CHANGES.txt

================
 Change History
================

Unreleased
==========

- Enforced usage of bytes for '_p_serial' of persistent objects (fixes
  compatibility with recent persistent releases).

4.0.0a3 (2012-12-01)
=====================

- Fixed: An elaborate test for trvial logic corrupted module state in a
        way that made other tests fail spuriously.

4.0.0a2 (2012-11-13)
=====================

Bugs Fixed
----------

- An unneeded left-over setting in setup.py caused installation with
  pip to fail.

4.0.0a1 (2012-11-07)
=====================

New Features
------------

- The ``persistent`` and ``BTrees`` packages are now released as separate
  distributions, on which ZODB now depends.

- ZODB no longer depends on zope.event.  It now uses ZODB.event, which
  uses zope.event if it is installed.  You can override
  ZODB.event.notify to provide your own event handling, although
  zope.event is recommended.

- BTrees allowed object keys with insane comparison. (Comparison
  inherited from object, which compares based on in-process address.)
  Now BTrees raise TypeError if an attempt is made to save a key with
  comparison inherited from object. (This doesn't apply to old-style
  class instances.)

Bugs Fixed
----------

- Ensured that the export file and index file created by ``repozo`` share
  the same timestamp.

  https://bugs.launchpad.net/zodb/+bug/993350

- Pinned the ``transaction`` and ``manuel`` dependencies to Python 2.5-
  compatible versions when installing under Python 2.5.

3.10.5 (2011-11-19)
===================

Bugs Fixed
----------

- Conflict resolution failed when state included cross-database
  persistent references with classes that couldn't be imported.

3.10.4 (2011-11-17)
===================

Bugs Fixed
----------

- Conflict resolution failed when state included persistent references
  with classes that couldn't be imported.

3.10.3 (2011-04-12)
===================

Bugs Fixed
----------

- "activity monitor not updated for subconnections when connection
  returned to pool"

  https://bugs.launchpad.net/zodb/+bug/737198

- "Blob temp file get's removed before it should",
  https://bugs.launchpad.net/zodb/+bug/595378

  A way this to happen is that a transaction is aborted after the
  commit process has started. I don't know how this would happen in
  the wild.

  In 3.10.3, the ZEO tpc_abort call to the server is changed to be
  synchronous, which should address this case. Maybe there's another
  case.


Performance enhancements
------------------------

- Improved ZEO client cache implementation to make it less likely to
  evict objects that are being used.

- Small (possibly negligable) reduction in CPU in ZEO storage servers
  to service object loads and in networking code.

3.10.2 (2011-02-12)
===================

Bugs Fixed
----------

- 3.10 introduced an optimization to try to address BTree conflict
  errors arrising for basing BTree keys on object ids. The
  optimization caused object ids allocated in aborted transactions to
  be reused. Unfortunately, this optimzation led to some rather
  severe failures in some applications.  The symptom is a conflict
  error in which one of the serials mentioned is zero.  This
  optimization has been removed.

  See (for example): https://bugs.launchpad.net/zodb/+bug/665452

- ZEO server transaction timeouts weren't logged as critical.

  https://bugs.launchpad.net/zodb/+bug/670986

3.10.1 (2010-10-27)
===================

Bugs Fixed
----------

- When a transaction rolled back a savepoint after adding objects and
  subsequently added more objects and committed, an error could be
  raised "ValueError: A different object already has the same oid"
  causing the transaction to fail. Worse, this could leave a database
  in a state where subsequent transactions in the same process would
  fail.

  https://bugs.launchpad.net/zodb/+bug/665452

- Unix domain sockets didn't work for ZEO (since the addition of IPv6
  support). https://bugs.launchpad.net/zodb/+bug/663259

- Removed a missfeature that can cause performance problems when using
  an external garbage collector with ZEO.  When objects were deleted
  from a storage, invalidations were sent to clients. This makes no
  sense.  It's wildly unlikely that the other connections/clients have
  copies of the garbage.  In normal storage garbage collection, we
  don't send invalidations. There's no reason to send them when an
  external garbage collector is used.

