fix(bootstrap): bootstrap sequentially

The default timeout is 10s so this won't take that long anyways. On the
other hand, if we do this all at once, we max the swarms dial queue.

dht_bootstrap.go

@@ -2,9 +2,6 @@ package dht
 
 import (
 	"context"
-	"fmt"
-	"strings"
-	"sync"
 	"time"
 
 	process "github.com/jbenet/goprocess"
@@ -12,7 +9,6 @@ import (
 	"github.com/libp2p/go-libp2p-core/routing"
 	"github.com/multiformats/go-multiaddr"
 	_ "github.com/multiformats/go-multiaddr-dns"
-	"github.com/pkg/errors"
 )
 
 var DefaultBootstrapPeers []multiaddr.Multiaddr
@@ -76,16 +72,12 @@ func (dht *IpfsDHT) startBootstrapping() error {
 }
 
 func (dht *IpfsDHT) doBootstrap(ctx context.Context) {
-	if err := dht.selfWalk(ctx); err != nil {
-		logger.Warningf("error while bootstrapping self: %s", err)
-	}
-	if err := dht.bootstrapBuckets(ctx); err != nil {
-		logger.Warningf("error while bootstrapping buckets: %s", err)
-	}
+	dht.selfWalk(ctx)
+	dht.bootstrapBuckets(ctx)
 }
 
 // bootstrapBuckets scans the routing table, and does a random walk on k-buckets that haven't been queried since the given bucket period
-func (dht *IpfsDHT) bootstrapBuckets(ctx context.Context) error {
+func (dht *IpfsDHT) bootstrapBuckets(ctx context.Context) {
 	doQuery := func(bucketId int, target string, f func(context.Context) error) error {
 		logger.Infof("starting bootstrap query for bucket %d to %s (routing table size was %d)",
 			bucketId, target, dht.routingTable.Size())
@@ -103,60 +95,36 @@ func (dht *IpfsDHT) bootstrapBuckets(ctx context.Context) error {
 	}
 
 	buckets := dht.routingTable.GetAllBuckets()
-	var wg sync.WaitGroup
-	errChan := make(chan error)
-
 	for bucketID, bucket := range buckets {
 		if time.Since(bucket.RefreshedAt()) > dht.bootstrapPeriod {
-			wg.Add(1)
-			go func(bucketID int, errChan chan<- error) {
-				defer wg.Done()
-				// gen rand peer in the bucket
-				randPeerInBucket := dht.routingTable.GenRandPeerID(bucketID)
-
-				// walk to the generated peer
-				walkFnc := func(c context.Context) error {
-					_, err := dht.FindPeer(ctx, randPeerInBucket)
-					if err == routing.ErrNotFound {
-						return nil
-					}
-					return err
+			// gen rand peer in the bucket
+			randPeerInBucket := dht.routingTable.GenRandPeerID(bucketID)
+
+			// walk to the generated peer
+			walkFnc := func(c context.Context) error {
+				_, err := dht.FindPeer(ctx, randPeerInBucket)
+				if err == routing.ErrNotFound {
+					return nil
 				}
+				return err
+			}
 
-				if err := doQuery(bucketID, randPeerInBucket.String(), walkFnc); err != nil {
-					errChan <- errors.Wrapf(err, "failed to do a random walk on bucket %d", bucketID)
-				}
-			}(bucketID, errChan)
+			if err := doQuery(bucketID, randPeerInBucket.String(), walkFnc); err != nil {
+				logger.Warningf("failed to do a random walk on bucket %d", bucketID)
+			}
 		}
 	}
-
-	// wait for all walks to finish & close the error channel
-	go func() {
-		wg.Wait()
-		close(errChan)
-	}()
-
-	// accumulate errors from all go-routines. ensures wait group is completed by reading errChan until closure.
-	var errStrings []string
-	for err := range errChan {
-		errStrings = append(errStrings, err.Error())
-	}
-	if len(errStrings) == 0 {
-		return nil
-	} else {
-		return fmt.Errorf("errors encountered while running bootstrap on RT:\n%s", strings.Join(errStrings, "\n"))
-	}
 }
 
 // Traverse the DHT toward the self ID
-func (dht *IpfsDHT) selfWalk(ctx context.Context) error {
+func (dht *IpfsDHT) selfWalk(ctx context.Context) {
 	queryCtx, cancel := context.WithTimeout(ctx, dht.bootstrapTimeout)
 	defer cancel()
 	_, err := dht.FindPeer(queryCtx, dht.self)
 	if err == routing.ErrNotFound {
-		return nil
+		return
 	}
-	return err
+	logger.Warningf("failed to bootstrap self: %s", err)
 }
 
 // Bootstrap tells the DHT to get into a bootstrapped state.

go.mod

@@ -4,7 +4,6 @@ go 1.12
 
 require (
 	github.com/gogo/protobuf v1.3.0
-	github.com/google/uuid v1.1.1
 	github.com/hashicorp/golang-lru v0.5.3
 	github.com/ipfs/go-cid v0.0.3
 	github.com/ipfs/go-datastore v0.1.0
@@ -25,7 +24,6 @@ require (
 	github.com/multiformats/go-multiaddr v0.0.4
 	github.com/multiformats/go-multiaddr-dns v0.0.3
 	github.com/multiformats/go-multistream v0.1.0
-	github.com/pkg/errors v0.8.1
 	github.com/stretchr/testify v1.3.0
 	github.com/whyrusleeping/base32 v0.0.0-20170828182744-c30ac30633cc
 	go.opencensus.io v0.22.1

go.sum

@@ -395,8 +395,6 @@ golang.org/x/tools v0.0.0-20181130052023-1c3d964395ce/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=