path: root/core/types/block.go

// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.

// TODO(jimmy-dexon): remove comments of WitnessAck before open source.

package types

import (
    "bytes"
    "fmt"
    "io"
    "time"

    "github.com/dexon-foundation/dexon/rlp"

    "github.com/dexon-foundation/dexon-consensus/common"
    "github.com/dexon-foundation/dexon-consensus/core/crypto"
)

// GenesisHeight refers to the initial height the genesis block should be.
const GenesisHeight uint64 = 1

// BlockVerifyStatus is the return code for core.Application.VerifyBlock
type BlockVerifyStatus int

// Enums for return value of core.Application.VerifyBlock.
const (
    // VerifyOK: Block is verified.
    VerifyOK BlockVerifyStatus = iota
    // VerifyRetryLater: Block is unable to be verified at this moment.
    // Try again later.
    VerifyRetryLater
    // VerifyInvalidBlock: Block is an invalid one.
    VerifyInvalidBlock
)

type rlpTimestamp struct {
    time.Time
}

func (t *rlpTimestamp) EncodeRLP(w io.Writer) error {
    return rlp.Encode(w, uint64(t.UTC().UnixNano()))
}

func (t *rlpTimestamp) DecodeRLP(s *rlp.Stream) error {
    var nano uint64
    err := s.Decode(&nano)
    if err == nil {
        sec := int64(nano) / 1000000000
        nsec := int64(nano) % 1000000000
        t.Time = time.Unix(sec, nsec).UTC()
    }
    return err
}

// Witness represents the consensus information on the compaction chain.
type Witness struct {
    Height uint64 `json:"height"`
    Data   []byte `json:"data"`
}

// Block represents a single event broadcasted on the network.
type Block struct {
    ProposerID  NodeID           `json:"proposer_id"`
    ParentHash  common.Hash      `json:"parent_hash"`
    Hash        common.Hash      `json:"hash"`
    Position    Position         `json:"position"`
    Timestamp   time.Time        `json:"timestamp"`
    Payload     []byte           `json:"payload"`
    PayloadHash common.Hash      `json:"payload_hash"`
    Witness     Witness          `json:"witness"`
    Randomness  []byte           `json:"randomness"`
    Signature   crypto.Signature `json:"signature"`

    CRSSignature crypto.Signature `json:"crs_signature"`
}

type rlpBlock struct {
    ProposerID  NodeID
    ParentHash  common.Hash
    Hash        common.Hash
    Position    Position
    Timestamp   *rlpTimestamp
    Payload     []byte
    PayloadHash common.Hash
    Witness     *Witness
    Randomness  []byte
    Signature   crypto.Signature

    CRSSignature crypto.Signature
}

// EncodeRLP implements rlp.Encoder
func (b *Block) EncodeRLP(w io.Writer) error {
    return rlp.Encode(w, rlpBlock{
        ProposerID:   b.ProposerID,
        ParentHash:   b.ParentHash,
        Hash:         b.Hash,
        Position:     b.Position,
        Timestamp:    &rlpTimestamp{b.Timestamp},
        Payload:      b.Payload,
        PayloadHash:  b.PayloadHash,
        Witness:      &b.Witness,
        Randomness:   b.Randomness,
        Signature:    b.Signature,
        CRSSignature: b.CRSSignature,
    })
}

// DecodeRLP implements rlp.Decoder
func (b *Block) DecodeRLP(s *rlp.Stream) error {
    var dec rlpBlock
    err := s.Decode(&dec)
    if err == nil {
        *b = Block{
            ProposerID:   dec.ProposerID,
            ParentHash:   dec.ParentHash,
            Hash:         dec.Hash,
            Position:     dec.Position,
            Timestamp:    dec.Timestamp.Time,
            Payload:      dec.Payload,
            PayloadHash:  dec.PayloadHash,
            Witness:      *dec.Witness,
            Randomness:   dec.Randomness,
            Signature:    dec.Signature,
            CRSSignature: dec.CRSSignature,
        }
    }
    return err
}

func (b *Block) String() string {
    return fmt.Sprintf("Block{Hash:%v %s}", b.Hash.String()[:6], b.Position)
}

// Clone returns a deep copy of a block.
func (b *Block) Clone() (bcopy *Block) {
    bcopy = &Block{}
    bcopy.ProposerID = b.ProposerID
    bcopy.ParentHash = b.ParentHash
    bcopy.Hash = b.Hash
    bcopy.Position.Round = b.Position.Round
    bcopy.Position.Height = b.Position.Height
    bcopy.Signature = b.Signature.Clone()
    bcopy.CRSSignature = b.CRSSignature.Clone()
    bcopy.Witness.Height = b.Witness.Height
    bcopy.Witness.Data = common.CopyBytes(b.Witness.Data)
    bcopy.Timestamp = b.Timestamp
    bcopy.Payload = common.CopyBytes(b.Payload)
    bcopy.PayloadHash = b.PayloadHash
    bcopy.Randomness = common.CopyBytes(b.Randomness)
    return
}

// IsGenesis checks if the block is a genesisBlock
func (b *Block) IsGenesis() bool {
    return b.Position.Height == GenesisHeight && b.ParentHash == common.Hash{}
}

// IsFinalized checks if the block is finalized.
func (b *Block) IsFinalized() bool {
    return len(b.Randomness) > 0
}

// IsEmpty checks if the block is an 'empty block'.
func (b *Block) IsEmpty() bool {
    return b.ProposerID.Hash == common.Hash{}
}

// ByHash is the helper type for sorting slice of blocks by hash.
type ByHash []*Block

func (b ByHash) Len() int {
    return len(b)
}

func (b ByHash) Less(i int, j int) bool {
    return bytes.Compare([]byte(b[i].Hash[:]), []byte(b[j].Hash[:])) == -1
}

func (b ByHash) Swap(i int, j int) {
    b[i], b[j] = b[j], b[i]
}

// BlocksByPosition is the helper type for sorting slice of blocks by position.
type BlocksByPosition []*Block

// Len implements Len method in sort.Sort interface.
func (bs BlocksByPosition) Len() int {
    return len(bs)
}

// Less implements Less method in sort.Sort interface.
func (bs BlocksByPosition) Less(i int, j int) bool {
    return bs[j].Position.Newer(bs[i].Position)
}

// Swap implements Swap method in sort.Sort interface.
func (bs BlocksByPosition) Swap(i int, j int) {
    bs[i], bs[j] = bs[j], bs[i]
}

// Push implements Push method in heap interface.
func (bs *BlocksByPosition) Push(x interface{}) {
    *bs = append(*bs, x.(*Block))
}

// Pop implements Pop method in heap interface.
func (bs *BlocksByPosition) Pop() (ret interface{}) {
    n := len(*bs)
    *bs, ret = (*bs)[0:n-1], (*bs)[n-1]
    return
}