Re: [gobo-eiffel-develop] Crash in DS_HASH_TABLE

[Eric B. <er...@go...>]

Wolfgang Jansen wrote:
> some time ago I already asked a related question and you
> gave an answer. But I may have misunderstood something.
> The problem is as follows. I have a class like
> 
>   class C
>   inherit
>     DS_EQUALITY_TESTER [KEY_TYPE]
>       redefine test
>     end
> 
>   feature
> 
>     table: DS_HASH_TABLE [ITEM_TYPE,KEY_TYPE]
> 
>     make is
>       do
>         create table.make_with_equality_testers(1000, Void, Current)
>       end
> 
>     build(k: KEY_TYPE): ITEM_TYPE is
>       do
>         if table.has(k) then
>           Result := table.item(k)
>         else
>           create Result.make(k)
>           table.force(Result,k)
>         end
>       end
> 
>     test(u,v: STRING) is
>       do
>         -- I would like to do this more intelligent,
>         -- but this is a different problem
>         Result := u = v
>       end
> 
>    -- other features
> 
>   end
> 
> This works very well for some time (hundreds of calls)
> but then routine `search_position' enters an infinite loop:
> Lines 590,591 of DS_SPARSE_CONTAINER are
>   prev := i
>   i := clashes_item(i)
> and have the effect that `prev=1', `i=1', i.e. no further
> progress happens. A particular observation:
> `table' has currently 1028 elements.
> 
> So, what has gone wrong and how can I fix the bug?

Is the value of the hash_code of your keys changing while
these keys are used in the hash table?

-- 
Eric Bezault
mailto:er...@go...
http://www.gobosoft.com