Translucent persistent objects
persistent: automatic persistence for Python objects.. image:: https://github.com/zopefoundation/persistent/actions/workflows/tests.yml/badge.svg :target: https://github.com/zopefoundation/persistent/actions/workflows/tests.yml
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This package contains a generic persistence implementation for Python. It forms the core protocol for making objects interact "transparently" with a database such as the ZODB.
Please see the Sphinx documentation (docs/index.rst) for further
information, or view the documentation at Read The Docs, for either
the latest (https://persistent.readthedocs.io/en/latest/) or stable
release (https://persistent.readthedocs.io/en/stable/).
.. note::
Use of this standalone persistent release is not recommended or
supported with ZODB < 3.11. ZODB 3.10 and earlier bundle their own
version of the persistent package.
persistent ChangelogBuild Linux binary wheels for Python 3.11.
Drop support for Python 2.7, 3.5, 3.6.
Update Python 3.11 support to 3.11.0-rc1.
Disable unsafe math optimizations in C code. See pull request 176 <https://github.com/zopefoundation/persistent/pull/176>_.
#168 <https://github.com/zopefoundation/persistent/pull/168>_)__class__ and __dict__. This matches the
behaviour of the C implementation. See issue 155 <https://github.com/zopefoundation/persistent/issues/155>_.PURE_PYTHON=1) to not print unraisable AttributeErrors from
_WeakValueDictionary during garbage collection. See issue 150 <https://github.com/zopefoundation/persistent/issues/150>_.gc.collect()) on full_sweep, incrgc and
minimize if it detects that an object that was weakly
referenced has been ejected. This solves issues on PyPy with ZODB raising
ConnectionStateError when there are persistent
zope.interface utilities/adapters registered. This partly
reverts a change from release 4.2.3.issue 144 <https://github.com/zopefoundation/persistent/issues/144>_.issue 143 <https://github.com/zopefoundation/persistent/issues/143>_.issue 137 <https://github.com/zopefoundation/persistent/issues/137>. Fix by
Jerry James <https://github.com/jamesjer>.AssertionError clearing a non-empty PersistentMapping
that has no connection. See issue 139 <https://github.com/zopefoundation/persistent/issues/139>_.issue 135 <https://github.com/zopefoundation/persistent/issues/135>_.Fix slicing of PersistentList to always return instances of the
same class. It was broken on Python 3 prior to 3.7.4.
Fix copying of PersistentList and PersistentMapping using
copy.copy to also copy the underlying data object. This was
broken prior to Python 3.7.4.
Update the handling of the PURE_PYTHON environment variable.
Now, a value of "0" requires that the C extensions be used; any other
non-empty value prevents the extensions from being used. Also, all C
extensions are required together or none of them will be used. This
prevents strange errors that arise from a mismatch of Python and C
implementations. See issue 131 <https://github.com/zopefoundation/persistent/issues/131>_.
Note that some private implementation details such as the names of the pure-Python implementations have changed.
Fix PersistentList to mark itself as changed after calling
clear (if needed). See PR 115 <https://github.com/zopefoundation/persistent/pull/115/>_.
Fix PersistentMapping.update to accept keyword arguments like
the native UserDict. Previously, most uses of keyword arguments
resulted in TypeError; in the undocumented and extremely
unlikely event of a single keyword argument called b that
happens to be a dictionary, the behaviour will change. Also adjust
the signatures of setdefault and pop to match the native
version.
Fix PersistentList.clear, PersistentMapping.clear and
PersistentMapping.popitem to no longer mark the object as
changed if it was empty.
Add preliminary support for Python 3.9a3+.
See issue 124 <https://github.com/zopefoundation/persistent/issues/124>_.
Fix the Python implementation of the PickleCache to be able to store
objects that cannot be weakly referenced. See issue 133 <https://github.com/zopefoundation/persistent/issues/133>_.
Note that ctypes is required to use the Python implementation
(except on PyPy).
Add support for Python 3.8.
Update documentation to Python 3.
Fully test the C implementation of the PickleCache, and fix discrepancies between it and the Python implementation:
ValueError instead of
AssertionError for certain types of bad inputs.IPickleCache; methods
unique to the Python implementation were moved to
IExtendedPickleCache.AttributeError if a
persistent class doesn't have a p_jar attribute.See issue 102 <https://github.com/zopefoundation/persistent/issues/102>_.