- ZEO client cache simulation misshandled invalidations
  causing incorrect statistics and errors.

3.10.0 (2010-10-08)
===================

New Features
------------

- There are a number of performance enhancements for ZEO storage
  servers.

- FileStorage indexes use a new format. They are saved and loaded much
  faster and take less space. Old indexes can still be read, but new
  indexes won't be readable by older versions of ZODB.

- The API for undoing multiple transactions has changed.  To undo
  multiple transactions in a single transaction, pass a list of
  transaction identifiers to a database's undoMultiple method. Calling a
  database's undo method multiple times in the same transaction now
  raises an exception.

- The ZEO protocol for undo has changed.  The only user-visible
  consequence of this is that when ZODB 3.10 ZEO servers won't support
  undo for older clients.

- The storage API (IStorage) has been tightened. Now, storages should
  raise a StorageTransactionError when invalid transactions are passed
  to tpc_begin, tpc_vote, or tpc_finish.

- ZEO clients (``ClientStorage`` instances) now work in forked processes,
  including those created via ``multiprocessing.Process`` instances.

- Broken objects now provide the IBroken interface.

- As a convenience, you can now pass an integer port as an address to
  the ZEO ClientStorage constructor.

- As a convenience, there's a new ``client`` function in the ZEO
  package for constructing a ClientStorage instance.  It takes the
  same arguments as the ClientStorage constructor.

- DemoStorages now accept constructor athuments, close_base_on_close
  and close_changes_on_close, to control whether underlying storages
  are closed when the DemoStorage is closed.

  https://bugs.launchpad.net/zodb/+bug/118512

- Removed the dependency on zope.proxy.

- Removed support for the _p_independent mini framework, which was
  made moot by the introduction of multi-version concurrency control
  several years ago.

- Added support for the transaction retry convenience
  (transaction-manager attempts method) introduced in the
  ``transaction`` 1.1.0 release.

- Enhanced the database opening conveniences:

  - You can now pass storage keyword arguments to ZODB.DB and
    ZODB.connection.

  - You can now pass None (rather than a storage or file name) to get
    a database with a mapping storage.

- Databases now warn when committing very large records (> 16MB).
  This is to try to warn people of likely design mistakes.  There is a
  new option (large_record_size/large-record-size) to control the
  record size at which the warning is issued.

- Added support for wrapper storages that transform pickle data.
  Applications for this include compression and encryption.  An
  example wrapper storage implementation, ZODB.tests.hexstorage, was
  included for testing.

  It is important that storage implementations not assume that
  storages contain pickles.  Renamed IStorageDB to IStorageWrapper and
  expanded it to provide methods for transforming and untransforming
  data records.  Storages implementations should use these methods to
  get pickle data from stored records.

- Deprecated ZODB.interfaces.StorageStopIteration.  Storage
  iterator implementations should just raise StopIteration, which
  means they can now be implemented as generators.

- The filestorage packer configuration option noe accepts values of
  the form ``modname:expression``, allowing the use of packer
  factories with options.

- Added a new API that allows applications to make sure that current
  data are read. For example, with::

    self._p_jar.readCurrent(ob)

  A conflict error will be raised if the version of ob read by the
  transaction isn't current when the transaction is committed.

  Normally, ZODB only assures that objects read are consistent, but not
  necessarily up to date.  Checking whether an object is up to date is
  important when information read from one object is used to update
  another.

  BTrees are an important case of reading one object to update
  another.  Internal nodes are read to decide which leave notes are
  updated when a BTree is updated.  BTrees now use this new API to
  make sure that internal nodes are up to date on updates.

- When transactions are aborted, new object ids allocated during the
  transaction are saved and used in subsequent transactions. This can
  help in situations where object ids are used as BTree keys and the
  sequential allocation of object ids leads to conflict errors.

- ZEO servers now support a server_status method for for getting
  information on the number of clients, lock requests and general
  statistics.

- ZEO clients now support a client_label constructor argument and
  client-label configuration-file option to specify a label for a
  client in server logs. This makes it easier to identify specific
  clients corresponding to server log entries, especially when there
  are multiple clients originating from the same machine.

