Merge lp:~allenap/launchpad/storm-bulk-reload-bug-572211 into lp:launchpad

[Gavin Panella]

New function, lp.services.database.bulk.reload(), to efficiently reload database objects.

Adds a new module, lp.services.database.bulk, that contains a single public function, reload(). Given an arbitrary list of Storm model objects, this attempts to reload them from the database in the most efficient way it can. The model objects can be a mix of types, and loaded from any number of different stores, but they must not have compound primary keys. See the linked bug for the rationale behind this new function.

[Abel Deuring (adeuring)]

I really like this branch. Thanks!

review: Approve (code)

=== added file 'lib/lp/services/database/bulk.py'
--- lib/lp/services/database/bulk.py	1970-01-01 00:00:00 +0000
+++ lib/lp/services/database/bulk.py	2010-04-30 15:26:06 +0000
@@ -0,0 +1,66 @@
+# Copyright 2010 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Optimized bulk operations against the database."""
+
+__metaclass__ = type
+__all__ = [
+    'reload',
+    ]
+
+
+from collections import defaultdict
+
+from zope.security.proxy import removeSecurityProxy
+
+from storm.base import Storm
+from storm.expr import In
+from storm.info import get_cls_info
+from storm.store import Store
+
+
+def collate(things, key):
+    """Collate the given objects according to a key function.
+
+    Generates (common-key-value, list-of-things) tuples, like groupby,
+    except that the given objects do not need to be sorted.
+    """
+    collection = defaultdict(list)
+    for thing in things:
+        collection[key(thing)].append(thing)
+    return collection.iteritems()
+
+
+def get_type(thing):
+    """Return the type of the given object.
+
+    If the given object is wrapped by a security proxy, the type
+    returned is that of the wrapped object.
+    """
+    return type(removeSecurityProxy(thing))
+
+
+def gen_reload_queries(objects):
+    """Prepare queries to reload the given objects."""
+    for object_type, objects in collate(objects, get_type):
+        if not issubclass(object_type, Storm):
+            raise AssertionError(
+                "Cannot load objects of type %s: %r" % (
+                    object_type.__name__, objects))
+        primary_key = get_cls_info(object_type).primary_key
+        if len(primary_key) != 1:
+            raise AssertionError(
+                "Compound primary keys are not supported: %s." %
+                object_type.__name__)
+        primary_key_column = primary_key[0]
+        primary_key_column_getter = primary_key_column.__get__
+        for store, objects in collate(objects, Store.of):
+            primary_keys = map(primary_key_column_getter, objects)
+            condition = In(primary_key_column, primary_keys)
+            yield store.find(object_type, condition)
+
+
+def reload(objects):
+    """Reload a large number of objects efficiently."""
+    for query in gen_reload_queries(objects):
+        list(query)

