discovery: pass contexts to NetworkPeerBootstrapper methods

We will later implement this interface with a backing RPC connection and
so it makes sense to pass a context through for cancellation.

discovery/bootstrapper.go

@@ -2,6 +2,7 @@ package discovery
 
 import (
 	"bytes"
+	"context"
 	"crypto/rand"
 	"crypto/sha256"
 	"errors"
@@ -36,12 +37,13 @@ type NetworkPeerBootstrapper interface {
 	// denotes how many valid peer addresses to return. The passed set of
 	// node nodes allows the caller to ignore a set of nodes perhaps
 	// because they already have connections established.
-	SampleNodeAddrs(numAddrs uint32,
+	SampleNodeAddrs(ctx context.Context, numAddrs uint32,
-		ignore map[autopilot.NodeID]struct{}) ([]*lnwire.NetAddress, error)
+		ignore map[autopilot.NodeID]struct{}) ([]*lnwire.NetAddress,
+		error)
 
 	// Name returns a human readable string which names the concrete
 	// implementation of the NetworkPeerBootstrapper.
-	Name() string
+	Name(ctx context.Context) string
 }
 
 // MultiSourceBootstrap attempts to utilize a set of NetworkPeerBootstrapper
@@ -53,6 +55,8 @@ type NetworkPeerBootstrapper interface {
 func MultiSourceBootstrap(ignore map[autopilot.NodeID]struct{}, numAddrs uint32,
 	bootstrappers ...NetworkPeerBootstrapper) ([]*lnwire.NetAddress, error) {
 
+	ctx := context.TODO()
+
 	// We'll randomly shuffle our bootstrappers before querying them in
 	// order to avoid from querying the same bootstrapper method over and
 	// over, as some of these might tend to provide better/worse results
@@ -67,19 +71,23 @@ func MultiSourceBootstrap(ignore map[autopilot.NodeID]struct{}, numAddrs uint32,
 			break
 		}
 
-		log.Infof("Attempting to bootstrap with: %v", bootstrapper.Name())
+		name := bootstrapper.Name(ctx)
+
+		log.Infof("Attempting to bootstrap with: %v", name)
 
 		// If we still need additional addresses, then we'll compute
 		// the number of address remaining that we need to fetch.
 		numAddrsLeft := numAddrs - uint32(len(addrs))
 		log.Tracef("Querying for %v addresses", numAddrsLeft)
-		netAddrs, err := bootstrapper.SampleNodeAddrs(numAddrsLeft, ignore)
+		netAddrs, err := bootstrapper.SampleNodeAddrs(
+			ctx, numAddrsLeft, ignore,
+		)
 		if err != nil {
 			// If we encounter an error with a bootstrapper, then
 			// we'll continue on to the next available
 			// bootstrapper.
-			log.Errorf("Unable to query bootstrapper %v: %v",
+			log.Errorf("Unable to query bootstrapper %v: %v", name,
-				bootstrapper.Name(), err)
+				err)
 			continue
 		}
 
@@ -152,8 +160,9 @@ func NewGraphBootstrapper(cg autopilot.ChannelGraph) (NetworkPeerBootstrapper, e
 // many valid peer addresses to return.
 //
 // NOTE: Part of the NetworkPeerBootstrapper interface.
-func (c *ChannelGraphBootstrapper) SampleNodeAddrs(numAddrs uint32,
+func (c *ChannelGraphBootstrapper) SampleNodeAddrs(_ context.Context,
-	ignore map[autopilot.NodeID]struct{}) ([]*lnwire.NetAddress, error) {
+	numAddrs uint32, ignore map[autopilot.NodeID]struct{}) (
+	[]*lnwire.NetAddress, error) {
 
 	// We'll merge the ignore map with our currently selected map in order
 	// to ensure we don't return any duplicate nodes.
@@ -269,7 +278,7 @@ func (c *ChannelGraphBootstrapper) SampleNodeAddrs(numAddrs uint32,
 // of the NetworkPeerBootstrapper.
 //
 // NOTE: Part of the NetworkPeerBootstrapper interface.
-func (c *ChannelGraphBootstrapper) Name() string {
+func (c *ChannelGraphBootstrapper) Name(_ context.Context) string {
 	return "Authenticated Channel Graph"
 }
 
@@ -382,8 +391,9 @@ func (d *DNSSeedBootstrapper) fallBackSRVLookup(soaShim string,
 // network peer bootstrapper source. The num addrs field passed in denotes how
 // many valid peer addresses to return. The set of DNS seeds are used
 // successively to retrieve eligible target nodes.
-func (d *DNSSeedBootstrapper) SampleNodeAddrs(numAddrs uint32,
+func (d *DNSSeedBootstrapper) SampleNodeAddrs(_ context.Context,
-	ignore map[autopilot.NodeID]struct{}) ([]*lnwire.NetAddress, error) {
+	numAddrs uint32, ignore map[autopilot.NodeID]struct{}) (
+	[]*lnwire.NetAddress, error) {
 
 	var netAddrs []*lnwire.NetAddress
 
@@ -532,6 +542,6 @@ search:
 
 // Name returns a human readable string which names the concrete
 // implementation of the NetworkPeerBootstrapper.
-func (d *DNSSeedBootstrapper) Name() string {
+func (d *DNSSeedBootstrapper) Name(_ context.Context) string {
 	return fmt.Sprintf("BOLT-0010 DNS Seed: %v", d.dnsSeeds)
 }