core, consensus: pluggable consensus engines (#3817)

This commit adds pluggable consensus engines to go-ethereum. In short, it
introduces a generic consensus interface, and refactors the entire codebase to
use this interface.

5 files changed, 96 insertions, 108 deletions

diff --git a/miner/agent.go b/miner/agent.go
index 3c407f20b..855892a07 100644
--- a/miner/agent.go
+++ b/miner/agent.go
@@ -17,56 +17,49 @@
 package miner
 
 import (
-	"fmt"
 	"sync"
 
 	"sync/atomic"
 
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/log"
-	"github.com/ethereum/go-ethereum/pow"
 )
 
 type CpuAgent struct {
 	mu sync.Mutex
 
 	workCh        chan *Work
-	quit          chan struct{}
+	stop          chan struct{}
 	quitCurrentOp chan struct{}
 	returnCh      chan<- *Result
 
-	index int
-	pow   pow.PoW
+	chain  consensus.ChainReader
+	engine consensus.Engine
 
 	isMining int32 // isMining indicates whether the agent is currently mining
 }
 
-func NewCpuAgent(index int, pow pow.PoW) *CpuAgent {
+func NewCpuAgent(chain consensus.ChainReader, engine consensus.Engine) *CpuAgent {
 	miner := &CpuAgent{
-		pow:    pow,
-		index:  index,
-		quit:   make(chan struct{}),
+		chain:  chain,
+		engine: engine,
+		stop:   make(chan struct{}, 1),
 		workCh: make(chan *Work, 1),
 	}
-
 	return miner
 }
 
 func (self *CpuAgent) Work() chan<- *Work            { return self.workCh }
-func (self *CpuAgent) Pow() pow.PoW                  { return self.pow }
 func (self *CpuAgent) SetReturnCh(ch chan<- *Result) { self.returnCh = ch }
 
 func (self *CpuAgent) Stop() {
-	close(self.quit)
+	self.stop <- struct{}{}
 }
 
 func (self *CpuAgent) Start() {
-
 	if !atomic.CompareAndSwapInt32(&self.isMining, 0, 1) {
 		return // agent already started
 	}
-
 	go self.update()
 }
 
@@ -82,7 +75,7 @@ out:
 			self.quitCurrentOp = make(chan struct{})
 			go self.mine(work, self.quitCurrentOp)
 			self.mu.Unlock()
-		case <-self.quit:
+		case <-self.stop:
 			self.mu.Lock()
 			if self.quitCurrentOp != nil {
 				close(self.quitCurrentOp)
@@ -99,27 +92,27 @@ done:
 		select {
 		case <-self.workCh:
 		default:
-			close(self.workCh)
 			break done
 		}
 	}
-
 	atomic.StoreInt32(&self.isMining, 0)
 }
 
 func (self *CpuAgent) mine(work *Work, stop <-chan struct{}) {
-	log.Debug(fmt.Sprintf("(re)started agent[%d]. mining...\n", self.index))
-
-	// Mine
-	nonce, mixDigest := self.pow.Search(work.Block, stop)
-	if nonce != 0 {
-		block := work.Block.WithMiningResult(types.EncodeNonce(nonce), common.BytesToHash(mixDigest))
-		self.returnCh <- &Result{work, block}
+	if result, err := self.engine.Seal(self.chain, work.Block, stop); result != nil {
+		log.Info("Successfully sealed new block", "number", result.Number(), "hash", result.Hash())
+		self.returnCh <- &Result{work, result}
 	} else {
+		if err != nil {
+			log.Warn("Block sealing failed", "err", err)
+		}
 		self.returnCh <- nil
 	}
 }
 
 func (self *CpuAgent) GetHashRate() int64 {
-	return int64(self.pow.Hashrate())
+	if pow, ok := self.engine.(consensus.PoW); ok {
+		return int64(pow.Hashrate())
+	}
+	return 0
 }
diff --git a/miner/miner.go b/miner/miner.go
index dc0591b9a..453fff04d 100644
--- a/miner/miner.go
+++ b/miner/miner.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -32,7 +33,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 )
 
 // Backend wraps all methods required for mining.
@@ -49,24 +49,24 @@ type Miner struct {
 
 	worker *worker
 
-	threads  int
 	coinbase common.Address
 	mining   int32
 	eth      Backend
-	pow      pow.PoW
+	engine   consensus.Engine
 
 	canStart    int32 // can start indicates whether we can start the mining operation
 	shouldStart int32 // should start indicates whether we should start after sync
 }
 
