Drop use of six

No need for this in a Python 3-only world.

Change-Id: I8923f2b87c1bd114b8c55210100c7485a0de8f28
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

18 files changed, 40 insertions, 121 deletions

diff --git a/lower-constraints.txt b/lower-constraints.txt
index 3fef2eb..6e34d7b 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -52,7 +52,6 @@ PyYAML==3.12
 requests==2.14.2
 requestsexceptions==1.2.0
 rfc3986==0.3.1
-six==1.10.0
 smmap==0.9.0
 SQLAlchemy==1.2.0
 sqlalchemy-migrate==0.11.0
diff --git a/oslo_db/api.py b/oslo_db/api.py
index 7f92756..fc52113 100644
--- a/oslo_db/api.py
+++ b/oslo_db/api.py
@@ -23,6 +23,7 @@ takes no arguments. The method can return any object that implements DB
 API methods.
 """
 
+import functools
 import logging
 import random
 import threading
@@ -31,7 +32,6 @@ import time
 from oslo_utils import excutils
 from oslo_utils import importutils
 from oslo_utils import reflection
-import six
 
 from oslo_db import exception
 from oslo_db import options
@@ -132,7 +132,7 @@ class wrap_db_retry(object):
         self.max_retry_interval = max_retry_interval
 
     def __call__(self, f):
-        @six.wraps(f)
+        @functools.wraps(f)
         def wrapper(*args, **kwargs):
             sleep_time = next_interval = self.retry_interval
             remaining = self.max_retries
diff --git a/oslo_db/exception.py b/oslo_db/exception.py
index ee6bbb2..2db34ef 100644
--- a/oslo_db/exception.py
+++ b/oslo_db/exception.py
@@ -45,7 +45,6 @@ database errors.
 
 from debtcollector import moves
 from oslo_utils.excutils import CausedByException
-import six
 
 from oslo_db._i18n import _
 from oslo_db import warning
@@ -61,7 +60,7 @@ class DBError(CausedByException):
 
     def __init__(self, inner_exception=None, cause=None):
         self.inner_exception = inner_exception
-        super(DBError, self).__init__(six.text_type(inner_exception), cause)
+        super(DBError, self).__init__(str(inner_exception), cause)
 
 
 class DBDuplicateEntry(DBError):
diff --git a/oslo_db/sqlalchemy/enginefacade.py b/oslo_db/sqlalchemy/enginefacade.py
index efe947e..b56883f 100644
--- a/oslo_db/sqlalchemy/enginefacade.py
+++ b/oslo_db/sqlalchemy/enginefacade.py
@@ -634,7 +634,6 @@ class _TransactionContext(object):
                         # TODO(zzzeek) do we need save_and_reraise() here,
                         # or do newer eventlets not have issues?  we are using
                         # raw "raise" in many other places in oslo.db already
-                        # (and one six.reraise()).
                         raise
                     finally:
                         self.transaction = None
diff --git a/oslo_db/sqlalchemy/engines.py b/oslo_db/sqlalchemy/engines.py
index 999d4c3..25215b9 100644
--- a/oslo_db/sqlalchemy/engines.py
+++ b/oslo_db/sqlalchemy/engines.py
@@ -21,9 +21,9 @@ import logging
 import os
 import re
 import time
+from urllib import parse
 
 import debtcollector.renames
-import six
 import sqlalchemy
 from sqlalchemy import event
 from sqlalchemy import exc
@@ -105,7 +105,7 @@ def _setup_logging(connection_debug=0):
 
 
 def _extend_url_parameters(url, connection_parameters):
-    for key, value in six.moves.urllib.parse.parse_qs(
+    for key, value in parse.parse_qs(
             connection_parameters).items():
         if key in url.query:
             existing = url.query[key]
@@ -262,10 +262,7 @@ def _init_connection_args(url, engine_args, **kw):
     # to internal usage of Python unicode objects in the driver
     #  http://docs.sqlalchemy.org/en/rel_0_9/dialects/mysql.html
     if 'use_unicode' not in url.query:
-        if six.PY3:
-            engine_args['connect_args']['use_unicode'] = 1
-        else:
-            engine_args['connect_args']['use_unicode'] = 0
+        engine_args['connect_args']['use_unicode'] = 1
 
