path: root/miner/worker.go

// Copyright 2015 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 miner

import (
    "bytes"
    "fmt"
    "math/big"
    "sync"
    "sync/atomic"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/consensus"
    "github.com/ethereum/go-ethereum/consensus/misc"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/core/vm"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/params"
    "gopkg.in/fatih/set.v0"
)

const (
    resultQueueSize  = 10
    miningLogAtDepth = 5

    // txChanSize is the size of channel listening to TxPreEvent.
    // The number is referenced from the size of tx pool.
    txChanSize = 4096
    // chainHeadChanSize is the size of channel listening to ChainHeadEvent.
    chainHeadChanSize = 10
    // chainSideChanSize is the size of channel listening to ChainSideEvent.
    chainSideChanSize = 10
)

// Agent can register themself with the worker
type Agent interface {
    Work() chan<- *Work
    SetReturnCh(chan<- *Result)
    Stop()
    Start()
    GetHashRate() int64
}

// Work is the workers current environment and holds
// all of the current state information
type Work struct {
    config *params.ChainConfig
    signer types.Signer

    state     *state.StateDB // apply state changes here
    ancestors *set.Set       // ancestor set (used for checking uncle parent validity)
    family    *set.Set       // family set (used for checking uncle invalidity)
    uncles    *set.Set       // uncle set
    tcount    int            // tx count in cycle

    Block *types.Block // the new block

    header   *types.Header
    txs      []*types.Transaction
    receipts []*types.Receipt

    createdAt time.Time
}

type Result struct {
    Work  *Work
    Block *types.Block
}

// worker is the main object which takes care of applying messages to the new state
type worker struct {
    config *params.ChainConfig
    engine consensus.Engine

    mu sync.Mutex

    // update loop
    mux          *event.TypeMux
    txCh         chan core.TxPreEvent
    txSub        event.Subscription
    chainHeadCh  chan core.ChainHeadEvent
    chainHeadSub event.Subscription
    chainSideCh  chan core.ChainSideEvent
    chainSideSub event.Subscription
    wg           sync.WaitGroup

    agents map[Agent]struct{}
    recv   chan *Result

    eth     Backend
    chain   *core.BlockChain
    proc    core.Validator
    chainDb ethdb.Database

    coinbase common.Address
    extra    []byte

    currentMu sync.Mutex
    current   *Work

    snapshotMu    sync.RWMutex
    snapshotBlock *types.Block
    snapshotState *state.StateDB

    uncleMu        sync.Mutex
    possibleUncles map[common.Hash]*types.Block

    unconfirmed *unconfirmedBlocks // set of locally mined blocks pending canonicalness confirmations

    // atomic status counters
    mining int32
    atWork int32
}

func newWorker(config *params.ChainConfig, engine consensus.Engine, coinbase common.Address, eth Backend, mux *event.TypeMux) *worker {
    worker := &worker{
        config:         config,
        engine:         engine,
        eth:            eth,
        mux:            mux,
        txCh:           make(chan core.TxPreEvent, txChanSize),
        chainHeadCh:    make(chan core.ChainHeadEvent, chainHeadChanSize),
        chainSideCh:    make(chan core.ChainSideEvent, chainSideChanSize),
        chainDb:        eth.ChainDb(),
        recv:           make(chan *Result, resultQueueSize),
        chain:          eth.BlockChain(),
        proc:           eth.BlockChain().Validator(),
        possibleUncles: make(map[common.Hash]*types.Block),
        coinbase:       coinbase,
        agents:         make(map[Agent]struct{}),
        unconfirmed:    newUnconfirmedBlocks(eth.BlockChain(), miningLogAtDepth),
    }
    // Subscribe TxPreEvent for tx pool
    worker.txSub = eth.TxPool().SubscribeTxPreEvent(worker.txCh)
    // Subscribe events for blockchain
    worker.chainHeadSub = eth.BlockChain().SubscribeChainHeadEvent(worker.chainHeadCh)
    worker.chainSideSub = eth.BlockChain().SubscribeChainSideEvent(worker.chainSideCh)
    go worker.update()