=== added file 'lib/lp/services/database/tests/test_bulk.py'
--- lib/lp/services/database/tests/test_bulk.py	1970-01-01 00:00:00 +0000
+++ lib/lp/services/database/tests/test_bulk.py	2010-04-30 15:26:06 +0000
@@ -0,0 +1,152 @@
+# Copyright 2010 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Test the bulk database functions."""
+
+__metaclass__ = type
+
+import unittest
+
+import transaction
+
+import zope.security.checker
+import zope.security.proxy
+
+from storm.info import get_obj_info
+
+from canonical.launchpad.interfaces.lpstorm import (
+    IMasterStore, ISlaveStore, IStore)
+from canonical.testing import LaunchpadZopelessLayer
+
+from lp.bugs.model.bug import BugAffectsPerson
+from lp.services.database import bulk
+from lp.testing import TestCase, TestCaseWithFactory
+
+
+object_is_key = lambda thing: thing
+
+
+class TestBasicFunctions(TestCase):
+
+    def test_collate_empty_list(self):
+        self.failUnlessEqual([], list(bulk.collate([], object_is_key)))
+
+    def test_collate_when_object_is_key(self):
+        self.failUnlessEqual(
+            [(1, [1])],
+            list(bulk.collate([1], object_is_key)))
+        self.failUnlessEqual(
+            [(1, [1]), (2, [2, 2])],
+            sorted(bulk.collate([1, 2, 2], object_is_key)))
+
+    def test_collate_with_key_function(self):
+        self.failUnlessEqual(
+            [(4, ['fred', 'joss']), (6, ['barney'])],
+            sorted(bulk.collate(['fred', 'barney', 'joss'], len)))
+
+    def test_get_type(self):
+        self.failUnlessEqual(object, bulk.get_type(object()))
+
+    def test_get_type_with_proxied_object(self):
+        proxied_object = zope.security.proxy.Proxy(
+            'fred', zope.security.checker.Checker({}))
+        self.failUnlessEqual(str, bulk.get_type(proxied_object))
+
+
+class TestLoaders(TestCaseWithFactory):
+
+    layer = LaunchpadZopelessLayer
+
+    def test_gen_reload_queries_with_empty_list(self):
+        self.failUnlessEqual([], list(bulk.gen_reload_queries([])))
+
+    def test_gen_reload_queries_with_single_object(self):
+        # gen_reload_queries() should generate a single query for a
+        # single object.
+        db_objects = [self.factory.makeSourcePackageName()]
+        db_queries = list(bulk.gen_reload_queries(db_objects))
+        self.failUnlessEqual(1, len(db_queries))
+        db_query = db_queries[0]
+        self.failUnlessEqual(db_objects, list(db_query))
+
+    def test_gen_reload_queries_with_multiple_similar_objects(self):
+        # gen_reload_queries() should generate a single query to load
+        # multiple objects of the same type.
+        db_objects = set(
+            self.factory.makeSourcePackageName() for i in range(5))
+        db_queries = list(bulk.gen_reload_queries(db_objects))
+        self.failUnlessEqual(1, len(db_queries))
+        db_query = db_queries[0]
+        self.failUnlessEqual(db_objects, set(db_query))
+
+    def test_gen_reload_queries_with_mixed_objects(self):
+        # gen_reload_queries() should return one query for each
+        # distinct object type in the given objects.
+        db_objects = set(
+            self.factory.makeSourcePackageName() for i in range(5))
+        db_objects.update(
+            self.factory.makeComponent() for i in range(5))
+        db_queries = list(bulk.gen_reload_queries(db_objects))
+        self.failUnlessEqual(2, len(db_queries))
+        db_objects_loaded = set()
+        for db_query in db_queries:
+            objects = set(db_query)
+            # None of these objects should have been loaded before.
+            self.failUnlessEqual(
+                set(), objects.intersection(db_objects_loaded))
+            db_objects_loaded.update(objects)
+        self.failUnlessEqual(db_objects, db_objects_loaded)
+
+    def test_gen_reload_queries_with_mixed_stores(self):
+        # gen_reload_queries() returns one query for each distinct
+        # store even for the same object type.
+        db_object = self.factory.makeComponent()
+        db_object_type = bulk.get_type(db_object)
+        # Commit so the database object is available in both master
+        # and slave stores.
+        transaction.commit()
+        db_objects = set(
+            (IMasterStore(db_object).get(db_object_type, db_object.id),
+             ISlaveStore(db_object).get(db_object_type, db_object.id)))
+        db_queries = list(bulk.gen_reload_queries(db_objects))
+        self.failUnlessEqual(2, len(db_queries))
+        db_objects_loaded = set()
+        for db_query in db_queries:
+            objects = set(db_query)
+            # None of these objects should have been loaded before.
+            self.failUnlessEqual(
+                set(), objects.intersection(db_objects_loaded))
+            db_objects_loaded.update(objects)
+        self.failUnlessEqual(db_objects, db_objects_loaded)
+
+    def test_gen_reload_queries_with_non_Storm_objects(self):
+        # gen_reload_queries() does not like non-Storm objects.
+        self.assertRaisesWithContent(
+            AssertionError,
+            "Cannot load objects of type str: ['fred']",
+            list, bulk.gen_reload_queries(['fred']))
+
+    def test_gen_reload_queries_with_compound_primary_keys(self):
+        # gen_reload_queries() does not like compound primary keys.
+        db_queries = bulk.gen_reload_queries([BugAffectsPerson()])
+        self.assertRaisesWithContent(
+            AssertionError,
+            'Compound primary keys are not supported: BugAffectsPerson.',
+            list, db_queries)
+
+    def test_load(self):
+        # load() loads the given objects using queries generated by
+        # gen_reload_queries().
+        db_object = self.factory.makeComponent()
+        db_object_naked = zope.security.proxy.removeSecurityProxy(db_object)
+        db_object_info = get_obj_info(db_object_naked)
+        IStore(db_object).flush()
+        self.failUnlessEqual(None, db_object_info.get('invalidated'))
+        IStore(db_object).invalidate(db_object)
+        self.failUnlessEqual(True, db_object_info.get('invalidated'))
+        bulk.reload([db_object])
+        self.failUnlessEqual(None, db_object_info.get('invalidated'))
+
+
+def test_suite():
+    return unittest.TestLoader().loadTestsFromName(__name__)