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Commit 3488cfb3 authored by Jeremy Hylton's avatar Jeremy Hylton
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Move referencesf to ZODB.serialize.

parent ed44eaff
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Showing with 11 additions and 440 deletions
trunk/src/ZEO/StorageServer.py
View file @ 3488cfb3
......@@ -39,7 +39,7 @@ import zLOG
from ZODB.ConflictResolution import ResolvedSerial
from ZODB.POSException import StorageError, StorageTransactionError
from ZODB.POSException import TransactionError, ReadOnlyError, ConflictError
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.Transaction import Transaction
from ZODB.utils import u64, oid_repr
......
trunk/src/ZODB/ExportImport.py
View file @ 3488cfb3
......@@ -19,7 +19,7 @@ from tempfile import TemporaryFile
from ZODB.POSException import ExportError
from ZODB.utils import p64, u64
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
import zLOG
class ExportImport:
......
trunk/src/ZODB/FileStorage/format.py
View file @ 3488cfb3
......@@ -117,7 +117,7 @@
import struct
from ZODB.POSException import POSKeyError
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.utils import p64, u64, z64, oid_repr, t32
from zLOG import LOG, BLATHER, WARNING, ERROR, PANIC
......
trunk/src/ZODB/FileStorage/fspack.py
View file @ 3488cfb3
......@@ -26,7 +26,7 @@ a backpointer after that time.
import os
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.utils import p64, u64, z64
from ZODB.fsIndex import fsIndex
......
trunk/src/ZODB/fspack.py
View file @ 3488cfb3
......@@ -32,7 +32,7 @@ import os
import struct
from types import StringType
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.utils import p64, u64, z64, oid_repr
from zLOG import LOG, BLATHER, WARNING, ERROR, PANIC
......
trunk/src/ZODB/fsrecover.py
View file @ 3488cfb3
......@@ -365,7 +365,7 @@ def recover(inp, outp, verbose=0, partial=0, force=0, pack=0):
if pack is not None:
print "Packing ..."
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
ofs.pack(pack, referencesf)
ofs.close()
......
trunk/src/ZODB/serialize.py deleted 100644 → 0
View file @ ed44eaff
##############################################################################
#
# Copyright (c) 2003 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.
#
##############################################################################
"""Support for ZODB object serialization.
ZODB serializes objects using a custom format based on Python pickles.
When an object is unserialized, it can be loaded as either a ghost or
a real object. A ghost is a persistent object of the appropriate type
but without any state. The first time a ghost is accessed, the
persistence machinery traps access and loads the actual state. A
ghost allows many persistent objects to be loaded while minimizing the
memory consumption of referenced but otherwise unused objects.
Pickle format
-------------
ZODB stores serialized objects using a custom format based on pickle.
Each serialized object has two parts: the class metadata and the
object state. The class description must provide enough information
to call the class's ``__new__`` and create an empty object. Once the
object exists as a ghost, its state is passed to ``__setstate__``.
The class metadata can be represented in two different ways, in order
to provide backwards compatibility with many earlier versions of ZODB.
The class metadata is always a two-tuple. The first element may also
be a tuple, containing two string elements: name of a module and the
name of a class. The second element of the class metadata tuple is a
tuple of arguments to pass to the class's ``__new__``.
Persistent references
---------------------
A persistent reference is a pair containing an oid and class metadata.
When one persistent object pickle refers to another persistent object,
the database uses a persistent reference. The format allows a
significant optimization, because ghosts can be created directly from
persistent references. If the reference was just an oid, a database
access would be required to determine the class of the ghost.
Because the persistent reference includes the class, it is not
possible to change the class of a persistent object. If a transaction
changed the class of an object, a new record with new class metadata
would be written but all the old references would still include the
old class.
"""
import cPickle
import cStringIO
from persistent import Persistent
from persistent.wref import WeakRefMarker, WeakRef
from ZODB.POSException import InvalidObjectReference
# Might to update or redo to reflect weakrefs
# from ZODB.coptimizations import new_persistent_id
def myhasattr(obj, name, _marker=object()):
"""Make sure we don't mask exceptions like hasattr().
We don't want exceptions other than AttributeError to be masked,
since that too often masks other programming errors.
Three-argument getattr() doesn't mask those, so we use that to
implement our own hasattr() replacement.
"""
return getattr(obj, name, _marker) is not _marker
class BaseObjectWriter:
"""Serializes objects for storage in the database.
The ObjectWriter creates object pickles in the ZODB format. It
also detects new persistent objects reachable from the current
object.
"""
def __init__(self, jar=None):
self._file = cStringIO.StringIO()
self._p = cPickle.Pickler(self._file, 1)
self._stack = []
self._p.persistent_id = self.persistent_id
if jar is not None:
assert myhasattr(jar, "new_oid")
self._jar = jar
def persistent_id(self, obj):
"""Return the persistent id for obj.
