Add fsrefs.py script to help track down dangling references, and

dangle.py script that creates one.

src/ZODB/tests/dangle.py

+#! /usr/bin/env python
+
+##############################################################################
+#
+# Copyright (c) 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+# 
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+# 
+##############################################################################
+
+"""Functional test to produce a dangling reference."""
+
+import time
+
+from ZODB.FileStorage import FileStorage
+from ZODB import DB
+
+from Persistence import Persistent
+
+class P(Persistent):
+    pass
+
+def create_dangling_ref(db):
+    rt = db.open().root()
+
+    rt[1] = o1 = P()
+    get_transaction().note("create o1")
+    get_transaction().commit()
+
+    rt[2] = o2 = P()
+    get_transaction().note("create o2")
+    get_transaction().commit()
+
+    c = o1.child = P()
+    get_transaction().note("set child on o1")
+    get_transaction().commit()
+
+    o1.child = P()
+    get_transaction().note("replace child on o1")
+    get_transaction().commit()
+
+    time.sleep(2)
+    # The pack should remove the reference to c, because it is no
+    # longer referenced from o1.  But the object still exists and has
+    # an oid, so a new commit of it won't create a new object.
+    db.pack()
+
+    print repr(c._p_oid)
+    o2.child = c
+    get_transaction().note("set child on o2")
+    get_transaction().commit()
+
+def main():
+    fs = FileStorage("dangle.fs")
+    db = DB(fs)
+    create_dangling_ref(db)
+    db.close()
+    
+if __name__ == "__main__":
+    main()

src/scripts/fsrefs.py

+#! /usr/bin/env python
+
+##############################################################################
+#
+# Copyright (c) 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+# 
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+# 
+##############################################################################
+
+"""Check FileStorage for dangling references.
+
+usage: fsrefs.py data.fs
+
+This script ignores versions, which might produce incorrect results
+for storages that use versions.
+"""
+
+from ZODB.FileStorage import FileStorage
+from ZODB.utils import u64
+from ZODB.fsdump import get_pickle_metadata
+
+import cPickle
+import cStringIO
+import types
+
+def get_refs(pickle):
+    refs = []
+    f = cStringIO.StringIO(pickle)
+    u = cPickle.Unpickler(f)
+    u.persistent_load = refs
+    u.noload()
+    u.noload()
+    return refs
+
+def report(oid, data, serial, fs, missing):
+    from_mod, from_class = get_pickle_metadata(data)
+    if len(missing) > 1:
+        plural = "s"
+    else:
+        plural = ""
+    print "oid %s %s.%s" % (hex(u64(oid)), from_mod, from_class)
+    print "refers to unknown object%s:" % plural
+    for oid, info in missing:
+        if isinstance(info, types.TupleType):
+            description = "%s.%s" % info
+        else:
+            description = str(info)
+        print "\toid %s: %s" % (hex(u64(oid)), description)
+
+def main(path):
+    fs = FileStorage(path, read_only=1)
+    for oid in fs._index.keys():
+        data, serial = fs.load(oid, "")
+        refs = get_refs(data)
+        missing = []
+        for ref, klass in refs:
+            if not fs._index.has_key(ref):
+                missing.append((ref, klass))
+        if missing:
+            report(oid, data, serial, fs, missing)
+
+if __name__ == "__main__":
+    import sys
+    main(sys.argv[1])