openstack/tooz
Code Issues Proposed changes

Merge "Translate psycopg2 errors/exceptions into tooz exceptions"

Browse Source
This commit is contained in:
Jenkins 2014-11-18 10:45:02 +00:00 committed by Gerrit Code Review
commit cdf092d7d9
4 changed files with 189 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
test-requirements.txt
View File

@ -2,6 +2,7 @@ pep8>=1.4.5
pyflakes>=0.7.2,<0.7.4
flake8>=2.1.0
discover
mock>=1.0 # only needed on < python 3.3
sphinx>=1.1.2,<1.2
python-subunit
testrepository>=0.0.17

83
tooz/drivers/pgsql.py
View File

@ -15,6 +15,8 @@
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import contextlib
import hashlib
import psycopg2
@ -24,6 +26,64 @@ import tooz
from tooz import coordination
from tooz.drivers import _retry
from tooz import locking
from tooz import utils
# See: psycopg/diagnostics_type.c for what kind of fields these
# objects may have (things like 'schema_name', 'internal_query'
# and so-on which are useful for figuring out what went wrong...)
_DIAGNOSTICS_ATTRS = tuple([
'column_name',
'constraint_name',
'context',
'datatype_name',
'internal_position',
'internal_query',
'message_detail',
'message_hint',
'message_primary',
'schema_name',
'severity',
'source_file',
'source_function',
'source_line',
'sqlstate',
'statement_position',
'table_name',
])
def _format_exception(e):
lines = [
"%s: %s" % (type(e).__name__, utils.exception_message(e).strip()),
]
if hasattr(e, 'pgcode') and e.pgcode is not None:
lines.append("Error code: %s" % e.pgcode)
# The reason this hasattr check is done is that the 'diag' may not always
# be present, depending on how new of a psycopg is installed... so better
# to be safe than sorry...
if hasattr(e, 'diag') and e.diag is not None:
diagnostic_lines = []
for attr_name in _DIAGNOSTICS_ATTRS:
if not hasattr(e.diag, attr_name):
continue
attr_value = getattr(e.diag, attr_name)
if attr_value is None:
continue
diagnostic_lines.append(" %s = %s" (attr_name, attr_value))
if diagnostic_lines:
lines.append('Diagnostics:')
lines.extend(diagnostic_lines)
return "\n".join(lines)
@contextlib.contextmanager
def _translating_cursor(conn):
try:
with conn.cursor() as cur:
yield cur
except psycopg2.Error as e:
raise coordination.ToozError(_format_exception(e))
class PostgresLock(locking.Lock):
@ -41,16 +101,16 @@ class PostgresLock(locking.Lock):
def acquire(self, blocking=True):
if blocking is True:
with self._conn.cursor() as cur:
with _translating_cursor(self._conn) as cur:
cur.execute("SELECT pg_advisory_lock(%s, %s);", self.key)
return True
return True
elif blocking is False:
with self._conn.cursor() as cur:
with _translating_cursor(self._conn) as cur:
cur.execute("SELECT pg_try_advisory_lock(%s, %s);", self.key)
return cur.fetchone()[0]
else:
def _acquire():
with self._conn.cursor() as cur:
with _translating_cursor(self._conn) as cur:
cur.execute("SELECT pg_try_advisory_lock(%s, %s);",
self.key)
if cur.fetchone()[0] is True:
@ -61,7 +121,7 @@ class PostgresLock(locking.Lock):
return _retry.Retrying(**kwargs).call(_acquire)
def release(self):
with self._conn.cursor() as cur:
with _translating_cursor(self._conn) as cur:
cur.execute("SELECT pg_advisory_unlock(%s, %s);", self.key)
return cur.fetchone()[0]
@ -78,11 +138,14 @@ class PostgresDriver(coordination.CoordinationDriver):
self._password = parsed_url.password
def _start(self):
self._conn = psycopg2.connect(host=self._host,
port=self._port,
user=self._username,
password=self._password,
database=self._dbname)
try:
self._conn = psycopg2.connect(host=self._host,
port=self._port,
user=self._username,
password=self._password,
database=self._dbname)
except psycopg2.Error as e:
raise coordination.ToozConnectionError(_format_exception(e))
def _stop(self):
self._conn.close()

