RFR: 8202634: Metaspace: simplify SpaceManager lists

[Zhengyu Gu]

Hi Thomas,

Looks good to me.

Nits:

metaspace.cpp L3049
   assertion is no longer needed.


Thanks.

-Zhengyu


On 05/08/2018 12:47 AM, Thomas Stüfe wrote:
> (jdk-submit tests ok. SAP tests did not show anything attributable to
> this patch.)
> 
> On Mon, May 7, 2018 at 5:29 PM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
>> Hi all,
>>
>> may I please have reviews for this small simplification.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8202634
>> webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8202634-simplify-spacemanager/webrev.00/webrev/
>>
>> This replaces the four separate in-use-chunk-lists in SpaceManager
>> with a single one. The reasoning behind this is that we do not need to
>> keep the chunks sorted by chunk size, a single list containing all
>> chunks of all sizes in use by this SpaceManager is enough, and it
>> simplifies the coding.
>>
>> There is only one place where we really did use the former
>> by-chunktype lists - that is to count how many chunks per chunk type
>> there are.
>>
>> However, arguably that is better done with running counters, so this
>> is what I did. The added benefit is that in
>> SpaceManager::calc_chunk_size() we do not need to walk the lists
>> anymore to sum up chunks.
>>
>> Changes in detail:
>>
>> - removed the "ChunkIndex" argument in
>> ChunkManager::return_single_chunk() and
>> Chunkmanager::return_chunk_list() - that argument was unnecessary,
>> since the Metachunk we return knows its index.
>>
>> - Unfolded SpaceManager::initialize into Spacemanager constructor (I
>> prefer initializing members in ctor init lists)
>>
>> - replaces SpaceManager::sum_count_chunks_in_use() with running counters.
>>
>> - I dumbed down the logging inside ChunkManager::return_chunk_list()
>> somewhat. Should anyone miss the former details, I can reinstate it.
>>
>> Thank you,
>>
>> Thomas