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utils.go
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/
utils.go
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// Copyright 2020 Thinkium
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package common
import (
"crypto/rand"
"errors"
"fmt"
"io"
"os/user"
"reflect"
"strconv"
)
func CloneByteSlice(bytes []byte) []byte {
if bytes == nil {
return nil
}
if len(bytes) == 0 {
return make([]byte, 0, 0)
}
clone := make([]byte, len(bytes), len(bytes))
copy(clone, bytes)
return clone
}
func ReverseBytes(bs []byte) []byte {
l := len(bs)
for j := 0; j < l/2; j++ {
k := l - j - 1
bs[j], bs[k] = bs[k], bs[j]
}
return bs
}
func RandomBytes(length int) []byte {
b := make([]byte, length)
_, _ = io.ReadFull(rand.Reader, b)
return b
}
func RandomByteSlices(count, size int) [][]byte {
if count == 0 {
return [][]byte{}
}
r := make([][]byte, count)
for i := 0; i < count; i++ {
r[i] = RandomBytes(size)
}
return r
}
func HomeDir() string {
u, err := user.Current()
if err != nil {
panic(DvppError{"could not get current user", err})
} else {
return u.HomeDir
}
}
func FormalizeBasePath(path string) string {
p := []byte(path)
if len(p) > 0 {
if p[len(p)-1] != '/' {
path = path + "/"
}
} else {
path = "./"
}
return path
}
func DatabasePath(basePath string, id ChainID) string {
return basePath + "db" + strconv.Itoa(int(id))
}
// When sorting a pointer type object slice, the Less method needs to be written. The first part
// is to determine whether the object indicated by the i and j is nil. Nil is considered to be
// the smallest. If both are nil, they are considered to be equal. Only when both of them are not
// nil, the subsequent comparison is needed, and there is no need to check nil at this time.
// When needCompare returns false, the Less method can directly return the returned less value;
// otherwise, the comparison of the indexed objects needs to continue
func PointerSliceLess(slice interface{}, i, j int) (less bool, needCompare bool) {
if slice == nil {
return false, false
}
val := reflect.ValueOf(slice)
if val.Kind() != reflect.Slice {
return false, false
}
if i == j || i < 0 || j < 0 || val.IsNil() || val.Len() <= i || val.Len() <= j {
return false, false
}
vali, valj := val.Index(i), val.Index(j)
if vali.Kind() != reflect.Ptr || valj.Kind() != reflect.Ptr {
return false, false
}
if vali.IsNil() && valj.IsNil() {
return false, false
}
if vali.IsNil() {
return true, false
}
if valj.IsNil() {
return false, false
}
return false, true
}
func PointerCompare(a, b interface{}) (cmp int, needCompare bool) {
va, vb := reflect.ValueOf(a), reflect.ValueOf(b)
if va.IsNil() && vb.IsNil() {
return 0, false
}
if va.IsNil() {
return -1, false
}
if vb.IsNil() {
return 1, false
}
return 0, true
}
func CompareSlices(a, b interface{}, objComparer func(x, y interface{}) int) int {
va, vb := reflect.ValueOf(a), reflect.ValueOf(b)
if va.IsNil() && vb.IsNil() {
return 0
}
if va.IsNil() {
return -1
}
if vb.IsNil() {
return 1
}
if va.Len() == 0 && vb.Len() == 0 {
return 0
}
if va.Len() == vb.Len() {
for i := 0; i < va.Len(); i++ {
p := objComparer(va.Index(i).Interface(), vb.Index(i).Interface())
if p != 0 {
return p
}
}
return 0
} else if va.Len() < vb.Len() {
return -1
} else {
return 1
}
}
func ByteSlicesToNodeIDs(bss [][]byte) (NodeIDs, error) {
if len(bss) == 0 {
return nil, nil
}
dedup := make(map[NodeID]struct{})
nids := make(NodeIDs, 0, len(bss))
for _, nodeid := range bss {
if len(nodeid) != NodeIDBytes {
return nil, fmt.Errorf("illegal nodeid: %x", nodeid)
}
nid := BytesToNodeID(nodeid)
if _, exist := dedup[nid]; exist {
return nil, errors.New("duplicated node found")
}
dedup[nid] = struct{}{}
nids = append(nids, nid)
}
return nids, nil
}
func IsNodeIDIn(nidhs []Hash, nid NodeID) bool {
if len(nidhs) == 0 {
return false
}
h := nid.Hash()
for _, nidh := range nidhs {
if nidh == h {
return true
}
}
return false
}