default. Running in this mode breaks interoperability with Linux, but providing a Linux environment is the *primary* goal of Cygwin.
Mark