Merge pull request #6221 from Crypt-iQ/link_handoff

multi: reliable hand-off from htlcswitch to contractcourt

contractcourt/chain_arbitrator.go

@@ -964,16 +964,9 @@ type ContractUpdate struct {
 	Htlcs []channeldb.HTLC
 }
 
-// ContractSignals wraps the two signals that affect the state of a channel
-// being watched by an arbitrator. The two signals we care about are: the
-// channel has a new set of HTLC's, and the remote party has just broadcast
-// their version of the commitment transaction.
+// ContractSignals is used by outside subsystems to notify a channel arbitrator
+// of its ShortChannelID.
 type ContractSignals struct {
-	// HtlcUpdates is a channel that the link will use to update the
-	// designated channel arbitrator when the set of HTLCs on any valid
-	// commitment changes.
-	HtlcUpdates chan *ContractUpdate
-
 	// ShortChanID is the up to date short channel ID for a contract. This
 	// can change either if when the contract was added it didn't yet have
 	// a stable identifier, or in the case of a reorg.
@@ -1001,6 +994,25 @@ func (c *ChainArbitrator) UpdateContractSignals(chanPoint wire.OutPoint,
 	return nil
 }
 
+// NotifyContractUpdate lets a channel arbitrator know that a new
+// ContractUpdate is available. This calls the ChannelArbitrator's internal
+// method NotifyContractUpdate which waits for a response on a done chan before
+// returning. This method will return an error if the ChannelArbitrator is not
+// in the activeChannels map. However, this only happens if the arbitrator is
+// resolved and the related link would already be shut down.
+func (c *ChainArbitrator) NotifyContractUpdate(chanPoint wire.OutPoint,
+	update *ContractUpdate) error {
+
+	c.Lock()
+	arbitrator, ok := c.activeChannels[chanPoint]
+	c.Unlock()
+	if !ok {
+		return fmt.Errorf("can't find arbitrator for %v", chanPoint)
+	}
+
+	return arbitrator.notifyContractUpdate(update)
+}
+
 // GetChannelArbitrator safely returns the channel arbitrator for a given
 // channel outpoint.
 func (c *ChainArbitrator) GetChannelArbitrator(chanPoint wire.OutPoint) (