-func New(eth Backend, config *params.ChainConfig, mux *event.TypeMux, pow pow.PoW) *Miner {
+func New(eth Backend, config *params.ChainConfig, mux *event.TypeMux, engine consensus.Engine) *Miner {
 	miner := &Miner{
 		eth:      eth,
 		mux:      mux,
-		pow:      pow,
-		worker:   newWorker(config, common.Address{}, eth, mux),
+		engine:   engine,
+		worker:   newWorker(config, engine, common.Address{}, eth, mux),
 		canStart: 1,
 	}
+	miner.Register(NewCpuAgent(eth.BlockChain(), engine))
 	go miner.update()
 
 	return miner
@@ -86,7 +86,7 @@ out:
 			if self.Mining() {
 				self.Stop()
 				atomic.StoreInt32(&self.shouldStart, 1)
-				log.Info(fmt.Sprint("Mining operation aborted due to sync operation"))
+				log.Info("Mining aborted due to sync")
 			}
 		case downloader.DoneEvent, downloader.FailedEvent:
 			shouldStart := atomic.LoadInt32(&self.shouldStart) == 1
@@ -94,7 +94,7 @@ out:
 			atomic.StoreInt32(&self.canStart, 1)
 			atomic.StoreInt32(&self.shouldStart, 0)
 			if shouldStart {
-				self.Start(self.coinbase, self.threads)
+				self.Start(self.coinbase)
 			}
 			// unsubscribe. we're only interested in this event once
 			events.Unsubscribe()
@@ -116,23 +116,18 @@ func (m *Miner) SetGasPrice(price *big.Int) {
 	m.worker.setGasPrice(price)
 }
 
-func (self *Miner) Start(coinbase common.Address, threads int) {
+func (self *Miner) Start(coinbase common.Address) {
 	atomic.StoreInt32(&self.shouldStart, 1)
 	self.worker.setEtherbase(coinbase)
 	self.coinbase = coinbase
-	self.threads = threads
 
 	if atomic.LoadInt32(&self.canStart) == 0 {
-		log.Info(fmt.Sprint("Can not start mining operation due to network sync (starts when finished)"))
+		log.Info("Network syncing, will start miner afterwards")
 		return
 	}
 	atomic.StoreInt32(&self.mining, 1)
 
-	for i := 0; i < threads; i++ {
-		self.worker.register(NewCpuAgent(i, self.pow))
-	}
-
-	log.Info(fmt.Sprintf("Starting mining operation (CPU=%d TOT=%d)\n", threads, len(self.worker.agents)))
+	log.Info("Starting mining operation")
 	self.worker.start()
 	self.worker.commitNewWork()
 }
@@ -159,7 +154,9 @@ func (self *Miner) Mining() bool {
 }
 
 func (self *Miner) HashRate() (tot int64) {
-	tot += int64(self.pow.Hashrate())
+	if pow, ok := self.engine.(consensus.PoW); ok {
+		tot += int64(pow.Hashrate())
+	}
 	// do we care this might race? is it worth we're rewriting some
 	// aspects of the worker/locking up agents so we can get an accurate
 	// hashrate?
diff --git a/miner/remote_agent.go b/miner/remote_agent.go
index 08c5fc6f0..bb223ba1b 100644
--- a/miner/remote_agent.go
+++ b/miner/remote_agent.go
@@ -18,16 +18,16 @@ package miner
 
 import (
 	"errors"
-	"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/ethash"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/log"
-	"github.com/ethereum/go-ethereum/pow"
 )
 
 type hashrate struct {
@@ -42,7 +42,8 @@ type RemoteAgent struct {
 	workCh   chan *Work
 	returnCh chan<- *Result
 
-	pow         pow.PoW
+	chain       consensus.ChainReader
+	engine      consensus.Engine
 	currentWork *Work
 	work        map[common.Hash]*Work
 
@@ -52,9 +53,10 @@ type RemoteAgent struct {
 	running int32 // running indicates whether the agent is active. Call atomically
 }
 
-func NewRemoteAgent(pow pow.PoW) *RemoteAgent {
+func NewRemoteAgent(chain consensus.ChainReader, engine consensus.Engine) *RemoteAgent {
 	return &RemoteAgent{
-		pow:      pow,
+		chain:    chain,
+		engine:   engine,
 		work:     make(map[common.Hash]*Work),
 		hashrate: make(map[common.Hash]hashrate),
 	}
@@ -114,7 +116,7 @@ func (a *RemoteAgent) GetWork() ([3]string, error) {
 		block := a.currentWork.Block
 
 		res[0] = block.HashNoNonce().Hex()
-		seedHash := pow.EthashSeedHash(block.NumberU64())
+		seedHash := ethash.SeedHash(block.NumberU64())
 		res[1] = common.BytesToHash(seedHash).Hex()
 		// Calculate the "target" to be returned to the external miner
 		n := big.NewInt(1)
@@ -129,8 +131,8 @@ func (a *RemoteAgent) GetWork() ([3]string, error) {
 	return res, errors.New("No work available yet, don't panic.")
 }
 
