On Friday 11 April 2008 02:25, Daniel Cheng wrote:
> On Thu, Apr 10, 2008 at 11:10 PM, Matthew Toseland
> <toad at amphibian.dyndns.org> wrote:
> >
> > On Thursday 10 April 2008 01:15, Daniel Cheng wrote:
> > > On Thu, Apr 10, 2008 at 6:26 AM, Matthew Toseland
> > > <toad at amphibian.dyndns.org> wrote:
> > > > On Wednesday 09 April 2008 17:01, you wrote:
> > > > > Author: j16sdiz
> > > > > Date: 2008-04-09 16:01:28 +0000 (Wed, 09 Apr 2008)
> > > > > New Revision: 19114
> > > > >
> > > > > Modified:
> > > > > trunk/freenet/src/freenet/support/DoublyLinkedList.java
> > > > > trunk/freenet/src/freenet/support/DoublyLinkedListImpl.java
> > > > >
> > > >
> >
trunk/freenet/src/freenet/support/math/BootstrappingDecayingRunningAverage.java
> > > > > Log:
> > > > > javadoc and style fix
> > > > >
> > > > >
> > > > > Modified: trunk/freenet/src/freenet/support/DoublyLinkedList.java
> > > > >
===================================================================
> > > > > --- trunk/freenet/src/freenet/support/DoublyLinkedList.java
> > 2008-04-09
> > > > 16:01:05 UTC (rev 19113)
> > > > > +++ trunk/freenet/src/freenet/support/DoublyLinkedList.java
> > 2008-04-09
> > > > 16:01:28 UTC (rev 19114)
> > > > > @@ -7,30 +7,54 @@
> > > > > * @author tavin
> > > > > */
> > > > > public interface DoublyLinkedList {
> > > > > + public abstract Object clone();
> > > > >
> > > > > - public abstract Object clone();
> > > > > -
> > > > > + /**
> > > > > + * List element
> > > > > + */
> > > > > public interface Item {
> > > > > + /**
> > > > > + * Get next {@link Item}. May or may not return
> > > > > + * <code>null</code> if this is the last
> > <code>Item</code>.
> > > >
> > > > IIRC we have a bumper stopper item, don't we? Hmm, but we do check
for
> > null...
> > > >
> > >
> > > No, we have two different method / behavior when that is the last
item.
> > > 1. DoublyLinkedList.getNext(Item)
> > > --> always return null
> > >
> > > 2. DoublyLinkedList.Item.getNext() .
> > > --> return null /or/ DoublyLinkedListImpl._tailptr
> > >
> > > The second one involve some implementation details, hence the "may or
may
> > not"
> > > phase. I did wondered why we need two different method.
> > >
> > > Eventually, I want to migrate all DoublyLinkedList usage to
> > > java.util.LinkedList / ArrayList / SortedSet. They are better tested
> > > and optimized by jre vendors. But this migration would take some time.
> >
> > Yes and no.
> >
> > We should only use DoublyLinkedList where we need it. But there are
places
> > where we do need it. Specifically, anywhere where an element needs to be
able
> > to remove itself - LRUHashtable for example, and IIRC there are other
classes
> > in support/ that need it. Using DoublyLinkedList gives us a significant
> > performance gain here.
>
> Except if we can use java.util.concurrent.ConcurrentHashMap, which is
> a thread-safe,
> yet lock-free alternative.
>
> I am not saying I would try to remove DoublyLinkedList now, I said
> "eventually",
> which could be years later.
Well, we need access to the list items implementation (in some classes),
that's the point.
>
> Regards,
> Daniel Cheng
>
>
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