[crac] RFR: Provide arguments for restore [v4]

[Anton Kozlov]

On Sat, 5 Mar 2022 09:17:26 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> This change adds an ability to receive a new set of command-line arguments in the restored Java instance. The supplied demo code shows a faster replacement for `javac`.
>
> Anton Kozlov has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Better error handling in hotspot
>  - Call the main of provided class

I think I found a better approach to achieve the same. I didn't like the first argument was going to be ignored most of the time (considering use-cases like in the demo). So instead, we can require arguments provided for restore need to be an actual Class, which main method will be called, and the arguments. So `java -XX:CRaCRestore Main arg1" will restore the instance and execute Main.main(arg1) in that instance. 

Comparing with the previous approach, it's like a program did

checkpointRestore();
mainClass, arguments = getAndParseNewArguments()
invoke(mainClass, "main", arguments)


Now the target Main class may handle new arguments right away, or store them to be used for later, like it was done in versions up to v3[1].

The demo is extended for Compile to be the Class, so examples above are still valid. Start-up time is roughly the same (actually a bit better, but it should be a noise).

[1] https://mail.openjdk.java.net/pipermail/crac-dev/2022-March/000132.html

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PR: https://git.openjdk.java.net/crac/pull/16