[jsword-devel] Bookset

[Chris Burrell]

Key thingfor me is to have an O (1) lookup time. We could key by categories
name and initials if it makes our easier.

A Set gives the impression you have fast insertion and contains operations
On 26 Jan 2014 18:02, "DM Smith" <dmsmith at crosswire.org> wrote:

> I'm trying to figure out how to change this so that it works for all.
> Since it is ingrained in the Book installer of Bible Desktop, having been
> designed for it, it may take a bit. I should be able to start today.
> -- DM
>
> On Jan 25, 2014, at 10:24 PM, DM Smith <dmsmith at crosswire.org> wrote:
>
> >
> > On Jan 25, 2014, at 4:41 PM, Chris Burrell <chris at burrell.me.uk> wrote:
> >
> >> Hi
> >>
> >> I'm looking to refactor Books.installed().getBook(name) because it
> takes too long when you need to look up books multiple times (and don't
> have an easy way of caching the JSword lookup). It's particular slow when
> you have 200+ resources (our server will have). This will also be more
> prevalent in Android where method calls are quite expensive.
> >>
> >> In STEP we always have the initials of the module (the user selects by
> name/initials/STEP name in the browser, where it always gets translated to
> initials well before it hits JSword). Do any other frontends use the
> getBook(name) by name?
> >>
> >> I want to at least provide way of getting the book directly from its
> initials. As part of this, we can several things:
> >>
> >> In Books:
> >> - refactor the getBook() method to not search first against the name,
> then against name insensitive and then against the initials in the BMD, and
> then against the initials directly
> > Feel free to change the order. BibleDesktop uses the name of the Book,
> not the initials.
> >
> > There's a bit of history here that's not necessarily pertinent. At one
> point, we included the repository name in the name of the Book to
> disambiguate a module that might be in two repositories. E.g. CrossWire
> main and CrossWire beta. Or CrossWire main and the NET site.
> >
> > This allowed two different versions of the same module. The repository
> name is not part of it any more.
> >
> >
> >> - If the above is not possible then at least provide a
> getBookByInitials (which would just look up the initials against their
> lower case value.
> >>
> >> In BookSet:
> >> - I can't work out why we're sorting the inserts in add(). They cause
> unecessary copies of the ArrayList contents in the creation of it.
> >> - I can't work out why it also implements Set. Especially, since
> contains would be a good candidate for using
> > I don't think you finished the sentence.
> >
> > The BookSet implements both List and Set. It implements List because it
> works better when tying it to a list or tree in Swing. It keeps it sorted
> so that it makes sense to a user. It implements Set because a Book cannot
> be in the list twice. Note that this is determined by compareTo, equals and
> hashcode on BookMetaData which uses category, initials and name in that
> order.
> >
> > If Set is not on the class the class has the wrong contract. It is
> merely a marker. The contract is maintained by the add and addAll methods.
> >
> > Regarding add. The contract of the class is that it maintains the books
> in sorted order (category, initials, name). That has to be invariant. The
> method addAll has a comment that it probably shouldn't call add for all the
> members but rather stuff them all in and then sort the array.
> >
> >
> >>
> >>
> >> So there are two options really:
> >> - change BookSet to be based on a Map. getBooksByInitials would use the
> map directly. getBook would iterate through the contents (or key the
> contents in a separate map for faster access)
> >> - Add a map to BookSet to cache the lookups
> >
> > I think the second would be fine. However, it will be tough to maintain.
> It has to handle collisions properly. Currently, the class allows
> duplicates by initials or by name or by name and initials (provided that
> they are in different categories.) During lookup, it grabs the first that
> it finds. Not the last. So if there's a dictionary and a Bible both with
> the initials KJV, it will find the KJV Bible because the Biblical Material
> category comes before Dictionary category. If you merely do it based upon
> insertion order, there's no telling what you'll get.
> >
> > The example is made up, but these things have happened.
> >
> > Give a real possibility. A module makes it into the Xiphos repository
> and later into the CrossWire repository. Same initials and same name.
> Likewise for Beta and main. For example, there is a KJV module in the Beta
> repository and also in the main repository.
> >
> >>
> >> My preference would be to replace the BookSet implementation
> altogether. But the easy option would be to have a Map lookup. Do we use
> any of the Set<> methods?
> >
> > I'm not seeing any Set methods other than those implemented by List. The
> notion of Set was that it could be used in a Set context.
> >
> >> Would it make sense to replace BookSet with a LinkedHashMap?
> >
> > How would that maintain natural ordering? (category, initials, name)
> >
> >>
> >>
> >> Chris
> >>
> >> _______________________________________________
> >> jsword-devel mailing list
> >> jsword-devel at crosswire.org
> >> http://www.crosswire.org/mailman/listinfo/jsword-devel
> >
> > _______________________________________________
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>
>
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