add a gevent+psycopg2 dialect for sqlalchemy

setup.py

@@ -45,7 +45,7 @@
     'zope.container',
     'zope.site',
     'zope.generations',
-    'RelStorage==3.0b3',
+    'RelStorage',
     'zc.zlibstorage',
     'nti.i18n',
     'z3c.schema',

src/nti/app/environments/__init__.py

@@ -3,6 +3,9 @@
 import gevent.monkey
 gevent.monkey.patch_all()
 
+from nti.app.environments._monkey import patch
+patch()
+
 from zope.component import getGlobalSiteManager
 
 import zope.i18nmessageid as zope_i18nmessageid

src/nti/app/environments/_monkey.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+When RelStorage is installed with psycopg2 and gevent a global wait callback is installed.
+That wait callback expects the Relstorage custom connection which creates issues
+when trying to use psycopg2 with sqlalchmey.
+
+Install a custom dialect that uses the RelStorage connection for sqlalchemy.
+"""
+
+from __future__ import division
+from __future__ import print_function
+from __future__ import absolute_import
+
+logger = __import__('logging').getLogger(__name__)
+
+try:
+    from sqlalchemy.dialects.postgresql.psycopg2 import PGDialect_psycopg2
+    from relstorage.adapters.postgresql.drivers.psycopg2 import GeventPsycopg2Driver
+    import psycopg2
+except ImportError:
+    pass
+else:
+    class geventPostgresclient_dialect(PGDialect_psycopg2):
+        driver = "gevent+postgres"
+
+        def __init__(self, *args, **kwargs):
+            super(geventPostgresclient_dialect, self).__init__(*args, **kwargs)
+            self._conn_class = GeventPsycopg2Driver().connect
+
+        def connect(self, *args, **kwargs):
+            kwargs['connection_factory'] = self._conn_class
+            return psycopg2.connect(*args, **kwargs)
+
+    from sqlalchemy.dialects import registry
+    registry.register("gevent.postgres", __name__, "geventPostgresclient_dialect")
+
+def patch():
+    pass

src/nti/app/environments/tests/test_monkey.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+from __future__ import division
+from __future__ import print_function
+from __future__ import absolute_import
+
+import fudge
+
+from hamcrest import not_none
+from hamcrest import assert_that
+from hamcrest import instance_of
+
+import unittest
+
+from sqlalchemy import create_engine
+
+from .._monkey import geventPostgresclient_dialect
+
+
+class TestPatchSqlalchemy(unittest.TestCase):
+
+    def test_postres_engine(self):
+        from .._monkey import patch
+        patch()
+        engine = create_engine('gevent+postgres:///testdb.db')
+        assert_that(engine, not_none())
+        assert_that(engine.dialect, instance_of(geventPostgresclient_dialect))
+
+    @fudge.patch('psycopg2.connect')
+    def test_connect_uses_relstorage(self, pconn):
+        from .._monkey import patch
+        patch()
+        engine = create_engine('gevent+postgres:///testdb.db')
+
+        class StopExecution(Exception):
+            pass
+
+        # Make sure connect get gets called with the right connection_factory
+        # Make calling it raise to stop all the crazy first connection initialization that sqlalchemy does
+        # no luck trying to mock all the necessary things
+        pconn.expects_call().with_args(database='testdb.db', connection_factory=engine.dialect._conn_class).raises(StopExecution)
+
+        try:
+            engine.connect()
+        except StopExecution:
+            pass
+
+
+
+