-// SubmitWork tries to inject a PoW solution tinto the remote agent, returning
-// whether the solution was acceted or not (not can be both a bad PoW as well as
+// SubmitWork tries to inject a pow solution into the remote agent, returning
+// whether the solution was accepted or not (not can be both a bad pow as well as
 // any other error, like no work pending).
 func (a *RemoteAgent) SubmitWork(nonce types.BlockNonce, mixDigest, hash common.Hash) bool {
 	a.mu.Lock()
@@ -139,15 +141,20 @@ func (a *RemoteAgent) SubmitWork(nonce types.BlockNonce, mixDigest, hash common.
 	// Make sure the work submitted is present
 	work := a.work[hash]
 	if work == nil {
-		log.Info(fmt.Sprintf("Work was submitted for %x but no pending work found", hash))
+		log.Info("Work submitted but none pending", "hash", hash)
 		return false
 	}
-	// Make sure the PoW solutions is indeed valid
-	block := work.Block.WithMiningResult(nonce, mixDigest)
-	if err := a.pow.Verify(block); err != nil {
-		log.Warn(fmt.Sprintf("Invalid PoW submitted for %x: %v", hash, err))
+	// Make sure the Engine solutions is indeed valid
+	result := work.Block.Header()
+	result.Nonce = nonce
+	result.MixDigest = mixDigest
+
+	if err := a.engine.VerifySeal(a.chain, result); err != nil {
+		log.Warn("Invalid proof-of-work submitted", "hash", hash, "err", err)
 		return false
 	}
+	block := work.Block.WithSeal(result)
+
 	// Solutions seems to be valid, return to the miner and notify acceptance
 	a.returnCh <- &Result{work, block}
 	delete(a.work, hash)
diff --git a/miner/unconfirmed.go b/miner/unconfirmed.go
index bb7d0ff26..ee52d8512 100644
--- a/miner/unconfirmed.go
+++ b/miner/unconfirmed.go
@@ -18,7 +18,6 @@ package miner
 
 import (
 	"container/ring"
-	"fmt"
 	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -80,7 +79,7 @@ func (set *unconfirmedBlocks) Insert(index uint64, hash common.Hash) {
 		set.blocks.Move(-1).Link(item)
 	}
 	// Display a log for the user to notify of a new mined block unconfirmed
-	log.Info(fmt.Sprintf("🔨  mined potential block #%d [%x…], waiting for %d blocks to confirm", index, hash.Bytes()[:4], set.depth))
+	log.Info("🔨 mined potential block", "number", index, "hash", hash)
 }
 
 // Shift drops all unconfirmed blocks from the set which exceed the unconfirmed sets depth
@@ -100,11 +99,11 @@ func (set *unconfirmedBlocks) Shift(height uint64) {
 		header := set.chain.GetHeaderByNumber(next.index)
 		switch {
 		case header == nil:
-			log.Warn(fmt.Sprintf("failed to retrieve header of mined block #%d [%x…]", next.index, next.hash.Bytes()[:4]))
+			log.Warn("Failed to retrieve header of mined block", "number", next.index, "hash", next.hash)
 		case header.Hash() == next.hash:
-			log.Info(fmt.Sprintf("🔗  mined block #%d [%x…] reached canonical chain", next.index, next.hash.Bytes()[:4]))
+			log.Info("🔗 block reached canonical chain", "number", next.index, "hash", next.hash)
 		default:
-			log.Info(fmt.Sprintf("⑂ mined block #%d [%x…] became a side fork", next.index, next.hash.Bytes()[:4]))
+			log.Info("⑂ block  became a side fork", "number", next.index, "hash", next.hash)
 		}
 		// Drop the block out of the ring
 		if set.blocks.Value == set.blocks.Next().Value {
diff --git a/miner/worker.go b/miner/worker.go
index 2f090924e..347de4e08 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -26,6 +26,8 @@ import (
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"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"
@@ -34,7 +36,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/pow"
 	"gopkg.in/fatih/set.v0"
 )
 
@@ -84,6 +85,7 @@ type Result struct {
 // 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
 
