Add structcheck, unused, and varcheck linters.

Warn on unused and dead code

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

metadata/buckets.go

@@ -31,7 +31,6 @@ var (
 	bucketKeyVersion          = []byte(schemaVersion)
 	bucketKeyDBVersion        = []byte("version")    // stores the version of the schema
 	bucketKeyObjectLabels     = []byte("labels")     // stores the labels for a namespace.
-	bucketKeyObjectIndexes    = []byte("indexes")    // reserved
 	bucketKeyObjectImages     = []byte("images")     // stores image objects
 	bucketKeyObjectContainers = []byte("containers") // stores container objects
 	bucketKeyObjectSnapshots  = []byte("snapshots")  // stores snapshot references

metadata/gc_test.go

@@ -402,22 +402,6 @@ func addLeaseContent(ns, lid string, dgst digest.Digest) alterFunc {
 	}
 }
 
-func addContainer(ns, name, snapshotter, snapshot string, labels map[string]string) alterFunc {
-	return func(bkt *bolt.Bucket) error {
-		cbkt, err := createBuckets(bkt, ns, string(bucketKeyObjectContainers), name)
-		if err != nil {
-			return err
-		}
-		if err := cbkt.Put(bucketKeySnapshotter, []byte(snapshotter)); err != nil {
-			return err
-		}
-		if err := cbkt.Put(bucketKeySnapshotKey, []byte(snapshot)); err != nil {
-			return err
-		}
-		return boltutil.WriteLabels(cbkt, labels)
-	}
-}
-
 func createBuckets(bkt *bolt.Bucket, names ...string) (*bolt.Bucket, error) {
 	for _, name := range names {
 		nbkt, err := bkt.CreateBucketIfNotExists([]byte(name))

metadata/snapshot.go

@@ -39,14 +39,6 @@ func createKey(id uint64, namespace, key string) string {
 	return fmt.Sprintf("%s/%d/%s", namespace, id, key)
 }
 
-func trimKey(key string) string {
-	parts := strings.SplitN(key, "/", 3)
-	if len(parts) < 3 {
-		return ""
-	}
-	return parts[2]
-}
-
 func getKey(tx *bolt.Tx, ns, name, key string) string {
 	bkt := getSnapshotterBucket(tx, ns, name)
 	if bkt == nil {