    go worker.wait()
    worker.commitNewWork()

    return worker
}

func (self *worker) setEtherbase(addr common.Address) {
    self.mu.Lock()
    defer self.mu.Unlock()
    self.coinbase = addr
}

func (self *worker) setExtra(extra []byte) {
    self.mu.Lock()
    defer self.mu.Unlock()
    self.extra = extra
}

func (self *worker) pending() (*types.Block, *state.StateDB) {
    if atomic.LoadInt32(&self.mining) == 0 {
        // return a snapshot to avoid contention on currentMu mutex
        self.snapshotMu.RLock()
        defer self.snapshotMu.RUnlock()
        return self.snapshotBlock, self.snapshotState.Copy()
    }

    self.currentMu.Lock()
    defer self.currentMu.Unlock()
    return self.current.Block, self.current.state.Copy()
}

func (self *worker) pendingBlock() *types.Block {
    if atomic.LoadInt32(&self.mining) == 0 {
        // return a snapshot to avoid contention on currentMu mutex
        self.snapshotMu.RLock()
        defer self.snapshotMu.RUnlock()
        return self.snapshotBlock
    }

    self.currentMu.Lock()
    defer self.currentMu.Unlock()
    return self.current.Block
}

func (self *worker) start() {
    self.mu.Lock()
    defer self.mu.Unlock()

    atomic.StoreInt32(&self.mining, 1)

    // spin up agents
    for agent := range self.agents {
        agent.Start()
    }
}

func (self *worker) stop() {
    self.wg.Wait()

    self.mu.Lock()
    defer self.mu.Unlock()
    if atomic.LoadInt32(&self.mining) == 1 {
        for agent := range self.agents {
            agent.Stop()
        }
    }
    atomic.StoreInt32(&self.mining, 0)
    atomic.StoreInt32(&self.atWork, 0)
}

func (self *worker) register(agent Agent) {
    self.mu.Lock()
    defer self.mu.Unlock()
    self.agents[agent] = struct{}{}
    agent.SetReturnCh(self.recv)
}

func (self *worker) unregister(agent Agent) {
    self.mu.Lock()
    defer self.mu.Unlock()
    delete(self.agents, agent)
    agent.Stop()
}

func (self *worker) update() {
    defer self.txSub.Unsubscribe()
    defer self.chainHeadSub.Unsubscribe()
    defer self.chainSideSub.Unsubscribe()

    for {
        // A real event arrived, process interesting content
        select {
        // Handle ChainHeadEvent
        case <-self.chainHeadCh:
            self.commitNewWork()

        // Handle ChainSideEvent
        case ev := <-self.chainSideCh:
            self.uncleMu.Lock()
            self.possibleUncles[ev.Block.Hash()] = ev.Block
            self.uncleMu.Unlock()

        // Handle TxPreEvent
        case ev := <-self.txCh:
            // Apply transaction to the pending state if we're not mining
            if atomic.LoadInt32(&self.mining) == 0 {
                self.currentMu.Lock()
                acc, _ := types.Sender(self.current.signer, ev.Tx)
                txs := map[common.Address]types.Transactions{acc: {ev.Tx}}
                txset := types.NewTransactionsByPriceAndNonce(self.current.signer, txs)

                self.current.commitTransactions(self.mux, txset, self.chain, self.coinbase)
                self.updateSnapshot()
                self.currentMu.Unlock()
            } else {
                // If we're mining, but nothing is being processed, wake on new transactions
                if self.config.Clique != nil && self.config.Clique.Period == 0 {
                    self.commitNewWork()
                }
            }

        // System stopped
        case <-self.txSub.Err():
            return
        case <-self.chainHeadSub.Err():
            return
        case <-self.chainSideSub.Err():
            return
        }
    }
}

func (self *worker) wait() {
    for {
        mustCommitNewWork := true
        for result := range self.recv {
            atomic.AddInt32(&self.atWork, -1)

            if result == nil {
                continue
            }
            block := result.Block
            work := result.Work

