.

wcfs/btree.go

@@ -36,7 +36,7 @@ type KEY int64
 // are chained together via 'next', so that the entire BTree contents
 // can be traversed in sorted order quickly and easily.
 type ZBucket struct {
-	pyobj *PyObject
+	pyobj *pyObject
 
 	next   *ZBucket		// the bucket with the next-larger keys
 	keys   []KEY		// 'len' keys, in increasing order
@@ -54,7 +54,7 @@ type zBTreeItem struct {
 // See https://github.com/zopefoundation/BTrees/blob/4.5.0-1-gc8bf24e/BTrees/Development.txt#L198
 // for details.
 type ZBTree struct {
-	pyobj *PyObject
+	pyobj *pyObject
 
 	// firstbucket points to the bucket containing the smallest key in
 	// the BTree.  This is found by traversing leftmost child pointers
@@ -239,11 +239,11 @@ func (b *ZBucket) PActivate(ctx context.Context) error {
 
 // ----------------------------------------
 
-func bucketNew(pyobj *PyObject) interface{} {
+func bucketNew(pyobj *pyObject) interface{} {
 	return &ZBucket{pyobj: pyobj}
 }
 
-func btreeNew(pyobj *PyObject) interface{} {
+func btreeNew(pyobj *pyObject) interface{} {
 	return &ZBTree{pyobj: pyobj}
 }
 

wcfs/zblk.go

@@ -39,7 +39,7 @@ import (
 
 // ZBigFile mimics ZBigFile from python.
 type ZBigFile struct {
-	pyobj *PyObject
+	pyobj *pyObject
 
 	blksize	int64
 	blktab  *ZBTree	// LOBtree{}  blk -> ZBlk*(blkdata)

wcfs/zodb.go

@@ -16,6 +16,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"sync"
 
 	"lab.nexedi.com/kirr/neo/go/zodb"
@@ -23,16 +24,16 @@ import (
 	pickle "github.com/kisielk/og-rek"
 )
 
-// Object is common base for in-process representation of ZODB object.
-type Object struct {
+// object is common base for in-process representation of ZODB object.
+type object struct {
 	jar	*Connection
 	oid	zodb.Oid
 	serial	zodb.Tid
 }
 
-// PyObject is common base for in-process representation of ZODB Python objects.
-type PyObject struct {
-	Object
+// pyObject is common base for in-process representation of ZODB Python objects.
+type pyObject struct {
+	object
 
 	pyclass pickle.Class // python class of this object
 	pystate interface{}  // object state. python passes this to pyclass.__new__().__setstate__()
@@ -98,7 +99,7 @@ type Connection struct {
 	// NOTE2 finalizers don't run on when they are attached to an object in cycle.
 	// Hopefully we don't have cycles with ZBtree/ZBucket	XXX verify this
 	objmu  sync.Mutex
-	//objtab map[zodb.Oid]interface{}	// oid -> WeakRef(PyObject) | loadInProgress
+	//objtab map[zodb.Oid]interface{}	// oid -> WeakRef(pyObject) | loadInProgress
 	objtab map[zodb.Oid]*WeakRef
 }
 
@@ -109,7 +110,7 @@ type loadInProgress struct {
 	ready chan struct{} // closed when loading finishes
 
 	// result of the load
-	pyobj interface{} // XXX -> PyObject iface
+	pyobj interface{} // XXX -> pyObject iface
 	err   error
 }
 */
@@ -143,7 +144,10 @@ func (conn *Connection) Get(ctx context.Context, oid zodb.Oid) (interface{} /*Py
 		return nil, err		// XXX errctx
 	}
 
-	xobj = conn.get(pyclass, oid)
+	xobj, err = conn.get(pyclass, oid)
+	if err != nil {
+		return nil, err
+	}
 
 	// XXX we are dropping just loaded pystate. Usually Get should be used
 	// to only load root object, so maybe that is ok.
@@ -209,6 +213,15 @@ func (conn *Connection) Get(ctx context.Context, oid zodb.Oid) (interface{} /*Py
 */
 }
 
