swarm/chunk: move chunk related declarations to chunk package (#19170)
This commit is contained in:
Janoš Guljaš
committed by
Anton Evangelatov
Anton Evangelatov
parent
b7e0dec6bd
commit
f0233948d2
@ -1,5 +1,109 @@
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package chunk
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const (
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DefaultSize = 4096
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import (
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"errors"
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"fmt"
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"github.com/ethereum/go-ethereum/common"
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)
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const (
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DefaultSize = 4096
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MaxPO = 16
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AddressLength = 32
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)
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var (
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ErrChunkNotFound = errors.New("chunk not found")
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ErrChunkInvalid = errors.New("invalid chunk")
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)
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type Chunk interface {
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Address() Address
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Data() []byte
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}
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type chunk struct {
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addr Address
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sdata []byte
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}
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func NewChunk(addr Address, data []byte) *chunk {
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return &chunk{
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addr: addr,
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sdata: data,
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}
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}
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func (c *chunk) Address() Address {
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return c.addr
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}
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func (c *chunk) Data() []byte {
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return c.sdata
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}
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func (self *chunk) String() string {
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return fmt.Sprintf("Address: %v Chunksize: %v", self.addr.Log(), len(self.sdata))
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}
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type Address []byte
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var ZeroAddr = Address(common.Hash{}.Bytes())
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func (a Address) Hex() string {
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return fmt.Sprintf("%064x", []byte(a[:]))
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}
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func (a Address) Log() string {
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if len(a[:]) < 8 {
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return fmt.Sprintf("%x", []byte(a[:]))
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}
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return fmt.Sprintf("%016x", []byte(a[:8]))
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}
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func (a Address) String() string {
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return fmt.Sprintf("%064x", []byte(a))
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}
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func (a Address) MarshalJSON() (out []byte, err error) {
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return []byte(`"` + a.String() + `"`), nil
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}
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func (a *Address) UnmarshalJSON(value []byte) error {
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s := string(value)
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*a = make([]byte, 32)
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h := common.Hex2Bytes(s[1 : len(s)-1])
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copy(*a, h)
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return nil
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}
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// Proximity returns the proximity order of the MSB distance between x and y
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//
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// The distance metric MSB(x, y) of two equal length byte sequences x an y is the
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// value of the binary integer cast of the x^y, ie., x and y bitwise xor-ed.
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// the binary cast is big endian: most significant bit first (=MSB).
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//
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// Proximity(x, y) is a discrete logarithmic scaling of the MSB distance.
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// It is defined as the reverse rank of the integer part of the base 2
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// logarithm of the distance.
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// It is calculated by counting the number of common leading zeros in the (MSB)
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// binary representation of the x^y.
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//
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// (0 farthest, 255 closest, 256 self)
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func Proximity(one, other []byte) (ret int) {
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b := (MaxPO-1)/8 + 1
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if b > len(one) {
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b = len(one)
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}
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m := 8
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for i := 0; i < b; i++ {
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oxo := one[i] ^ other[i]
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for j := 0; j < m; j++ {
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if (oxo>>uint8(7-j))&0x01 != 0 {
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return i*8 + j
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}
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}
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}
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return MaxPO
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}
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186
swarm/chunk/proximity_test.go
Normal file
186
swarm/chunk/proximity_test.go
Normal file
@ -0,0 +1,186 @@
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// Copyright 2018 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package chunk
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import (
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"strconv"
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"testing"
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)
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// TestProximity validates Proximity function with explicit
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// values in a table-driven test. It is highly dependant on
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// MaxPO constant and it validates cases up to MaxPO=32.
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func TestProximity(t *testing.T) {
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// integer from base2 encoded string
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bx := func(s string) uint8 {
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i, err := strconv.ParseUint(s, 2, 8)
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if err != nil {
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t.Fatal(err)
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}
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return uint8(i)
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}
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// adjust expected bins in respect to MaxPO
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limitPO := func(po uint8) uint8 {
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if po > MaxPO {
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return MaxPO
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}
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return po
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}
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base := []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00000000")}
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for _, tc := range []struct {
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addr []byte
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po uint8
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}{
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{
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addr: base,
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po: MaxPO,
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},
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{
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addr: []byte{bx("10000000"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(0),
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},
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{
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addr: []byte{bx("01000000"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(1),
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},
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{
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addr: []byte{bx("00100000"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(2),
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},
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{
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addr: []byte{bx("00010000"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(3),
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},
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{
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addr: []byte{bx("00001000"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(4),
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},
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{
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addr: []byte{bx("00000100"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(5),
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},
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{
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addr: []byte{bx("00000010"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(6),
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},
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{
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addr: []byte{bx("00000001"), bx("00000000"), bx("00000000"), bx("00000000")},
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po: limitPO(7),
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},
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{
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addr: []byte{bx("00000000"), bx("10000000"), bx("00000000"), bx("00000000")},
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po: limitPO(8),
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},
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{
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addr: []byte{bx("00000000"), bx("01000000"), bx("00000000"), bx("00000000")},
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po: limitPO(9),
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},
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{
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addr: []byte{bx("00000000"), bx("00100000"), bx("00000000"), bx("00000000")},
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po: limitPO(10),
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},
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{
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addr: []byte{bx("00000000"), bx("00010000"), bx("00000000"), bx("00000000")},
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po: limitPO(11),
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},
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{
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addr: []byte{bx("00000000"), bx("00001000"), bx("00000000"), bx("00000000")},
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po: limitPO(12),
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},
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{
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addr: []byte{bx("00000000"), bx("00000100"), bx("00000000"), bx("00000000")},
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po: limitPO(13),
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},
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{
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addr: []byte{bx("00000000"), bx("00000010"), bx("00000000"), bx("00000000")},
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po: limitPO(14),
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},
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{
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addr: []byte{bx("00000000"), bx("00000001"), bx("00000000"), bx("00000000")},
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po: limitPO(15),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("10000000"), bx("00000000")},
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po: limitPO(16),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("01000000"), bx("00000000")},
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po: limitPO(17),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00100000"), bx("00000000")},
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po: limitPO(18),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00010000"), bx("00000000")},
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po: limitPO(19),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00001000"), bx("00000000")},
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po: limitPO(20),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000100"), bx("00000000")},
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po: limitPO(21),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000010"), bx("00000000")},
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po: limitPO(22),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000001"), bx("00000000")},
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po: limitPO(23),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("10000000")},
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po: limitPO(24),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("01000000")},
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po: limitPO(25),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00100000")},
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po: limitPO(26),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00010000")},
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po: limitPO(27),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00001000")},
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po: limitPO(28),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00000100")},
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po: limitPO(29),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00000010")},
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po: limitPO(30),
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},
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{
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addr: []byte{bx("00000000"), bx("00000000"), bx("00000000"), bx("00000001")},
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po: limitPO(31),
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},
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} {
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got := uint8(Proximity(base, tc.addr))
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if got != tc.po {
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t.Errorf("got %v bin, want %v", got, tc.po)
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}
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}
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}
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