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ZODB v3.4.b1 Release Notes

  • 🚀 Release date: 19-May-2005

    🚀 What follows is combined news from the "internal releases" (to support ongoing Zope 2.8 and Zope3 development) since the last public ZODB 3.4 🚀 release. These are the dates of the internal releases:

    • 3.4b1 19-May-2005
    • 3.4a9 12-May-2005
    • 3.4a8 09-May-2005
    • 3.4a7 06-May-2005
    • 3.4a6 05-May-2005
    • 3.4a5 25-Apr-2005
    • 3.4a4 23-Apr-2005
    • 3.4a3 13-Apr-2005
    • 3.4a2 03-Apr-2005

    transaction

    • 👀 (3.4a7) If the first activity seen by a new ThreadTransactionManager was an explicit begin() call, then synchronizers registered after that (but still during the first transaction) were not communicated to the transaction object. As a result, the afterCompletion() methods of registered synchronizers weren't called when the first transaction ended.

    • (3.4a6) Doing a subtransaction commit erroneously processed invalidations, which could lead to an inconsistent view of the database. For example, let T be the transaction of which the subtransaction commit was a part. If T read a persistent object O's state before the subtransaction commit, did not commit new state of its own for O during its subtransaction commit, and O was modified before the subtransaction commit by a different transaction, then the subtransaction commit processed an invalidation for O, and the state T read for O originally was discarded in T. If T went on to access O again, it saw the newly committed (by a different transaction) state for O::

      o_attr = O.some_attribute get_transaction().commit(True) assert o_attr == O.some_attribute

    could fail, and despite that T never modifed O.

    • 👍 (3.4a4) Transactions now support savepoints. Savepoints allow changes to be periodically checkpointed within a transaction. You can then rollback to a previously created savepoint. See transaction/savepoint.txt.

    • (3.4a6) A getBeforeCommitHooks() method was added. It returns an iterable producing the registered beforeCommit hooks.

    • (3.4a6) The ISynchronizer interface has a new newTransaction() method. This is invoked whenever a transaction manager's begin() method is called. (Note that a transaction object's (as opposed to a transaction manager's) begin() method is deprecated, and newTransaction() is not called when using the deprecated method.)

    • (3.4a6) Relatedly, Connection implements ISynchronizer, and Connection's afterCompletion() and newTransaction() methods now call sync() on the underlying storage (if the underlying storage has such a method), in addition to processing invalidations. The practical implication is that storage synchronization will be done automatically now, whenever a transaction is explicitly started, and after top-level transaction commit or abort. As a result, Connection.sync() should virtually never be needed anymore, and will eventually be deprecated.

    • (3.4a3) Transaction objects have a new method, beforeCommitHook(hook, *args, **kws). Hook functions registered with a transaction are called at the start of a top-level commit, before any of the work is begun, so a hook function can perform any database operations it likes. See test_beforeCommitHook() in transaction/tests/test_transaction.py for a tutorial doctest, and the ITransaction interface for details. Thanks to Florent Guillaume for contributing code and tests.

    • (3.4a3) Clarifications were made to transaction interfaces.

    👌 Support for ZODB4 savepoint-aware data managers has been dropped

    • 👍 (3.4a4) In adding savepoint support, we dropped the attempted support for ZODB4 data managers that support savepoints. We don't think that this will affect anyone.

    ZEO

    • (3.4a4) The ZODB and ZEO version numbers are now the same. Concretely::

      import ZODB, ZEO assert ZODB.version == ZEO.version

    no longer fails. If interested, see the README file for details about earlier version numbering schemes.

    • (3.4b1) ZConfig version 2.3 adds new socket address types, for smoother default behavior across platforms. The hostname portion of socket-binding-address defaults to an empty string, which acts like INADDR_ANY on Windows and Linux (bind to any interface). The hostname portion of socket-connection-address defaults to "127.0.0.1" (aka "localhost"). In config files, the types of zeo section keys address and monitor-address changed to socket-binding-address, and the type of the zeoclient section key server changed to socket-connection-address.

    • 0️⃣ (3.4a4) The default logging setup in runzeo.py was broken. It was changed so that running runzeo.py from a command line now, and without using a config file, prints output to the console much as ZODB 3.2 did.

    🏁 ZEO on Windows

    🏁 Thanks to Mark Hammond for these runzeo.py enhancements on Windows:

    • (3.4b1) Collector 1788: Repair one of the new features below.

    • (3.4a4) A pid file (containing the process id as a decimal string) is created now for a ZEO server started via runzeo.py. External programs can read the pid from this file and derive a "signal name" used in a new signal-emulation scheme for Windows. This is only necessary on Windows, but the pid file is created on all platforms that implement os.getpid(), as long as the pid-filename option is set, or environment variable INSTANCE_HOME is defined. The pid-filename option can be set in a ZEO config file, or passed as the new --pid-file argument to runzeo.py.

    • 🚦 (3.4a4) If available, runzeo.py now uses Zope's new 'Signal' mechanism for Windows, to implement clean shutdown and log rotation handlers for Windows. Note that the Python in use on the ZEO server must also have the Python Win32 extensions installed for this to be useful.

    Tools

    • (3.4a4) fsdump.py now displays the size (in bytes) of data records. This actually went in several months go, but wasn't noted here at the time. Thanks to Dmitry Vasiliev for contributing code and tests.

    FileStorage

    • (3.4a9) The undoLog() and undoInfo() methods almost always returned a wrong number of results, one too many if last < 0 (the default is such a case), or one too few if last >= 0. These have been repaired, new tests were added, and these methods are now documented in ZODB.interfaces.IStorageUndoable.

    • (3.4a2) A pdb.set_trace() call was mistakenly left in method FileStorage.modifiedInVersion().

    ZConfig

    • 🚀 (3.4b1) The "standalone" release of ZODB now includes ZConfig version 2.3.

    DemoStorage

    • (3.4a4) Appropriate implementations of the storage API's registerDB() and new_oid() methods were added, delegating to the base storage. This was needed to support wrapping a ZEO client storage as a DemoStorage base storage, as some new Zope tests want to do.

    BaseStorage

    • 🚚 (3.4a4) new_oid()'s undocumented last= argument was removed. It was used only for internal recursion, and injured code sanity elsewhere because not all storages included it in their new_oid()'s signature. Straightening this out required adding last= everywhere, or removing it everywhere. Since recursion isn't actually needed, and there was no other use for last=, removing it everywhere was the obvious choice.

    ✅ Tests

    • (3.4a3) The various flavors of the check2ZODBThreads and check7ZODBThreads tests are much less likely to suffer sproadic failures now.

    • 💅 (3.4a2) The test checkOldStyleRoot failed in Zope3, because of an obscure dependence on the Persistence package (which Zope3 doesn't use).

    ZApplication

    • 🚚 (3.4a8) The file ZApplication.py was moved, from ZODB to Zope(2). ZODB and Zope3 don't use it, but Zope2 does.

    • (3.4a7) The __call__ method didn't work if a non-None connection string argument was passed. Thanks to Stefan Holek for noticing.