Re: File as a directory - VFS Changes

[Jonathan Briggs <jbriggs@esoft.com>]

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On Tue, 2005-05-31 at 15:01 -0600, Jonathan Briggs wrote:
> I should create an example.
> 
> Wherever I used True Name previously, use OID instead.  True Name was
> simply another term for a unique object identifier.
> 
> Three files with OIDs of 1001, 1002, and 1003.
> Object 1001:
> name: /tmp/A/file1
> name: /tmp/A/B/file1
> name: /tmp/A/B/C/file1
> 
> Object 1002:
> name: /tmp/A/file2
> 
> Object 1003:
> name: /tmp/A/B/file3
> 
> Three query objects (directories) with OIDs of 1, 2, and 3.
> Object 1:
> name: /tmp/A
> name: /tmp/A/B/C/A
> query: name begins with /tmp/A/
> query result cache: B->2, file1->1001, file2->1002
> 
> Object 2:
> name: /tmp/A/B
> query: name begins with /tmp/A/B/
> query result cache: C->3, file1->1001, file3->1003
> 
> Object 3:
> name: /tmp/A/B/C
> query: name begins with /tmp/A/B/C/
> query result cache: A->1, file1->1001
> 
> Now there is a A -> B -> C -> A directory loop.  But removing
> name: /tmp/A/B/C/A from Object 1 fixes the loop.  Deleting Object 1 also
> fixes the loop.  Deleting any of Object 1, 2 or 3 does not affect any
> other object, because in this scheme, directory objects do not need to
> actually exist: they are just queries that return objects with certain
> names.

I forgot to address Nikita's point about reclaiming lost cycles.  In
this case, let me create Object 4 for /tmp
Object 4:
name: /tmp
query: name begins with /tmp/
query result cache: A->1

Now, if we delete Object 4, are Objects 1,2,3 lost?  I would say not
because they still have names.  When the shell calls chdir("/tmp") a new
query object (directory) must be created dynamically, and Objects
1001,1002,1003 still have their names that start with /tmp and so they
immediately appear again.  Their names still start with /, so the top
level query will still find them and /tmp as well.

Therefore, the cycle is never detached and lost.
-- 
Jonathan Briggs <jbriggs@esoft.com>
eSoft, Inc.

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