one byte change to file not detected ?

[Alexis S. L. Carvalho]

Thus spake Patrick Mézard:
> BuraphaLinux Server a écrit :
> > Clearly mercurial cares more about speed than safety.
> > 
> > Yeah, I can patch it but then I have to rehack it every time they
> > release since clearly this is some dumb policy decision to make their
> > stuff benchmark better at the cost of safety.
> 
> Just by curiosity, what VCS implementing the smart policy are you using ?

I don't remember what git does, but IIRC bzr and monotone avoid caching
the stat(2) data when the mtime is too recent.  E.g. if we're writing
the dirstate at time X, don't save data for files with mtime >= X-3.

And of course, if there's no stat data, do a full compare.

Something like the patch below (but it would need a better name for
ui.limit and I should probably use the mtime of the new dirstate instead
of time.time).

Alexis


diff -r b023915aa1bc mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -10,7 +10,7 @@ from node import *
 from node import *
 from i18n import _
 import struct, os, time, bisect, stat, strutil, util, re, errno, ignore
-import cStringIO, osutil
+import cStringIO, osutil, sys, time
 
 _unknown = ('?', 0, 0, 0)
 _format = ">cllll"
@@ -63,6 +63,12 @@ class dirstate(object):
         elif name == '_slash':
             self._slash = self._ui.configbool('ui', 'slash') and os.sep != '/'
             return self._slash
+        elif name == '_limit':
+            try:
+                self._limit = int(self._ui.config('ui', 'limit', 0))
+            except ValueError:
+                self._limit = 0
+            return self._limit
         else:
             raise AttributeError, name
 
@@ -310,6 +316,10 @@ class dirstate(object):
     def write(self):
         if not self._dirty:
             return
+        if self._limit > 0:
+            limit = int(time.time() - self._limit)
+        else:
+            limit = sys.maxint
         cs = cStringIO.StringIO()
         copymap = self._copymap
         pack = struct.pack
@@ -318,6 +328,10 @@ class dirstate(object):
         for f, e in self._map.iteritems():
             if f in copymap:
                 f = "%s\0%s" % (f, copymap[f])
+            if e[3] > limit:
+                self._ui.debug("ignoring stat data for %s. %d > %d\n"
+                               % (f, e[3], limit))
+                e = (e[0], 0, -1, -1, 0)
             e = pack(_format, e[0], e[1], e[2], e[3], len(f))
             write(e)
             write(f)