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451 lines
14 KiB
451 lines
14 KiB
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package ethash
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import (
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"bytes"
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"context"
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crand "crypto/rand"
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"encoding/json"
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"errors"
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"math"
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"math/big"
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"math/rand"
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"net/http"
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"runtime"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/hexutil"
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"github.com/ethereum/go-ethereum/consensus"
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"github.com/ethereum/go-ethereum/core/types"
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)
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const (
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// staleThreshold is the maximum depth of the acceptable stale but valid ethash solution.
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staleThreshold = 7
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)
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var (
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errNoMiningWork = errors.New("no mining work available yet")
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errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
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)
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// Seal implements consensus.Engine, attempting to find a nonce that satisfies
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// the block's difficulty requirements.
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func (ethash *Ethash) Seal(chain consensus.ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
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// If we're running a fake PoW, simply return a 0 nonce immediately
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if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
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header := block.Header()
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header.Nonce, header.MixDigest = types.BlockNonce{}, common.Hash{}
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select {
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case results <- block.WithSeal(header):
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default:
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ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
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}
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return nil
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}
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// If we're running a shared PoW, delegate sealing to it
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if ethash.shared != nil {
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return ethash.shared.Seal(chain, block, results, stop)
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}
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// Create a runner and the multiple search threads it directs
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abort := make(chan struct{})
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ethash.lock.Lock()
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threads := ethash.threads
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if ethash.rand == nil {
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seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
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if err != nil {
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ethash.lock.Unlock()
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return err
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}
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ethash.rand = rand.New(rand.NewSource(seed.Int64()))
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}
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ethash.lock.Unlock()
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if threads == 0 {
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threads = runtime.NumCPU()
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}
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if threads < 0 {
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threads = 0 // Allows disabling local mining without extra logic around local/remote
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}
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// Push new work to remote sealer
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if ethash.remote != nil {
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ethash.remote.workCh <- &sealTask{block: block, results: results}
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}
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var (
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pend sync.WaitGroup
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locals = make(chan *types.Block)
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)
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for i := 0; i < threads; i++ {
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pend.Add(1)
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go func(id int, nonce uint64) {
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defer pend.Done()
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ethash.mine(block, id, nonce, abort, locals)
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}(i, uint64(ethash.rand.Int63()))
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}
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// Wait until sealing is terminated or a nonce is found
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go func() {
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var result *types.Block
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select {
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case <-stop:
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// Outside abort, stop all miner threads
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close(abort)
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case result = <-locals:
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// One of the threads found a block, abort all others
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select {
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case results <- result:
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default:
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ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "local", "sealhash", ethash.SealHash(block.Header()))
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}
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close(abort)
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case <-ethash.update:
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// Thread count was changed on user request, restart
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close(abort)
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if err := ethash.Seal(chain, block, results, stop); err != nil {
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ethash.config.Log.Error("Failed to restart sealing after update", "err", err)
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}
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}
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// Wait for all miners to terminate and return the block
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pend.Wait()
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}()
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return nil
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}
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// mine is the actual proof-of-work miner that searches for a nonce starting from
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// seed that results in correct final block difficulty.
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func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
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// Extract some data from the header
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var (
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header = block.Header()
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hash = ethash.SealHash(header).Bytes()
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target = new(big.Int).Div(two256, header.Difficulty)
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number = header.Number.Uint64()
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dataset = ethash.dataset(number, false)
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)
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// Start generating random nonces until we abort or find a good one
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var (
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attempts = int64(0)
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nonce = seed
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powBuffer = new(big.Int)
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)
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logger := ethash.config.Log.New("miner", id)
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logger.Trace("Started ethash search for new nonces", "seed", seed)
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search:
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for {
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select {
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case <-abort:
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// Mining terminated, update stats and abort
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logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
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ethash.hashrate.Mark(attempts)
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break search
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default:
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// We don't have to update hash rate on every nonce, so update after after 2^X nonces
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attempts++
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if (attempts % (1 << 15)) == 0 {
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ethash.hashrate.Mark(attempts)
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attempts = 0
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}
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// Compute the PoW value of this nonce
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digest, result := hashimotoFull(dataset.dataset, hash, nonce)
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if powBuffer.SetBytes(result).Cmp(target) <= 0 {
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// Correct nonce found, create a new header with it
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header = types.CopyHeader(header)
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header.Nonce = types.EncodeNonce(nonce)
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header.MixDigest = common.BytesToHash(digest)
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// Seal and return a block (if still needed)
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select {
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case found <- block.WithSeal(header):
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logger.Trace("Ethash nonce found and reported", "attempts", nonce-seed, "nonce", nonce)
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case <-abort:
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logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
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}
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break search
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}
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nonce++
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}
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}
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// Datasets are unmapped in a finalizer. Ensure that the dataset stays live
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// during sealing so it's not unmapped while being read.
