package core
import (
"bytes"
"fmt"
"io"
"math/big"
"runtime"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/compression/rle"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/pow"
"github.com/ethereum/go-ethereum/rlp"
"github.com/hashicorp/golang-lru"
"github.com/rcrowley/go-metrics"
"github.com/syndtr/goleveldb/leveldb"
)
var (
chainlogger = logger.NewLogger("CHAIN")
jsonlogger = logger.NewJsonLogger()
blockHashPre = []byte("block-hash-")
blockNumPre = []byte("block-num-")
blockInsertTimer = metrics.GetOrRegisterTimer("core/BlockInsertions", metrics.DefaultRegistry)
)
const (
blockCacheLimit = 256
maxFutureBlocks = 256
maxTimeFutureBlocks = 30
)
// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block b should have when created at time
// given the parent block's time and difficulty.
func CalcDifficulty(time int64, parentTime int64, parentDiff *big.Int) *big.Int {
diff := new(big.Int)
adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
if big.NewInt(time-parentTime).Cmp(params.DurationLimit) < 0 {
diff.Add(parentDiff, adjust)
} else {
diff.Sub(parentDiff, adjust)
}
if diff.Cmp(params.MinimumDifficulty) < 0 {
return params.MinimumDifficulty
}
return diff
}
// CalcTD computes the total difficulty of block.
func CalcTD(block, parent *types.Block) *big.Int {
if parent == nil {
return block.Difficulty()
}
d := block.Difficulty()
d.Add(d, parent.Td)
return d
}
// CalcGasLimit computes the gas limit of the next block after parent.
// The result may be modified by the caller.
func CalcGasLimit(parent *types.Block) *big.Int {
decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
contrib = contrib.Div(contrib, big.NewInt(2))
contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)
gl := new(big.Int).Sub(parent.GasLimit(), decay)
gl = gl.Add(gl, contrib)
gl = gl.Add(gl, big.NewInt(1))
gl.Set(common.BigMax(gl, params.MinGasLimit))
if gl.Cmp(params.GenesisGasLimit) < 0 {
gl.Add(parent.GasLimit(), decay)
gl.Set(common.BigMin(gl, params.GenesisGasLimit))
}
return gl
}
type ChainManager struct {
//eth EthManager
blockDb common.Database
stateDb common.Database
processor types.BlockProcessor
eventMux *event.TypeMux
genesisBlock *types.Block
// Last known total difficulty
mu sync.RWMutex
chainmu sync.RWMutex
tsmu sync.RWMutex
td *big.Int
currentBlock *types.Block
lastBlockHash common.Hash
currentGasLimit *big.Int
transState *state.StateDB
txState *state.ManagedState
cache *lru.Cache // cache is the LRU caching
futureBlocks *BlockCache // future blocks are blocks added for later processing
pendingBlocks *BlockCache // pending blocks contain blocks not yet written to the db
quit chan struct{}
// procInterrupt must be atomically called
procInterrupt int32 // interrupt signaler for block processing
wg sync.WaitGroup
pow pow.PoW
}
func NewChainManager(genesis *types.Block, blockDb, stateDb common.Database, pow pow.PoW, mux *event.TypeMux) (*ChainManager, error) {
cache, _ := lru.New(blockCacheLimit)
bc := &ChainManager{
blockDb: blockDb,
stateDb: stateDb,
genesisBlock: GenesisBlock(42, stateDb),
eventMux: mux,
quit: make(chan struct{}),
cache: cache,
pow: pow,
}
// Check the genesis block given to the chain manager. If the genesis block mismatches block number 0
// throw an error. If no block or the same block's found continue.
if g := bc.GetBlockByNumber(0); g != nil && g.Hash() != genesis.Hash() {
return nil, fmt.Errorf("Genesis mismatch. Maybe different nonce (%d vs %d)? %x / %x", g.Nonce(), genesis.Nonce(), g.Hash().Bytes()[:4], genesis.Hash().Bytes()[:4])
}
bc.genesisBlock = genesis
bc.setLastState()
// Check the current state of the block hashes and make sure that we do not have any of the bad blocks in our chain
for hash, _ := range BadHashes {
if block := bc.GetBlock(hash); block != nil {
glog.V(logger.Error).Infof("Found bad hash. Reorganising chain to state %x\n", block.ParentHash().Bytes()[:4])
block = bc.GetBlock(block.ParentHash())
if block == nil {
glog.Fatal("Unable to complete. Parent block not found. Corrupted DB?")
