[Zope-CMF] Re: [CMF] 84/ 2 Accept "Excessive time consumption by "Filesystem Directory View""

[Dieter Maurer]

Hi Chris,

Chris Withers writes:
 > Dieter Maurer wrote:
 > >  > Checking only the modification time of directoreis doesn't always work as far as adding and deleting files is concerned.
 > > Can you please be more specific.
 > > Which tests fail and under what conditions, e.g. operating system.
 > 
 > I'm afraid I can't rememeber. What I'd suggest is making any changes you see as 
 > appropriate and then run all the tests and check that they pass.
Sounds good!

  The comment in "DirectoryInformation._changed" says that some Windows
  directories do not update the directory modification time for
  new/deleted files.

  In this case, we cannot rely on modification time and must use
  explicit scanning. "listdir" should be sufficient for this and
  a bit less expensive than "walk".

 > > Under Unix, I can only imagine two reasons why checking the modification
 > > time does not produce reliable results:
 > > 
 > >   1. the resolution (seconds) of the modification time is not enough
 > >      to check add/delete/modification reliably.
 > 
 > The tests get around this by updating the file in a loop until the modification 
 > date changes. Some of the tests were failing even with this :-(
Hm, almost unbelievable.

  Maybe, "_changed" is called and no reload called for despite "_changed"
  returned 1. A single call to "_changed" resets the state.

  As the "Directory Registry" and the contained "DirectoryInformation"
  instances live in a module, there may be the danger of race
  conditions.

  On the other hand, I would not expect that a test, unless explicitly
  designed to generate race conditions, should reveal one.

Lets see what tests fail.
I will then see whether I can reproduce it here and find out
the reason.


Dieter