Start of simple camli/lru class for fuse caches.

build.pl

@@ -403,6 +403,7 @@ TARGET: lib/go/camli/blobserver/localdisk
 TARGET: lib/go/camli/client
 TARGET: lib/go/camli/httputil
 TARGET: lib/go/camli/jsonsign
+TARGET: lib/go/camli/lru
 TARGET: lib/go/camli/magic
 TARGET: lib/go/camli/misc/httprange
 TARGET: lib/go/camli/mysqlindexer

clients/go/cammount/fs.go

@@ -27,6 +27,7 @@ import (
 	"sync"
 
 	"camli/blobref"
+	"camli/lru"
 	"camli/schema"
 	"camli/third_party/github.com/hanwen/go-fuse/fuse"
 )
@@ -40,8 +41,10 @@ type CamliFileSystem struct {
 	fetcher blobref.Fetcher
 	root    *blobref.BlobRef
 
+	schemaBlob *lru.Cache
+
 	lk         sync.Mutex
-	nameToBlob map[string]*blobref.BlobRef
+	nameToBlob map[string]*blobref.BlobRef  // TODO: bound this?
 }
 
 func NewCamliFileSystem(fetcher blobref.Fetcher, root *blobref.BlobRef) *CamliFileSystem {

lib/go/camli/lru/cache.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2011 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 lru
+
+import (
+	"container/list"
+	"sync"
+)
+
+type Cache struct {
+	maxEntries int
+
+	lk    sync.Mutex
+	ll    *list.List
+	cache map[string]*list.Element
+}
+
+func New(maxEntries int) *Cache {
+	return &Cache{
+		maxEntries: maxEntries,
+		cache:      make(map[string]*list.Element),
+	}
+}
+
+func (c *Cache) Add(key string, value interface{}) {
+	c.lk.Lock()
+	defer c.lk.Unlock()
+	if ee, ok := c.cache[key]; ok {
+		c.ll.MoveToFront(ee)
+		ee.Value = value
+		return
+	}
+	// TODO: check size, add new element, etc
+}