consensus, eth: don't CPU mine by default during remote mining

2 files changed, 20 insertions, 11 deletions

diff --git a/eth/api.go b/eth/api.go
index 041ccd397..947070515 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -139,16 +139,17 @@ func NewPrivateMinerAPI(e *Ethereum) *PrivateMinerAPI {
 // threads allowed to use.
 func (api *PrivateMinerAPI) Start(threads *int) error {
 	// Set the number of threads if the seal engine supports it
-	if threads != nil {
-		type threaded interface {
-			SetThreads(threads int)
-		}
-		if th, ok := api.e.engine.(threaded); ok {
-			log.Info("Updated mining threads", "threads", *threads)
-			th.SetThreads(*threads)
-		} else {
-			log.Warn("Current seal engine isn't threaded")
-		}
+	if threads == nil {
+		threads = new(int)
+	} else if *threads == 0 {
+		*threads = -1 // Disable the miner from within
+	}
+	type threaded interface {
+		SetThreads(threads int)
+	}
+	if th, ok := api.e.engine.(threaded); ok {
+		log.Info("Updated mining threads", "threads", *threads)
+		th.SetThreads(*threads)
 	}
 	// Start the miner and return
 	if !api.e.IsMining() {
@@ -159,6 +160,12 @@ func (api *PrivateMinerAPI) Start(threads *int) error {
 
 // Stop the miner
 func (api *PrivateMinerAPI) Stop() bool {
+	type threaded interface {
+		SetThreads(threads int)
+	}
+	if th, ok := api.e.engine.(threaded); ok {
+		th.SetThreads(-1)
+	}
 	api.e.StopMining()
 	return true
 }
diff --git a/eth/backend.go b/eth/backend.go
index f241d5f34..df5460201 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -240,8 +240,10 @@ func CreateConsensusEngine(ctx *node.ServiceContext, config *Config, chainConfig
 		log.Warn("Ethash used in shared mode")
 		return ethash.NewShared()
 	default:
-		return ethash.New(ctx.ResolvePath(config.EthashCacheDir), config.EthashCachesInMem, config.EthashCachesOnDisk,
+		engine := ethash.New(ctx.ResolvePath(config.EthashCacheDir), config.EthashCachesInMem, config.EthashCachesOnDisk,
 			config.EthashDatasetDir, config.EthashDatasetsInMem, config.EthashDatasetsOnDisk)
+		engine.SetThreads(-1) // Disable CPU mining
+		return engine
 	}
 }