Allow sweeping cache without cache_size. cache_size_bytes
works with cache_size=0, no need to set cache_size to a
large value.
Require CFFI on CPython for pure-Python operation. This drops
support for Jython (which was untested). See issue 77 <https://github.com/zopefoundation/persistent/issues/77>_.
Fix DeprecationWarning about PY_SSIZE_T_CLEAN.
See issue 108 <https://github.com/zopefoundation/persistent/issues/108>_.
Drop support for Python 3.4.
Fix the repr of the persistent objects to include the module name
when using the C extension. This matches the pure-Python behaviour
and the behaviour prior to 4.4.0. See issue 92 <https://github.com/zopefoundation/persistent/issues/92>_.
Change the repr of persistent objects to format the OID as in
integer in hexadecimal notation if it is an 8-byte byte string, as
ZODB does. This eliminates some issues in doctests. See issue 95 <https://github.com/zopefoundation/persistent/pull/95>_.
-fwrapv is not enabled. See issue 86 <https://github.com/zopefoundation/persistent/issues/86>_.issue 88 <https://github.com/zopefoundation/persistent/issues/88>_.Use unsigned constants when doing arithmetic on C timestamps,
possibly avoiding some overflow issues with some compilers or
compiler settings. See issue 86 <https://github.com/zopefoundation/persistent/issues/86>_.
Change the default representation of Persistent objects to
include the representation of their OID and jar, if set. Also add
the ability for subclasses to implement _p_repr() instead of
overriding __repr__ for better exception handling. See issue 11 <https://github.com/zopefoundation/persistent/issues/11>_.
Reach and maintain 100% test coverage.
Simplify __init__.py, including removal of an attempted legacy
import of persistent.TimeStamp. See PR 80 <https://github.com/zopefoundation/persistent/pull/80>_.
Add support for Python 3.7 and drop support for Python 3.3.
Build the CFFI modules (used on PyPy or when PURE_PYTHON is set) at installation or wheel building time <https://cffi.readthedocs.io/en/latest/cdef.html#ffibuilder-set-source-preparing-out-of-line-modules>_
when CFFI is available. This replaces the deprecated way <https://cffi.readthedocs.io/en/latest/overview.html#abi-versus-api>_
of building them at import time. If binary wheels are distributed,
it eliminates the need to have a functioning C compiler to use PyPy.
See issue 75 <https://github.com/zopefoundation/persistent/issues/75>_.
Fix deleting the _p_oid of a pure-Python persistent object when
it is in a cache.
Fix deleting special (_p) attributes of a pure-Python persistent
object that overrides __delattr__ and correctly calls _p_delattr.
Remove some internal compatibility shims that are no longer
necessary. See PR 82 <https://github.com/zopefoundation/persistent/pull/82>_.
Make the return value of TimeStamp.second() consistent across C
and Python implementations when the TimeStamp was created from 6
arguments with floating point seconds. Also make it match across
trips through TimeStamp.raw(). Previously, the C version could
initially have erroneous rounding and too much false precision,
while the Python version could have too much precision. The raw/repr
values have not changed. See issue 41 <https://github.com/zopefoundation/persistent/issues/41>_.
Fix the possibility of a rare crash in the C extension when deallocating items. See https://github.com/zopefoundation/persistent/issues/66
Change cPickleCache's comparison of object sizes to determine
whether an object can go in the cache to use PyObject_TypeCheck().
This matches what the pure Python implementation does and is a
stronger test that the object really is compatible with the cache.
Previously, an object could potentially include cPersistent_HEAD
and not set tp_base to cPersistenceCAPI->pertype and still
be eligible for the pickle cache; that is no longer the case. See
issue 69 <https://github.com/zopefoundation/persistent/issues/69>_.
manylinux wheels.manylinux wheel built automatically.SystemError: error return without exception set
when loading an object with slots whose jar generates an exception
(such as a ZODB POSKeyError) in setstate.Fix the hashcode of Python TimeStamp objects on 64-bit Python on
Windows. See https://github.com/zopefoundation/persistent/pull/55
Stop calling gc.collect every time PickleCache.incrgc is called (every
transaction boundary) in pure-Python mode (PyPy). This means that
the reported size of the cache may be wrong (until the next GC), but
it is much faster. This should not have any observable effects for
user code.
