Ensure that 'Session' instances are orderable.

spanner/google/cloud/spanner/session.py

@@ -14,6 +14,7 @@
 
 """Wrapper for Cloud Spanner Session objects."""
 
+from functools import total_ordering
 import time
 
 from google.gax.errors import GaxError
@@ -34,6 +35,7 @@
 """Default timeout used by :meth:`Session.run_in_transaction`."""
 
 
+@total_ordering
 class Session(object):
     """Representation of a Cloud Spanner Session.
 
@@ -53,6 +55,9 @@ class Session(object):
     def __init__(self, database):
         self._database = database
 
+    def __lt__(self, other):
+        return self._session_id < other._session_id
+
     @property
     def session_id(self):
         """Read-only ID, set by the back-end during :meth:`create`."""

spanner/unit_tests/test_pool.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 
+from functools import total_ordering
 import unittest
 
 
@@ -597,6 +598,32 @@ def test_bind(self):
 
         self.assertTrue(pool._pending_sessions.empty())
 
+    def test_bind_w_timestamp_race(self):
+        import datetime
+        from google.cloud._testing import _Monkey
+        from google.cloud.spanner import pool as MUT
+        NOW = datetime.datetime.utcnow()
+        pool = self._make_one()
+        database = _Database('name')
+        SESSIONS = [_Session(database) for _ in range(10)]
+        database._sessions.extend(SESSIONS)
+
+        with _Monkey(MUT, _NOW=lambda: NOW):
+            pool.bind(database)
+
+        self.assertIs(pool._database, database)
+        self.assertEqual(pool.size, 10)
+        self.assertEqual(pool.default_timeout, 10)
+        self.assertEqual(pool._delta.seconds, 3000)
+        self.assertTrue(pool._sessions.full())
+
+        for session in SESSIONS:
+            self.assertTrue(session._created)
+            txn = session._transaction
+            self.assertTrue(txn._begun)
+
+        self.assertTrue(pool._pending_sessions.empty())
+
     def test_put_full(self):
         from six.moves.queue import Full
 
@@ -755,6 +782,7 @@ def committed(self):
         return self._committed
 
 
+@total_ordering
 class _Session(object):
 
     _transaction = None
@@ -767,6 +795,9 @@ def __init__(self, database, exists=True, transaction=None):
         self._deleted = False
         self._transaction = transaction
 
+    def __lt__(self, other):
+        return id(self) < id(other)
+
     def create(self):
         self._created = True
 

spanner/unit_tests/test_session.py

@@ -42,6 +42,14 @@ def test_constructor(self):
         self.assertTrue(session.session_id is None)
         self.assertTrue(session._database is database)
 
+    def test___lt___(self):
+        database = _Database(self.DATABASE_NAME)
+        lhs = self._make_one(database)
+        lhs._session_id = b'123'
+        rhs = self._make_one(database)
+        rhs._session_id = b'234'
+        self.assertTrue(lhs < rhs)
+
     def test_name_property_wo_session_id(self):
         database = _Database(self.DATABASE_NAME)
         session = self._make_one(database)