RFR: 8307526: [JFR] Better handling of tampered JFR repository [v9]

[Erik Gahlin]

On Tue, 4 Jul 2023 07:37:20 GMT, Joakim Nordström <jnordstrom at openjdk.org> wrote:

>> This change makes sure that "JFR Periodic Task" isn't interrupted by any errors. This can happen when an unfinished chunkfile is removed "in-flight", which would lead to the chunkfiles not being rotated properly, and the maxsize/maxage being ignored.
>> 
>> With this fix, when an unfinished chunkfile is detected, all of the chunkfiles in the recording are checked for existence (since one likely cause for this could be f.i. 'rm -r /tmp' being invoked, effectively deleting all chunkfiles). Upon seeing missing chunkfiles, an error is logged, and emitted to the recording to signal that some data might be missing.
>> A check to catch any missing chunkfiles is also added when dumping a recording -- this can happen if only finished chunkfiles have been removed, which is not detected in-flight.
>> 
>> Also, a check was added to the file purger to check whether the file had already been deleted to not fill the purge list with already removed files.
>
> Joakim Nordström has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixes

Marked as reviewed by egahlin (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/14360#pullrequestreview-1512719925