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

["Donal Evans (Jira)" <ji...@apache.org>]

Donal Evans created GEODE-10171:
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             Summary: 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


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("lrem", 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}



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