cmd, eth: Added in the flag to step geth once sync based on input

cmd/geth/main.go

@@ -83,6 +83,7 @@ var (
 		utils.TxPoolGlobalQueueFlag,
 		utils.TxPoolLifetimeFlag,
 		utils.FastSyncFlag,
+		utils.ExitWhenSynced,
 		utils.LightModeFlag,
 		utils.SyncModeFlag,
 		utils.GCModeFlag,
@@ -317,6 +318,24 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 			}
 		}
 	}()
+
+	if exitWhenSynced := ctx.GlobalDuration(utils.ExitWhenSynced.Name); exitWhenSynced >= 0 {
+		go func() {
+						if ctx.GlobalBool(utils.LightModeFlag.Name) || ctx.GlobalString(utils.SyncModeFlag.Name) == "light" {
+							log.Warn("Exit after block synchronisation disabled for light mode")
+						} else {
+							var ethereum *eth.Ethereum
+							if err := stack.Service(&ethereum); err != nil {
+								utils.Fatalf("Ethereum service not running: %v", err)
+							}
+							<-ethereum.Downloader().SyncedCh
+							log.Info("Synchronisation completed, exitting", "countdown", exitWhenSynced)
+							time.Sleep(exitWhenSynced)
+							stack.Stop()
+						}
+		}()
+	}
+
 	// Start auxiliary services if enabled
 	if ctx.GlobalBool(utils.MiningEnabledFlag.Name) || ctx.GlobalBool(utils.DeveloperFlag.Name) {
 		// Mining only makes sense if a full Ethereum node is running

cmd/geth/usage.go

@@ -75,6 +75,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.TestnetFlag,
 			utils.RinkebyFlag,
 			utils.SyncModeFlag,
+			utils.ExitWhenSynced,
 			utils.GCModeFlag,
 			utils.EthStatsURLFlag,
 			utils.IdentityFlag,

cmd/utils/flags.go

@@ -162,6 +162,11 @@ var (
 		Name:  "fast",
 		Usage: "Enable fast syncing through state downloads (replaced by --syncmode)",
 	}
+	ExitWhenSynced = cli.DurationFlag{
+		Name: "exitwhensynced",
+		Usage: "Exists syncing by given time (default 0) after block synchronisation",
+		Value: -1,
+	}
 	LightModeFlag = cli.BoolFlag{
 		Name:  "light",
 		Usage: "Enable light client mode (replaced by --syncmode)",
@@ -1077,7 +1082,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	if ctx.GlobalIsSet(NetworkIdFlag.Name) {
 		cfg.NetworkId = ctx.GlobalUint64(NetworkIdFlag.Name)
 	}
-
+	if ctx.GlobalIsSet(ExitWhenSynced.Name) {
+		cfg.NetworkId = ctx.GlobalUint64(ExitWhenSynced.Name)
+	}
 	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheDatabaseFlag.Name) {
 		cfg.DatabaseCache = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheDatabaseFlag.Name) / 100
 	}

eth/config.go

@@ -114,6 +114,9 @@ type Config struct {
 
 	// Miscellaneous options
 	DocRoot string `toml:"-"`
+
+	// specify time to exit after syncing
+	ExitInSync time.Duration
 }
 
 type configMarshaling struct {

eth/downloader/downloader.go

@@ -128,6 +128,7 @@ type Downloader struct {
 	bodyWakeCh    chan bool            // [eth/62] Channel to signal the block body fetcher of new tasks
 	receiptWakeCh chan bool            // [eth/63] Channel to signal the receipt fetcher of new tasks
 	headerProcCh  chan []*types.Header // [eth/62] Channel to feed the header processor new tasks
+	SyncedCh      chan bool
 
 	// for stateFetcher
 	stateSyncStart chan *stateSync
@@ -226,6 +227,7 @@ func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, chain BlockC
 		syncStatsState: stateSyncStats{
 			processed: rawdb.ReadFastTrieProgress(stateDb),
 		},
+		SyncedCh:       make(chan bool, 1),
 		trackStateReq: make(chan *stateReq),
 	}
 	go dl.qosTuner()
@@ -317,6 +319,10 @@ func (d *Downloader) Synchronise(id string, head common.Hash, td *big.Int, mode
 	err := d.synchronise(id, head, td, mode)
 	switch err {
 	case nil:
+		select {
+		case d.SyncedCh <- true:
+					default:
+		}
 	case errBusy:
 
 	case errTimeout, errBadPeer, errStallingPeer,