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promql: use faster heap method for topk/bottomk 

Call `Fix()` instead of `Pop()` followed by `Push()`.

This is slightly faster.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
This commit is contained in:
Bryan Boreham 2023-03-28 10:42:15 +00:00
parent cf54a14f9c
commit f2fd85df82
1 changed files with 22 additions and 22 deletions
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44
promql/engine.go
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@ -2508,39 +2508,39 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
group.value += delta * (s.V - group.mean)
case parser.TOPK:
if int64(len(group.heap)) < k || group.heap[0].V < s.V || math.IsNaN(group.heap[0].V) {
if int64(len(group.heap)) == k {
if k == 1 { // For k==1 we can replace in-situ.
group.heap[0] = Sample{
Point: Point{V: s.V},
Metric: s.Metric,
}
break
}
heap.Pop(&group.heap)
}
// We build a heap of up to k elements, with the smallest element at heap[0].
if int64(len(group.heap)) < k {
heap.Push(&group.heap, &Sample{
Point: Point{V: s.V},
Metric: s.Metric,
})
} else if group.heap[0].V < s.V || (math.IsNaN(group.heap[0].V) && !math.IsNaN(s.V)) {
// This new element is bigger than the previous smallest element - overwrite that.
group.heap[0] = Sample{
Point: Point{V: s.V},
Metric: s.Metric,
}
if k > 1 {
heap.Fix(&group.heap, 0) // Maintain the heap invariant.
}
}
case parser.BOTTOMK:
if int64(len(group.reverseHeap)) < k || group.reverseHeap[0].V > s.V || math.IsNaN(group.reverseHeap[0].V) {
if int64(len(group.reverseHeap)) == k {
if k == 1 { // For k==1 we can replace in-situ.
group.reverseHeap[0] = Sample{
Point: Point{V: s.V},
Metric: s.Metric,
}
break
}
heap.Pop(&group.reverseHeap)
}
// We build a heap of up to k elements, with the biggest element at heap[0].
if int64(len(group.reverseHeap)) < k {
heap.Push(&group.reverseHeap, &Sample{
Point: Point{V: s.V},
Metric: s.Metric,
})
} else if group.reverseHeap[0].V > s.V || (math.IsNaN(group.reverseHeap[0].V) && !math.IsNaN(s.V)) {
// This new element is smaller than the previous biggest element - overwrite that.
group.reverseHeap[0] = Sample{
Point: Point{V: s.V},
Metric: s.Metric,
}
if k > 1 {
heap.Fix(&group.reverseHeap, 0) // Maintain the heap invariant.
}
}
case parser.QUANTILE: