What can I say that I haven't already said? If you have the code I sent
you, I would suggest making modifications to it and see if it works.
Larry
On Fri, Apr 24, 2009 at 5:54 PM, Sunburned Surveyor <
sunburned.surve...@gmail.com> wrote:
> If we are concerned about memory we might try a single int as a
> counter instead of using an int to count mods for each attribute. So
> you could do something like this:
>
>
> // Private member variable to count attribute modifications.
> private int attModCounter = 0;
>
> public void setAttribute()
> {
> // Do stuff here.
> this.attModCounter++;
> }
>
> public boolean isModified()
> {
> // Only return true if the modification counter is greater than the
> number
> // of attributes, because each attribute is set once during
> initialization/creation.
> FeatureSchema schema = this.getSchema();
> int numOfAtts = schema.getAttributeCount();
> if(this.attModCounter > numOfAtts)
> {
> return true;
> }
>
> else
> {
> return false;
> }
> }
>
> This will cut down on the number of ints we have to store as counters.
> However, if for some reason getAttribute() is called multiple times to
> set a single attribute value during initialization, then this system
> won't work. But I don't know why that would happen.
>
> Just a thought.
>
> SS
>
> On Fri, Apr 24, 2009 at 3:17 PM, Larry Becker <becker.la...@gmail.com>
> wrote:
> >> But there's something that could go wrong anyway, because an attribute
> >> has a NULL value by default and client code may decide to not set
> >> attributes at all if it has no value to set them to. If this happens,
> >> the Feature could remain not-modified for ever.
> >
> > This is possible, but not likely. Code like
> > (org.openjump.sigle.plugin.joinTable.JoinTable) join() calls
> setAttributes
> > with an array initialized with the attribute count. Then it iterates
> > through calls to setAttribute for each attribute, some of which may be
> > null. It would be bad practice to make the assumption that null
> attributes
> > can be skipped, and I found no cases of code like this in the main
> project.
> >
> > As far as putting the modification detection at the container level, I'm
> > open to the idea. I still think it should be part of the core so that
> each
> > database driver doesn't have to add its own listeners to the already
> > overburdened listener system. Can you sketch an outline of how it might
> > work?
> >
> > Larry
> >
> > On Fri, Apr 24, 2009 at 5:04 AM, Paolo Rizzi <g...@oicom.com> wrote:
> >>
> >> Maybe it would be possibile to add explicit init methods like:
> >> beginInit()
> >> endInit()
> >>
> >> or even a single "atomic" method:
> >> init(Object[])
> >>
> >> So that mod-aware calling code could call them to let the Feature "know"
> >> it is being initialized.
> >> Still the Feature could manage a disposable int[] array so that the
> >> first time a setAttribute() or setAttributes() method is called, if the
> >> beginInit() method has been called before it means that it's
> >> initialization time. If it has not been called but the int[] array has
> >> not been created, it's initialization time anyway, so it can create the
> >> int[] array and dispose of it as soon as all attributes have been set at
> >> least once.
> >> This way both mod-aware and non-mod-aware code would work.
> >>
> >> But there's something that could go wrong anyway, because an attribute
> >> has a NULL value by default and client code may decide to not set
> >> attributes at all if it has no value to set them to. If this happens,
> >> the Feature could remain not-modified for ever.
> >>
> >> I feel that the mod mechanism should require awareness by the client
> >> code in any case, since you have to write dirty Features out sooner or
> >> later, so it may not be the case to put too much burden on the Feature
> >> shoulders...
> >>
> >> Also, apart from modified Features, there're inserted and deleted one,
> >> that should be managed. So the Feature itself may not even be aware at
> >> all of it's own dirtyness. I see this information to pertain to Feature
> >> containers more than to Features themselves...
> >>
> >> Bye
> >> Paolo
> >>
> >>
> >> > I agree that a mechanism to reset the modified status is needed,
> >> > especially after the changes to the layer have been flushed to the
> >> > database. I'll add this to BasicFeature.
> >> >
> >> > Your comment about carrying around state data after it is needed is
> >> > reasonable. The code could check for modified on-the-fly while it is
> >> > incrementing the attribute mod count and if it is greater than one,
> set
> >> > a boolean instead and dispose of the array of ints. You would lose
> the
> >> > ability to determine individual attribute mods (not sure if it is
> >> > needed), however you would only save memory in modified records which
> >> > wouldn't usually be very much.
> >> >
> >> > I was hoping someone would come up with a clever hack that wouldn't
> >> > require the int array. All of the optimizations that I have
> considered
> >> > break in one case or another.
> >> >
> >> > BTW, if you really want to save memory on attribute storage, I have a
> >> > number of questionable schemes that load attributes on an as-needed
> >> > basis. :-) SkyJUMP even has an optimization were layers that aren't
> >> > visible are not loaded into memory until you make them visible,
> although
> >> > it doesn't go as far as removing them when you make them invisible.
