perf(chore): optimize binary search corner cases

[sivukhin]

Context

Several implementations of binary search in QuestDB have same bug in it - when reaching small range length binary search fallback to linear search, but without any lower bound on index. So, basically algorithms works in linear time (not O(log n)).

This PR fixes a bunch of such similar bugs and start linear scan from lower bound calculated during binary search routine.

Initially this PR were written in kind of "humorous" style. But, as it can violate code of conduct and actually confuses more then helps - I rewrote PR description but leave original text for historical reference

The labor union of algorithms reported that QuestDB (QDB) violates the rights of "binary search algorithm" (BSA) by requiring it to work without utilizing any of its results. The BSA has earned trust through its extensive use in production applications, making the complaint valid. Therefore, QDB must respect the rights of the algorithm.

During audit 4 violations were found.

One concrete example is here (commit hash: a077bee, file: IntLongPriorityQueue.java, line: 109, link)

private int binSearch0(long v) {
    int low = 0;
    int high = size;

    while (low < high) {

        if (high - low < 65) {
            return scanSearch(v); // binary search work completely ignored, so rude!
        }

        int mid = (low + high - 1) >>> 1;
        long midVal = buf.getQuick(mid);

        if (midVal < v)
            low = mid + 1;
        else if (midVal > v)
            high = mid;
        else {
            while (++mid < high && buf.getQuick(mid) == v) {
            }
            return mid;
        }
    }
    return low;
}

QDB must respect rights of algorithms, especially such honorable as BSA. PR fixes this uncomfortable situation.

Hope that all legal rights of algorithms will be respected in such amazing project as QDB from now on.

[bluestreak01]

Hi Nikita (@sivukhin), could you help me understand this report:

The labor union of algorithms reported that QuestDB (QDB) violates the rights of "binary search algorithm" (BSA)

by providing link with more information, perhaps the reference on the aforementioned report.

Or is this a joke?

[sivukhin]

Or is this a joke?

Yes, sorry, I guess bad one. For some reason this mistake made me laugh a bit.
I can for sure rewrite PR description if it's required.

[puzpuzpuz]

@sivukhin thanks for defending the honour of the noble BSA. 🛡️