[jira] [Commented] (GEODE-10171) AbstractRedisData version being incremented for no-op operations can lead to delta not being applied on secondary

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    [ https://issues.apache.org/jira/browse/GEODE-10171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17513376#comment-17513376 ] 

ASF subversion and git services commented on GEODE-10171:
---------------------------------------------------------

Commit 5aa6b625fecc2e3c03a5ea0ccf9eeaeb9dd32a7b in geode's branch refs/heads/develop from Jens Deppe
[ https://gitbox.apache.org/repos/asf?p=geode.git;h=5aa6b62 ]

GEODE-10171: AbstractRedisData version being incremented for no-op operations can lead to corruption (#7496)

For SADD, which may or may not modify the data in the region depending
on whether the member being added is already present in the set, the
version in AbstractRedisData is updated regardless of whether a Delta is
sent to the secondary. This can lead to the version on the primary
wrapping around to be equal to the version on the secondary, which means
that if a delta is sent, it will not be applied on the secondary,
leading to potential data loss.

> AbstractRedisData version being incremented for no-op operations can lead to delta not being applied on secondary
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: GEODE-10171
>                 URL: https://issues.apache.org/jira/browse/GEODE-10171
>             Project: Geode
>          Issue Type: Bug
>          Components: redis
>    Affects Versions: 1.15.0
>            Reporter: Donal Evans
>            Priority: Major
>              Labels: blocks-1.15.0​, pull-request-available
>
> For SADD, which may or may not modify the data in the region depending on whether the member being added is already present in the set, the version in AbstractRedisData is updated regardless of whether a Delta is sent to the secondary. This can lead to the version on the primary wrapping around to be equal to the version on the secondary, which means that if a delta is sent, it will not be applied on the secondary, leading to potential data loss.
> Below is a test to show this behaviour:
> {code:java}
> @Test
> public void deltaVersionOnPrimary_shouldNotUpdate_ifNoDeltaSent() {
>   String originalMember = "fixedMemberName";
>   String key = clusterStartUp.getKeyOnServer("tag", 1);
>   
>   // Version of primary = 0
>   // Version of secondary = 0
>   jedis.sadd(key, originalMember);
>   // No changes are made to the set, since adding an already existing member doesn't modify it
>   // Version of primary wraps around back to -1
>   // Version of secondary doesn't change because we don't send a delta
>   for (int i = 0; i < 255; ++i) {
>     jedis.sadd(key, originalMember);
>   }
>   String newMember = "aNewMemberName";
>   // Version of primary = 0
>   // Version of secondary = 0, delta is not applied
>   jedis.sadd(key, newMember);
>   assertThat(jedis.smembers(key)).containsExactlyInAnyOrder(originalMember, newMember);
>   clusterStartUp.crashVM(1); // kill primary server
>   assertThat(jedis.smembers(key)).containsExactlyInAnyOrder(originalMember, newMember);
> } {code}
> The example here uses SADD, but potentially, any command that can be a no-op and uses a versioned Delta is at risk of hitting this. All commands should be checked to ensure they're not vulnerable to this bug.



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