> Of
> >> > course the most famous attribute memory-saving scheme is Michael's
> >> > permgen attribute string scheme for dbf files. That one saves a ton
> of
> >> > memory on typically redundant data, until you run out of permgen
> memory.
> >> >
> >> > Larry
> >> >
> >> > On Thu, Apr 23, 2009 at 4:06 PM, Martin Davis <
> mbda...@refractions.net
> >> > <mailto:mbda...@refractions.net>> wrote:
> >> >
> >> > re Mutating Geometry in-place - JTS discourages this, but does not
> >> > prevent it. Sometimes people do this when they are transforming
> >> > coordinates (eg. translation or affine transform).. It's quite
> >> > possible that all the JUMP code is clean, however. In any case,
> >> > this
> >> > will only be an issue if that particular function is used.
> >> >
> >> > re tracking modifications - how about providing a method that lets
> >> > you
> >> > clear the modified flag? Then the feature can be constructed as
> >> > necessary and then marked as clean.
> >> >
> >> > It seems heavyweight to carry around a set of data which is only
> >> > really
> >> > of use during the construction phase of a Feature. To avoid this,
> >> > I'd
> >> > even suggest constructing a Feature as needed, then creating a new
> >> > Feature from it via a constructor which sets the modified flag
> >> > appropriately. Anything to avoid requiring more storage.
> >> >
> >> > How does GeoTools handle this?
> >> >
> >> > Larry Becker wrote:
> >> > > The tricky thing about modifications is not to find a record is
> >> > > modified just because you set the initial value. It is only
> >> > modified
> >> > > if you set it more than once, otherwise all records would be
> set
> >> > as
> >> > > modified as soon as they are loaded.
> >> > >
> >> > > The next trick is to consider that you call setAttribute
> multiple
> >> > > times with different attribute indexes, so it is necessary to
> >> > track
> >> > > the changes to each one separately.
> >> > >
> >> > > Mutating Geometries in place is a concern. I have never seen
> >> > code
> >> > > that does this, and certainly none of the edit tools or any
> >> > plugins
> >> > > that use transactions do this, but it may be possible. Could
> you
> >> > just
> >> > > modify the Coordinate.x and y values? I'll try to construct a
> >> > > Beanshell test for this, but I doubt that this is a serious
> >> > concern.
> >> > > All of the tools and plugins that I have tried so far play by
> the
> >> > rules.
> >> > >
> >> > > Larry
> >> > >
> >> > > On Thu, Apr 23, 2009 at 2:12 PM, Martin Davis
> >> > <mbda...@refractions.net <mailto:mbda...@refractions.net>
> >> > > <mailto:mbda...@refractions.net
> >> > <mailto:mbda...@refractions.net>>> wrote:
> >> > >
> >> > > Larry, why do you use an int rather than a boolean to flag
> >> > changed
> >> > > attributes?
> >> > >
> >> > > BTW, In order to track changes to Geometry attributes
> >> > correctly, the
> >> > > JUMP codebase needs to be scrutinized to make sure it isn't
> >> > mutating
> >> > > Geometries "in place".
> >> > >
> >> > >
> >> > >
> >> > > Larry Becker wrote:
> >> > > > Hi,
> >> > > >
> >> > > > As I mentioned in the other thread, before the problem
> of
> >> > partial
> >> > > > database updates can be solved, we must first be able to
> >> > > determine if
> >> > > > a Feature has been modified. This is not currently
> >> > possible in
> >> > > all of
> >> > > > the JUMP variants that I am familiar with, although Kosmo
> >> > may have
> >> > > > implemented it.
> >> > > >
> >> > > > The simplest way of implementing it that I can see is to
> >> > modify
> >> > > > BasicFeature to include:
> >> > > >
> >> > > > private int[] attributeModCount; //this is a parallel
> >> > array to
> >> > > > Object[] attributes
> >> > > >
> >> > > > Then it would be necessary to allocate the
> >> > attributeModCount array
> >> > > > when setAttributes(Object[] attributes) is called.
> >> > > >
> >> > > > In addition each time setAttribute(int attributeIndex,
> >> > Object
> >> > > > newAttribute) is called, add the line of code:
> >> > > >
> >> > > > attributeModCount[attributeIndex]++
> >> > > >
> >> > > > With these modifications we could then define:
> >> > > >
> >> > > > public boolean isFeatureModified() {
> >> > > > for (int i=0; i<attributeModCount.length; i++) {
> >> > > > if (attributeModCount[i] > 1) //modified is
> defined
> >> > as
> >> > > setting
> >> > > > an attribute more than once
> >> > > > return true;
> >> > > > }
> >> > > > return false;
> >> > > > }
> >> > > >
> >> > > > Would this work and does this seem like something we
> should
> >> > > consider?