114
tooz/tests/test_postgresql.py Normal file
View File

@ -0,0 +1,114 @@
# -*- coding: utf-8 -*-
# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import uuid
try:
# Added in python 3.3+
from unittest import mock
except ImportError:
import mock
import testtools
from testtools import testcase
from tooz import coordination
from tooz import utils
# Handle the case gracefully where the driver is not installed.
try:
import psycopg2
PGSQL_AVAILABLE = True
except ImportError:
PGSQL_AVAILABLE = False
@testtools.skipUnless(PGSQL_AVAILABLE, 'psycopg2 is not available')
class TestPostgreSQLFailures(testcase.TestCase):
# Not actually used (but required none the less), since we mock out
# the connect() method...
FAKE_URL = "postgresql://localhost:1"
def _create_coordinator(self):
def _safe_stop(coord):
try:
coord.stop()
except coordination.ToozError as e:
# TODO(harlowja): make this better, so that we don't have to
# do string checking...
message = utils.exception_message(e)
if (message != 'Can not stop a driver which has not'
' been started'):
raise
coord = coordination.get_coordinator(self.FAKE_URL,
str(uuid.uuid4()).encode('ascii'))
self.addCleanup(_safe_stop, coord)
return coord
@mock.patch("tooz.drivers.pgsql.psycopg2.connect")
def test_connect_failure(self, psycopg2_connector):
psycopg2_connector.side_effect = psycopg2.Error("Broken")
c = self._create_coordinator()
self.assertRaises(coordination.ToozConnectionError, c.start)
@mock.patch("tooz.drivers.pgsql.psycopg2.connect")
def test_connect_failure_operational(self, psycopg2_connector):
psycopg2_connector.side_effect = psycopg2.OperationalError("Broken")
c = self._create_coordinator()
self.assertRaises(coordination.ToozConnectionError, c.start)
@mock.patch("tooz.drivers.pgsql.psycopg2.connect")
def test_failure_acquire_lock(self, psycopg2_connector):
execute_mock = mock.MagicMock()
execute_mock.execute.side_effect = psycopg2.OperationalError("Broken")
cursor_mock = mock.MagicMock()
cursor_mock.__enter__ = mock.MagicMock(return_value=execute_mock)
cursor_mock.__exit__ = mock.MagicMock(return_value=False)
conn_mock = mock.MagicMock()
conn_mock.cursor.return_value = cursor_mock
psycopg2_connector.return_value = conn_mock
c = self._create_coordinator()
c.start()
test_lock = c.get_lock(b'test-lock')
self.assertRaises(coordination.ToozError, test_lock.acquire)
@mock.patch("tooz.drivers.pgsql.psycopg2.connect")
def test_failure_release_lock(self, psycopg2_connector):
execute_mock = mock.MagicMock()
execute_mock.execute.side_effect = [
True,
psycopg2.OperationalError("Broken"),
]
cursor_mock = mock.MagicMock()
cursor_mock.__enter__ = mock.MagicMock(return_value=execute_mock)
cursor_mock.__exit__ = mock.MagicMock(return_value=False)
conn_mock = mock.MagicMock()
conn_mock.cursor.return_value = cursor_mock
psycopg2_connector.return_value = conn_mock
c = self._create_coordinator()
c.start()
test_lock = c.get_lock(b'test-lock')
self.assertTrue(test_lock.acquire())
self.assertRaises(coordination.ToozError, test_lock.release)

1
tox.ini
View File

@ -106,3 +106,4 @@ show-source = True
[hacking]
import_exceptions = six.moves
unittest.mock