+// wrongClassError is the error cause returned when object's class is wrong.
+type wrongClassError struct {
+	want, have pickle.Class
+}
+
+func (e *wrongClassError) Error() string {
+	return fmt.Sprintf("wrong class: want %q; have %q", e.want, e.have)
+}
+
 // get returns in-RAM object corresponding to specified ZODB object according to current database view.
 //
 // If there is already in-RAM object that corresponds to oid, that in-RAM object is returned.
@@ -219,20 +232,34 @@ func (conn *Connection) Get(ctx context.Context, oid zodb.Oid) (interface{} /*Py
 //
 // use-case: in ZODB references are (pyclass, oid), so new ghost is created
 // without further loading anything.
-func (conn *Connection) get(pyclass pickle.Class, oid zodb.Oid) interface{}/*PyObject*/ {
+func (conn *Connection) get(pyclass pickle.Class, oid zodb.Oid) (interface{}/*PyObject*/, error) {
 	conn.objmu.Lock()		// XXX -> rlock
 	wobj := conn.objtab[oid]
 	var xobj interface{}
+	checkClass := false
 	if wobj != nil {
 		xobj = wobj.Get()
-		// XXX check pyclass match.
 	}
 	if xobj == nil {
 		xobj = conn.newGhost(pyclass, oid)
 		conn.objtab[oid] = NewWeakRef(xobj)
+	} else {
+		checkClass = true
 	}
 	conn.objmu.Unlock()
-	return xobj
+
+	if checkClass {
+		if cls := xobj.PyClass(); pyclass != cls {
+			return nil, &zodb.OpError{
+				URL:  conn.stor.URL(),
+				Op:   fmt.Sprintf("@%s: get", conn.at), // XXX abuse
+				Args: oid,
+				Err:  &wrongClassError{pyclass, cls},
+			}
+		}
+	}
+
+	return xobj, nil
 }
 
 
@@ -306,8 +333,8 @@ func (conn *Connection) get(pyclass pickle.Class, oid zodb.Oid) interface{}/*PyO
 
 	buf.Release()
 
-	return &PyObject{
-		Object:  Object{jar: conn,oid: oid, serial: serial},
+	return &pyObject{
+		object:  object{jar: conn,oid: oid, serial: serial},
 		pyclass: pyclass,
 		pystate: pystate,
 	}, nil
@@ -315,7 +342,7 @@ func (conn *Connection) get(pyclass pickle.Class, oid zodb.Oid) interface{}/*PyO
 */
 
 /*
-func (conn *Connection) load(ctx context.Context, oid zodb.Oid) (*PyObject, error) {
+func (conn *Connection) load(ctx context.Context, oid zodb.Oid) (*pyObject, error) {
 	// XXX
 }
 */
@@ -337,20 +364,20 @@ func (conn *Connection) loadpy(ctx context.Context, oid zodb.Oid) (pyclass pickl
 }
 
 // path(class) -> new(pyobj)
-var classTab = make(map[string]func(*PyObject)interface{})
+var classTab = make(map[string]func(*pyObject)interface{})
 
 // registerClass registers python class to be transformed to Go instance
 // created via classNew.
 //
 // must be called from global init().
-func registerClass(classPath string, classNew func(*PyObject)interface{}) {
+func registerClass(classPath string, classNew func(*pyObject)interface{}) {
 	classTab[classPath] = classNew
 }
 
 // newGhost creates new ghost object corresponding to pyclass and oid.
 func (conn *Connection) newGhost(pyclass pickle.Class, oid zodb.Oid) interface{} {
-	pyobj := &PyObject{
-		Object:  Object{jar: conn, oid: oid, serial: 0},
+	pyobj := &pyObject{
+		object:  object{jar: conn, oid: oid, serial: 0},
 		pyclass: pyclass,
 		pystate: nil,
 	}
@@ -370,7 +397,7 @@ func (conn *Connection) newGhost(pyclass pickle.Class, oid zodb.Oid) interface{}
 // PDeactivates transforms object to ghost state.
 //
 // In ghost state object data is dropped and only oid/pyclass information is left in RAM.
-func (pyobj *PyObject) PDeactivate() {
+func (pyobj *pyObject) PDeactivate() {
 	// FIXME if state=modified PDeactivate must be noop.
 
 	pyobj.pystate = nil
@@ -380,7 +407,7 @@ func (pyobj *PyObject) PDeactivate() {
 // PActivate brings object to live state.
 //
 // If object state is not in RAM - it is loaded from the database.
-func (pyobj *PyObject) PActivate(ctx context.Context) error {
+func (pyobj *pyObject) PActivate(ctx context.Context) error {
 	if pyobj.pystate != nil {
 		return nil // already loaded
 	}