Rename content/fs to content/local

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

content/local/locks.go

@@ -0,0 +1,38 @@
+package local
+
+import (
+	"sync"
+
+	"github.com/containerd/containerd/errdefs"
+	"github.com/pkg/errors"
+)
+
+// Handles locking references
+// TODO: use boltdb for lock status
+
+var (
+	// locks lets us lock in process
+	locks   = map[string]struct{}{}
+	locksMu sync.Mutex
+)
+
+func tryLock(ref string) error {
+	locksMu.Lock()
+	defer locksMu.Unlock()
+
+	if _, ok := locks[ref]; ok {
+		return errors.Wrapf(errdefs.ErrUnavailable, "ref %s locked", ref)
+	}
+
+	locks[ref] = struct{}{}
+	return nil
+}
+
+func unlock(ref string) {
+	locksMu.Lock()
+	defer locksMu.Unlock()
+
+	if _, ok := locks[ref]; ok {
+		delete(locks, ref)
+	}
+}