[ImageJ-devel] when to close cursors, was Re: [fiji-devel] imglib coding style

[Stephan Preibisch]

Hi guys,

right now the Cursor.close() call is not necessary for any of the containers. But it will be when we start paging data and each Cursor will get a lock on the cell it currently works on. So when writing stuff using imglib one should think ahead and close cursors when they are not needed anymore. 

I do not really see how the new design should get rid of that paging-lock-cell problem Stephan -  how should it work without explicitly closing the cursor so that it releases the cell it is currently on when not needed anymore...
It might also be that Cursors have a local cache (which might be again an Image) they can empty when they are not needed anymore or that only a certain number of Cursors in parallel is allowed for some reason. 

Ciao ciao,
Steffi

> -----Original Message-----
> From: Stephan Saalfeld [mailto:saalfeld at mpi-cbg.de]
> Sent: Donnerstag, 15. April 2010 00:34
> Cc: Johannes Schindelin; preibisch at mpi-cbg.de; fiji-
> devel at googlegroups.com; Imagejdev.org Developers
> Subject: Re: when to close cursors, was Re: [fiji-devel] imglib coding
> style
> 
> Hi,
> 
> Cursor.hasNext() == false does not mean that the cursor is out of image
> bounds and, depending on the container may still point to some data.
> Image keeping track of its cursors, it is good to close them for
> freeing
> this data.  Currently, this is important in cell containers only.
> 
> I think that the recent design changes regarding data access make this
> tracking of cursors obsolete and so Cursor.close() too.  A good hint is
> that Image.removeCursor() is just never called.  But I am very tired
> and
> have to check this.
> 
> Good night,
> Stephan
> 
> 
> 
> 
> On Wed, 2010-04-14 at 17:10 -0500, Curtis Rueden wrote:
> > Hi Johannes,
> >
> > At the hackathon Steffi told me it is best practice to always close
> > cursors. I had not done this in SquareTest so I committed a change
> > that now does so.
> >
> > Thanks,
> > Curtis
> >
> > On Wed, Apr 14, 2010 at 4:51 PM, Johannes Schindelin
> > <Johannes.Schindelin at gmx.de> wrote:
> >         Hi,
> >
> >         while writing a base class for JUnit tests, I realized that I
> >         did not
> >         close() the cursors when cursor.hasNext() returned false. Are
> >         you supposed
> >         to close() them even then?
> >
> >         Ciao,
> >         Johannes
> >
> >
> >