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auth: improve 'removeSubsetRangePerms' to O(n)

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This commit is contained in:
Gyu-Ho Lee 2016-12-13 15:42:12 -08:00
parent 454f1da2f2
commit a53175949e
2 changed files with 65 additions and 28 deletions
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47
auth/range_perm_cache.go
View File

@ -49,38 +49,30 @@ func isRangeEqual(a, b *rangePerm) bool {
// removeSubsetRangePerms removes any rangePerms that are subsets of other rangePerms.
// If there are equal ranges, removeSubsetRangePerms only keeps one of them.
func removeSubsetRangePerms(perms []*rangePerm) []*rangePerm {
// TODO(mitake): currently it is O(n^2), we need a better algorithm
var newp []*rangePerm
// It returns a sorted rangePerm slice.
func removeSubsetRangePerms(perms []*rangePerm) (newp []*rangePerm) {
sort.Sort(RangePermSliceByBegin(perms))
var prev *rangePerm
for i := range perms {
skip := false
for j := range perms {
if i == j {
continue
}
if isRangeEqual(perms[i], perms[j]) {
// if ranges are equal, we only keep the first range.
if i > j {
skip = true
break
}
} else if isSubset(perms[i], perms[j]) {
// if a range is a strict subset of the other one, we skip the subset.
skip = true
break
}
}
if skip {
if i == 0 {
prev = perms[i]
newp = append(newp, perms[i])
continue
}
if isRangeEqual(perms[i], prev) {
continue
}
if isSubset(perms[i], prev) {
continue
}
if isSubset(prev, perms[i]) {
prev = perms[i]
newp[len(newp)-1] = perms[i]
continue
}
prev = perms[i]
newp = append(newp, perms[i])
}
return newp
}
@ -88,7 +80,6 @@ func removeSubsetRangePerms(perms []*rangePerm) []*rangePerm {
func mergeRangePerms(perms []*rangePerm) []*rangePerm {
var merged []*rangePerm
perms = removeSubsetRangePerms(perms)
sort.Sort(RangePermSliceByBegin(perms))
i := 0
for i < len(perms) {

46
auth/range_perm_cache_test.go
View File

@ -16,6 +16,8 @@ package auth
import (
"bytes"
"fmt"
"reflect"
"testing"
)
@ -131,3 +133,47 @@ func TestGetMergedPerms(t *testing.T) {
}
}
}
func TestRemoveSubsetRangePerms(t *testing.T) {
tests := []struct {
perms []*rangePerm
expect []*rangePerm
}{
{ // subsets converge
[]*rangePerm{{[]byte{2}, []byte{3}}, {[]byte{2}, []byte{5}}, {[]byte{1}, []byte{4}}},
[]*rangePerm{{[]byte{1}, []byte{4}}, {[]byte{2}, []byte{5}}},
},
{ // subsets converge
[]*rangePerm{{[]byte{0}, []byte{3}}, {[]byte{0}, []byte{1}}, {[]byte{2}, []byte{4}}, {[]byte{0}, []byte{2}}},
[]*rangePerm{{[]byte{0}, []byte{3}}, {[]byte{2}, []byte{4}}},
},
{ // biggest range at the end
[]*rangePerm{{[]byte{2}, []byte{3}}, {[]byte{0}, []byte{2}}, {[]byte{1}, []byte{4}}, {[]byte{0}, []byte{5}}},
[]*rangePerm{{[]byte{0}, []byte{5}}},
},
{ // biggest range at the beginning
[]*rangePerm{{[]byte{0}, []byte{5}}, {[]byte{2}, []byte{3}}, {[]byte{0}, []byte{2}}, {[]byte{1}, []byte{4}}},
[]*rangePerm{{[]byte{0}, []byte{5}}},
},
{ // no overlapping ranges
[]*rangePerm{{[]byte{2}, []byte{3}}, {[]byte{0}, []byte{1}}, {[]byte{4}, []byte{7}}, {[]byte{8}, []byte{15}}},
[]*rangePerm{{[]byte{0}, []byte{1}}, {[]byte{2}, []byte{3}}, {[]byte{4}, []byte{7}}, {[]byte{8}, []byte{15}}},
},
}
for i, tt := range tests {
rs := removeSubsetRangePerms(tt.perms)
if !reflect.DeepEqual(rs, tt.expect) {
t.Fatalf("#%d: unexpected rangePerms %q, got %q", i, printPerms(rs), printPerms(tt.expect))
}
}
}
func printPerms(rs []*rangePerm) (txt string) {
for i, p := range rs {
if i != 0 {
txt += ","
}
txt += fmt.Sprintf("%+v", *p)
}
return
}