Redeclared the inode struct.

samples/memfs/inode.go

@@ -4,36 +4,57 @@
 package memfs
 
 import (
-	"fmt"
-	"reflect"
-
 	"github.com/jacobsa/fuse"
+	"github.com/jacobsa/fuse/fuseutil"
+	"github.com/jacobsa/gcloud/syncutil"
 )
 
 // Common attributes for files and directories.
 //
 // TODO(jacobsa): Add tests for interacting with a file/directory after it has
 // been unlinked, including creating a new file. Make sure we don't screw up
-// and reuse the inode while it is still in use.
+// and reuse an inode ID while it is still in use.
 type inode struct {
-	// The *memFile or *memDir for this inode, or nil if the inode is available
-	// for reuse.
+	/////////////////////////
+	// Constant data
+	/////////////////////////
+
+	// Is this a directory? If not, it is a file.
+	bool dir
+
+	/////////////////////////
+	// Mutable state
+	/////////////////////////
+
+	mu syncutil.InvariantMutex
+
+	// The current attributes of this inode.
 	//
-	// INVARIANT: impl is nil, or of type *memFile or *memDir
-	impl interface{}
+	// INVARIANT: No non-permission mode bits are set besides os.ModeDir
+	// INVARIANT: If dir, then os.ModeDir is set
+	// INVARIANT: If !dir, then os.ModeDir is not set
+	attributes fuse.InodeAttributes // GUARDED_BY(mu)
+
+	// For directories, entries describing the children of the directory.
+	//
+	// This array can never be shortened, nor can its elements be moved, because
+	// we use its indices for Dirent.Offset, which is exposed to the user who
+	// might be calling readdir in a loop while concurrently modifying the
+	// directory. Unused entries can, however, be reused.
+	//
+	// TODO(jacobsa): Add good tests exercising concurrent modifications while
+	// doing readdir, seekdir, etc. calls.
+	//
+	// INVARIANT: If dir is false, this is nil.
+	// INVARIANT: For each i, entries[i].Offset == i+1
+	entries []fuseutil.Dirent // GUARDED_BY(mu)
+
+	// For files, the current contents of the file.
+	//
+	// INVARIANT: If dir is true, this is nil.
+	contents []byte // GUARDED_BY(mu)
 }
 
-func (inode *inode) checkInvariants() {
-	switch inode.impl.(type) {
-	case nil:
-	case *memFile:
-	case *memDir:
-	default:
-		panic(
-			fmt.Sprintf("Unexpected inode impl type: %v", reflect.TypeOf(inode.impl)))
-	}
-}
+func newInode(dir bool) (inode *inode)
 
-func (inode *inode) Attributes() fuse.InodeAttributes {
-	return fuse.InodeAttributes{}
-}
+func (inode *inode) checkInvariants()