            // Update the block hash in all logs since it is now available and not when the
            // receipt/log of individual transactions were created.
            for _, r := range work.receipts {
                for _, l := range r.Logs {
                    l.BlockHash = block.Hash()
                }
            }
            for _, log := range work.state.Logs() {
                log.BlockHash = block.Hash()
            }
            stat, err := self.chain.WriteBlockWithState(block, work.receipts, work.state)
            if err != nil {
                log.Error("Failed writing block to chain", "err", err)
                continue
            }
            // check if canon block and write transactions
            if stat == core.CanonStatTy {
                // implicit by posting ChainHeadEvent
                mustCommitNewWork = false
            }
            // Broadcast the block and announce chain insertion event
            self.mux.Post(core.NewMinedBlockEvent{Block: block})
            var (
                events []interface{}
                logs   = work.state.Logs()
            )
            events = append(events, core.ChainEvent{Block: block, Hash: block.Hash(), Logs: logs})
            if stat == core.CanonStatTy {
                events = append(events, core.ChainHeadEvent{Block: block})
            }
            self.chain.PostChainEvents(events, logs)

            // Insert the block into the set of pending ones to wait for confirmations
            self.unconfirmed.Insert(block.NumberU64(), block.Hash())

            if mustCommitNewWork {
                self.commitNewWork()
            }
        }
    }
}

// push sends a new work task to currently live miner agents.
func (self *worker) push(work *Work) {
    if atomic.LoadInt32(&self.mining) != 1 {
        return
    }
    for agent := range self.agents {
        atomic.AddInt32(&self.atWork, 1)
        if ch := agent.Work(); ch != nil {
            ch <- work
        }
    }
}

// makeCurrent creates a new environment for the current cycle.
func (self *worker) makeCurrent(parent *types.Block, header *types.Header) error {
    state, err := self.chain.StateAt(parent.Root())
    if err != nil {
        return err
    }
    work := &Work{
        config:    self.config,
        signer:    types.NewEIP155Signer(self.config.ChainId),
        state:     state,
        ancestors: set.New(),
        family:    set.New(),
        uncles:    set.New(),
        header:    header,
        createdAt: time.Now(),
    }

    // when 08 is processed ancestors contain 07 (quick block)
    for _, ancestor := range self.chain.GetBlocksFromHash(parent.Hash(), 7) {
        for _, uncle := range ancestor.Uncles() {
            work.family.Add(uncle.Hash())
        }
        work.family.Add(ancestor.Hash())
        work.ancestors.Add(ancestor.Hash())
    }

    // Keep track of transactions which return errors so they can be removed
    work.tcount = 0
    self.current = work
    return nil
}

func (self *worker) commitNewWork() {
    self.mu.Lock()
    defer self.mu.Unlock()
    self.uncleMu.Lock()
    defer self.uncleMu.Unlock()
    self.currentMu.Lock()
    defer self.currentMu.Unlock()

    tstart := time.Now()
    parent := self.chain.CurrentBlock()

    tstamp := tstart.Unix()
    if parent.Time().Cmp(new(big.Int).SetInt64(tstamp)) >= 0 {
        tstamp = parent.Time().Int64() + 1
    }
    // this will ensure we're not going off too far in the future
    if now := time.Now().Unix(); tstamp > now+1 {
        wait := time.Duration(tstamp-now) * time.Second
        log.Info("Mining too far in the future", "wait", common.PrettyDuration(wait))
        time.Sleep(wait)
    }