 
 @utils.dispatch_for_dialect('*', multiple=True)
@@ -327,7 +324,7 @@ def _init_events(engine, sqlite_synchronous=True, sqlite_fk=False, **kw):
 
     def regexp(expr, item):
         reg = re.compile(expr)
-        return reg.search(six.text_type(item)) is not None
+        return reg.search(str(item)) is not None
 
     @sqlalchemy.event.listens_for(engine, "connect")
     def _sqlite_connect_events(dbapi_con, con_record):
@@ -369,7 +366,7 @@ def _test_connection(engine, max_retries, retry_interval):
     if max_retries == -1:
         attempts = itertools.count()
     else:
-        attempts = six.moves.range(max_retries)
+        attempts = range(max_retries)
     # See: http://legacy.python.org/dev/peps/pep-3110/#semantic-changes for
     # why we are not using 'de' directly (it can be removed from the local
     # scope).
@@ -384,7 +381,7 @@ def _test_connection(engine, max_retries, retry_interval):
             de_ref = de
     else:
         if de_ref is not None:
-            six.reraise(type(de_ref), de_ref)
+            raise de_ref
 
 
 def _add_process_guards(engine):
diff --git a/oslo_db/sqlalchemy/migration_cli/ext_base.py b/oslo_db/sqlalchemy/migration_cli/ext_base.py
index 184003d..903edd3 100644
--- a/oslo_db/sqlalchemy/migration_cli/ext_base.py
+++ b/oslo_db/sqlalchemy/migration_cli/ext_base.py
@@ -12,11 +12,8 @@
 
 import abc
 
-import six
 
-
-@six.add_metaclass(abc.ABCMeta)
-class MigrationExtensionBase(object):
+class MigrationExtensionBase(object, metaclass=abc.ABCMeta):
 
     # used to sort migration in logical order
     order = 0
diff --git a/oslo_db/sqlalchemy/models.py b/oslo_db/sqlalchemy/models.py
index 6fa0f6f..2bad0f5 100644
--- a/oslo_db/sqlalchemy/models.py
+++ b/oslo_db/sqlalchemy/models.py
@@ -20,8 +20,6 @@
 SQLAlchemy models.
 """
 
-import six
-
 from oslo_utils import timeutils
 from sqlalchemy import Column
 from sqlalchemy import DateTime
@@ -30,7 +28,7 @@ from sqlalchemy.orm import object_mapper
 from oslo_db.sqlalchemy import types
 
 
-class ModelBase(six.Iterator):
+class ModelBase(object):
     """Base class for models."""
     __table_initialized__ = False
 
@@ -119,7 +117,7 @@ class ModelBase(six.Iterator):
         return [key for key, value in self.iteritems()]
 
 
-class ModelIterator(six.Iterator):
+class ModelIterator(object):
 
     def __init__(self, model, columns):
         self.model = model
@@ -128,9 +126,8 @@ class ModelIterator(six.Iterator):
     def __iter__(self):
         return self
 
-    # In Python 3, __next__() has replaced next().
     def __next__(self):
-        n = six.advance_iterator(self.i)
+        n = next(self.i)
         return n, getattr(self.model, n)
 
 
diff --git a/oslo_db/sqlalchemy/provision.py b/oslo_db/sqlalchemy/provision.py
index fb1e191..2fc3a54 100644
--- a/oslo_db/sqlalchemy/provision.py
+++ b/oslo_db/sqlalchemy/provision.py
@@ -23,8 +23,6 @@ import random
 import re
 import string
 
-import six
-from six import moves
 import sqlalchemy
 from sqlalchemy.engine import url as sa_url
 from sqlalchemy import schema
@@ -370,8 +368,7 @@ class Backend(object):
                 Backend(database_type, url)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class BackendImpl(object):
+class BackendImpl(object, metaclass=abc.ABCMeta):
     """Provide database-specific implementations of key provisioning
 
     functions.
@@ -627,9 +624,7 @@ class PostgresqlBackendImpl(BackendImpl):
 
 
 def _random_ident():
-    return ''.join(
-        random.choice(string.ascii_lowercase)
-        for i in moves.range(10))
+    return ''.join(random.choice(string.ascii_lowercase) for i in range(10))
 
 
 Backend._setup()
diff --git a/oslo_db/sqlalchemy/test_base.py b/oslo_db/sqlalchemy/test_base.py
index 8c6fdbd..b437c3c 100644
--- a/oslo_db/sqlalchemy/test_base.py
+++ b/oslo_db/sqlalchemy/test_base.py
@@ -13,6 +13,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import functools
+
 import debtcollector
 import debtcollector.moves
 import fixtures
@@ -26,7 +28,6 @@ except ImportError:
 
 
 from oslo_utils import reflection
-import six
 
 from oslo_db import exception
 from oslo_db.sqlalchemy import enginefacade
@@ -200,6 +201,7 @@ class DbTestCase(test_base.BaseTestCase):
 class OpportunisticTestCase(DbTestCase):
     """Placeholder for backwards compatibility."""
 
