Reuse memoized mutDirs and mutFiles.

This provides a considerably improved experience for from a single FUSE
client, but not for free.

New dirents introduced outside of FUSE will be visible on the normal
refresh interval.

Removals outside of FUSE are tricky because it's not possible to tell
the difference between a file that was locally created and hasn't made
it into the index yet from a file that was deleted remotely.

Specific dirents that change permanodes outside of FUSE are replaced.

Dirents that change properties outside of FUSE without changing
permanodes (e.g. content, etc...) are never picked up.

Change-Id: I7cc8eaea5951644809053fc97c28455e96508bd4
Fixes:  http://calistore.org/issue/328

pkg/fs/mut.go

@@ -42,6 +42,10 @@ import (
 // How often to refresh directory nodes by reading from the blobstore.
 const populateInterval = 30 * time.Second
 
+// How long an item that was created locally will be present
+// regardless of its presence in the indexing server.
+const deletionRefreshWindow = time.Minute
+
 type nodeType int
 
 const (
@@ -58,6 +62,8 @@ type mutDir struct {
 	parent    *mutDir // or nil, if the root within its roots.go root.
 	name      string  // ent name (base name within parent)
 
+	localCreateTime time.Time // time this node was created locally (iff it was)
+
 	mu       sync.Mutex
 	lastPop  time.Time
 	children map[string]mutFileOrDir
@@ -133,6 +139,7 @@ func (n *mutDir) populate() error {
 	if n.children == nil {
 		n.children = make(map[string]mutFileOrDir)
 	}
+	currentChildren := map[string]bool{}
 	for k, v := range db.Permanode.Attr {
 		const p = "camliPath:"
 		if !strings.HasPrefix(k, p) || len(v) < 1 {
@@ -147,22 +154,22 @@ func (n *mutDir) populate() error {
 		}
 		if target := child.Permanode.Attr.Get("camliSymlinkTarget"); target != "" {
 			// This is a symlink.
-			n.children[name] = &mutFile{
+			n.maybeAddChild(name, child.Permanode, &mutFile{
 				fs:        n.fs,
 				permanode: blob.ParseOrZero(childRef),
 				parent:    n,
 				name:      name,
 				symLink:   true,
 				target:    target,
-			}
+			})
 		} else if isDir(child.Permanode) {
 			// This is a directory.
-			n.children[name] = &mutDir{
+			n.maybeAddChild(name, child.Permanode, &mutDir{
 				fs:        n.fs,
 				permanode: blob.ParseOrZero(childRef),
 				parent:    n,
 				name:      name,
-			}
+			})
 		} else if contentRef := child.Permanode.Attr.Get("camliContent"); contentRef != "" {
 			// This is a file.
 			content := res.Meta[contentRef]
@@ -174,23 +181,43 @@ func (n *mutDir) populate() error {
 				log.Printf("child not a file: %v", childRef)
 				continue
 			}
-			n.children[name] = &mutFile{
+			n.maybeAddChild(name, child.Permanode, &mutFile{
 				fs:        n.fs,
 				permanode: blob.ParseOrZero(childRef),
 				parent:    n,
 				name:      name,
 				content:   blob.ParseOrZero(contentRef),
 				size:      content.File.Size,
-			}
+			})
 		} else {
 			// unhandled type...
 			continue
 		}
-		n.children[name].xattr().load(child.Permanode)
+		currentChildren[name] = true
+	}
+	// Remove unreferenced children
+	for name, oldchild := range n.children {
+		if _, ok := currentChildren[name]; !ok {
+			if oldchild.eligibleToDelete() {
+				delete(n.children, name)
+			}
+		}
 	}
 	return nil
 }
 
+// maybeAddChild adds a child directory to this mutable directory
+// unless it already has one with this name and permanode.
+func (m *mutDir) maybeAddChild(name string, permanode *search.DescribedPermanode,
+	child mutFileOrDir) {
+	if current, ok := m.children[name]; !ok ||
+		current.permanodeString() != child.permanodeString() {
+
+		child.xattr().load(permanode)
+		m.children[name] = child
+	}
+}
+
 func isDir(d *search.DescribedPermanode) bool {
 	// Explicit
 	if d.Attr.Get("camliNodeType") == "directory" {
@@ -354,19 +381,21 @@ func (n *mutDir) creat(name string, typ nodeType) (fuse.Node, error) {
 	switch typ {
 	case dirType:
 		child = &mutDir{
-			fs:        n.fs,
-			permanode: pr.BlobRef,
-			parent:    n,
-			name:      name,
-			xattrs:    map[string][]byte{},
+			fs:              n.fs,
+			permanode:       pr.BlobRef,
+			parent:          n,
+			name:            name,
+			xattrs:          map[string][]byte{},
+			localCreateTime: time.Now(),
 		}
 	case fileType, symlinkType:
 		child = &mutFile{
-			fs:        n.fs,
-			permanode: pr.BlobRef,
-			parent:    n,
-			name:      name,
-			xattrs:    map[string][]byte{},
+			fs:              n.fs,
+			permanode:       pr.BlobRef,
+			parent:          n,
+			name:            name,
+			xattrs:          map[string][]byte{},
+			localCreateTime: time.Now(),
 		}
 	default:
 		panic("bogus creat type")
@@ -472,6 +501,8 @@ type mutFile struct {
 	parent    *mutDir
 	name      string // ent name (base name within parent)
 
+	localCreateTime time.Time // time this node was created locally (iff it was)
+
 	mu           sync.Mutex // protects all following fields
 	symLink      bool       // if true, is a symlink
 	target       string     // if a symlink
@@ -816,6 +847,7 @@ type mutFileOrDir interface {
 	invalidate()
 	permanodeString() string
 	xattr() *xattr
+	eligibleToDelete() bool
 }
 
 func (n *mutFile) permanodeString() string {
@@ -837,3 +869,11 @@ func (n *mutDir) invalidate() {
 	n.deleted = true
 	n.mu.Unlock()
 }
+
+func (n *mutFile) eligibleToDelete() bool {
+	return n.localCreateTime.Before(time.Now().Add(-deletionRefreshWindow))
+}
+
+func (n *mutDir) eligibleToDelete() bool {
+	return n.localCreateTime.Before(time.Now().Add(-deletionRefreshWindow))
+}

pkg/fs/mut_test.go

@@ -0,0 +1,49 @@
+// +build linux darwin
+
+/*
+Copyright 2014 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package fs
+
+import (
+	"testing"
+	"time"
+)
+
+func TestDeleteEligibility(t *testing.T) {
+	tests := []struct {
+		name string
+		ts   time.Time
+		exp  bool
+	}{
+		{"zero", time.Time{}, true},
+		{"now", time.Now(), false},
+		{"future", time.Now().Add(time.Hour), false},
+		{"recent", time.Now().Add(-(deletionRefreshWindow / 2)), false},
+		{"past", time.Now().Add(-(deletionRefreshWindow * 2)), true},
+	}
+
+	for _, test := range tests {
+		d := &mutDir{localCreateTime: test.ts}
+		if d.eligibleToDelete() != test.exp {
+			t.Errorf("Expected %v %T/%v", test.exp, d, test.name)
+		}
+		f := &mutFile{localCreateTime: test.ts}
+		if f.eligibleToDelete() != test.exp {
+			t.Errorf("Expected %v for %T/%v", test.exp, f, test.name)
+		}
+	}
+}