@@ -94,7 +96,6 @@ type worker struct {
 
 	agents map[Agent]struct{}
 	recv   chan *Result
-	pow    pow.PoW
 
 	eth     Backend
 	chain   *core.BlockChain
@@ -123,9 +124,10 @@ type worker struct {
 	fullValidation bool
 }
 
-func newWorker(config *params.ChainConfig, coinbase common.Address, eth Backend, mux *event.TypeMux) *worker {
+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,
 		chainDb:        eth.ChainDb(),
@@ -209,16 +211,10 @@ func (self *worker) stop() {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 	if atomic.LoadInt32(&self.mining) == 1 {
-		// Stop all agents.
 		for agent := range self.agents {
 			agent.Stop()
-			// Remove CPU agents.
-			if _, ok := agent.(*CpuAgent); ok {
-				delete(self.agents, agent)
-			}
 		}
 	}
-
 	atomic.StoreInt32(&self.mining, 0)
 	atomic.StoreInt32(&self.atWork, 0)
 }
@@ -277,7 +273,7 @@ func (self *worker) wait() {
 
 			if self.fullValidation {
 				if _, err := self.chain.InsertChain(types.Blocks{block}); err != nil {
-					log.Error(fmt.Sprint("mining err", err))
+					log.Error("Mined invalid block", "err", err)
 					continue
 				}
 				go self.mux.Post(core.NewMinedBlockEvent{Block: block})
@@ -285,19 +281,16 @@ func (self *worker) wait() {
 				work.state.Commit(self.config.IsEIP158(block.Number()))
 				parent := self.chain.GetBlock(block.ParentHash(), block.NumberU64()-1)
 				if parent == nil {
-					log.Error(fmt.Sprint("Invalid block found during mining"))
+					log.Error("Invalid block found during mining")
 					continue
 				}
-
-				auxValidator := self.eth.BlockChain().AuxValidator()
-				if err := core.ValidateHeader(self.config, auxValidator, block.Header(), parent.Header(), true, false); err != nil && err != core.BlockFutureErr {
-					log.Error(fmt.Sprint("Invalid header on mined block:", err))
+				if err := self.engine.VerifyHeader(self.chain, block.Header(), false); err != nil {
+					log.Error("Invalid header on mined block", "err", err)
 					continue
 				}
-
 				stat, err := self.chain.WriteBlock(block)
 				if err != nil {
-					log.Error(fmt.Sprint("error writing block to chain", err))
+					log.Error("Failed writing block to chain", "err", err)
 					continue
 				}
 
@@ -333,7 +326,7 @@ func (self *worker) wait() {
 						self.mux.Post(logs)
 					}
 					if err := core.WriteBlockReceipts(self.chainDb, block.Hash(), block.NumberU64(), receipts); err != nil {
-						log.Warn(fmt.Sprint("error writing block receipts:", err))
+						log.Warn("Failed writing block receipts", "err", err)
 					}
 				}(block, work.state.Logs(), work.receipts)
 			}
@@ -424,9 +417,9 @@ func (self *worker) commitNewWork() {
 		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+4 {
+	if now := time.Now().Unix(); tstamp > now+1 {
 		wait := time.Duration(tstamp-now) * time.Second
-		log.Info(fmt.Sprint("We are too far in the future. Waiting for", wait))
+		log.Info("Mining too far in the future", "wait", common.PrettyDuration(wait))
 		time.Sleep(wait)
 	}
 
@@ -434,13 +427,19 @@ func (self *worker) commitNewWork() {
 	header := &types.Header{
 		ParentHash: parent.Hash(),
 		Number:     num.Add(num, common.Big1),
-		Difficulty: core.CalcDifficulty(self.config, uint64(tstamp), parent.Time().Uint64(), parent.Number(), parent.Difficulty()),
 		GasLimit:   core.CalcGasLimit(parent),
 		GasUsed:    new(big.Int),
-		Coinbase:   self.coinbase,
 		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
@@ -457,21 +456,19 @@ func (self *worker) commitNewWork() {
 	// Could potentially happen if starting to mine in an odd state.
 	err := self.makeCurrent(parent, header)
 	if err != nil {
-		log.Info(fmt.Sprint("Could not create new env for mining, retrying on next block."))
+		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 {
-		core.ApplyDAOHardFork(work.state)
+		misc.ApplyDAOHardFork(work.state)
 	}
-
 	pending, err := self.eth.TxPool().Pending()
 	if err != nil {
-		log.Error(fmt.Sprintf("Could not fetch pending transactions: %v", err))
+		log.Error("Failed to fetch pending transactions", "err", err)
 		return
 	}
-
 	txs := types.NewTransactionsByPriceAndNonce(pending)
 	work.commitTransactions(self.mux, txs, self.gasPrice, self.chain)
 
