[CASSANDRA-18165] Investigate removing PriorityQueue usage from KeyRangeConcatIterator

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 5.0, 5.1
• Component/s: Feature/SAI
• Labels: SAI
• Epic Link: Storage Attached Indexes (Phase 3)
• Change Category: Code Clarity
• Complexity: Low Hanging Fruit
• Platform: All
• Assignee: Mike Adamson
• Reporter: Mike Adamson

Authors

Mike Adamson

• Created: 16/Jan/23 13:03
• Updated: 01/Apr/24 15:35
• Resolved: 01/Apr/24 15:10

Description

It has been identified during the review of CASSANDRA-18058 that the
KeyRangeConcatIterator could potentially stop using a PriorityQueue to maintain it's active list of sorted KeyRangeIterators.

The code suggested by maedhroz is as follows:

private int i = 0;
...
protected void performSkipTo(PrimaryKey primaryKey)
{
    while (i < toRelease.size())
    {
        RangeIterator currentIterator = toRelease.get(i);

        if (currentIterator.getCurrent().compareTo(primaryKey) >= 0)
            break;

        if (currentIterator.getMaximum().compareTo(primaryKey) >= 0)
        {
            currentIterator.skipTo(primaryKey);
            break;
        }

        i++;
    }
}
...
protected PrimaryKey computeNext()
{
    while (i < toRelease.size())
    {
        RangeIterator currentIterator = toRelease.get(i);
        
        if (currentIterator.hasNext())
            return currentIterator.next();
        
        i++;
    }

    return endOfData();
}

It was decided that this change would need performance and correctness testing in it's own right would not be included in the original SAI CEP ticket.

Issue Links

• Is contained by: CASSANDRA-19428 Clean up KeyRangeIterator classes
• is part of: CASSANDRA-19428 Clean up KeyRangeIterator classes