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// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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-core 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-core library. If not, see
// <http://www.gnu.org/licenses/>.
package test
import (
"math/rand"
"sort"
"time"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/blockdb"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
)
// isAllAckingBlockRevealed is a helper to check if all acking blocks of
// one block are revealed.
func isAllAckingBlockRevealed(
b *types.Block, revealed map[common.Hash]struct{}) bool {
for _, ack := range b.Acks {
if _, exists := revealed[ack]; !exists {
return false
}
}
return true
}
// loadAllBlocks is a helper to load all blocks from blockdb.BlockIterator.
func loadAllBlocks(iter blockdb.BlockIterator) (
blocks map[common.Hash]*types.Block, err error) {
blocks = make(map[common.Hash]*types.Block)
for {
block, err := iter.Next()
if err != nil {
if err == blockdb.ErrIterationFinished {
// It's safe to ignore iteraion-finished error.
err = nil
}
break
}
blocks[block.Hash] = &block
}
return
}
// RandomDAGRevealer implements Revealer interface, which would load
// all blocks from blockdb, and randomly pick one block to reveal if
// it still forms a valid DAG in revealed blocks.
type RandomDAGRevealer struct {
// blocksByNode group all blocks by nodes and sorting
// them by height.
blocksByNode map[types.NodeID][]*types.Block
// tipIndexes store the height of next block from one node
// to check if is candidate.
tipIndexes map[types.NodeID]int
// candidate are blocks that forms valid DAG with
// current revealed blocks.
candidates []*types.Block
// revealed stores block hashes of current revealed blocks.
revealed map[common.Hash]struct{}
randGen *rand.Rand
}
// NewRandomDAGRevealer constructs RandomDAGRevealer.
func NewRandomDAGRevealer(
iter blockdb.BlockIterator) (r *RandomDAGRevealer, err error) {
blocks, err := loadAllBlocks(iter)
if err != nil {
return
}
// Rearrange blocks by nodes and height.
blocksByNode := make(map[types.NodeID][]*types.Block)
for _, block := range blocks {
blocksByNode[block.ProposerID] =
append(blocksByNode[block.ProposerID], block)
}
// Make sure blocks are sorted by block heights, from lower to higher.
for nID := range blocksByNode {
sort.Sort(types.ByHeight(blocksByNode[nID]))
}
r = &RandomDAGRevealer{
blocksByNode: blocksByNode,
randGen: rand.New(rand.NewSource(time.Now().UnixNano())),
}
// Make sure this revealer is ready to use.
r.Reset()
return
}
// pickCandidates is a helper function to pick candidates from current tips.
func (r *RandomDAGRevealer) pickCandidates() {
for nID, tip := range r.tipIndexes {
blocks, exists := r.blocksByNode[nID]
if !exists {
continue
}
if tip >= len(blocks) {
continue
}
block := blocks[tip]
if isAllAckingBlockRevealed(block, r.revealed) {
r.tipIndexes[nID]++
r.candidates = append(r.candidates, block)
}
}
}
// Next implement Revealer.Next method, which would reveal blocks
// forming valid DAGs.
func (r *RandomDAGRevealer) Next() (types.Block, error) {
if len(r.candidates) == 0 {
r.pickCandidates()
if len(r.candidates) == 0 {
return types.Block{}, blockdb.ErrIterationFinished
}
}
// Pick next block to be revealed.
picked := r.randGen.Intn(len(r.candidates))
block := r.candidates[picked]
r.candidates =
append(r.candidates[:picked], r.candidates[picked+1:]...)
r.revealed[block.Hash] = struct{}{}
r.pickCandidates()
return *block, nil
}
// Reset implement Revealer.Reset method, which would reset the revealing.
func (r *RandomDAGRevealer) Reset() {
r.tipIndexes = make(map[types.NodeID]int)
for nID := range r.blocksByNode {
r.tipIndexes[nID] = 0
}
r.revealed = make(map[common.Hash]struct{})
r.candidates = []*types.Block{}
}
// RandomRevealer implements Revealer interface, which would load
// all blocks from blockdb, and randomly pick one block to reveal.
type RandomRevealer struct {
blocks map[common.Hash]*types.Block
remains common.Hashes
randGen *rand.Rand
}
// NewRandomRevealer constructs RandomRevealer.
func NewRandomRevealer(
iter blockdb.BlockIterator) (r *RandomRevealer, err error) {
blocks, err := loadAllBlocks(iter)
if err != nil {
return
}
r = &RandomRevealer{
blocks: blocks,
randGen: rand.New(rand.NewSource(time.Now().UnixNano())),
}
r.Reset()
return
}
// Next implements Revealer.Next method, which would reveal blocks randomly.
func (r *RandomRevealer) Next() (types.Block, error) {
if len(r.remains) == 0 {
return types.Block{}, blockdb.ErrIterationFinished
}
picked := r.randGen.Intn(len(r.remains))
block := r.blocks[r.remains[picked]]
r.remains =
append(r.remains[:picked], r.remains[picked+1:]...)
return *block, nil
}
// Reset implement Revealer.Reset method, which would reset revealing.
func (r *RandomRevealer) Reset() {
hashes := common.Hashes{}
for hash := range r.blocks {
hashes = append(hashes, hash)
}
r.remains = hashes
}
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