cmd/geth/main, cmd/utils, eth/downloader: add an option to stop geth once in sync

cmd/geth/main.go

@@ -72,6 +72,7 @@ var (
 		utils.EthashDatasetDirFlag,
 		utils.EthashDatasetsInMemoryFlag,
 		utils.EthashDatasetsOnDiskFlag,
+		utils.ExitInSyncFlag,
 		utils.TxPoolNoLocalsFlag,
 		utils.TxPoolJournalFlag,
 		utils.TxPoolRejournalFlag,
@@ -299,6 +300,26 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 			}
 		}
 	}()
+
+	// Schedule exit when synchronised if enabled
+	if exitInSync := ctx.GlobalDuration(utils.ExitInSyncFlag.Name); exitInSync >= 0 {
+		go func() {
+			// todo: support light mode
+			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", exitInSync)
+				time.Sleep(exitInSync)
+				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.ExitInSyncFlag,
 			utils.GCModeFlag,
 			utils.EthStatsURLFlag,
 			utils.IdentityFlag,

cmd/utils/flags.go

@@ -170,6 +170,11 @@ var (
 		Usage: `Blockchain sync mode ("fast", "full", or "light")`,
 		Value: &defaultSyncMode,
 	}
+	ExitInSyncFlag = cli.DurationFlag{
+		Name:  "exitinsync",
+		Usage: "Exit after block synchronisation",
+		Value: -1,
+	}
 	GCModeFlag = cli.StringFlag{
 		Name:  "gcmode",
 		Usage: `Blockchain garbage collection mode ("full", "archive")`,
@@ -1040,6 +1045,7 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	if ctx.GlobalIsSet(NetworkIdFlag.Name) {
 		cfg.NetworkId = ctx.GlobalUint64(NetworkIdFlag.Name)
 	}
+	cfg.ExitInSync = ctx.GlobalDuration(ExitInSyncFlag.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 +114,8 @@ type Config struct {
 
 	// Miscellaneous options
 	DocRoot string `toml:"-"`
+
+	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
@@ -220,6 +221,7 @@ func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, chain BlockC
 		bodyWakeCh:     make(chan bool, 1),
 		receiptWakeCh:  make(chan bool, 1),
 		headerProcCh:   make(chan []*types.Header, 1),
+		SyncedCh:       make(chan bool, 1),
 		quitCh:         make(chan struct{}),
 		stateCh:        make(chan dataPack),
 		stateSyncStart: make(chan *stateSync),
@@ -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,