file modifications get lost due to FAT 2s time resolution

'sleep_for_timestamps' is a weak solution and will
break for FAT disks, because FAT only records file modifications
with a resolution of 2 seconds.
remote mounted WC directories may have a similar problem.

the script below reproduces the effect:
only the FIRST revision gets committed,
even though there should be 5 commited revisions.
this means that 4 file modifications are LOST.

the effect only happens if the filesize does not change
due to the edit (happens often e.g. when editing
umcompressed images or editing data tables)


===========
example script
===========

@echo off

set repos=file:///C:/SVNFAT/Repos

rmdir /s/q Repos
rmdir /s/q Work

svnadmin create Repos
svn checkout %repos% Work

cd Work

echo mod01>file1.txt
svn st -v
svn commit file1.txt -m"C1"

echo mod02>file1.txt
svn st -v
svn commit file1.txt -m"C2"

echo mod03>file1.txt
svn st -v
svn commit file1.txt -m"C3"

echo mod04>file1.txt
svn st -v
svn commit file1.txt -m"C4"

echo mod05>file1.txt
svn st -v
svn commit file1.txt -m"C5"

cd ..\Work\..

pause


===========
OUTPUT:
===========

Checked out revision 0.
A         file1.txt
Adding         file1.txt
Transmitting file data .
Committed revision 1.
                0       ?   ?           .
                1        1 cat          file1.txt
                0       ?   ?           .
                1        1 cat          file1.txt
                0       ?   ?           .
                1        1 cat          file1.txt
                0       ?   ?           .
                1        1 cat          file1.txt
                0       ?   ?           .
                1        1 cat          file1.txt
===


- bug exists in svn 1.0.x and 1.1.x


-) one solution could be:
   write a ".svn/dummy" file to disk,
   read back its modification time and wait
   for that time to pass by.
   (but may still fail for remote mounted wc)


-) a stable solution could be to explicitly write the timestamps
   to a known value that is slightly _lower_ than the real time.

   example:
     -) an svn command starts and stores the current time
        in a variable. startTime = 00:00:20.5
     -) do_all_wc_work{
          whenever a wc file gets modified, set its timestamp
          to 'startTime' ( FAT would be 00:00:22 ).
          read back the timestamp value and
          store it in 'endTime' if higher.
          (and most likely store it in entries, too).
        }
     -) wait for the realtime clock to pass 'endTime'.
        this is a "zero" wait in all cases where the svn command
        already took longer than the filesystems time precision.

   

but please fix this for 1.0.6 and 1.1.0 releases,
at least by increasing that sleep to some "2.1second" wait.

=====
c.a.t.


some discussion occoured here
 http://www.contactor.se/~dast/svn/archive-2004-07/0502.shtml
 http://www.contactor.se/~dast/svn/archive-2004-06/0860.shtml

Original issue reported by catmagic