}
bc.SetHead(block)
glog.V(logger.Error).Infoln("Chain reorg was successfull. Resuming normal operation")
}
}
bc.transState = bc.State().Copy()
// Take ownership of this particular state
bc.txState = state.ManageState(bc.State().Copy())
bc.futureBlocks = NewBlockCache(maxFutureBlocks)
bc.makeCache()
go bc.update()
return bc, nil
}
func (bc *ChainManager) SetHead(head *types.Block) {
bc.mu.Lock()
defer bc.mu.Unlock()
for block := bc.currentBlock; block != nil && block.Hash() != head.Hash(); block = bc.GetBlock(block.ParentHash()) {
bc.removeBlock(block)
}
bc.cache, _ = lru.New(blockCacheLimit)
bc.currentBlock = head
bc.makeCache()
statedb := state.New(head.Root(), bc.stateDb)
bc.txState = state.ManageState(statedb)
bc.transState = statedb.Copy()
bc.setTotalDifficulty(head.Td)
bc.insert(head)
bc.setLastState()
}
func (self *ChainManager) Td() *big.Int {
self.mu.RLock()
defer self.mu.RUnlock()
return new(big.Int).Set(self.td)
}
func (self *ChainManager) GasLimit() *big.Int {
self.mu.RLock()
defer self.mu.RUnlock()
return self.currentBlock.GasLimit()
}
func (self *ChainManager) LastBlockHash() common.Hash {
self.mu.RLock()
defer self.mu.RUnlock()
return self.lastBlockHash
}
func (self *ChainManager) CurrentBlock() *types.Block {
self.mu.RLock()
defer self.mu.RUnlock()
return self.currentBlock
}
func (self *ChainManager) Status() (td *big.Int, currentBlock common.Hash, genesisBlock common.Hash) {
self.mu.RLock()
defer self.mu.RUnlock()
return new(big.Int).Set(self.td), self.currentBlock.Hash(), self.genesisBlock.Hash()
}
func (self *ChainManager) SetProcessor(proc types.BlockProcessor) {
self.processor = proc
}
func (self *ChainManager) State() *state.StateDB {
return state.New(self.CurrentBlock().Root(), self.stateDb)
}
func (self *ChainManager) TransState() *state.StateDB {
self.tsmu.RLock()
defer self.tsmu.RUnlock()
return self.transState
}
func (self *ChainManager) setTransState(statedb *state.StateDB) {
self.transState = statedb
}
func (bc *ChainManager) setLastState() {
data, _ := bc.blockDb.Get([]byte("LastBlock"))
if len(data) != 0 {
block := bc.GetBlock(common.BytesToHash(data))
if block != nil {
bc.currentBlock = block
bc.lastBlockHash = block.Hash()
} else {
glog.Fatalf("Fatal. LastBlock not found. Please run removedb and resync")
}
} else {
bc.Reset()
}
bc.td = bc.currentBlock.Td
bc.currentGasLimit = CalcGasLimit(bc.currentBlock)
if glog.V(logger.Info) {
glog.Infof("Last block (#%v) %x TD=%v\n", bc.currentBlock.Number(), bc.currentBlock.Hash(), bc.td)
}
}
func (bc *ChainManager) makeCache() {
bc.cache, _ = lru.New(blockCacheLimit)
// load in last `blockCacheLimit` - 1 blocks. Last block is the current.
for _, block := range bc.GetBlocksFromHash(bc.currentBlock.Hash(), blockCacheLimit) {
bc.cache.Add(block.Hash(), block)
}
}
func (bc *ChainManager) Reset() {
bc.mu.Lock()
defer bc.mu.Unlock()
for block := bc.currentBlock; block != nil; block = bc.GetBlock(block.ParentHash()) {
bc.removeBlock(block)
}
bc.cache, _ = lru.New(blockCacheLimit)
// Prepare the genesis block
bc.write(bc.genesisBlock)
bc.insert(bc.genesisBlock)
bc.currentBlock = bc.genesisBlock
bc.makeCache()
bc.setTotalDifficulty(common.Big("0"))
}
func (bc *ChainManager) removeBlock(block *types.Block) {
bc.blockDb.Delete(append(blockHashPre, block.Hash().Bytes()...))
