HDDS-6984. [Snapshot] Prevent bucket from being deleted if snapshot exists

[sadanand48]

What changes were proposed in this pull request?

Prevent bucket from being deleted if snapshot exists

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-6984

How was this patch tested?

Unit tests

[smengcl]

Thanks @sadanand48 for the patch. Overall looks good.

[smengcl]

UT in CI has failed twice in a row so far. Looks related:

Error:  Errors: 
Error:    TestOzoneManagerDoubleBufferWithOMResponse.testDoubleBufferWithMixOfTransactions:173->doMixTransactions:296->deleteBucket:313 » NullPointer
Error:    TestOzoneManagerDoubleBufferWithOMResponse.testDoubleBufferWithMixOfTransactionsParallel:253 » Timeout
Error:    TestOMBucketDeleteRequest.testValidateAndUpdateCache:67 » NullPointer
Error:    TestOMBucketDeleteRequestWithFSO>TestOMBucketDeleteRequest.testValidateAndUpdateCache:67 » NullPointer
Error:    TestOMBucketDeleteRequestWithFSO.testValidateAndUpdateCacheWithFSO:57 » NullPointer
[INFO] 
Error:  Tests run: 634, Failures: 0, Errors: 5, Skipped: 1

https://github.com/apache/ozone/actions/runs/3688005945/jobs/6249324380

https://github.com/apache/ozone/actions/runs/3688005945/jobs/6242294343

[sadanand48]

UT in CI has failed twice in a row so far. Looks related

Fixed these.

One more test failure I can see in org.apache.hadoop.ozone.freon.TestOMSnapshotDAG.testDAGReconstruction

java.io.IOException: Snapshot Chain corruption:  previous snapshotID given but no associated snapshot found in snapshot chain: SnapshotID 2454ada9-2134-489f-8b97-d1ecadc80b74
3171	at org.apache.hadoop.ozone.om.SnapshotChainManager.addSnapshotGlobal(SnapshotChainManager.java:81)
3172	at org.apache.hadoop.ozone.om.SnapshotChainManager.addSnapshot(SnapshotChainManager.java:274)
3173	at org.apache.hadoop.ozone.om.SnapshotChainManager.loadFromSnapshotInfoTable(SnapshotChainManager.java:265)
3174	at org.apache.hadoop.ozone.om.SnapshotChainManager.<init>(SnapshotChainManager.java:61)
3175	at org.apache.hadoop.ozone.om.OzoneManager.instantiateServices(OzoneManager.java:731)
3176	at org.apache.hadoop.ozone.om.OzoneManager.restart(OzoneManager.java:1575)
3177	at org.apache.hadoop.ozone.MiniOzoneClusterImpl.restartOzoneManager(MiniOzoneClusterImpl.java:362)
3178	at org.apache.hadoop.ozone.freon.TestOMSnapshotDAG.testDAGReconstruction(TestOMSnapshotDAG.java:257) 

Looks like this needs to be fixed before plugging in SnapshotChainManager code. Reverted the optimisation for this PR. Filed HDDS-7689 for the above error.

[prashantpogde]

@sadanand48 can we close this after resolving conflicts and comments ?

[prashantpogde]

Thank you @sadanand48 for working on this.