RFR 8056084: Refactor Hashtable to allow implementations without rehashing support

[Mikael Gerdin]

Coleen,

On 2014-08-28 23:56, Coleen Phillimore wrote:
>
> Mikael, Thank you for doing this.
>
> Can you remove the comments in hashtable.hpp:
>
>    34 // This is a generic hashtable, designed to be used for the symbol
>    35 // and string tables.

Will do.

>
> also this comment is outdated so should be removed.
>
>    38 //
>    39 // %note:
>    40 //  - TableEntrys are allocated in blocks to reduce the space
> overhead.
>    41

That comment is still correct for callers of
BasicHashtableEntry<F>* BasicHashtable<F>::new_entry


>
> This refactoring looks good.

Thanks
/Mikael

>
> Thanks!
> Coleen
>
>
> On 8/26/14, 11:26 AM, Mikael Gerdin wrote:
>> Hi all,
>>
>> For JDK-8048268 I need to do some refactoring of the Hashtable class
>> template.
>>
>>  From the bug description:
>> In order to simplify usage of the Hashtable<T, F> class the code to
>> perform
>> rehashing of the SymbolTable and StringTable should be factored out to an
>> intermediate class common to those two tables.
>> Also factor out HashtableEntry freelist allocation to allow
>> implementors an
>> easier route for providing their own memory management.
>>
>> Introducing the new intermediary superclass requires some calls to
>> superclass
>> functions to be qualified using the "this->" syntax due to the C++
>> template
>> name lookup rules.
>>
>> a comment about hashtable.cpp RehashableHashtable::dump_table:
>>
>> -  int bucket_bytes = (int)num_buckets * sizeof(bucket(0));
>> +  int bucket_bytes = (int)num_buckets * sizeof(HashtableBucket<F>);
>>
>> I decided to change the sizeof to count the size of the hashtable
>> bucket class
>> instead of the HashtableEntry* returned by bucket(0), even though they
>> may be
>> of the same size currently.
>>
>> Note that the webrev url refers to another bug.
>> Webrev:
>> http://cr.openjdk.java.net/~mgerdin/8048268/hashtable-refactor/webrev/
>> Buglink: https://bugs.openjdk.java.net/browse/JDK-8056084
>>
>> Testing: JPRT.
>>
>