}
func (bc *ChainManager) ResetWithGenesisBlock(gb *types.Block) {
bc.mu.Lock()
defer bc.mu.Unlock()
for block := bc.currentBlock; block != nil; block = bc.GetBlock(block.ParentHash()) {
bc.removeBlock(block)
}
// Prepare the genesis block
gb.Td = gb.Difficulty()
bc.genesisBlock = gb
bc.write(bc.genesisBlock)
bc.insert(bc.genesisBlock)
bc.currentBlock = bc.genesisBlock
bc.makeCache()
bc.td = gb.Difficulty()
}
// Export writes the active chain to the given writer.
func (self *ChainManager) Export(w io.Writer) error {
if err := self.ExportN(w, uint64(0), self.currentBlock.NumberU64()); err != nil {
return err
}
return nil
}
// ExportN writes a subset of the active chain to the given writer.
func (self *ChainManager) ExportN(w io.Writer, first uint64, last uint64) error {
self.mu.RLock()
defer self.mu.RUnlock()
if first > last {
return fmt.Errorf("export failed: first (%d) is greater than last (%d)", first, last)
}
glog.V(logger.Info).Infof("exporting %d blocks...\n", last-first+1)
for nr := first; nr <= last; nr++ {
block := self.GetBlockByNumber(nr)
if block == nil {
return fmt.Errorf("export failed on #%d: not found", nr)
}
if err := block.EncodeRLP(w); err != nil {
return err
}
}
return nil
}
// insert injects a block into the current chain block chain. Note, this function
// assumes that the `mu` mutex is held!
func (bc *ChainManager) insert(block *types.Block) {
key := append(blockNumPre, block.Number().Bytes()...)
err := bc.blockDb.Put(key, block.Hash().Bytes())
if err != nil {
glog.Fatal("db write fail:", err)
}
err = bc.blockDb.Put([]byte("LastBlock"), block.Hash().Bytes())
if err != nil {
glog.Fatal("db write fail:", err)
}
bc.currentBlock = block
bc.lastBlockHash = block.Hash()
}
func (bc *ChainManager) write(block *types.Block) {
tstart := time.Now()
go func() {
enc, _ := rlp.EncodeToBytes((*types.StorageBlock)(block))
key := append(blockHashPre, block.Hash().Bytes()...)
err := bc.blockDb.Put(key, enc)
if err != nil {
glog.Fatal("db write fail:", err)
}
}()
if glog.V(logger.Debug) {
glog.Infof("wrote block #%v %s. Took %v\n", block.Number(), common.PP(block.Hash().Bytes()), time.Since(tstart))
}
}
// Accessors
func (bc *ChainManager) Genesis() *types.Block {
return bc.genesisBlock
}
// Block fetching methods
func (bc *ChainManager) HasBlock(hash common.Hash) bool {
if bc.cache.Contains(hash) {
return true
}
if bc.pendingBlocks != nil {
if block := bc.pendingBlocks.Get(hash); block != nil {
return true
}
}
data, _ := bc.blockDb.Get(append(blockHashPre, hash[:]...))
return len(data) != 0
}
func (self *ChainManager) GetBlockHashesFromHash(hash common.Hash, max uint64) (chain []common.Hash) {
block := self.GetBlock(hash)
if block == nil {
return
}
// XXX Could be optimised by using a different database which only holds hashes (i.e., linked list)
for i := uint64(0); i < max; i++ {
block = self.GetBlock(block.ParentHash())
if block == nil {
break
}
chain = append(chain, block.Hash())
if block.Number().Cmp(common.Big0) <= 0 {
break
}
}
return
}
func (self *ChainManager) GetBlock(hash common.Hash) *types.Block {
if block, ok := self.cache.Get(hash); ok {
return block.(*types.Block)
}
if self.pendingBlocks != nil {
if block := self.pendingBlocks.Get(hash); block != nil {
return block
}
}
data, _ := self.blockDb.Get(append(blockHashPre, hash[:]...))
