// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package ethash
import (
"bytes"
crand "crypto/rand"
"encoding/json"
"errors"
"math"
"math/big"
"math/rand"
"net/http"
"runtime"
"sync"
"time"
"github.com/ava-labs/coreth/consensus"
"github.com/ava-labs/coreth/core/types"
"github.com/ava-labs/go-ethereum/common"
"github.com/ava-labs/go-ethereum/common/hexutil"
"github.com/ava-labs/go-ethereum/log"
)
const (
// staleThreshold is the maximum depth of the acceptable stale but valid ethash solution.
staleThreshold = 7
)
var (
errNoMiningWork = errors.New("no mining work available yet")
errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
)
// Seal implements consensus.Engine, attempting to find a nonce that satisfies
// the block's difficulty requirements.
func (ethash *Ethash) Seal(chain consensus.ChainReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
// If we're running a fake PoW, simply return a 0 nonce immediately
if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
header := block.Header()
header.Nonce, header.MixDigest = types.BlockNonce{}, common.Hash{}
select {
case results <- block.WithSeal(header):
default:
log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
}
return nil
}
// If we're running a shared PoW, delegate sealing to it
if ethash.shared != nil {
return ethash.shared.Seal(chain, block, results, stop)
}
// Create a runner and the multiple search threads it directs
abort := make(chan struct{})
ethash.lock.Lock()
threads := ethash.threads
if ethash.rand == nil {
seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
ethash.lock.Unlock()
return err
}
ethash.rand = rand.New(rand.NewSource(seed.Int64()))
}
ethash.lock.Unlock()
if threads == 0 {
threads = runtime.NumCPU()
}
if threads < 0 {
threads = 0 // Allows disabling local mining without extra logic around local/remote
}
// Push new work to remote sealer
if ethash.workCh != nil {
ethash.workCh <- &sealTask{block: block, results: results}
}
var (
pend sync.WaitGroup
locals = make(chan *types.Block)
)
for i := 0; i < threads; i++ {
pend.Add(1)
go func(id int, nonce uint64) {
defer pend.Done()
ethash.mine(block, id, nonce, abort, locals)
}(i, uint64(ethash.rand.Int63()))
}
// Wait until sealing is terminated or a nonce is found
go func() {
var result *types.Block
select {
case <-stop:
// Outside abort, stop all miner threads
close(abort)
case result = <-locals:
// One of the threads found a block, abort all others
select {
case results <- result:
default:
log.Warn("Sealing result is not read by miner", "mode", "local", "sealhash", ethash.SealHash(block.Header()))
}
close(abort)
case <-ethash.update:
// Thread count was changed on user request, restart
close(abort)
if err := ethash.Seal(chain, block, results, stop); err != nil {
log.Error("Failed to restart sealing after update", "err", err)
}
}
// Wait for all miners to terminate and return the block
pend.Wait()
}()
return nil
}
// mine is the actual proof-of-work miner that searches for a nonce starting from
// seed that results in correct final block difficulty.
func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
// Extract some data from the header
var (
header = block.Header()
hash = ethash.SealHash(header).Bytes()
target = new(big.Int).Div(two256, header.Difficulty)
number = header.Number.Uint64()
dataset = ethash.dataset(number, false)
)
// Start generating random nonces until we abort or find a good one
var (
attempts = int64(0)
nonce = seed
)
logger := log.New("miner", id)
logger.Trace("Started ethash search for new nonces", "seed", seed)
search:
for {
select {
case <-abort:
// Mining terminated, update stats and abort
logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
ethash.hashrate.Mark(attempts)
break search
default:
// We don't have to update hash rate on every nonce, so update after after 2^X nonces
attempts++
if (attempts % (1 << 15)) == 0 {
ethash.hashrate.Mark(attempts)
attempts = 0
}
// Compute the PoW value of this nonce
digest, result := hashimotoFull(dataset.dataset, hash, nonce)
if new(big.Int).SetBytes(result).Cmp(target) <= 0 {
// Correct nonce found, create a new header with it
header = types.CopyHeader(header)
header.Nonce = types.EncodeNonce(nonce)
header.MixDigest = common.BytesToHash(digest)
// Seal and return a block (if still needed)
select {
case found <- block.WithSeal(header):
logger.Trace("Ethash nonce found and reported", "attempts", nonce-seed, "nonce", nonce)
case <-abort:
logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
}
break search
}
nonce++
}
}
// Datasets are unmapped in a finalizer. Ensure that the dataset stays live
// during sealing so it's not unmapped while being read.
runtime.KeepAlive(dataset)
}
// remote is a standalone goroutine to handle remote mining related stuff.
func (ethash *Ethash) remote(notify []string, noverify bool) {
var (
works = make(map[common.Hash]*types.Block)
rates = make(map[common.Hash]hashrate)
results chan<- *types.Block
currentBlock *types.Block
currentWork [4]string
notifyTransport = &http.Transport{}
notifyClient = &http.Client{
Transport: notifyTransport,
Timeout: time.Second,
}
notifyReqs = make([]*http.Request, len(notify))
)
// notifyWork notifies all the specified mining endpoints of the availability of
// new work to be processed.
notifyWork := func() {
work := currentWork
blob, _ := json.Marshal(work)
for i, url := range notify {
// Terminate any previously pending request and create the new work
if notifyReqs[i] != nil {
notifyTransport.CancelRequest(notifyReqs[i])
}
notifyReqs[i], _ = http.NewRequest("POST", url, bytes.NewReader(blob))
notifyReqs[i].Header.Set("Content-Type", "application/json")
// Push the new work concurrently to all the remote nodes
go func(req *http.Request, url string) {
res, err := notifyClient.Do(req)
if err != nil {
log.Warn("Failed to notify remote miner", "err", err)
} else {
log.Trace("Notified remote miner", "miner", url, "hash", log.Lazy{Fn: func() common.Hash { return common.HexToHash(work[0]) }}, "target", work[2])
res.Body.Close()
}
}(notifyReqs[i], url)
}
}
// makeWork creates a work package for external miner.
//
// The work package consists of 3 strings:
// result[0], 32 bytes hex encoded current block header pow-hash
// result[1], 32 bytes hex encoded seed hash used for DAG
//