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runtime.KeepAlive(dataset)
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}
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// This is the timeout for HTTP requests to notify external miners.
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const remoteSealerTimeout = 1 * time.Second
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type remoteSealer struct {
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works map[common.Hash]*types.Block
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rates map[common.Hash]hashrate
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currentBlock *types.Block
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currentWork [4]string
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notifyCtx context.Context
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cancelNotify context.CancelFunc // cancels all notification requests
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reqWG sync.WaitGroup // tracks notification request goroutines
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ethash *Ethash
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noverify bool
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notifyURLs []string
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results chan<- *types.Block
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workCh chan *sealTask // Notification channel to push new work and relative result channel to remote sealer
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fetchWorkCh chan *sealWork // Channel used for remote sealer to fetch mining work
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submitWorkCh chan *mineResult // Channel used for remote sealer to submit their mining result
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fetchRateCh chan chan uint64 // Channel used to gather submitted hash rate for local or remote sealer.
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submitRateCh chan *hashrate // Channel used for remote sealer to submit their mining hashrate
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requestExit chan struct{}
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exitCh chan struct{}
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}
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// sealTask wraps a seal block with relative result channel for remote sealer thread.
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type sealTask struct {
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block *types.Block
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results chan<- *types.Block
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}
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// mineResult wraps the pow solution parameters for the specified block.
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type mineResult struct {
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nonce types.BlockNonce
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mixDigest common.Hash
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hash common.Hash
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errc chan error
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}
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// hashrate wraps the hash rate submitted by the remote sealer.
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type hashrate struct {
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id common.Hash
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ping time.Time
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rate uint64
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done chan struct{}
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}
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// sealWork wraps a seal work package for remote sealer.
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type sealWork struct {
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errc chan error
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res chan [4]string
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}
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func startRemoteSealer(ethash *Ethash, urls []string, noverify bool) *remoteSealer {
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ctx, cancel := context.WithCancel(context.Background())
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s := &remoteSealer{
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ethash: ethash,
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noverify: noverify,
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notifyURLs: urls,
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notifyCtx: ctx,
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cancelNotify: cancel,
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works: make(map[common.Hash]*types.Block),
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rates: make(map[common.Hash]hashrate),
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workCh: make(chan *sealTask),
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fetchWorkCh: make(chan *sealWork),
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submitWorkCh: make(chan *mineResult),
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fetchRateCh: make(chan chan uint64),
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submitRateCh: make(chan *hashrate),
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requestExit: make(chan struct{}),
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exitCh: make(chan struct{}),
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}
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go s.loop()
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return s
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}
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func (s *remoteSealer) loop() {
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defer func() {
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s.ethash.config.Log.Trace("Ethash remote sealer is exiting")
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s.cancelNotify()
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s.reqWG.Wait()
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close(s.exitCh)
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}()
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ticker := time.NewTicker(5 * time.Second)
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defer ticker.Stop()
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for {
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select {
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case work := <-s.workCh:
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// Update current work with new received block.
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// Note same work can be past twice, happens when changing CPU threads.
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s.results = work.results
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s.makeWork(work.block)
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s.notifyWork()
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case work := <-s.fetchWorkCh:
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// Return current mining work to remote miner.
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if s.currentBlock == nil {
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work.errc <- errNoMiningWork
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} else {
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work.res <- s.currentWork
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}
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case result := <-s.submitWorkCh:
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// Verify submitted PoW solution based on maintained mining blocks.
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if s.submitWork(result.nonce, result.mixDigest, result.hash) {
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result.errc <- nil
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} else {
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result.errc <- errInvalidSealResult
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}
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case result := <-s.submitRateCh:
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// Trace remote sealer's hash rate by submitted value.
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s.rates[result.id] = hashrate{rate: result.rate, ping: time.Now()}
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close(result.done)
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case req := <-s.fetchRateCh:
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// Gather all hash rate submitted by remote sealer.
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var total uint64
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for _, rate := range s.rates {
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// this could overflow
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total += rate.rate
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}
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req <- total
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case <-ticker.C:
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// Clear stale submitted hash rate.