if len(data) == 0 {
return nil
}
var block types.StorageBlock
if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
glog.V(logger.Error).Infof("invalid block RLP for hash %x: %v", hash, err)
return nil
}
// Add the block to the cache
self.cache.Add(hash, (*types.Block)(&block))
return (*types.Block)(&block)
}
func (self *ChainManager) GetBlockByNumber(num uint64) *types.Block {
self.mu.RLock()
defer self.mu.RUnlock()
return self.getBlockByNumber(num)
}
// GetBlocksFromHash returns the block corresponding to hash and up to n-1 ancestors.
func (self *ChainManager) GetBlocksFromHash(hash common.Hash, n int) (blocks []*types.Block) {
for i := 0; i < n; i++ {
block := self.GetBlock(hash)
if block == nil {
break
}
blocks = append(blocks, block)
hash = block.ParentHash()
}
return
}
// non blocking version
func (self *ChainManager) getBlockByNumber(num uint64) *types.Block {
key, _ := self.blockDb.Get(append(blockNumPre, big.NewInt(int64(num)).Bytes()...))
if len(key) == 0 {
return nil
}
return self.GetBlock(common.BytesToHash(key))
}
func (self *ChainManager) GetUnclesInChain(block *types.Block, length int) (uncles []*types.Header) {
for i := 0; block != nil && i < length; i++ {
uncles = append(uncles, block.Uncles()...)
block = self.GetBlock(block.ParentHash())
}
return
}
// setTotalDifficulty updates the TD of the chain manager. Note, this function
// assumes that the `mu` mutex is held!
func (bc *ChainManager) setTotalDifficulty(td *big.Int) {
bc.td = new(big.Int).Set(td)
}
func (bc *ChainManager) Stop() {
close(bc.quit)
atomic.StoreInt32(&bc.procInterrupt, 1)
bc.wg.Wait()
glog.V(logger.Info).Infoln("Chain manager stopped")
}
type queueEvent struct {
queue []interface{}
canonicalCount int
sideCount int
splitCount int
}
func (self *ChainManager) procFutureBlocks() {
var blocks []*types.Block
self.futureBlocks.Each(func(i int, block *types.Block) {
blocks = append(blocks, block)
})
if len(blocks) > 0 {
types.BlockBy(types.Number).Sort(blocks)
self.InsertChain(blocks)
}
}
func (self *ChainManager) enqueueForWrite(block *types.Block) {
self.pendingBlocks.Push(block)
}
func (self *ChainManager) flushQueuedBlocks() {
db, batchWrite := self.blockDb.(*ethdb.LDBDatabase)
batch := new(leveldb.Batch)
self.pendingBlocks.Each(func(i int, block *types.Block) {
enc, _ := rlp.EncodeToBytes((*types.StorageBlock)(block))
key := append(blockHashPre, block.Hash().Bytes()...)
if batchWrite {
batch.Put(key, rle.Compress(enc))
} else {
self.blockDb.Put(key, enc)
}
})
if batchWrite {
db.LDB().Write(batch, nil)
}
}
// InsertChain will attempt to insert the given chain in to the canonical chain or, otherwise, create a fork. It an error is returned
// it will return the index number of the failing block as well an error describing what went wrong (for possible errors see core/errors.go).
func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
self.wg.Add(1)
defer self.wg.Done()
self.chainmu.Lock()
defer self.chainmu.Unlock()
self.pendingBlocks = NewBlockCache(len(chain))
// A queued approach to delivering events. This is generally
// faster than direct delivery and requires much less mutex
// acquiring.
var (
queue = make([]interface{}, len(chain))
queueEvent = queueEvent{queue: queue}
stats struct{ queued, processed, ignored int }
tstart = time.Now()
nonceDone = make(chan nonceResult, len(chain))
nonceQuit = make(chan struct{})
nonceChecked = make([]bool, len(chain))
)
// Start the parallel nonce verifier.
go verifyNonces(self.pow, chain, nonceQuit, nonceDone)
defer close(nonceQuit)
defer self.flushQueuedBlocks()
txcount := 0
for i, block := range chain {
if atomic.LoadInt32(&self.procInterrupt) == 1 {
glog.V(logger.Debug).Infoln("Premature abort during chain processing")
break
}
bstart := time.Now()
// Wait for block i's nonce to be verified before processing
// its state transition.
