Commit ac7443e2 authored by Jim Fulton's avatar Jim Fulton Committed by GitHub

Merge pull request #92 from zopefoundation/prefetch

Added a connection prefetch method
parents 61af5586 7875e65b
......@@ -2,6 +2,21 @@
Change History
================
5.0.0a6 (unreleased)
====================
- Added a connection ``prefetch`` method that can be used to request
that a storage prefect data an application will need::
conn.prefetch(obj, ...)
Where arguments can be objects, object ids, or iterables of objects
or object ids.
Added optional ``prefetch`` methods to the storage APIs. If a
storage doesn't support prefetch, then the connection prefetch
method is a noop.
5.0.0a5 (2016-07-06)
====================
......
......@@ -1080,6 +1080,27 @@ class Connection(ExportImport, object):
# Savepoint support
#####################################################################
def prefetch(self, *args):
try:
self._storage.prefetch(self._prefetch_flatten(args))
except AttributeError:
if not hasattr(self._storage, 'prefetch'):
self.prefetch = lambda *a: None
else:
raise
def _prefetch_flatten(self, args):
for arg in args:
if isinstance(arg, bytes):
yield arg
elif hasattr(arg, '_p_oid'):
yield arg._p_oid
else:
for ob in arg:
if isinstance(ob, bytes):
yield ob
else:
yield ob._p_oid
@implementer(IDataManagerSavepoint)
class Savepoint:
......
......@@ -754,6 +754,16 @@ class IStorage(Interface):
"""
class IPrefetchStorage(IStorage):
def prefetch(oids, tid):
"""Prefetch data for the given object ids before the given tid
The oids argument is an iterable that should be iterated no
more than once.
"""
class IMultiCommitStorage(IStorage):
"""A multi-commit storage can commit multiple transactions at once.
......@@ -1112,6 +1122,14 @@ class IMVCCStorage(IStorage):
A POSKeyError is raised if there is no record for the object id.
"""
class IMVCCPrefetchStorage(IMVCCStorage):
def prefetch(oids):
"""Prefetch data for the given object ids
The oids argument is an iterable that should be iterated no
more than once.
"""
class IStorageCurrentRecordIteration(IStorage):
......
......@@ -146,6 +146,15 @@ class MVCCAdapterInstance(Base):
raise POSException.ReadConflictError(repr(oid))
return r[:2]
def prefetch(self, oids):
try:
self._storage.prefetch(oids, self._start)
except AttributeError:
if not hasattr(self._storage, 'prefetch'):
self.prefetch = lambda *a: None
else:
raise
_modified = None # Used to keep track of oids modified within a
# transaction, so we can invalidate them later.
......
import unittest
from ZODB.utils import z64, u64
import ZODB
from .MVCCMappingStorage import MVCCMappingStorage
class PrefetchTests(unittest.TestCase):
def test_prefetch(self):
db = ZODB.DB(None)
fetched = []
def prefetch(oids, tid):
fetched.append((list(map(u64, oids)), tid))
db.storage.prefetch = prefetch
with db.transaction() as conn:
for i in range(10):
conn.root()[i] = conn.root().__class__()
conn = db.open()
conn.prefetch(z64)
conn.prefetch([z64])
conn.prefetch(conn.root())
conn.prefetch(z64, (conn.root()[i] for i in range(3)), conn.root()[3])
self.assertEqual(fetched,
[([0], conn._storage._start),
([0], conn._storage._start),
([0], conn._storage._start),
([0, 1, 2, 3, 4], conn._storage._start),
])
db.close()
def test_prefetch_optional(self):
conn = ZODB.connection(None)
conn.prefetch(z64)
conn.prefetch([z64])
conn.prefetch(conn.root())
conn.prefetch(z64, [z64])
conn.prefetch(z64, [z64], conn.root())
conn.close()
def test_prefetch_optional_imvcc(self):
conn = ZODB.connection(MVCCMappingStorage())
conn.prefetch(z64)
conn.prefetch([z64])
conn.prefetch(conn.root())
conn.prefetch(z64, [z64])
conn.prefetch(z64, [z64], conn.root())
conn.close()
def test_suite():
return unittest.makeSuite(PrefetchTests)
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