Stop clearing the dict and slots of objects added to
PickleCache.new_ghost (typically these values are passed to
__new__ from the pickle data) in pure-Python mode (PyPy). This
matches the behaviour of the C code.
Add support for Python 3.6.
Fix __setstate__ interning when state parameter is not a built-in dict
Drop use of ctypes for determining maximum integer size, to increase
pure-Python compatibility. See https://github.com/zopefoundation/persistent/pull/31
Ensure that __slots__ attributes are cleared when a persistent
object is ghostified. (This excluses classes that override
__new__. See
https://github.com/zopefoundation/persistent/wiki/Notes_on_state_new_and_slots
if you're curious.)
TimeStamp objects on 64-bit Python 3 on
Windows.Fixed the Python(/PYPY) implementation TimeStamp.timeTime method
to have subsecond precision.
When testing PURE_PYTHON environments under tox, avoid poisoning
the user's global wheel cache.
Add support for Python 3.5.
Drop support for Python 2.6 and 3.2.
Make the Python implementation of Persistent and PickleCache
behave more similarly to the C implementation. In particular, the
Python version can now run the complete ZODB and ZEO test suites.
Fix the hashcode of the Python TimeStamp on 32-bit platforms.
Make the C and Python TimeStamp objects behave more alike. The
Python version now produces the same repr and .raw() output as
the C version, and has the same hashcode. In addition, the Python
version is now supports ordering and equality like the C version.
Intern keys of object state in __setstate__ to reduce memory usage
when unpickling multiple objects with the same attributes.
Add support for PyPy3.
100% branch coverage.
Add support for Python 3.4.
In pure-Python Persistent, avoid loading state in _p_activate
for non-ghost objects (which could corrupt their state). (PR #9)
In pure-Python, and don't throw POSKeyError if _p_activate is
called on an object that has never been committed. (PR #9)
In pure-Python Persistent, avoid calling a subclass's __setattr__
at instance creation time. (PR #8)
Make it possible to delete _p_jar / _p_oid of a pure-Python
Persistent object which has been removed from the jar's cache
(fixes aborting a ZODB Connection that has added objects). (PR #7)
Avoid a KeyError from _p_accessed() on newly-created objects under
pure-Python: these objects may be assigned to a jar, but not yet added
to its cache. (PR #6)
Avoid a failure in Persistent.__setstate__ when the state dict
contains exactly two keys. (PR #5)
Fix a hang in picklecache invalidation if OIDs are manually passed
out-of-order. (PR #4)
Add PURE_PYTHON environment variable support: if set, the C
extensions will not be built, imported, or tested.
Added support for Python 3.3.
C extenstions now build under Python 3.2, passing the same tests as the pure-Python reference implementation.
Fixed: In the C implimentation, an integer was compared with a pointer, with undefined results and a compiler warning.
Fixed: the Python implementation of the _p_estimated_size propety
didn't support deletion.
Simplified implementation of the _p_estimated_size property to
only accept integers. A TypeError is raised if an incorrect type is
provided.
_timestamp extension.Worked around test failure due to overflow to long on 32-bit systems.
Renamed TimeStamp extension module to avoid clash with pure-Python
timestamp module on case-insensitive filesystems.
N.B: the canonical way to import the TimeStamp class is now::
from persistent.timestamp import TimeStamp
which will yield the class from the extension module (if available), falling back to the pure-Python reference implementation.
Added explicit support for Python 3.2 and PyPy.
Dropped support for Python < 2.6.
100% unit test coverage.
Removed all ZODB-dependent tests:
Rewrote some to avoid the dependency
Cloned the remainder into new ZODB.tests modules.
Refactored some doctests refactored as unittests.
Completed pure-Python reference implementations of 'Persistent', 'PickleCache', and 'TimeStamp'.
All covered platforms tested under tox.
Added support for continuous integration using tox and jenkins.
Added setup.py dev alias (installs nose and coverage).
Dropped dependency on zope.testing / zope.testrunner: tests now
run with setup.py test.
Refactored many Doctests as Sphinx documentation (snippets are exercised via 'tox').
Added setup.py docs alias (installs Sphinx and
repoze.sphinx.autointerface).