[crac] RFR: 8350845: [CRaC] Support C/R engines in form of a library [v2]

[Timofei Pushkin]

On Tue, 4 Mar 2025 13:06:48 GMT, Radim Vansa <rvansa at openjdk.org> wrote:

>> Timofei Pushkin has updated the pull request incrementally with five additional commits since the last revision:
>> 
>>  - Fix platform-specific issues
>>  - Rewrite crexec on C++
>>  - Change engine options help
>>  - Move engine wrapper into its own files
>>  - Address review comments
>
> src/hotspot/share/runtime/crac.cpp line 492:
> 
>> 490: 
>> 491:   // Note that this is a local, i.e. the handle will be destroyed if we fail to restore
>> 492:   auto engine = CracEngine(CRaCRestoreFrom);
> 
> A nitpick/question: why do you use this syntax that does an extra copy rather than
> 
> CracEngine engine(CRaCRestoreFrom);
> 
> ?

This is a mistake, thanks for catching

> src/hotspot/share/runtime/globals.hpp line 1964:
> 
>> 1962:   product_pd(ccstr, CRaCEngine, RESTORE_SETTABLE,                           \
>> 1963:       "Path or name of a program or a shared library implementing "         \
>> 1964:       "checkpoint and restore. On restore this option applies only to "     \
> 
> I would even say that the CREngine must match on checkpoint and restore.

While the engine itself should indeed be the same, when the value is a path it can vary in checkpoint and restore environments

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PR Review Comment: https://git.openjdk.org/crac/pull/207#discussion_r1979527005
PR Review Comment: https://git.openjdk.org/crac/pull/207#discussion_r1979534105