@@ -488,31 +485,26 @@ func (self *worker) commitNewWork() {
 			break
 		}
 		if err := self.commitUncle(work, uncle.Header()); err != nil {
-			log.Trace(fmt.Sprintf("Bad uncle found and will be removed (%x)\n", hash[:4]))
+			log.Trace("Bad uncle found and will be removed", "hash", hash)
 			log.Trace(fmt.Sprint(uncle))
 
 			badUncles = append(badUncles, hash)
 		} else {
-			log.Debug(fmt.Sprintf("committing %x as uncle\n", hash[:4]))
+			log.Debug("Committing new uncle to block", "hash", hash)
 			uncles = append(uncles, uncle.Header())
 		}
 	}
 	for _, hash := range badUncles {
 		delete(self.possibleUncles, hash)
 	}
-
-	if atomic.LoadInt32(&self.mining) == 1 {
-		// commit state root after all state transitions.
-		core.AccumulateRewards(work.state, header, uncles)
-		header.Root = work.state.IntermediateRoot(self.config.IsEIP158(header.Number))
+	// 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
 	}
-
-	// create the new block whose nonce will be mined.
-	work.Block = types.NewBlock(header, work.txs, uncles, work.receipts)
-
 	// We only care about logging if we're actually mining.
 	if atomic.LoadInt32(&self.mining) == 1 {
-		log.Info(fmt.Sprintf("commit new work on block %v with %d txs & %d uncles. Took %v\n", work.Block.Number(), work.tcount, len(uncles), time.Since(tstart)))
+		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)
@@ -521,13 +513,13 @@ func (self *worker) commitNewWork() {
 func (self *worker) commitUncle(work *Work, uncle *types.Header) error {
 	hash := uncle.Hash()
 	if work.uncles.Has(hash) {
-		return core.UncleError("Uncle not unique")
+		return core.UncleError("uncle not unique")
 	}
 	if !work.ancestors.Has(uncle.ParentHash) {
-		return core.UncleError(fmt.Sprintf("Uncle's parent unknown (%x)", uncle.ParentHash[0:4]))
+		return core.UncleError(fmt.Sprintf("uncle's parent unknown (%x)", uncle.ParentHash[0:4]))
 	}
 	if work.family.Has(hash) {
-		return core.UncleError(fmt.Sprintf("Uncle already in family (%x)", hash))
+		return core.UncleError(fmt.Sprintf("uncle already in family (%x)", hash))
 	}
 	work.uncles.Add(uncle.Hash())
 	return nil
@@ -552,7 +544,7 @@ func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsB
 		// 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(fmt.Sprintf("Transaction (%x) is replay protected, but we haven't yet hardforked. Transaction will be ignored until we hardfork.\n", tx.Hash()))
+			log.Trace("Ignoring reply protected transaction", "hash", tx.Hash(), "eip155", env.config.EIP155Block)
 
 			txs.Pop()
 			continue
@@ -561,7 +553,7 @@ func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsB
 		// Ignore any transactions (and accounts subsequently) with low gas limits
 		if tx.GasPrice().Cmp(gasPrice) < 0 && !env.ownedAccounts.Has(from) {
 			// Pop the current low-priced transaction without shifting in the next from the account
-			log.Info(fmt.Sprintf("Transaction (%x) below gas price (tx=%dwei ask=%dwei). All sequential txs from this address(%x) will be ignored\n", tx.Hash().Bytes()[:4], tx.GasPrice(), gasPrice, from[:4]))
+			log.Warn("Transaction below gas price", "sender", from, "hash", tx.Hash(), "have", tx.GasPrice(), "want", gasPrice)
 
 			env.lowGasTxs = append(env.lowGasTxs, tx)
 			txs.Pop()
@@ -575,12 +567,12 @@ func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsB
 		switch {
 		case core.IsGasLimitErr(err):
 			// Pop the current out-of-gas transaction without shifting in the next from the account
-			log.Trace(fmt.Sprintf("Gas limit reached for (%x) in this block. Continue to try smaller txs\n", from[:4]))
+			log.Trace("Gas limit exceeded for current block", "sender", from)
 			txs.Pop()
 
 		case err != nil:
 			// Pop the current failed transaction without shifting in the next from the account
-			log.Trace(fmt.Sprintf("Transaction (%x) failed, will be removed: %v\n", tx.Hash().Bytes()[:4], err))
+			log.Trace("Transaction failed, will be removed", "hash", tx.Hash(), "err", err)
 			env.failedTxs = append(env.failedTxs, tx)
 			txs.Pop()