[LUCENE-2087] Remove recursion in NumericRangeTermEnum

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.9, 2.9.1, 3.0
• Fix Version/s: 3.0, 4.0-ALPHA
• Component/s: core/search
• Lucene Fields: New, Patch Available
• Assignee: Uwe Schindler
• Reporter: Uwe Schindler
• Created: 21/Nov/09 19:02
• Updated: 28/Aug/22 12:14
• Resolved: 21/Nov/09 19:50

Description

The current FilteredTermEnum in NRQ uses setEnum() which itsself calls next(). This may lead to a recursion that can overflow stack, if the index is empty and a large range with low precStep is used. With 64 bit numbers and precStep == 1 there may be 127 recursions, as each sub-range would hit no term on empty index and the setEnum call would then call next() which itsself calls setEnum again. This leads to recursion depth of 256.

Attached is a patch that converts to iterative approach. setEnum is now unused and throws UOE (like endEnum()).