1 files changed, 371 insertions, 0 deletions
diff --git a/consensus/ethash/sealer.go b/consensus/ethash/sealer.go
new file mode 100644
index 0000000..799be05
--- /dev/null
+++ b/consensus/ethash/sealer.go
@@ -0,0 +1,371 @@
+// 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
+	//   result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
+	//   result[3], hex encoded block number
+	makeWork := func(block *types.Block) {
+		hash := ethash.SealHash(block.Header())
+
+		currentWork[0] = hash.Hex()
+		currentWork[1] = common.BytesToHash(SeedHash(block.NumberU64())).Hex()
+		currentWork[2] = common.BytesToHash(new(big.Int).Div(two256, block.Difficulty()).Bytes()).Hex()
+		currentWork[3] = hexutil.EncodeBig(block.Number())
+
+		// Trace the seal work fetched by remote sealer.
+		currentBlock = block
+		works[hash] = block
+	}
+	// submitWork verifies the submitted pow solution, returning
+	// whether the solution was accepted or not (not can be both a bad pow as well as
+	// any other error, like no pending work or stale mining result).
+	submitWork := func(nonce types.BlockNonce, mixDigest common.Hash, sealhash common.Hash) bool {
+		if currentBlock == nil {
+			log.Error("Pending work without block", "sealhash", sealhash)
+			return false
+		}
+		// Make sure the work submitted is present
+		block := works[sealhash]
+		if block == nil {
+			log.Warn("Work submitted but none pending", "sealhash", sealhash, "curnumber", currentBlock.NumberU64())
+			return false
+		}
+		// Verify the correctness of submitted result.
+		header := block.Header()
+		header.Nonce = nonce
+		header.MixDigest = mixDigest
+
+		start := time.Now()
+		if !noverify {
+			if err := ethash.verifySeal(nil, header, true); err != nil {
+				log.Warn("Invalid proof-of-work submitted", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)), "err", err)
+				return false
+			}
+		}
+		// Make sure the result channel is assigned.
+		if results == nil {
+			log.Warn("Ethash result channel is empty, submitted mining result is rejected")
+			return false
+		}
+		log.Trace("Verified correct proof-of-work", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)))
+
+		// Solutions seems to be valid, return to the miner and notify acceptance.
+		solution := block.WithSeal(header)
+
+		// The submitted solution is within the scope of acceptance.
+		if solution.NumberU64()+staleThreshold > currentBlock.NumberU64() {
+			select {
+			case results <- solution:
+				log.Debug("Work submitted is acceptable", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
+				return true
+			default:
+				log.Warn("Sealing result is not read by miner", "mode", "remote", "sealhash", sealhash)
+				return false
+			}
+		}
+		// The submitted block is too old to accept, drop it.
+		log.Warn("Work submitted is too old", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
+		return false
+	}
+
+	ticker := time.NewTicker(5 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case work := <-ethash.workCh:
+			// Update current work with new received block.
+			// Note same work can be past twice, happens when changing CPU threads.
+			results = work.results
+
+			makeWork(work.block)
+
+			// Notify and requested URLs of the new work availability
+			notifyWork()
+
+		case work := <-ethash.fetchWorkCh:
+			// Return current mining work to remote miner.
+			if currentBlock == nil {
+				work.errc <- errNoMiningWork
+			} else {
+				work.res <- currentWork
+			}
+
+		case result := <-ethash.submitWorkCh:
+			// Verify submitted PoW solution based on maintained mining blocks.
+			if submitWork(result.nonce, result.mixDigest, result.hash) {
+				result.errc <- nil
+			} else {
+				result.errc <- errInvalidSealResult
+			}
+
+		case result := <-ethash.submitRateCh:
+			// Trace remote sealer's hash rate by submitted value.
+			rates[result.id] = hashrate{rate: result.rate, ping: time.Now()}
+			close(result.done)
+
+		case req := <-ethash.fetchRateCh:
+			// Gather all hash rate submitted by remote sealer.
+			var total uint64
+			for _, rate := range rates {
+				// this could overflow
+				total += rate.rate
+			}
+			req <- total
+
+		case <-ticker.C:
+			// Clear stale submitted hash rate.
+			for id, rate := range rates {
+				if time.Since(rate.ping) > 10*time.Second {
+					delete(rates, id)
+				}
+			}
+			// Clear stale pending blocks
+			if currentBlock != nil {
+				for hash, block := range works {
+					if block.NumberU64()+staleThreshold <= currentBlock.NumberU64() {
+						delete(works, hash)
+					}
+				}
+			}
+
+		case errc := <-ethash.exitCh:
+			// Exit remote loop if ethash is closed and return relevant error.
+			errc <- nil
+			log.Trace("Ethash remote sealer is exiting")
+			return
+		}
+	}
+}