:class:`.RootTransaction` or :class:`.TwoPhaseTransaction` with its immediate :class:`._ConnectionFairy` as a "reset handler" for the span of that transaction, which takes over the task of calling commit() or rollback() for the "reset on return" behavior of :class:`.Pool` if the transaction was not otherwise completed. This resolves the issue that a picky transaction like that of MySQL two-phase will be properly closed out when the connection is closed without an explicit rollback or commit (e.g. no longer raises "XAER_RMFAIL" in this case - note this only shows up in logging as the exception is not propagated within pool reset). This issue would arise e.g. when using an orm :class:`.Session` with ``twophase`` set, and then :meth:`.Session.close` is called without an explicit rollback or commit. The change also has the effect that you will now see an explicit "ROLLBACK" in the logs when using a :class:`.Session` object in non-autocommit mode regardless of how that session was discarded. Thanks to Jeff Dairiki and Laurence Rowe for isolating the issue here. [ticket:2907]
events including auto-invalidation, which is useful both for tests here as well as detecting failure conditions within the "reset" or "close" cases. - rename the argument for PoolEvents.reset() to dbapi_connection and connection_record to be consistent with everything else. - add new documentation sections on invalidation, including auto-invalidation and the invalidation process within the pool. - add _ConnectionFairy and _ConnectionRecord to the pool documentation. Establish docs for common _ConnectionFairy/_ConnectionRecord methods and accessors and have PoolEvents docs refer to _ConnectionRecord, since it is passed to all events. Rename a few _ConnectionFairy methods that are actually private to pool such as _checkout(), _checkin() and _checkout_existing(); there should not be any external code calling these
attempts when an existing connection attempt is blocking. Previously, the production of new connections was serialized within the block that monitored overflow; the overflow counter is now altered within it's own critical section outside of the connection process itself. [ticket:2880]
- rework the event system so that event modules load after their targets, dependencies are reversed - create an improved strategy lookup system for the ORM - rework the ORM to have very few import cycles - move out "importlater" to just util.dependency - other tricks to cross-populate modules in as clear a way as possible
ideas in general:
- pypy2.1 w/ sqlite3 is the first DBAPI we're seeing returning
unicode in cursor.description without being py3k. add a new on-connect
check for this, if we get back a u"", just don't do description decoding,
should be OK for now.
- the set tests in test_collection were assuming the two sets would be ordered
the same when it tested pop(), can't really assume that.
- test_serializer gets worse and worse, pickle is just not really viable here,
ding out pypy
- pypy2.1b2 seems to allow cursor.lastrowid to work (or we changed something?)
- pool._threadconns.current() is a weakref, it can be None
- another one of those logging.handlers imports
checked out count if an existing pooled connection failed to reconnect after an invalidate or recycle event. Also in 0.8.3. [ticket:2772]
make sure that the DBAPI connection passed to the reset-on-return events/dialect hooks is also a "fairy", so that dictionaries like "info" are available. [ticket:2770] - rework the execution_options system so that the dialect is given the job of making any immediate adjustments based on a set event. move the "isolation level" logic to use this new system. Also work things out so that even engine-level execution options can be used for things like isolation level; the dialect attaches a connect-event handler in this case to handle the task. - to support this new system as well as further extensibiltiy of execution options add events engine_connect(), set_connection_execution_options(), set_engine_execution_options()