> >> > > >
> >> > > > regards,
> >> > > > Larry
> >> > > > --
> >> > > > http://amusingprogrammer.blogspot.com/
> >> > > >
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> > > >
> >> > > >
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > > >
> >> > > >
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> > > >
> >> > > > _______________________________________________
> >> > > > Jump-pilot-devel mailing list
> >> > > > Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> >> > > <mailto:Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>>
> >> > > >
> >> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >> > > >
> >> > >
> >> > > --
> >> > > Martin Davis
> >> > > Senior Technical Architect
> >> > > Refractions Research, Inc.
> >> > > (250) 383-3022
> >> > >
> >> > >
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > > Crystal Reports - New Free Runtime and 30 Day Trial
> >> > > Check out the new simplified licensign option that enables
> >> > unlimited
> >> > > royalty-free distribution of the report engine for
> >> > externally
> >> > > facing
> >> > > server and web deployment.
> >> > > http://p.sf.net/sfu/businessobjects
> >> > > _______________________________________________
> >> > > Jump-pilot-devel mailing list
> >> > > Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> >> > > <mailto:Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>>
> >> > >
> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > --
> >> > > http://amusingprogrammer.blogspot.com/
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> > >
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > > Crystal Reports - New Free Runtime and 30 Day Trial
> >> > > Check out the new simplified licensign option that enables
> >> > unlimited
> >> > > royalty-free distribution of the report engine for
> externally
> >> > facing
> >> > > server and web deployment.
> >> > > http://p.sf.net/sfu/businessobjects
> >> > >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> > >
> >> > > _______________________________________________
> >> > > Jump-pilot-devel mailing list
> >> > > Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> >> > > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >> > >
> >> >
> >> > --
> >> > Martin Davis
> >> > Senior Technical Architect
> >> > Refractions Research, Inc.
> >> > (250) 383-3022
> >> >
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > Crystal Reports - New Free Runtime and 30 Day Trial
> >> > Check out the new simplified licensign option that enables
> unlimited
> >> > royalty-free distribution of the report engine for externally
> >> > facing
> >> > server and web deployment.
> >> > http://p.sf.net/sfu/businessobjects
> >> > _______________________________________________
> >> > Jump-pilot-devel mailing list
> >> > Jump-pilot-devel@lists.sourceforge.net
> >> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> >> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >> >
> >> >
> >> >
> >> >
> >> > --
> >> > http://amusingprogrammer.blogspot.com/
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > Crystal Reports - New Free Runtime and 30 Day Trial
> >> > Check out the new simplified licensign option that enables unlimited
> >> > royalty-free distribution of the report engine for externally
> facing
> >> > server and web deployment.
> >> > http://p.sf.net/sfu/businessobjects
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------
> >> >
> >> > _______________________________________________
> >> > Jump-pilot-devel mailing list
> >> > Jump-pilot-devel@lists.sourceforge.net
> >> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >>
> >>
> >>
> >>
> ------------------------------------------------------------------------------
> >> Crystal Reports - New Free Runtime and 30 Day Trial
> >> Check out the new simplified licensign option that enables unlimited
> >> royalty-free distribution of the report engine for externally facing
> >> server and web deployment.
> >> http://p.sf.net/sfu/businessobjects
> >> _______________________________________________
> >> Jump-pilot-devel mailing list
> >> Jump-pilot-devel@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >
> >
> >
> > --
> > http://amusingprogrammer.blogspot.com/
> >
> >
> ------------------------------------------------------------------------------
> > Crystal Reports - New Free Runtime and 30 Day Trial
> > Check out the new simplified licensign option that enables unlimited
> > royalty-free distribution of the report engine for externally facing
> > server and web deployment.
> > http://p.sf.net/sfu/businessobjects
> > _______________________________________________
> > Jump-pilot-devel mailing list
> > Jump-pilot-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >
> >
>
>
> ------------------------------------------------------------------------------
> Crystal Reports - New Free Runtime and 30 Day Trial
> Check out the new simplified licensign option that enables unlimited
> royalty-free distribution of the report engine for externally facing
> server and web deployment.
> http://p.sf.net/sfu/businessobjects
> _______________________________________________
> Jump-pilot-devel mailing list
> Jump-pilot-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
>
--
http://amusingprogrammer.blogspot.com/
------------------------------------------------------------------------------
Crystal Reports - New Free Runtime and 30 Day Trial
Check out the new simplified licensign option that enables unlimited
royalty-free distribution of the report engine for externally facing
server and web deployment.
http://p.sf.net/sfu/businessobjects
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