- Improved ZEO server commit lock logging.  Now, locking activity is
  logged at the debug level until the number of waiting lock requests
  gets above 3.  Log at the critical level when the number of waiting
  lock requests gets above 9.

- The file-storage backup script, repozo, will now create a backup
  index file if an output file name is given via the --output/-o
  option.

- Added a '--kill-old-on-full' argument to the repozo backup options:
  if passed, remove any older full or incremental backup files from the
  repository after doing a full backup.
  (https://bugs.launchpad.net/zope2/+bug/143158)

- The mkzeoinst script has been moved to a separate project:

    http://pypi.python.org/pypi/zope.mkzeoinstance

  and is no-longer included with ZODB.

- Removed untested unsupported dbmstorage fossile.

- ZEO servers no longer log their pids in every log message. It's just
  not interesting. :)

Bugs fixed
----------

- When a pool timeout was specified for a database and old connections
  were removed due to timing out, an error occured due to a bug in the
  connection cleanup logic.

- When multi-database connections were no longer used and cleaned up,
  their subconnections weren't cleaned up properly.

- ZEO didn't work with IPv6 addrsses.
  Added IPv6 support contributed by Martin v. Löwis.

- A file storage bug could cause ZEO clients to have incorrect
  information about current object revisions after reconnecting to a
  database server.

- Updated the 'repozo --kill-old-on-full' option to remove any '.index'
  files corresponding to backups being removed.

- ZEO extension methods failed when a client reconnected to a
  storage. (https://bugs.launchpad.net/zodb/+bug/143344)

- Clarified the return Value for lastTransaction in the case when
  there aren't any transactions.  Now a string of 8 nulls (aka "z64")
  is specified.

- Setting _p_changed on a blob wo actually writing anything caused an
  error. (https://bugs.launchpad.net/zodb/+bug/440234)

- The verbose mode of the fstest was broken.
  (https://bugs.launchpad.net/zodb/+bug/475996)

- Object ids created in a savepoint that is rolled back wren't being
  reused. (https://bugs.launchpad.net/zodb/+bug/588389)

- Database connections didn't invalidate cache entries when conflict
  errors were raised in response to checkCurrentSerialInTransaction
  errors. Normally, this shouldn't be a problem, since there should be
  pending invalidations for these oids which will cause the object to
  be invalidated. There have been issues with ZEO persistent cache
  management that have caused out of date data to remain in the cache.
  (It's possible that the last of these were addressed in the
  3.10.0b5.) Invalidating read data when there is a conflict error
  provides some extra insurance.

- The interface, ZODB.interfaces.IStorage was incorrect. The store
  method should never return a sequence of oid and serial pairs.

- When a demo storage push method was used to create a new demo
  storage and the new storage was closed, the original was
  (incorrectly) closed.

- There were numerous bugs in the ZEO cache tracing and analysis code.
  Cache simulation, while not perfect, seems to be much more accurate
  now than it was before.

  The ZEO cache trace statistics and simulation scripts have been
  given more descriptive names and moved to the ZEO scripts package.

- BTree sets and tree sets didn't correctly check values passed to
  update or to constructors, causing Python to exit under certain
  circumstances.

- Fixed bug in copying a BTrees.Length instance.
  (https://bugs.launchpad.net/zodb/+bug/516653)

- Fixed a serious bug that caused cache failures when run
  with Python optimization turned on.

  https://bugs.launchpad.net/zodb/+bug/544305

- When using using a ClientStorage in a Storage server, there was a
  threading bug that caused clients to get disconnected.

- On Mac OS X, clients that connected and disconnected quickly could
  cause a ZEO server to stop accepting connections, due to a failure
  to catch errors in the initial part of the connection process.

  The failure to properly handle exceptions while accepting
  connections is potentially problematic on other platforms.

  Fixes: https://bugs.launchpad.net/zodb/+bug/135108

- Object state management wasn't done correctly when classes
  implemented custom _p_deavtivate methods.
  (https://bugs.launchpad.net/zodb/+bug/185066)