On 28/07/12 19:58, Michael Van Canneyt wrote:
On Sat, 28 Jul 2012, SteveG wrote:
I am enumerating thru large numbers of files on my disk, and find I
cant come close with findfirst / findnext to matching the speed of
cmd line apps available in linux :eg ls / du
A regular ls only does a getdents() call.
FindFirst/FindNext does a getdents, but then additionally, per file in
the result, a stat() call.
I have a fairly tight file search function, and dont see how to gain
more speed
Would anybody know what the limiting factors would be ?
The number of calls to stat() to get extended file information.
I suspect that if you do a ls -l, it will be as slow as
findfirst/findnext, because it does then 3 calls per file:
from strace ls -l /etc I get:
lstat("/etc/odbc.ini", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
lgetxattr("/etc/odbc.ini", "security.selinux", 0x14de920, 255) = -1
ENODATA (No data available)
getxattr("/etc/odbc.ini", "system.posix_acl_access", 0x0, 0) = -1
EOPNOTSUPP (Operation not supported)
If you want speedier operation, and have enough file information with
the name, you can simply do a getdents().
does the operating system keep an index somewhere ?
Normally not (at least other than the regular disc cache).
Thanks Michael - I will do some study (ie find out what getdents() does)
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