RFR: 8301106 allow cds interned strings to be moved by gc [v2]

[Ioi Lam]

On Fri, 17 Feb 2023 06:34:42 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Ioi Lam has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - renamed obsolete functions to ArchiveHeapLoader::is_in_use()
>>  - fixed typos in comment
>
> src/hotspot/share/cds/archiveHeapLoader.hpp line 68:
> 
>> 66:   }
>> 67: 
>> 68:   static bool are_archived_strings_available() {
> 
> The functions don't seem to carry their weight any more. Perhaps we can just rename `is_fully_available` to `is_archive_available` and always call it directly?

We use to allow the archive to be partially loaded. This is no longer true anymore. I renamed the three functions `are_archived_strings_available`, `are_archived_mirrors_available` and `is_fully_available` to `is_in_use()`. The name corresponds to the `ArchiveHeapLoader::can_use()` function.

(It's a pity that the archive can be "used" either by "mapping" or "loading" -- see comments at the top of archiveHeapLoader.hpp. Eventually we will support only mapping. At that time,  `is_in_use()` will be renamed to `is_mapped()` ...)

> src/hotspot/share/cds/heapShared.cpp line 426:
> 
>> 424:   oop shared_strings_array = StringTable::init_shared_table(_dumped_interned_strings);
>> 425:   bool success = archive_reachable_objects_from(1, _default_subgraph_info, shared_strings_array, /*is_closed_archive=*/ false);
>> 426:   guarantee(success, "shared strings array should not point to any unachivable objects");
> 
> typo: unachivable

Fixed.

> src/hotspot/share/cds/heapShared.cpp line 592:
> 
>> 590:   assert(HeapShared::can_write(), "must be");
>> 591: 
>> 592:   {
> 
> Why do  you need a new  scope here?

I used the scope to mark that the two archiving operations must be done within the scope of


{
    init_seen_objects_table();
       ....
    delete_seen_objects_table();
}


And the `delete_seen_objects_table()` must be called before the rest of the function can proceed.

-------------

PR: https://git.openjdk.org/jdk/pull/12607