Add experimental findprovs

Author: Kubuxu

shell.go

@@ -3,6 +3,7 @@ package shell
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -13,6 +14,8 @@ import (
 	"strings"
 	"time"
 
+	pstore "github.com/libp2p/go-libp2p-peerstore"
+	notif "github.com/libp2p/go-libp2p-routing/notifications"
 	ma "github.com/multiformats/go-multiaddr"
 	manet "github.com/multiformats/go-multiaddr-net"
 	files "github.com/whyrusleeping/go-multipart-files"
@@ -371,6 +374,53 @@ func (s *Shell) FindPeer(peer string) (*PeerInfo, error) {
 	return &str.Responses[0], nil
 }
 
+func (s *Shell) FindProvs(ctx context.Context, cid string) (<-chan pstore.PeerInfo, error) {
+	ctx, cancel := context.WithCancel(ctx)
+
+	resp, err := s.newRequest("dht/findprovs", cid).Send(s.httpcli)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.Error != nil {
+		return nil, resp.Error
+	}
+
+	// 4 is arbitrary here just to make the channel buffered
+	outchan := make(chan pstore.PeerInfo, 4)
+
+	go func() {
+		defer close(outchan)
+		defer cancel()
+
+		var n notif.QueryEvent
+		decoder := json.NewDecoder(resp.Output)
+		for {
+			err := decoder.Decode(&n)
+			if err != nil {
+				return
+			}
+
+			if n.Type == notif.Provider {
+				for _, p := range n.Responses {
+					select {
+					case outchan <- *p:
+					case <-ctx.Done():
+						return
+					}
+				}
+			}
+		}
+	}()
+
+	go func() {
+		<-ctx.Done()
+		resp.Close()
+	}()
+
+	return outchan, nil
+}
+
 func (s *Shell) Refs(hash string, recursive bool) (<-chan string, error) {
 	req := s.newRequest("refs", hash)
 	if recursive {

shell_test.go

@@ -2,6 +2,7 @@ package shell
 
 import (
 	"bytes"
+	"context"
 	"crypto/md5"
 	"fmt"
 	"io"
@@ -212,3 +213,18 @@ func TestObjectStat(t *testing.T) {
 	is.Equal(stat.LinksSize, 3)
 	is.Equal(stat.CumulativeSize, 1688)
 }
+
+func TestFindProvs(t *testing.T) {
+	is := is.New(t)
+	s := NewShell(shellUrl)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	c, err := s.FindProvs(ctx, "Qme1g4e3m2SmdiSGGU3vSWmUStwUjc5oECnEriaK9Xa1HU")
+	is.Nil(err)
+
+	p := <-c
+	t.Logf("prov: %s", p)
+	is.NotNil(p)
+	is.NotNil(p.ID)
+}