>>> from ZODB.tests.util import P
>>> class DummyJar:
... def new_oid(self):
... return 42
>>> jar = DummyJar()
>>> writer = BaseObjectWriter(jar)
Normally, object references include the oid and a cached
reference to the class. Having the class available allows
fast creation of the ghost, avoiding requiring an additional
database lookup.
>>> bob = P('bob')
>>> oid, cls = writer.persistent_id(bob)
>>> oid
42
>>> cls is P
True
If a persistent object does not already have an oid and jar,
these will be assigned by persistent_id():
>>> bob._p_oid
42
>>> bob._p_jar is jar
True
If the object already has a persistent id, it is not changed:
>>> bob._p_oid = 24
>>> oid, cls = writer.persistent_id(bob)
>>> oid
24
>>> cls is P
True
If the jar doesn't match that of the writer, an error is raised:
>>> bob._p_jar = DummyJar()
>>> writer.persistent_id(bob)
Traceback (most recent call last):
...
InvalidObjectReference: Attempt to store an object from a """ \
"""foreign database connection
Constructor arguments used by __new__(), as returned by
__getnewargs__(), can affect memory allocation, but also may
change over the life of the object. This makes it useless to
cache even the object's class.
>>> class PNewArgs(P):
... def __getnewargs__(self):
... return ()
>>> sam = PNewArgs('sam')
>>> writer.persistent_id(sam)
42
>>> sam._p_oid
42
>>> sam._p_jar is jar
True
Check that simple objects don't get accused of persistence:
>>> writer.persistent_id(42)
>>> writer.persistent_id(object())
Check that a classic class doesn't get identified improperly:
>>> class ClassicClara:
... pass
>>> clara = ClassicClara()
>>> writer.persistent_id(clara)
"""
# Most objects are not persistent. The following cheap test
# identifies most of them. For these, we return None,
# signalling that the object should be pickled normally.
if not isinstance(obj, (Persistent, type, WeakRef)):
# Not persistent, pickle normally
return None
# Any persistent object mosy have an oid:
try:
oid = obj._p_oid
except AttributeError:
# Not persistent, pickle normally
return None
if not (oid is None or isinstance(oid, str)):
# Deserves a closer look:
# Make sure it's not a descr
if hasattr(oid, '__get__'):
# The oid is a decriptor. That means obj is a non-persistent
# class whose instances are persistent, so ...
# Not persistent, pickle normally
return None
if oid is WeakRefMarker:
# we have a weakref, see weakref.py
oid = obj.oid
if oid is None:
obj = obj() # get the referenced object
oid = obj._p_oid
if oid is None:
# Here we are causing the object to be saved in
# the database. One could argue that we shouldn't
# do this, because a wekref should not cause an object
# to be added. We'll be optimistic, though, and
# assume that the object will be added eventually.
oid = self._jar.new_oid()
obj._p_jar = self._jar
obj._p_oid = oid
self._stack.append(obj)
return [oid]
# Since we have an oid, we have either a persistent instance
# (an instance of Persistent), or a persistent class.
# NOTE! Persistent classes don't (and can't) subclass persistent.
if oid is None:
oid = obj._p_oid = self._jar.new_oid()
obj._p_jar = self._jar
self._stack.append(obj)
elif obj._p_jar is not self._jar:
raise InvalidObjectReference(
"Attempt to store an object from a foreign "
"database connection"
)
klass = type(obj)
if hasattr(klass, '__getnewargs__'):
# We don't want to save newargs in object refs.
# It's possible that __getnewargs__ is degenerate and
# returns (), but we don't want to have to deghostify
# the object to find out.
return oid
return oid, klass
def serialize(self, obj):
# We don't use __class__ here, because obj could be a persistent proxy.
# We don't want to be folled by proxies.
klass = type(obj)
newargs = getattr(obj, "__getnewargs__", None)
if newargs is None:
meta = klass
else:
meta = klass, newargs()
return self._dump(meta, obj.__getstate__())
def _dump(self, classmeta, state):
# To reuse the existing cStringIO object, we must reset
# the file position to 0 and truncate the file after the
# new pickle is written.
self._file.seek(0)
self._p.clear_memo()
self._p.dump(classmeta)
self._p.dump(state)
self._file.truncate()
return self._file.getvalue()
class ObjectWriter(BaseObjectWriter):
def __init__(self, obj):
BaseObjectWriter.__init__(self, obj._p_jar)
self._stack.append(obj)
def __iter__(self):
return NewObjectIterator(self._stack)
class NewObjectIterator:
# The pickler is used as a forward iterator when the connection
# is looking for new objects to pickle.
def __init__(self, stack):
self._stack = stack
def __iter__(self):
return self
def next(self):
if self._stack:
elt = self._stack.pop()
return elt
else:
raise StopIteration
class BaseObjectReader:
def _persistent_load(self, oid):
