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Merge pull request #5405 from multiversx/fix-backwards-compatibility-…
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…in-go-1205

go v1.20.5 sort backwards compatibility fix
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iulianpascalau authored Jul 8, 2023
2 parents bb5b6b1 + f6cb39b commit 192ebc3
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Showing 9 changed files with 2,472 additions and 9 deletions.
11 changes: 11 additions & 0 deletions common/compatibility/export_test.go
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package compatibility

import "sort"

// Sort sorts data.
// It makes one call to data.Len to determine n and O(n*log(n)) calls to
// data.Less and data.Swap. The sort is not guaranteed to be stable.
func Sort(data sort.Interface) {
n := data.Len()
quickSort_func(data, 0, n, maxDepth(n))
}
163 changes: 163 additions & 0 deletions common/compatibility/quickSorter.go
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package compatibility

type lessSwapHandler interface {
Less(i, j int) bool
Swap(i, j int)
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L10
func insertionSort_func(data lessSwapHandler, a, b int) {
for i := a + 1; i < b; i++ {
for j := i; j > a && data.Less(j, j-1); j-- {
data.Swap(j, j-1)
}
}
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L19
func siftDown_func(data lessSwapHandler, lo, hi, first int) {
root := lo
for {
child := 2*root + 1
if child >= hi {
break
}
if child+1 < hi && data.Less(first+child, first+child+1) {
child++
}
if !data.Less(first+root, first+child) {
return
}
data.Swap(first+root, first+child)
root = child
}
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L37
func heapSort_func(data lessSwapHandler, a, b int) {
first := a
lo := 0
hi := b - a
for i := (hi - 1) / 2; i >= 0; i-- {
siftDown_func(data, i, hi, first)
}
for i := hi - 1; i >= 0; i-- {
data.Swap(first, first+i)
siftDown_func(data, lo, i, first)
}
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L52
func medianOfThree_func(data lessSwapHandler, m1, m0, m2 int) {
if data.Less(m1, m0) {
data.Swap(m1, m0)
}
if data.Less(m2, m1) {
data.Swap(m2, m1)
if data.Less(m1, m0) {
data.Swap(m1, m0)
}
}
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L72
func doPivot_func(data lessSwapHandler, lo, hi int) (midlo, midhi int) {
m := int(uint(lo+hi) >> 1)
if hi-lo > 40 {
s := (hi - lo) / 8
medianOfThree_func(data, lo, lo+s, lo+2*s)
medianOfThree_func(data, m, m-s, m+s)
medianOfThree_func(data, hi-1, hi-1-s, hi-1-2*s)
}
medianOfThree_func(data, lo, m, hi-1)
pivot := lo
a, c := lo+1, hi-1
for ; a < c && data.Less(a, pivot); a++ {
}
b := a
for {
for ; b < c && !data.Less(pivot, b); b++ {
}
for ; b < c && data.Less(pivot, c-1); c-- {
}
if b >= c {
break
}
data.Swap(b, c-1)
b++
c--
}
protect := hi-c < 5
if !protect && hi-c < (hi-lo)/4 {
dups := 0
if !data.Less(pivot, hi-1) {
data.Swap(c, hi-1)
c++
dups++
}
if !data.Less(b-1, pivot) {
b--
dups++
}
if !data.Less(m, pivot) {
data.Swap(m, b-1)
b--
dups++
}
protect = dups > 1
}
if protect {
for {
for ; a < b && !data.Less(b-1, pivot); b-- {
}
for ; a < b && data.Less(a, pivot); a++ {
}
if a >= b {
break
}
data.Swap(a, b-1)
a++
b--
}
}
data.Swap(pivot, b-1)
return b - 1, c
}

// from go implementation v1.17.6 /src/sort/zfuncversion.go L136
func quickSort_func(data lessSwapHandler, a, b, maxDepth int) {
for b-a > 12 {
if maxDepth == 0 {
heapSort_func(data, a, b)
return
}
maxDepth--
mlo, mhi := doPivot_func(data, a, b)
if mlo-a < b-mhi {
quickSort_func(data, a, mlo, maxDepth)
a = mhi
} else {
quickSort_func(data, mhi, b, maxDepth)
b = mlo
}
}
if b-a > 1 {
for i := a + 6; i < b; i++ {
if data.Less(i, i-6) {
data.Swap(i, i-6)
}
}
insertionSort_func(data, a, b)
}
}

// maxDepth returns a threshold at which quicksort should switch
// to heapsort. It returns 2*ceil(lg(n+1)).
// from go implementation v1.17.6 /src/sort/sort.go L236
func maxDepth(n int) int {
var depth int
for i := n; i > 0; i >>= 1 {
depth++
}
return depth * 2
}
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