[jira] [Updated] (IGNITE-23417) Fix race between compaction and KeyValueStorage#range

["Kirill Tkalenko (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-23417?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kirill Tkalenko updated IGNITE-23417:
-------------------------------------
    Reviewer: Ivan Zlenko

> Fix race between compaction and KeyValueStorage#range
> -----------------------------------------------------
>
>                 Key: IGNITE-23417
>                 URL: https://issues.apache.org/jira/browse/IGNITE-23417
>             Project: Ignite
>          Issue Type: Bug
>            Reporter: Kirill Tkalenko
>            Assignee: Kirill Tkalenko
>            Priority: Major
>              Labels: ignite-3
>             Fix For: 3.0
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> I found that in IGNITE-23288 a problem with *org.apache.ignite.internal.metastorage.server.KeyValueStorage#range* was not solved.
> To understand it, let's look at an example:
> * Let's say there is a key "bar" and it has revisions 1, 3, 5 (tombstone).
> * We set the compaction revision to 5, via *KeyValueStorage#setCompactionRevision*.
> * We waited for complete all cursors on revision less than or equal to 5.
> * We invoke *KeyValueStorage#compact* on revision 5 and let's say it will be quite long.
> * We will not be able to create a cursor on revision 5, but on 6 it is quite possible.
> * We create a cursor for revision 6.
> * Cursor reaches the key "bar" and what can happen:
> # Compaction deleted the key "bar" from storage before opening the cursor - then everything is {color:#00875A}fine{color}.
> # Compaction did not have time to delete the "bar" key - the cursor will return an entry with revision 5, which {color:#DE350B}should not present{color}.
> # Compaction started deleting the "bar" key in parallel - the cursor will either {color:#DE350B}get a value for revision 5 or throw an error{color}.
> In this ticket we need to fix cases 2 and 3.
> Also, we must not forget the case that if the cursor was created on a revision less than or equal to the new revision of the compaction, from the example this is on revision 5 but strictly before calling *KeyValueStorage#setCompactionRevision(5)*. Then we must return the entry on revision 5 after *KeyValueStorage#setCompactionRevision(5)*.



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