On Wed, Sep 24, 2008 at 9:10 AM, Jayarajan Jn <[EMAIL PROTECTED]> wrote:

> Hi Jürgen,
>
> First of all thank you for your reply....
> hmm you are right too... And i am comfortable with the explicit delete. But
> in my prototype for i have also added webDAV interface for managing
> extfile.... Then when a user deletes the extfile object through webDAV
> interface, the file remains there.... coz i don't know where to put my codes
> to call delete() in that case... And in my project there wont be more than
> one extfiles refering to same file! so in my case its ok to go for implicit
> delete! but its now working!
>

You can never be sure if a file  is only used once. If two user upload the
same file only one copy is stored in extfile because both files have the
same hash.


>
> But form a general perspective you are correct.... may be HashDir will have
> to evolve to add reference counting feture just like python do!
>
> On Wed, Sep 24, 2008 at 11:34 AM, Jürgen kartnaller <
> [EMAIL PROTECTED]> wrote:
>
>> Hi jayaraj,
>> it is definitely not a good idea to implicitily delete files.
>>
>> What if two ExtFile objects reference the same file ?
>>
>> Jürgen
>>
>> On Wed, Sep 24, 2008 at 4:37 AM, Jayarajan Jn <[EMAIL PROTECTED]>wrote:
>>
>>> Hi,
>>> i am now doing some prototypes for my projects which will be dealing with
>>> tones of files. After a little scouting i decided to try z3c.extfile. Every
>>> thing works fine. But i found it strange that there is no delete feature in
>>> z3c.extfile. ie, even if i can delete a ExtFile object, the file in the hash
>>> directory is not getting deleted! and it keeps on accumulating...
>>>
>>> So i  thought i 'll add a delete feature... but  my  __del__() approach
>>> doesn't  work for me. but i added an additional delete() function too which
>>> can be invoked explicitly to delete the file before trying to delete ExtFile
>>> object.
>>>
>>> i made following  changes to the source...
>>> inside  z3c.extfile.file.file.ExtFile,
>>>
>>>
>>> ----------------------------------------------------------------------------------------------
>>> class ExtFile(Persistent):
>>>
>>>     """A zope file implementation based on z3c.extfile"""
>>>
>>>     interface.implements(IExtFile)
>>>     data = ExtBytesProperty('data')
>>>
>>>     def __init__(self, data='', contentType=''):
>>>         self.data = data
>>>         self.contentType = contentType
>>>
>>>     # added the following lines#
>>>
>>> *    def __del__(self):   # <- this is not being invoked when i try to
>>> delete an extfile object
>>>         del self.data
>>>         #print "deleted data via destructor"
>>>
>>>     def delete(self):     # <- added this to be able to manually able to
>>> delete files
>>>         del self.data
>>>         #print "deleted data via delete()"
>>>
>>>     # # # # # # #  # # # # # # #  #
>>> *
>>>     def getSize(self):
>>>         return len(self.data)
>>>
>>>
>>> ----------------------------------------------------------------------------------------------
>>>
>>> and the 'data' is a 'property'  (ExtBytesProperty)
>>> so i made following changes to z3c.extfile.property.ExtBytesProperty
>>>
>>>
>>> ----------------------------------------------------------------------------------------------
>>> class ExtBytesProperty(object):
>>>
>>>     """a property which's values are stored as external files"""
>>>
>>>     def __init__(self, name):
>>>         self.__name = name
>>>
>>>
>>>
>>>     # added the following lines#
>>>
>>> *    def __delete__(self,inst):
>>>         digest = inst.__dict__[self.__name]
>>>         self.hd.delete(digest)
>>>
>>> *    *# # # # # # #  # # # # # # #  #
>>>
>>>
>>>
>>> *    @property
>>>     def hd(self):
>>>         return component.getUtility(interfaces.IHashDir)
>>>
>>>     def __get__(self, inst, klass):
>>>
>>>         if inst is None:
>>>             return self
>>>         digest = inst.__dict__.get(self.__name, _marker)
>>>         if digest is _marker:
>>>             return None
>>>         return getFile(digest)
>>>
>>>     def __set__(self, inst, value):
>>>         # ignore if value is None
>>>         if value is None:
>>>             if inst.__dict__.has_key(self.__name):
>>>                 del inst.__dict__[self.__name]
>>>             return
>>>         # Handle case when value is a string
>>>         if isinstance(value, unicode):
>>>             value = value.encode('UTF-8')
>>>         if isinstance(value, str):
>>>             value = StringIO(value)
>>>         value.seek(0)
>>>         f = self.hd.new()
>>>         while True:
>>>             chunk = value.read(BLOCK_SIZE)
>>>             if not chunk:
>>>                 newDigest = f.commit()
>>>                 oldDigest = inst.__dict__.get(self.__name, _marker)
>>>                 if newDigest == oldDigest:
>>>                     # we have no change, so we have to seek to zero
>>>                     # because this is normal behaviour when setting a
>>>                     # new value
>>>                     if hasattr(_storage, 'dataManager'):
>>>                         if newDigest in _storage.dataManager.files:
>>>                             f = _storage.dataManager.files[newDigest]
>>>                             f.seek(0)
>>>                 else:
>>>                     inst.__dict__[self.__name] = newDigest
>>>                 break
>>>             f.write(chunk)
>>>
>>> ----------------------------------------------------------------------------------------------------
>>>
>>> and at last added the real code which delete the file in hash directory
>>> too
>>>
>>> i added following codes inside z3c.extfile.hashdir.HashDir class
>>> ---------------------------------------------------
>>> def delete(self,digest):
>>>         """delete the file"""
>>>         path=self.getPath(digest)
>>>         if os.path.exists(path):
>>>             os.remove(path)
>>>         return
>>> ----------------------------------------------------
>>>
>>> Now, everything works fine when i try to delete an ExtFile object in
>>> ZODB, __del__() is not being invoked!!!!!
>>>
>>> can anyone tell me how can i fix this???
>>>
>>> thanks in advance
>>>
>>> jayaraj
>>>
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>>>
>>
>
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