.

wcfs/wcfs.go

@@ -457,6 +457,23 @@ func (bf *BigFile) Read(_ nodefs.File, dest []byte, off int64, _ fuse.Context) (
 */
 
 
+// zodbCacheControl tunes ZODB wrt caching XXX
+// XXX set it to Connection.CacheControl
+type zodbCacheControl struct {}
+
+type (cc *zodbCacheControl) WantEvict(obj Object) {
+	// we want to keep ZBTree/ZBucket always alive becuse it is essentially
+	// the index where to find ZBigFile data.
+	switch obj.(type) {
+	default:
+		return true
+
+	case *ZBtree:
+	case *ZBucket:
+	}
+
+	return false
+}
 
 // XXX option to prevent starting if wcfs was already started ?
 

wcfs/zodb.go

@@ -105,6 +105,15 @@ func (pyobj *pyObject) PyClass() pickle.Class	{ return pyobj.pyclass	}
 func (pyobj *pyObject) PyState() interface{}	{ return pyobj.pystate	}
 
 
+// ConnCacheControl is the interface that allows applications to influence
+// Connection decisions with respect to its cache.
+type ConnCacheControl interface {
+	// WantEvict is called when object is going to be evicted from live cache and made ghost.
+	// If !ok the object will remain live.
+	WantEvict(obj Object) (ok bool)
+}
+
+
 // Connection represents a view of ZODB database.
 //
 // The view is representing state of ZODB objects as of `at` transaction.