for !nonceChecked[i] {
r := <-nonceDone
nonceChecked[r.i] = true
if !r.valid {
block := chain[r.i]
return r.i, &BlockNonceErr{Hash: block.Hash(), Number: block.Number(), Nonce: block.Nonce()}
}
}
if BadHashes[block.Hash()] {
err := fmt.Errorf("Found known bad hash in chain %x", block.Hash())
blockErr(block, err)
return i, err
}
// Setting block.Td regardless of error (known for example) prevents errors down the line
// in the protocol handler
block.Td = new(big.Int).Set(CalcTD(block, self.GetBlock(block.ParentHash())))
// Call in to the block processor and check for errors. It's likely that if one block fails
// all others will fail too (unless a known block is returned).
logs, err := self.processor.Process(block)
if err != nil {
if IsKnownBlockErr(err) {
stats.ignored++
continue
}
if err == BlockFutureErr {
// Allow up to MaxFuture second in the future blocks. If this limit
// is exceeded the chain is discarded and processed at a later time
// if given.
if max := time.Now().Unix() + maxTimeFutureBlocks; block.Time() > max {
return i, fmt.Errorf("%v: BlockFutureErr, %v > %v", BlockFutureErr, block.Time(), max)
}
self.futureBlocks.Push(block)
stats.queued++
continue
}
if IsParentErr(err) && self.futureBlocks.Has(block.ParentHash()) {
self.futureBlocks.Push(block)
stats.queued++
continue
}
blockErr(block, err)
return i, err
}
txcount += len(block.Transactions())
cblock := self.currentBlock
// Compare the TD of the last known block in the canonical chain to make sure it's greater.
// At this point it's possible that a different chain (fork) becomes the new canonical chain.
if block.Td.Cmp(self.Td()) > 0 {
// chain fork
if block.ParentHash() != cblock.Hash() {
// during split we merge two different chains and create the new canonical chain
err := self.merge(cblock, block)
if err != nil {
return i, err
}
queue[i] = ChainSplitEvent{block, logs}
queueEvent.splitCount++
}
self.mu.Lock()
self.setTotalDifficulty(block.Td)
self.insert(block)
self.mu.Unlock()
jsonlogger.LogJson(&logger.EthChainNewHead{
BlockHash: block.Hash().Hex(),
BlockNumber: block.Number(),
ChainHeadHash: cblock.Hash().Hex(),
BlockPrevHash: block.ParentHash().Hex(),
})
self.setTransState(state.New(block.Root(), self.stateDb))
self.txState.SetState(state.New(block.Root(), self.stateDb))
queue[i] = ChainEvent{block, block.Hash(), logs}
queueEvent.canonicalCount++
if glog.V(logger.Debug) {
glog.Infof("[%v] inserted block #%d (%d TXs %d UNCs) (%x...). Took %v\n", time.Now().UnixNano(), block.Number(), len(block.Transactions()), len(block.Uncles()), block.Hash().Bytes()[0:4], time.Since(bstart))
}
} else {
if glog.V(logger.Detail) {
glog.Infof("inserted forked block #%d (TD=%v) (%d TXs %d UNCs) (%x...). Took %v\n", block.Number(), block.Difficulty(), len(block.Transactions()), len(block.Uncles()), block.Hash().Bytes()[0:4], time.Since(bstart))
}
queue[i] = ChainSideEvent{block, logs}
queueEvent.sideCount++
}
self.enqueueForWrite(block)
// Delete from future blocks
self.futureBlocks.Delete(block.Hash())
stats.processed++
blockInsertTimer.UpdateSince(bstart)
}
if (stats.queued > 0 || stats.processed > 0 || stats.ignored > 0) && bool(glog.V(logger.Info)) {
tend := time.Since(tstart)
start, end := chain[0], chain[len(chain)-1]
glog.Infof("imported %d block(s) (%d queued %d ignored) including %d txs in %v. #%v [%x / %x]\n", stats.processed, stats.queued, stats.ignored, txcount, tend, end.Number(), start.Hash().Bytes()[:4], end.Hash().Bytes()[:4])
}
go self.eventMux.Post(queueEvent)
return 0, nil
}
// diff takes two blocks, an old chain and a new chain and will reconstruct the blocks and inserts them
// to be part of the new canonical chain.
