Evgenii Stratonikov
806ea37101
Benchmark results:
```
goos: linux
goarch: amd64
pkg: git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama
cpu: 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
│ old │ new │
│ sec/op │ sec/op vs base │
ForestSortedIteration/bbolt,root-8 207.2µ ± 6% 173.6µ ± 6% -16.23% (p=0.000 n=10)
ForestSortedIteration/bbolt,leaf-8 3.910µ ± 5% 3.928µ ± 7% ~ (p=0.529 n=10)
geomean 28.46µ 26.11µ -8.27%
```
They are not representative, as the worst case is when we have multiple
items of different lengths. However, `FileName` is usually less than 100
in practice, so the asymptotics is the same.
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
85 lines
1.6 KiB
Go
85 lines
1.6 KiB
Go
package pilorama
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import (
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"container/heap"
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"slices"
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"strings"
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)
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type heapInfo struct {
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id MultiNode
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filename string
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}
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type filenameHeap []heapInfo
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func (h filenameHeap) Len() int { return len(h) }
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func (h filenameHeap) Less(i, j int) bool { return h[i].filename < h[j].filename }
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func (h filenameHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
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func (h *filenameHeap) Push(x any) {
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*h = append(*h, x.(heapInfo))
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}
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func (h *filenameHeap) Pop() any {
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old := *h
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n := len(old)
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x := old[n-1]
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*h = old[0 : n-1]
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return x
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}
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// fixedHeap maintains a fixed number of smallest elements started at some point.
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type fixedHeap struct {
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start *string
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sorted bool
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count int
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h *filenameHeap
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}
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func newHeap(start *string, count int) *fixedHeap {
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h := new(filenameHeap)
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heap.Init(h)
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return &fixedHeap{
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start: start,
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count: count,
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h: h,
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}
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}
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const amortizationMultiplier = 5
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func (h *fixedHeap) push(id MultiNode, filename string) bool {
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if h.start != nil && filename <= *h.start {
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return false
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}
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*h.h = append(*h.h, heapInfo{id: id, filename: filename})
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h.sorted = false
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if h.h.Len() > h.count*amortizationMultiplier {
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slices.SortFunc(*h.h, func(a, b heapInfo) int {
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return strings.Compare(a.filename, b.filename)
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})
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*h.h = (*h.h)[:h.count]
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}
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return true
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}
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func (h *fixedHeap) pop() (heapInfo, bool) {
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if !h.sorted {
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slices.SortFunc(*h.h, func(a, b heapInfo) int {
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return strings.Compare(a.filename, b.filename)
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})
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if len(*h.h) > h.count {
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*h.h = (*h.h)[:h.count]
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}
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h.sorted = true
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}
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if len(*h.h) != 0 {
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info := (*h.h)[0]
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*h.h = (*h.h)[1:]
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return info, true
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}
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return heapInfo{}, false
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}
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