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https://gitlab.com/pulsechaincom/erigon-pulse.git
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231e468e19
git-subtree-dir: erigon-lib git-subtree-mainline:3c8cbda809git-subtree-split:93d9c9d9fe
123 lines
2.6 KiB
Go
123 lines
2.6 KiB
Go
/*
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Copyright 2021 Erigon contributors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distwributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package etl
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import (
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"bytes"
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)
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type HeapElem struct {
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Key []byte
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Value []byte
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TimeIdx int
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}
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type Heap struct {
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elems []*HeapElem
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}
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func (h *Heap) Len() int {
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return len(h.elems)
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}
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func (h *Heap) Less(i, j int) bool {
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if c := bytes.Compare(h.elems[i].Key, h.elems[j].Key); c != 0 {
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return c < 0
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}
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return h.elems[i].TimeIdx < h.elems[j].TimeIdx
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}
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func (h *Heap) Swap(i, j int) {
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h.elems[i], h.elems[j] = h.elems[j], h.elems[i]
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}
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func (h *Heap) Push(x *HeapElem) {
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h.elems = append(h.elems, x)
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}
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func (h *Heap) Pop() *HeapElem {
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old := h.elems
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n := len(old) - 1
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x := old[n]
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//old[n].Key, old[n].Value, old[n].TimeIdx = nil, nil, 0
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old[n] = nil
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h.elems = old[0:n]
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return x
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}
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// ------ Copy-Paste of `container/heap/heap.go` without interface conversion
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// Init establishes the heap invariants required by the other routines in this package.
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// Init is idempotent with respect to the heap invariants
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// and may be called whenever the heap invariants may have been invalidated.
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// The complexity is O(n) where n = h.Len().
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func heapInit(h *Heap) {
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// heapify
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n := h.Len()
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for i := n/2 - 1; i >= 0; i-- {
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down(h, i, n)
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}
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}
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// Push pushes the element x onto the heap.
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// The complexity is O(log n) where n = h.Len().
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func heapPush(h *Heap, x *HeapElem) {
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h.Push(x)
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up(h, h.Len()-1)
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}
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// Pop removes and returns the minimum element (according to Less) from the heap.
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// The complexity is O(log n) where n = h.Len().
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// Pop is equivalent to Remove(h, 0).
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func heapPop(h *Heap) *HeapElem {
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n := h.Len() - 1
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h.Swap(0, n)
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down(h, 0, n)
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return h.Pop()
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}
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func up(h *Heap, j int) {
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for {
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i := (j - 1) / 2 // parent
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if i == j || !h.Less(j, i) {
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break
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}
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h.Swap(i, j)
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j = i
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}
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}
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func down(h *Heap, i0, n int) bool {
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i := i0
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for {
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j1 := 2*i + 1
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if j1 >= n || j1 < 0 { // j1 < 0 after int overflow
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break
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}
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j := j1 // left child
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if j2 := j1 + 1; j2 < n && h.Less(j2, j1) {
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j = j2 // = 2*i + 2 // right child
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}
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if !h.Less(j, i) {
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break
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}
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h.Swap(i, j)
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i = j
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}
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return i > i0
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}
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