+
 ALLOWED_DIALECTS = ['sqlite', 'mysql', 'postgresql']
 
 
@@ -209,7 +211,7 @@ def backend_specific(*dialects):
     ::dialects: list of dialects names under which the test will be launched.
     """
     def wrap(f):
-        @six.wraps(f)
+        @functools.wraps(f)
         def ins_wrap(self):
             if not set(dialects).issubset(ALLOWED_DIALECTS):
                 raise ValueError(
diff --git a/oslo_db/sqlalchemy/test_migrations.py b/oslo_db/sqlalchemy/test_migrations.py
index 8c8484b..07d058b 100644
--- a/oslo_db/sqlalchemy/test_migrations.py
+++ b/oslo_db/sqlalchemy/test_migrations.py
@@ -24,7 +24,6 @@ import alembic
 import alembic.autogenerate
 import alembic.migration
 import pkg_resources as pkg
-import six
 import sqlalchemy
 import sqlalchemy.exc
 import sqlalchemy.sql.expression as expr
@@ -37,8 +36,7 @@ from oslo_db.sqlalchemy import utils
 LOG = logging.getLogger(__name__)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class WalkVersionsMixin(object):
+class WalkVersionsMixin(object, metaclass=abc.ABCMeta):
     """Test mixin to check upgrade and downgrade ability of migration.
 
     This is only suitable for testing of migrate_ migration scripts. An
@@ -274,8 +272,7 @@ class WalkVersionsMixin(object):
             raise
 
 
-@six.add_metaclass(abc.ABCMeta)
-class ModelsMigrationsSync(object):
+class ModelsMigrationsSync(object, metaclass=abc.ABCMeta):
     """A helper class for comparison of DB migration scripts and models.
 
     It's intended to be inherited by test cases in target projects. They have
diff --git a/oslo_db/sqlalchemy/utils.py b/oslo_db/sqlalchemy/utils.py
index 02992f0..b7e101e 100644
--- a/oslo_db/sqlalchemy/utils.py
+++ b/oslo_db/sqlalchemy/utils.py
@@ -17,12 +17,7 @@
 #    under the License.
 
 import collections
-# TODO(smcginnis) update this once six has support for collections.abc
-# (https://github.com/benjaminp/six/pull/241) or clean up once we drop py2.7.
-try:
-    from collections.abc import Iterable
-except ImportError:
-    from collections import Iterable
+from collections import abc
 import contextlib
 import inspect as pyinspect
 import itertools
@@ -32,7 +27,6 @@ import re
 from alembic.migration import MigrationContext
 from alembic.operations import Operations
 from oslo_utils import timeutils
-import six
 import sqlalchemy
 from sqlalchemy import Boolean
 from sqlalchemy import CheckConstraint
@@ -286,7 +280,7 @@ def paginate_query(query, model, limit, sort_keys, marker=None,
 def to_list(x, default=None):
     if x is None:
         return default
-    if not isinstance(x, Iterable) or isinstance(x, six.string_types):
+    if not isinstance(x, abc.Iterable) or isinstance(x, str):
         return [x]
     elif isinstance(x, list):
         return x
@@ -941,7 +935,7 @@ class DialectFunctionDispatcher(object):
     def _url_from_target(self, target):
         if isinstance(target, Connectable):
             return target.engine.url
-        elif isinstance(target, six.string_types):
+        elif isinstance(target, str):
             if "://" not in target:
                 target_url = sa_url.make_url("%s://" % target)
             else:
diff --git a/oslo_db/tests/sqlalchemy/test_exc_filters.py b/oslo_db/tests/sqlalchemy/test_exc_filters.py
index 6b3782a..4ba03c1 100644
--- a/oslo_db/tests/sqlalchemy/test_exc_filters.py
+++ b/oslo_db/tests/sqlalchemy/test_exc_filters.py
@@ -19,7 +19,6 @@ import itertools
 