    num := parent.Number()
    header := &types.Header{
        ParentHash: parent.Hash(),
        Number:     num.Add(num, common.Big1),
        GasLimit:   core.CalcGasLimit(parent),
        Extra:      self.extra,
        Time:       big.NewInt(tstamp),
    }
    // Only set the coinbase if we are mining (avoid spurious block rewards)
    if atomic.LoadInt32(&self.mining) == 1 {
        header.Coinbase = self.coinbase
    }
    if err := self.engine.Prepare(self.chain, header); err != nil {
        log.Error("Failed to prepare header for mining", "err", err)
        return
    }
    // If we are care about TheDAO hard-fork check whether to override the extra-data or not
    if daoBlock := self.config.DAOForkBlock; daoBlock != nil {
        // Check whether the block is among the fork extra-override range
        limit := new(big.Int).Add(daoBlock, params.DAOForkExtraRange)
        if header.Number.Cmp(daoBlock) >= 0 && header.Number.Cmp(limit) < 0 {
            // Depending whether we support or oppose the fork, override differently
            if self.config.DAOForkSupport {
                header.Extra = common.CopyBytes(params.DAOForkBlockExtra)
            } else if bytes.Equal(header.Extra, params.DAOForkBlockExtra) {
                header.Extra = []byte{} // If miner opposes, don't let it use the reserved extra-data
            }
        }
    }
    // Could potentially happen if starting to mine in an odd state.
    err := self.makeCurrent(parent, header)
    if err != nil {
        log.Error("Failed to create mining context", "err", err)
        return
    }
    // Create the current work task and check any fork transitions needed
    work := self.current
    if self.config.DAOForkSupport && self.config.DAOForkBlock != nil && self.config.DAOForkBlock.Cmp(header.Number) == 0 {
        misc.ApplyDAOHardFork(work.state)
    }
    pending, err := self.eth.TxPool().Pending()
    if err != nil {
        log.Error("Failed to fetch pending transactions", "err", err)
        return
    }
    txs := types.NewTransactionsByPriceAndNonce(self.current.signer, pending)
    work.commitTransactions(self.mux, txs, self.chain, self.coinbase)

    // compute uncles for the new block.
    var (
        uncles    []*types.Header
        badUncles []common.Hash
    )
    for hash, uncle := range self.possibleUncles {
        if len(uncles) == 2 {
            break
        }
        if err := self.commitUncle(work, uncle.Header()); err != nil {
            log.Trace("Bad uncle found and will be removed", "hash", hash)
            log.Trace(fmt.Sprint(uncle))

            badUncles = append(badUncles, hash)
        } else {
            log.Debug("Committing new uncle to block", "hash", hash)
            uncles = append(uncles, uncle.Header())
        }
    }
    for _, hash := range badUncles {
        delete(self.possibleUncles, hash)
    }
    // Create the new block to seal with the consensus engine
    if work.Block, err = self.engine.Finalize(self.chain, header, work.state, work.txs, uncles, work.receipts); err != nil {
        log.Error("Failed to finalize block for sealing", "err", err)
        return
    }
    // We only care about logging if we're actually mining.
    if atomic.LoadInt32(&self.mining) == 1 {
        log.Info("Commit new mining work", "number", work.Block.Number(), "txs", work.tcount, "uncles", len(uncles), "elapsed", common.PrettyDuration(time.Since(tstart)))
        self.unconfirmed.Shift(work.Block.NumberU64() - 1)
    }
    self.push(work)
    self.updateSnapshot()
}

func (self *worker) commitUncle(work *Work, uncle *types.Header) error {
    hash := uncle.Hash()
    if work.uncles.Has(hash) {
        return fmt.Errorf("uncle not unique")
    }
    if !work.ancestors.Has(uncle.ParentHash) {
        return fmt.Errorf("uncle's parent unknown (%x)", uncle.ParentHash[0:4])
    }
    if work.family.Has(hash) {
        return fmt.Errorf("uncle already in family (%x)", hash)
    }
    work.uncles.Add(uncle.Hash())
    return nil
}

func (self *worker) updateSnapshot() {
    self.snapshotMu.Lock()
    defer self.snapshotMu.Unlock()

