eth: update default gas price when not mining too

eth/api.go

@@ -154,7 +154,11 @@ func (api *PrivateMinerAPI) Start(threads *int) error {
 	// Start the miner and return
 	if !api.e.IsMining() {
 		// Propagate the initial price point to the transaction pool
-		api.e.txPool.SetGasPrice(api.e.gasPrice)
+		api.e.lock.RLock()
+		price := api.e.gasPrice
+		api.e.lock.RUnlock()
+
+		api.e.txPool.SetGasPrice(price)
 		return api.e.StartMining(true)
 	}
 	return nil
@@ -182,6 +186,10 @@ func (api *PrivateMinerAPI) SetExtra(extra string) (bool, error) {
 
 // SetGasPrice sets the minimum accepted gas price for the miner.
 func (api *PrivateMinerAPI) SetGasPrice(gasPrice hexutil.Big) bool {
+	api.e.lock.Lock()
+	api.e.gasPrice = (*big.Int)(&gasPrice)
+	api.e.lock.Unlock()
+
 	api.e.txPool.SetGasPrice((*big.Int)(&gasPrice))
 	return true
 }

eth/backend.go

@@ -76,14 +76,14 @@ type Ethereum struct {
 
 	ApiBackend *EthApiBackend
 
-	miner        *miner.Miner
-	gasPrice     *big.Int
-	Mining       bool
-	MinerThreads int
-	etherbase    common.Address
+	miner     *miner.Miner
+	gasPrice  *big.Int
+	etherbase common.Address
 
 	networkId     uint64
 	netRPCService *ethapi.PublicNetAPI
+
+	lock sync.RWMutex // Protects the variadic fields (e.g. gas price and etherbase)
 }
 
 func (s *Ethereum) AddLesServer(ls LesServer) {
@@ -121,8 +121,8 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		shutdownChan:   make(chan bool),
 		stopDbUpgrade:  stopDbUpgrade,
 		networkId:      config.NetworkId,
+		gasPrice:       config.GasPrice,
 		etherbase:      config.Etherbase,
-		MinerThreads:   config.MinerThreads,
 	}
 
 	if err := addMipmapBloomBins(chainDb); err != nil {
@@ -169,7 +169,6 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 	}
 
 	eth.miner = miner.New(eth, eth.chainConfig, eth.EventMux(), eth.engine)
-	eth.gasPrice = config.GasPrice
 	eth.miner.SetExtra(makeExtraData(config.ExtraData))
 
 	eth.ApiBackend = &EthApiBackend{eth, nil}
@@ -295,8 +294,12 @@ func (s *Ethereum) ResetWithGenesisBlock(gb *types.Block) {
 }
 
 func (s *Ethereum) Etherbase() (eb common.Address, err error) {
-	if s.etherbase != (common.Address{}) {
-		return s.etherbase, nil
+	s.lock.RLock()
+	etherbase := s.etherbase
+	s.lock.RUnlock()
+
+	if etherbase != (common.Address{}) {
+		return etherbase, nil
 	}
 	if wallets := s.AccountManager().Wallets(); len(wallets) > 0 {
 		if accounts := wallets[0].Accounts(); len(accounts) > 0 {
@@ -308,7 +311,10 @@ func (s *Ethereum) Etherbase() (eb common.Address, err error) {
 
 // set in js console via admin interface or wrapper from cli flags
 func (self *Ethereum) SetEtherbase(etherbase common.Address) {
+	self.lock.Lock()
 	self.etherbase = etherbase
+	self.lock.Unlock()
+
 	self.miner.SetEtherbase(etherbase)
 }