func (self *ChainManager) diff(oldBlock, newBlock *types.Block) (types.Blocks, error) {
var (
newChain types.Blocks
commonBlock *types.Block
oldStart = oldBlock
newStart = newBlock
)
// first reduce whoever is higher bound
if oldBlock.NumberU64() > newBlock.NumberU64() {
// reduce old chain
for oldBlock = oldBlock; oldBlock != nil && oldBlock.NumberU64() != newBlock.NumberU64(); oldBlock = self.GetBlock(oldBlock.ParentHash()) {
}
} else {
// reduce new chain and append new chain blocks for inserting later on
for newBlock = newBlock; newBlock != nil && newBlock.NumberU64() != oldBlock.NumberU64(); newBlock = self.GetBlock(newBlock.ParentHash()) {
newChain = append(newChain, newBlock)
}
}
if oldBlock == nil {
return nil, fmt.Errorf("Invalid old chain")
}
if newBlock == nil {
return nil, fmt.Errorf("Invalid new chain")
}
numSplit := newBlock.Number()
for {
if oldBlock.Hash() == newBlock.Hash() {
commonBlock = oldBlock
break
}
newChain = append(newChain, newBlock)
oldBlock, newBlock = self.GetBlock(oldBlock.ParentHash()), self.GetBlock(newBlock.ParentHash())
if oldBlock == nil {
return nil, fmt.Errorf("Invalid old chain")
}
if newBlock == nil {
return nil, fmt.Errorf("Invalid new chain")
}
}
if glog.V(logger.Info) {
commonHash := commonBlock.Hash()
glog.Infof("Fork detected @ %x. Reorganising chain from #%v %x to %x", commonHash[:4], numSplit, oldStart.Hash().Bytes()[:4], newStart.Hash().Bytes()[:4])
}
return newChain, nil
}
// merge merges two different chain to the new canonical chain
func (self *ChainManager) merge(oldBlock, newBlock *types.Block) error {
newChain, err := self.diff(oldBlock, newBlock)
if err != nil {
return fmt.Errorf("chain reorg failed: %v", err)
}
// insert blocks. Order does not matter. Last block will be written in ImportChain itself which creates the new head properly
self.mu.Lock()
for _, block := range newChain {
self.insert(block)
}
self.mu.Unlock()
return nil
}
func (self *ChainManager) update() {
events := self.eventMux.Subscribe(queueEvent{})
futureTimer := time.Tick(5 * time.Second)
out:
for {
select {
case ev := <-events.Chan():
switch ev := ev.(type) {
case queueEvent:
for _, event := range ev.queue {
switch event := event.(type) {
case ChainEvent:
// We need some control over the mining operation. Acquiring locks and waiting for the miner to create new block takes too long
// and in most cases isn't even necessary.
if self.lastBlockHash == event.Hash {
self.currentGasLimit = CalcGasLimit(event.Block)
self.eventMux.Post(ChainHeadEvent{event.Block})
}
}
self.eventMux.Post(event)
}
}
case <-futureTimer:
self.procFutureBlocks()
case <-self.quit:
break out
}
}
}
func blockErr(block *types.Block, err error) {
h := block.Header()
glog.V(logger.Error).Infof("Bad block #%v (%x)\n", h.Number, h.Hash().Bytes())
glog.V(logger.Error).Infoln(err)
glog.V(logger.Debug).Infoln(verifyNonces)
}
type nonceResult struct {
i int
valid bool
}
// block verifies nonces of the given blocks in parallel and returns
// an error if one of the blocks nonce verifications failed.
func verifyNonces(pow pow.PoW, blocks []*types.Block, quit <-chan struct{}, done chan<- nonceResult) {
// Spawn a few workers. They listen for blocks on the in channel
// and send results on done. The workers will exit in the
// background when in is closed.
var (
in = make(chan int)
nworkers = runtime.GOMAXPROCS(0)
)
defer close(in)
if len(blocks) < nworkers {
nworkers = len(blocks)
}
for i := 0; i < nworkers; i++ {
go func() {
for i := range in {
done <- nonceResult{i: i, valid: pow.Verify(blocks[i])}
}
}()
}
// Feed block indices to the workers.
for i := range blocks {
select {
case in <- i:
continue
case <-quit:
return
}
}
}