 import mock
 from oslotest import base as oslo_test_base
-import six
 import sqlalchemy as sqla
 from sqlalchemy.engine import url as sqla_url
 from sqlalchemy import event
@@ -53,11 +52,8 @@ class _SQLAExceptionMatcher(object):
             self.assertEqual(exception_type, exc.__class__.__name__)
         if isinstance(message, tuple):
             self.assertEqual(
-                [m.lower()
-                 if isinstance(m, six.string_types) else m for m in message],
-                [a.lower()
-                 if isinstance(a, six.string_types) else a
-                 for a in exc.orig.args]
+                [m.lower() if isinstance(m, str) else m for m in message],
+                [a.lower() if isinstance(a, str) else a for a in exc.orig.args]
             )
         else:
             self.assertEqual(message.lower(), str(exc.orig).lower())
@@ -227,14 +223,14 @@ class TestFallthroughsAndNonDBAPI(TestsExceptionFilter):
         # or at least not documented anywhere.
         uee_ref = None
         try:
-            six.u('\u2435').encode('ascii')
+            '\u2435'.encode('ascii')
         except UnicodeEncodeError as uee:
             # Python3.x added new scoping rules here (sadly)
             # http://legacy.python.org/dev/peps/pep-3110/#semantic-changes
             uee_ref = uee
 
         self._run_test(
-            "postgresql", six.u('select \u2435'),
+            'postgresql', 'select \u2435',
             uee_ref,
             exception.DBInvalidUnicodeParameter
             )
@@ -738,42 +734,6 @@ class TestExceptionCauseMySQLSavepoint(test_base._MySQLOpportunisticTestCase):
             assert False, "no exception raised"
 
 
-class TestDBDataErrorSQLite(_SQLAExceptionMatcher, test_base._DbTestCase):
-
-    def setUp(self):
-        super(TestDBDataErrorSQLite, self).setUp()
-
-        if six.PY3:
-            self.skipTest("SQLite database supports unicode value for python3")
-
-        meta = sqla.MetaData(bind=self.engine)
-
-        self.table_1 = sqla.Table(
-            "resource_foo", meta,
-            sqla.Column("name", sqla.String),
-        )
-        self.table_1.create()
-
-    def test_raise(self):
-
-        matched = self.assertRaises(
-            exception.DBDataError,
-            self.engine.execute,
-            self.table_1.insert({'name': u'\u2713'.encode('utf-8')})
-        )
-
-        self.assertInnerException(
-            matched,
-            "ProgrammingError",
-            "You must not use 8-bit bytestrings unless you use a "
-            "text_factory that can interpret 8-bit bytestrings "
-            "(like text_factory = str). It is highly recommended that "
-            "you instead just switch your application to Unicode strings.",
-            "INSERT INTO resource_foo (name) VALUES (?)",
-            (u'\u2713'.encode('utf-8'),)
-        )
-
-
 class TestConstraint(TestsExceptionFilter):
     def test_postgresql(self):
         matched = self._run_test(
diff --git a/oslo_db/tests/sqlalchemy/test_migrations.py b/oslo_db/tests/sqlalchemy/test_migrations.py
index 17cdf8e..5d27b07 100644
--- a/oslo_db/tests/sqlalchemy/test_migrations.py
+++ b/oslo_db/tests/sqlalchemy/test_migrations.py
@@ -18,7 +18,6 @@ import fixtures
 from migrate.versioning import api as versioning_api
 import mock
 from oslotest import base as test
-import six
 import sqlalchemy as sa
 import sqlalchemy.ext.declarative as sa_decl
 
@@ -304,8 +303,7 @@ class ModelsMigrationSyncMixin(test_base._DbTestCase):
                 ]
             filter_mock.side_effect = filter_diffs
 
-            msg = six.text_type(self.assertRaises(AssertionError,
-                                self.test_models_sync))
+            msg = str(self.assertRaises(AssertionError, self.test_models_sync))
             self.assertNotIn('defaulttest', msg)
             self.assertNotIn('defaulttest3', msg)
             self.assertNotIn('remove_fk', msg)
@@ -342,8 +340,7 @@ class ModelsMigrationSyncMixin(test_base._DbTestCase):
             mysql_engine='InnoDB'
         )
 
