Re: A micro-optimisation for walkdir()

Hi,

On 2020-09-02 17:51:27 +0200, Juan José Santamaría Flecha wrote:
> Win32 could also benefit from this micro-optimisation if we expanded the
> dirent port to include d_type. Please find attached a patch that does
> so
.
> }
> strcpy(d->ret.d_name, fd.cFileName); /* Both strings are MAX_PATH long */
> d->ret.d_namlen = strlen(d->ret.d_name);
> + /*
> + * The only identifed types are: directory, regular file or symbolic link.
> + * Errors are treated as a file type that could not be determined.
> + */
> + attrib = GetFileAttributes(d->ret.d_name);
> + if (attrib == INVALID_FILE_ATTRIBUTES)
> + d->ret.d_type = DT_UNKNOWN;
> + else if ((attrib & FILE_ATTRIBUTE_DIRECTORY) != 0)
> + d->ret.d_type = DT_DIR;
> + else if ((attrib & FILE_ATTRIBUTE_REPARSE_POINT) != 0)
> + d->ret.d_type = DT_LNK;
> + else
> + d->ret.d_type = DT_REG;
>
> return &d->ret;
> }

Is this really an optimization? The benefit of Thomas' patch is that
that information sometimes already is there. But here you're doing a
separate lookup with GetFileAttributes()?

What am I missing?

Greetings,

Andres Freund