[HBASE-8355] BaseRegionObserver#pre(Compact|Flush|Store)ScannerOpen returns null

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.98.0, 0.94.8, 0.95.1
• Fix Version/s: 0.98.0, 0.94.8, 0.95.1
• Component/s: Coprocessors

Release Note

As pointed out in https://github.com/forcedotcom/phoenix/pull/131, BaseRegionObserver#preCompactScannerOpen returns null by default, which hoses any coprocessors down the line, making override of this method mandatory in all subclasses of BaseRegionObserver, when there are multiple levels of coprocessor stacking - this same behavior is present in preFlushScannerOpen and preStoreScannerOpen.

Instead, we default to returning the passed scanner so earlier coprocessor changes are preserved and still support the default "no custom scanner" by returning null (default scanner passed to each hook).

• Assignee: Jesse Yates
• Reporter: Andrew Kyle Purtell
• Created: 16/Apr/13 18:55
• Updated: 04/Jun/13 00:06
• Resolved: 15/May/13 21:51

Description

As pointed out in https://github.com/forcedotcom/phoenix/pull/131, BaseRegionObserver#preCompactScannerOpen returns null by default, which hoses any coprocessors down the line, making override of this method mandatory. The fix is trivial, patch coming momentarily.

Update:
This same behavior is present in the Flush and Store versions of the same method - this should all be moved to the proposed 'return passed scanner' default behavior.

Sub-Tasks

• Add a unit test verifying BaseRegionObserver's expected behavior: Closed
• Add a unit test verifying BaseMasterObserver's expected behavior: Closed