cmd, eth: clean up miner startup API, drop noop config field

eth/api.go

@@ -24,6 +24,7 @@ import (
 	"io"
 	"math/big"
 	"os"
+	"runtime"
 	"strings"
 	"time"
 
@@ -34,7 +35,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
-	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
@@ -94,47 +94,22 @@ func NewPrivateMinerAPI(e *Ethereum) *PrivateMinerAPI {
 	return &PrivateMinerAPI{e: e}
 }
 
-// Start the miner with the given number of threads. If threads is nil the number
-// of workers started is equal to the number of logical CPUs that are usable by
-// this process. If mining is already running, this method adjust the number of
-// threads allowed to use and updates the minimum price required by the transaction
-// pool.
+// Start starts the miner with the given number of threads. If threads is nil,
+// the number of workers started is equal to the number of logical CPUs that are
+// usable by this process. If mining is already running, this method adjust the
+// number of threads allowed to use and updates the minimum price required by the
+// transaction pool.
 func (api *PrivateMinerAPI) Start(threads *int) error {
-	// Set the number of threads if the seal engine supports it
 	if threads == nil {
-		threads = new(int)
-	} else if *threads == 0 {
-		*threads = -1 // Disable the miner from within
+		return api.e.StartMining(runtime.NumCPU())
 	}
-	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() {
-		// Propagate the initial price point to the transaction pool
-		api.e.lock.RLock()
-		price := api.e.gasPrice
-		api.e.lock.RUnlock()
-		api.e.txPool.SetGasPrice(price)
-		return api.e.StartMining(true)
-	}
-	return nil
+	return api.e.StartMining(*threads)
 }
 
-// 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)
-	}
+// Stop terminates the miner, both at the consensus engine level as well as at
+// the block creation level.
+func (api *PrivateMinerAPI) Stop() {
 	api.e.StopMining()
-	return true
 }
 
 // SetExtra sets the extra data string that is included when this miner mines a block.