Merge pull request #140 from cloudstruct/feat/chainsync-current-tip

feat: support for getting chain tip via chain-sync

Author: agaffney

cmd/go-ouroboros-network/chainsync.go

@@ -25,13 +25,15 @@ var syncState chainSyncState
 type chainSyncFlags struct {
 	flagset  *flag.FlagSet
 	startEra string
+	tip      bool
 }
 
 func newChainSyncFlags() *chainSyncFlags {
 	f := &chainSyncFlags{
 		flagset: flag.NewFlagSet("chain-sync", flag.ExitOnError),
 	}
 	f.flagset.StringVar(&f.startEra, "start-era", "genesis", "era which to start chain-sync at")
+	f.flagset.BoolVar(&f.tip, "tip", false, "start chain-sync at current chain tip")
 	return f
 }
 
@@ -135,7 +137,14 @@ func testChainSync(f *globalFlags) {
 	syncState.oConn = o
 	syncState.nodeToNode = f.ntnProto
 	var point common.Point
-	if len(eraIntersect[f.networkMagic][chainSyncFlags.startEra]) > 0 {
+	if chainSyncFlags.tip {
+		tip, err := o.ChainSync.Client.GetCurrentTip()
+		if err != nil {
+			fmt.Printf("ERROR: failed to get current tip: %s\n", err)
+			os.Exit(1)
+		}
+		point = tip.Point
+	} else if len(eraIntersect[f.networkMagic][chainSyncFlags.startEra]) > 0 {
 		// Slot
 		slot := uint64(eraIntersect[f.networkMagic][chainSyncFlags.startEra][0].(int))
 		// Block hash

protocol/chainsync/client.go

@@ -14,6 +14,8 @@ type Client struct {
 	busyMutex             sync.Mutex
 	intersectResultChan   chan error
 	readyForNextBlockChan chan bool
+	wantCurrentTip        bool
+	currentTipChan        chan Tip
 }
 
 func NewClient(protoOptions protocol.ProtocolOptions, cfg *Config) *Client {
@@ -29,6 +31,7 @@ func NewClient(protoOptions protocol.ProtocolOptions, cfg *Config) *Client {
 		config:                cfg,
 		intersectResultChan:   make(chan error),
 		readyForNextBlockChan: make(chan bool),
+		currentTipChan:        make(chan Tip),
 	}
 	protoConfig := protocol.ProtocolConfig{
 		Name:                PROTOCOL_NAME,
@@ -75,6 +78,19 @@ func (c *Client) Stop() error {
 	return nil
 }
 
+func (c *Client) GetCurrentTip() (*Tip, error) {
+	c.busyMutex.Lock()
+	defer c.busyMutex.Unlock()
+	c.wantCurrentTip = true
+	msg := NewMsgFindIntersect([]common.Point{})
+	if err := c.SendMessage(msg); err != nil {
+		return nil, err
+	}
+	tip := <-c.currentTipChan
+	c.wantCurrentTip = false
+	return &tip, nil
+}
+
 func (c *Client) Sync(intersectPoints []common.Point) error {
 	c.busyMutex.Lock()
 	defer c.busyMutex.Unlock()
@@ -178,11 +194,21 @@ func (c *Client) handleRollBackward(msgGeneric protocol.Message) error {
 }
 
 func (c *Client) handleIntersectFound(msgGeneric protocol.Message) error {
-	c.intersectResultChan <- nil
+	if c.wantCurrentTip {
+		msgIntersectFound := msgGeneric.(*MsgIntersectFound)
+		c.currentTipChan <- msgIntersectFound.Tip
+	} else {
+		c.intersectResultChan <- nil
+	}
 	return nil
 }
 
 func (c *Client) handleIntersectNotFound(msgGeneric protocol.Message) error {
-	c.intersectResultChan <- IntersectNotFoundError{}
+	if c.wantCurrentTip {
+		msgIntersectNotFound := msgGeneric.(*MsgIntersectNotFound)
+		c.currentTipChan <- msgIntersectNotFound.Tip
+	} else {
+		c.intersectResultChan <- IntersectNotFoundError{}
+	}
 	return nil
 }