# subclasses must define _persistent_load().
raise NotImplementedError
def _get_class(self, module, name):
# subclasses must define _get_class()
raise NotImplementedError
def _get_unpickler(self, pickle):
file = cStringIO.StringIO(pickle)
unpickler = cPickle.Unpickler(file)
unpickler.persistent_load = self._persistent_load
return unpickler
def _new_object(self, klass, args):
if not args and not myhasattr(klass, "__getnewargs__"):
obj = klass.__new__(klass)
else:
obj = klass(*args)
if not isinstance(klass, type):
obj.__dict__.clear()
return obj
def getClassName(self, pickle):
unpickler = self._get_unpickler(pickle)
klass = unpickler.load()
if isinstance(klass, tuple):
klass, args = klass
if isinstance(klass, tuple):
# old style reference
return "%s.%s" % klass
return "%s.%s" % (klass.__module__, klass.__name__)
def getGhost(self, pickle):
unpickler = self._get_unpickler(pickle)
klass = unpickler.load()
if isinstance(klass, tuple):
# Here we have a separate class and args.
# This could be an old record, so the class module ne a named
# refernce
klass, args = klass
if isinstance(klass, tuple):
# Old module_name, class_name tuple
klass = self._get_class(*klass)
if args is None:
return klass.__new__(klass)
else:
return klass.__new__(klass, *args)
else:
# Definately new style direct class reference
return klass.__new__(klass)
def getState(self, pickle):
unpickler = self._get_unpickler(pickle)
unpickler.load() # skip the class metadata
return unpickler.load()
def setGhostState(self, obj, pickle):
state = self.getState(pickle)
obj.__setstate__(state)
class ExternalReference(object):
pass
class SimpleObjectReader(BaseObjectReader):
"""Can be used to inspect a single object pickle.
It returns an ExternalReference() object for other persistent
objects. It can't instantiate the object.
"""
ext_ref = ExternalReference()
def _persistent_load(self, oid):
return self.ext_ref
def _get_class(self, module, name):
return None
class ConnectionObjectReader(BaseObjectReader):
def __init__(self, conn, cache, factory):
self._conn = conn
self._cache = cache
self._factory = factory
def _get_class(self, module, name):
return self._factory(self._conn, module, name)
def _persistent_load(self, oid):
if isinstance(oid, tuple):
# Quick instance reference. We know all we need to know
# to create the instance w/o hitting the db, so go for it!
oid, klass = oid
obj = self._cache.get(oid, None) # XXX it's not a dict
if obj is not None:
return obj
if isinstance(klass, tuple):
klass = self._get_class(*klass)
try:
obj = klass.__new__(klass)
except TypeError:
# Couldn't create the instance. Maybe there's more
# current data in the object's actual record!
return self._conn[oid]
# XXX should be done by connection
obj._p_oid = oid
obj._p_jar = self._conn
# When an object is created, it is put in the UPTODATE
# state. We must explicitly deactivate it to turn it into
# a ghost.
obj._p_changed = None
self._cache[oid] = obj
return obj
elif isinstance(oid, list):
# see weakref.py
[oid] = oid
obj = WeakRef.__new__(WeakRef)
obj.oid = oid
obj.dm = self._conn
return obj
obj = self._cache.get(oid, None)
if obj is not None:
return obj
return self._conn[oid]
trunk/src/ZODB/tests/PackableStorage.py
View file @ 3488cfb3
......@@ -30,7 +30,7 @@ import time
from ZODB import DB
from persistent import Persistent
from persistent.mapping import PersistentMapping
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.tests.MinPO import MinPO
from ZODB.tests.StorageTestBase import snooze
from ZODB.POSException import ConflictError, StorageError
......
trunk/src/ZODB/tests/RecoveryStorage.py
View file @ 3488cfb3
......@@ -17,7 +17,7 @@ from ZODB.Transaction import Transaction
from ZODB.tests.IteratorStorage import IteratorDeepCompare
from ZODB.tests.StorageTestBase import MinPO, zodb_unpickle, snooze
from ZODB import DB
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
import time
......
trunk/src/ZODB/tests/TransactionalUndoStorage.py
View file @ 3488cfb3
......@@ -20,7 +20,7 @@ import time
import types
from ZODB import POSException
from ZODB.Transaction import Transaction
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.utils import u64, p64
from ZODB import DB
......
trunk/src/ZODB/tests/TransactionalUndoVersionStorage.py
View file @ 3488cfb3
......@@ -17,7 +17,7 @@
import time
from ZODB import POSException
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.Transaction import Transaction
from ZODB.tests.MinPO import MinPO
from ZODB.tests.StorageTestBase import zodb_unpickle
......
trunk/src/ZODB/tests/VersionStorage.py
View file @ 3488cfb3
......@@ -19,7 +19,7 @@ Any storage that supports versions should be able to pass all these tests.
import time
from ZODB import POSException
from ZODB.referencesf import referencesf
from ZODB.serialize import referencesf
from ZODB.Transaction import Transaction
from ZODB.tests.MinPO import MinPO
from ZODB.tests.StorageTestBase import zodb_unpickle, snooze
......
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