.

wcfs/zodb.go

@@ -26,11 +26,40 @@ import (
 
 // Object is the interface that every in-RAM object representing any ZODB object implements.
 type Object interface {
+	// XXX make methods private, e.g. _pJar ?
 	PJar()    *Connection
 	POid()    zodb.Oid
 	PSerial() zodb.Tid
 
-	// XXX activate/deactivate/invalidate here?
+
+	// PActivate requests in-RAM object data to be present.
+	//
+	// On successful return the object data is either the same as in the
+	// database or, if this data was previously modified by user of
+	// object's jar, that modified data.
+	//
+	// Object data must be accessed only after corresponding PActivate
+	// call, which marks that object's data as being in use.
+	PActivate(ctx context.Context) error	// XXX + -> nuse ?
+
+	// PDeactivate indicates that corresponding PActivate caller finished access to object's data.
+	//
+	// As PActivate makes sure object's data is present in-RAM, PDeactivate
+	// tells persistency layer that this data is no longer used by
+	// corresponding PActivate caller.
+	//
+	// Note that it is valid to have several concurrent uses of object
+	// data, each protected with corresponding PActivate/PDeactivate pair:
+	// As long as there is still any PActivate not yet compensated with
+	// corresponding PDeactivate, object data will stay alive in RAM.
+	//
+	// Besides exotic cases, the caller thus must not use object's data
+	// after PDeactivate call.
+	PDeactivate()	// XXX + -> nuse ?
+
+
+
+	PInvalidate()	// XXX must not be called while there are users.
 }
 
 // PyObject is the interface that every in-RAM object representing Python ZODB object implements.
@@ -448,8 +477,9 @@ func (pyobj *pyObject) PActivate(ctx context.Context) error {
 	}
 
 	if pyclass != pyobj.pyclass {
-		// XXX complain pyclass changed
-		// XXX both ref and object data uses pyclass so it indeed can be different
+		// complain pyclass changed
+		// (both ref and object data uses pyclass so it indeed can be different)
+		return &wrongClassError{want: pyobj.pyclass, have: pyclass} // XXX + err ctx
 	}
 
 	pyobj.serial  = serial