-        msg = six.text_type(self.assertRaises(AssertionError,
-                                              self.test_models_sync))
+        msg = str(self.assertRaises(AssertionError, self.test_models_sync))
         # NOTE(I159): Check mentioning of the table and columns.
         # The log is invalid json, so we can't parse it and check it for
         # full compliance. We have no guarantee of the log items ordering,
diff --git a/oslo_db/tests/sqlalchemy/test_models.py b/oslo_db/tests/sqlalchemy/test_models.py
index 302a994..1c7339e 100644
--- a/oslo_db/tests/sqlalchemy/test_models.py
+++ b/oslo_db/tests/sqlalchemy/test_models.py
@@ -13,12 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-# TODO(smcginnis) update this once six has support for collections.abc
-# (https://github.com/benjaminp/six/pull/241) or clean up once we drop py2.7.
-try:
-    from collections.abc import Iterable
-except ImportError:
-    from collections import Iterable
+from collections import abc
 import datetime
 
 import mock
@@ -56,7 +51,7 @@ class ModelBaseTest(test_base._DbTestCase):
                             "Method %s() is not found" % method)
 
     def test_modelbase_is_iterable(self):
-        self.assertTrue(issubclass(models.ModelBase, Iterable))
+        self.assertTrue(issubclass(models.ModelBase, abc.Iterable))
 
     def test_modelbase_set(self):
         self.mb['world'] = 'hello'
diff --git a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
index 9ebf58c..bde7303 100644
--- a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
+++ b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
@@ -24,7 +24,6 @@ import fixtures
 import mock
 from oslo_config import cfg
 from oslotest import base as oslo_test
-import six
 import sqlalchemy
 from sqlalchemy import Column, MetaData, Table
 from sqlalchemy.engine import url
@@ -683,12 +682,8 @@ class CreateEngineTest(oslo_test.BaseTestCase):
         self.assertNotIn('poolclass', self.args)
 
     def _test_mysql_connect_args_default(self, connect_args):
-        if six.PY3:
-            self.assertEqual({'charset': 'utf8', 'use_unicode': 1},
-                             connect_args)
-        else:
-            self.assertEqual({'charset': 'utf8', 'use_unicode': 0},
-                             connect_args)
+        self.assertEqual({'charset': 'utf8', 'use_unicode': 1},
+                         connect_args)
 
     def test_mysql_connect_args_default(self):
         engines._init_connection_args(
diff --git a/oslo_db/tests/sqlalchemy/test_utils.py b/oslo_db/tests/sqlalchemy/test_utils.py
index f193dfd..4ca09e1 100644
--- a/oslo_db/tests/sqlalchemy/test_utils.py
+++ b/oslo_db/tests/sqlalchemy/test_utils.py
@@ -13,10 +13,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from urllib import parse
+
 import fixtures
 import mock
 from oslotest import base as test_base
-from six.moves.urllib import parse
 import sqlalchemy
 from sqlalchemy.dialects import mysql
 from sqlalchemy import Boolean, Index, Integer, DateTime, String, SmallInteger
diff --git a/oslo_db/tests/utils.py b/oslo_db/tests/utils.py
index bbf1fa8..c7e1e1f 100644
--- a/oslo_db/tests/utils.py
+++ b/oslo_db/tests/utils.py
@@ -17,16 +17,12 @@ import contextlib
 
 from oslo_config import cfg
 from oslotest import base as test_base
-import six
 
 
-if six.PY3:
-    @contextlib.contextmanager
-    def nested(*contexts):
-        with contextlib.ExitStack() as stack:
-            yield [stack.enter_context(c) for c in contexts]
-else:
-    nested = contextlib.nested
+@contextlib.contextmanager
+def nested(*contexts):
+    with contextlib.ExitStack() as stack:
+        yield [stack.enter_context(c) for c in contexts]
 
 
 class BaseTestCase(test_base.BaseTestCase):
diff --git a/requirements.txt b/requirements.txt
index c4cd79b..bf998e1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,7 +11,6 @@ oslo.utils>=3.33.0 # Apache-2.0
 SQLAlchemy>=1.2.0 # MIT
 sqlalchemy-migrate>=0.11.0 # Apache-2.0
 stevedore>=1.20.0 # Apache-2.0
-six>=1.10.0 # MIT
 # these are used by downstream libraries that require
 # oslo.db as one of their test requirements - do not remove!
 testresources>=2.0.0 # Apache-2.0/BSD