fix(core) tear-down leveldb

@jbenet @whyrusleeping @mappum

If we permit initialization in `ipfs daemon`, then we must ensure that
the node instantiated in `ipfs init` (to create the welcome file) shuts
down and releases resources.

Kept running into "resource temporarily unavailable". Discovered that it
was our cousins Jeff and Sanjay over at LevelDB Ave.

go-datastore doesn't expose Close() so I extended the TsDs interface and
submitted a patch.

License: MIT
Signed-off-by: Brian Tiger Chow <brian@perfmode.com>
Signed-off-by: Brian Tiger Chow <brian.holderchow@gmail.com>

core/core.go

@@ -48,7 +48,7 @@ type IpfsNode struct {
 	Peerstore peer.Peerstore
 
 	// the local datastore
-	Datastore ds.ThreadSafeDatastore
+	Datastore ds.ThreadSafeDatastoreCloser
 
 	// the network message stream
 	Network inet.Network
@@ -192,6 +192,11 @@ func NewIpfsNode(cfg *config.Config, online bool) (n *IpfsNode, err error) {
 	return n, nil
 }
 
+func (n *IpfsNode) Close() {
+	n.ContextCloser.Close()
+	n.Datastore.Close()
+}
+
 func (n *IpfsNode) OnlineMode() bool {
 	return n.onlineMode
 }

core/datastore.go

@@ -14,7 +14,7 @@ import (
 	u "github.com/jbenet/go-ipfs/util"
 )
 
-func makeDatastore(cfg config.Datastore) (ds.ThreadSafeDatastore, error) {
+func makeDatastore(cfg config.Datastore) (ds.ThreadSafeDatastoreCloser, error) {
 	if len(cfg.Type) == 0 {
 		return nil, fmt.Errorf("config datastore.type required")
 	}
@@ -39,7 +39,7 @@ func makeDatastore(cfg config.Datastore) (ds.ThreadSafeDatastore, error) {
 	return nil, fmt.Errorf("Unknown datastore type: %s", cfg.Type)
 }
 
-func makeLevelDBDatastore(cfg config.Datastore) (ds.ThreadSafeDatastore, error) {
+func makeLevelDBDatastore(cfg config.Datastore) (ds.ThreadSafeDatastoreCloser, error) {
 	if len(cfg.Path) == 0 {
 		return nil, fmt.Errorf("config datastore.path required for leveldb")
 	}