[crac] RFR: Support passing extra options in CREngine [v3]

[Radim Vansa]

On Tue, 13 Jun 2023 13:57:03 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fixup
>
> src/hotspot/os/linux/os_linux.cpp line 440:
> 
>> 438: static const char* _crengine = NULL;
>> 439: static char* _crengine_arg_str = NULL;
>> 440: static const char* _crengine_args[32] = { NULL, NULL, NULL };
> 
> Should it be really 3 NULLs?

Yes. First is in place of the binary; second is the operation (`checkpoint`/`restore`) and we want the third position initialized to NULL - when add_crengine_arg is called it should find a NULL and paste the value in there, initializing the 'tail' to NULL.

> src/hotspot/os/linux/os_linux.cpp line 5945:
> 
>> 5943: static void add_crengine_arg(const char *arg) {
>> 5944:   for (size_t i = 2; i < ARRAY_SIZE(_crengine_args) - 1; ++i) {
>> 5945:     if (_crengine_args[i] == NULL) {
> 
> The last empty position can be remembered along _crengine_args

The fewer static vars the better IMO, but I can certainly use an explicit index var and drop the initialization to three NULLs if you think it's better.

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PR Review Comment: https://git.openjdk.org/crac/pull/63#discussion_r1228293023
PR Review Comment: https://git.openjdk.org/crac/pull/63#discussion_r1228294803