    self.snapshotBlock = types.NewBlock(
        self.current.header,
        self.current.txs,
        nil,
        self.current.receipts,
    )
    self.snapshotState = self.current.state.Copy()
}

func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsByPriceAndNonce, bc *core.BlockChain, coinbase common.Address) {
    gp := new(core.GasPool).AddGas(env.header.GasLimit)

    var coalescedLogs []*types.Log

    for {
        // If we don't have enough gas for any further transactions then we're done
        if gp.Gas() < params.TxGas {
            log.Trace("Not enough gas for further transactions", "gp", gp)
            break
        }
        // Retrieve the next transaction and abort if all done
        tx := txs.Peek()
        if tx == nil {
            break
        }
        // Error may be ignored here. The error has already been checked
        // during transaction acceptance is the transaction pool.
        //
        // We use the eip155 signer regardless of the current hf.
        from, _ := types.Sender(env.signer, tx)
        // Check whether the tx is replay protected. If we're not in the EIP155 hf
        // phase, start ignoring the sender until we do.
        if tx.Protected() && !env.config.IsEIP155(env.header.Number) {
            log.Trace("Ignoring reply protected transaction", "hash", tx.Hash(), "eip155", env.config.EIP155Block)

            txs.Pop()
            continue
        }
        // Start executing the transaction
        env.state.Prepare(tx.Hash(), common.Hash{}, env.tcount)

        err, logs := env.commitTransaction(tx, bc, coinbase, gp)
        switch err {
        case core.ErrGasLimitReached:
            // Pop the current out-of-gas transaction without shifting in the next from the account
            log.Trace("Gas limit exceeded for current block", "sender", from)
            txs.Pop()

        case core.ErrNonceTooLow:
            // New head notification data race between the transaction pool and miner, shift
            log.Trace("Skipping transaction with low nonce", "sender", from, "nonce", tx.Nonce())
            txs.Shift()

        case core.ErrNonceTooHigh:
            // Reorg notification data race between the transaction pool and miner, skip account =
            log.Trace("Skipping account with hight nonce", "sender", from, "nonce", tx.Nonce())
            txs.Pop()

        case nil:
            // Everything ok, collect the logs and shift in the next transaction from the same account
            coalescedLogs = append(coalescedLogs, logs...)
            env.tcount++
            txs.Shift()

        default:
            // Strange error, discard the transaction and get the next in line (note, the
            // nonce-too-high clause will prevent us from executing in vain).
            log.Debug("Transaction failed, account skipped", "hash", tx.Hash(), "err", err)
            txs.Shift()
        }
    }

    if len(coalescedLogs) > 0 || env.tcount > 0 {
        // make a copy, the state caches the logs and these logs get "upgraded" from pending to mined
        // logs by filling in the block hash when the block was mined by the local miner. This can
        // cause a race condition if a log was "upgraded" before the PendingLogsEvent is processed.
        cpy := make([]*types.Log, len(coalescedLogs))
        for i, l := range coalescedLogs {
            cpy[i] = new(types.Log)
            *cpy[i] = *l
        }
        go func(logs []*types.Log, tcount int) {
            if len(logs) > 0 {
                mux.Post(core.PendingLogsEvent{Logs: logs})
            }
            if tcount > 0 {
                mux.Post(core.PendingStateEvent{})
            }
        }(cpy, env.tcount)
    }
}

func (env *Work) commitTransaction(tx *types.Transaction, bc *core.BlockChain, coinbase common.Address, gp *core.GasPool) (error, []*types.Log) {
    snap := env.state.Snapshot()

    receipt, _, err := core.ApplyTransaction(env.config, bc, &coinbase, gp, env.state, env.header, tx, &env.header.GasUsed, vm.Config{})
    if err != nil {
        env.state.RevertToSnapshot(snap)
        return err, nil
    }
    env.txs = append(env.txs, tx)
    env.receipts = append(env.receipts, receipt)

    return nil, receipt.Logs
}