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for id, rate := range s.rates {
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if time.Since(rate.ping) > 10*time.Second {
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delete(s.rates, id)
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}
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}
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// Clear stale pending blocks
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if s.currentBlock != nil {
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for hash, block := range s.works {
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if block.NumberU64()+staleThreshold <= s.currentBlock.NumberU64() {
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delete(s.works, hash)
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}
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}
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}
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case <-s.requestExit:
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return
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}
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}
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}
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// makeWork creates a work package for external miner.
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//
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// The work package consists of 3 strings:
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//
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// result[0], 32 bytes hex encoded current block header pow-hash
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// result[1], 32 bytes hex encoded seed hash used for DAG
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// result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
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// result[3], hex encoded block number
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func (s *remoteSealer) makeWork(block *types.Block) {
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hash := s.ethash.SealHash(block.Header())
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s.currentWork[0] = hash.Hex()
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s.currentWork[1] = common.BytesToHash(SeedHash(block.NumberU64())).Hex()
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s.currentWork[2] = common.BytesToHash(new(big.Int).Div(two256, block.Difficulty()).Bytes()).Hex()
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s.currentWork[3] = hexutil.EncodeBig(block.Number())
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// Trace the seal work fetched by remote sealer.
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s.currentBlock = block
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s.works[hash] = block
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}
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// notifyWork notifies all the specified mining endpoints of the availability of
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// new work to be processed.
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func (s *remoteSealer) notifyWork() {
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work := s.currentWork
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// Encode the JSON payload of the notification. When NotifyFull is set,
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// this is the complete block header, otherwise it is a JSON array.
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var blob []byte
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if s.ethash.config.NotifyFull {
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blob, _ = json.Marshal(s.currentBlock.Header())
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} else {
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blob, _ = json.Marshal(work)
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}
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s.reqWG.Add(len(s.notifyURLs))
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for _, url := range s.notifyURLs {
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go s.sendNotification(s.notifyCtx, url, blob, work)
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}
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}
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func (s *remoteSealer) sendNotification(ctx context.Context, url string, json []byte, work [4]string) {
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defer s.reqWG.Done()
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req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(json))
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if err != nil {
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s.ethash.config.Log.Warn("Can't create remote miner notification", "err", err)
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return
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}
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ctx, cancel := context.WithTimeout(ctx, remoteSealerTimeout)
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defer cancel()
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req = req.WithContext(ctx)
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req.Header.Set("Content-Type", "application/json")
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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s.ethash.config.Log.Warn("Failed to notify remote miner", "err", err)
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} else {
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s.ethash.config.Log.Trace("Notified remote miner", "miner", url, "hash", work[0], "target", work[2])
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resp.Body.Close()
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}
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}
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// submitWork verifies the submitted pow solution, returning
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// whether the solution was accepted or not (not can be both a bad pow as well as
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// any other error, like no pending work or stale mining result).
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func (s *remoteSealer) submitWork(nonce types.BlockNonce, mixDigest common.Hash, sealhash common.Hash) bool {
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if s.currentBlock == nil {
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s.ethash.config.Log.Error("Pending work without block", "sealhash", sealhash)
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return false
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}
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// Make sure the work submitted is present
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block := s.works[sealhash]
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if block == nil {
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s.ethash.config.Log.Warn("Work submitted but none pending", "sealhash", sealhash, "curnumber", s.currentBlock.NumberU64())
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return false
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}
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// Verify the correctness of submitted result.
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header := block.Header()
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header.Nonce = nonce
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header.MixDigest = mixDigest
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start := time.Now()
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if !s.noverify {
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if err := s.ethash.verifySeal(nil, header, true); err != nil {
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s.ethash.config.Log.Warn("Invalid proof-of-work submitted", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)), "err", err)
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return false
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}
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}
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// Make sure the result channel is assigned.
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if s.results == nil {
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s.ethash.config.Log.Warn("Ethash result channel is empty, submitted mining result is rejected")
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return false
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}
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s.ethash.config.Log.Trace("Verified correct proof-of-work", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)))
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// Solutions seems to be valid, return to the miner and notify acceptance.
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solution := block.WithSeal(header)
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// The submitted solution is within the scope of acceptance.
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if solution.NumberU64()+staleThreshold > s.currentBlock.NumberU64() {
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select {
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case s.results <- solution:
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s.ethash.config.Log.Debug("Work submitted is acceptable", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
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return true
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default:
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s.ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "remote", "sealhash", sealhash)
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return false
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}
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}
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// The submitted block is too old to accept, drop it.
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s.ethash.config.Log.Warn("Work submitted is too old", "number", solution.NumberU64(), "sealhash", sealhash, "hash", solution.Hash())
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return false
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}
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