RFR: 8202634: Metaspace: simplify SpaceManager lists

[Thomas Stüfe]

HI Zhengyu,

On Tue, May 8, 2018 at 2:51 PM, Zhengyu Gu <zgu at redhat.com> wrote:
> Hi Thomas,
>
> Looks good to me.
>

Thanks!

> Nits:
>
> metaspace.cpp L3049
>   assertion is no longer needed.
>

You are right, I'll remove it before I push.

>
> Thanks.
>
> -Zhengyu
>

..Thomas

>
>
> 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