BIND 10 #2811: Make some DomainTree code updates

[BIND 10 Development]

#2811: Make some DomainTree code updates
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            Reporter:  muks          |                        Owner:  muks
                Type:  enhancement   |                       Status:
            Priority:  medium        |  reviewing
           Component:  data source   |                    Milestone:
            Keywords:                |  Sprint-20130806
           Sensitive:  0             |                   Resolution:
         Sub-Project:  DNS           |                 CVSS Scoring:
Estimated Difficulty:  3             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Changes (by vorner):

 * owner:  vorner => muks


Comment:

 Replying to [comment:14 muks]:
 > This is a minor optimization. In the specific case that the new node is
 the new root of a sub-tree, calling `insertRebalance()` on it is redundant
 as its main loop will exit without running and it will recolor it to BLACK
 unnecessarily.

 Ah, now I see. The first is else if, not only if. Then it makes sense.

 > > Looking at the loop, shouldn't we stop it after the first rotation?
 >
 > Which loop are you referring to?

 The big loop in the `insertRebalance`, the one starting with:
 {{{#!c++
     // The node enters this method colored RED. We assume in our
     // red-black implementation that NULL values in left and right
     // children are BLACK.
     //
     // Case 1. If node is at the subtree root, we don't need to change
     // its position in the tree. We re-color it BLACK further below
     // (right before we return).
     while (node != (*subtree_root).get()) {
         // Case 2. If the node is not subtree root, but its parent is
         // colored BLACK, then we're done. This is because the new node
         // introduces a RED node in the path through it (from its
         // subtree root to its children colored BLACK) but doesn't
         // change the red-black properties.
 }}}

 In the case 4, it rotates the tree. I had the impression that once we
 rotate, the whole update rebalancing ends.

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Ticket URL: <http://bind10.isc.org/ticket/2811#comment:15>
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