Commit 64d1f40b by Kirill Smelkov

bigfile/zodb: Monkey-patch for ZODB.Connection to support callback on .open()

ZODB.Connection has support for calling callbacks on .close() but not on
.open() . We'll need to hook into both Connection open/close process in the
next patch (for _ZBigFileH to stay in sync with Connection state).

NOTE

on-open  callbacks are setup once and fire many times on every open,
on-close callbacks are setup once and fire only once on next close.

The reason for this is that on-close callbacks are useful for scheduling
current connection cleanup, after its processing is done. But on-open
callback is for future connection usage, which is generally not related
to current connection.

/cc @jm, @vpelletier
1 parent b92f82c8
......@@ -35,6 +35,7 @@ from transaction.interfaces import IDataManager, ISynchronizer
from persistent import Persistent, PickleCache
from BTrees.LOBTree import LOBTree
from zope.interface import implementer
from ZODB.Connection import Connection
# TODO document that first data access must be either after commit or Connection.add
......@@ -227,6 +228,33 @@ class ZBigFile(LivePersistent):
# patch for ZODB.Connection to support callback on .open()
# NOTE on-open callbacks are setup once and fire many times on every open
# on-close callbacks are setup once and fire only once on next close
Connection._onOpenCallbacks = None
def Connection_onOpenCallback(self, f):
if self._onOpenCallbacks is None:
# NOTE WeakSet does not work for bound methods - the are always create
# anew for each obj.method access, and thus will go away almost immediately
self._onOpenCallbacks = set()
self._onOpenCallbacks.add(f)
assert not hasattr(Connection, 'onOpenCallback')
Connection.onOpenCallback = Connection_onOpenCallback
orig_Connection_open = Connection.open
def Connection_open(self, transaction_manager=None, delegate=True):
orig_Connection_open(self, transaction_manager, delegate)
if self._onOpenCallbacks:
for f in self._onOpenCallbacks:
f()
Connection.open = Connection_open
# ------------
# BigFileH wrapper that also acts as DataManager proxying changes back to ZODB
# objects at two-phase-commit (TPC) level.
#
......
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