namecache: basic persistent version

License: MIT
Signed-off-by: Łukasz Magiera <magik6k@gmail.com>

core/core.go

@@ -297,6 +297,10 @@ func (n *IpfsNode) startOnlineServices(ctx context.Context, routingOption Routin
 
 	if follow {
 		n.Namecache = namecache.NewNameCache(ctx, n.Namesys, n.Pinning, n.DAG, n.Blockstore)
+		n.Namecache, err = namecache.NewPersistentCache(n.Namecache, n.Repo.Datastore())
+		if err != nil {
+			return err
+		}
 	}
 
 	// setup local discovery

namecache/namecache.go

@@ -105,7 +105,7 @@ func (nc *nameCache) ListFollows() []string {
 	defer nc.mx.Unlock()
 
 	follows := make([]string, 0, len(nc.follows))
-	for name, _ := range nc.follows {
+	for name := range nc.follows {
 		follows = append(follows, name)
 	}
 

namecache/persistent.go

@@ -0,0 +1,72 @@
+package namecache
+
+import (
+	"encoding/json"
+	"time"
+
+	ds "gx/ipfs/Qmf4xQhNomPNhrtZc67qSnfJSjxjXs9LWvknJtSXwimPrM/go-datastore"
+	nsds "gx/ipfs/Qmf4xQhNomPNhrtZc67qSnfJSjxjXs9LWvknJtSXwimPrM/go-datastore/namespace"
+	dsq "gx/ipfs/Qmf4xQhNomPNhrtZc67qSnfJSjxjXs9LWvknJtSXwimPrM/go-datastore/query"
+)
+
+var dsPrefix = ds.NewKey("/namecache")
+
+// persistent is a cache layer which persists followed names between node
+// restarts
+type persistent struct {
+	NameCache
+
+	ds ds.Datastore
+}
+
+type follow struct {
+	Pin bool
+	Deadline time.Time
+}
+
+func NewPersistentCache(base NameCache, d ds.Datastore) (NameCache, error) {
+	d = nsds.Wrap(d, dsPrefix)
+
+	q ,err := d.Query(dsq.Query{})
+	if err != nil {
+		return nil, err
+	}
+	defer q.Close()
+	for e := range q.Next() {
+		var f follow
+		if err := json.Unmarshal(e.Value, &f); err != nil {
+			return nil, err
+		}
+		if err := base.Follow(e.Key, f.Pin, time.Now().Sub(f.Deadline)); err != nil {
+			return nil, err
+		}
+	}
+
+
+	return &persistent{
+		NameCache: base,
+		ds: d,
+	}, nil
+}
+
+func (p *persistent) Follow(name string, dopin bool, followInterval time.Duration) error {
+	b, err := json.Marshal(&follow{
+		Pin: dopin,
+		Deadline: time.Now().Add(followInterval),
+	})
+	if err != nil {
+		return err
+	}
+
+	if err := p.NameCache.Follow(name, dopin, followInterval); err != nil {
+		return err
+	}
+	return p.ds.Put(ds.NewKey(name), b)
+}
+
+func (p *persistent) Unfollow(name string) error {
+	if err := p.NameCache.Unfollow(name); err != nil {
+		return err
+	}
+	return p.ds.Delete(ds.NewKey(name))
+}