RFR 8056084: Refactor Hashtable to allow implementations without rehashing support

[Mikael Gerdin]

Coleen,

On 2014-08-29 09:06, Mikael Gerdin wrote:
> 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 also this comment is outdated so should be removed.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

I changed it to:
+// HashtableEntrys are allocated in blocks to reduce the space overhead.
+template <MEMFLAGS F> BasicHashtableEntry<F>* 
BasicHashtable<F>::new_entry(unsigned int hashValue) {
+  BasicHashtableEntry<F>* entry = new_entry_free_list();
+

Is that ok?

/Mikael

>
>
>>
>> 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.
>>>
>>