/usr/lib/python2.7/dist-packages/tooz/drivers/pgsql.py is in python-tooz 1.40.0-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 | # -*- coding: utf-8 -*-
#
# Copyright © 2014 eNovance
#
# 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 contextlib
import hashlib
import logging
from oslo_utils import encodeutils
import psycopg2
import six
import tooz
from tooz import coordination
from tooz.drivers import _retry
from tooz import locking
from tooz import utils
LOG = logging.getLogger(__name__)
# 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__,
encodeutils.exception_to_unicode(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:
coordination.raise_with_cause(coordination.ToozError,
_format_exception(e),
cause=e)
class PostgresLock(locking.Lock):
"""A PostgreSQL based lock."""
def __init__(self, name, parsed_url, options):
super(PostgresLock, self).__init__(name)
self.acquired = False
self._conn = PostgresDriver.get_connection(parsed_url, options)
h = hashlib.md5()
h.update(name)
if six.PY2:
self.key = list(map(ord, h.digest()[0:2]))
else:
self.key = h.digest()[0:2]
def acquire(self, blocking=True):
@_retry.retry(stop_max_delay=blocking)
def _lock():
# NOTE(sileht) One the same session the lock is not exclusive
# so we track it internally if the process already has the lock.
if self.acquired is True:
if blocking:
raise _retry.Retry
return False
with _translating_cursor(self._conn) as cur:
if blocking is True:
cur.execute("SELECT pg_advisory_lock(%s, %s);", self.key)
cur.fetchone()
self.acquired = True
return True
else:
cur.execute("SELECT pg_try_advisory_lock(%s, %s);",
self.key)
if cur.fetchone()[0] is True:
self.acquired = True
return True
elif blocking is False:
return False
else:
raise _retry.Retry
return _lock()
def release(self):
if not self.acquired:
return False
with _translating_cursor(self._conn) as cur:
cur.execute("SELECT pg_advisory_unlock(%s, %s);",
self.key)
cur.fetchone()
self.acquired = False
return True
def __del__(self):
if self.acquired:
LOG.warning("unreleased lock %s garbage collected", self.name)
class PostgresDriver(coordination.CoordinationDriver):
"""A `PostgreSQL`_ based driver.
This driver users `PostgreSQL`_ database tables to
provide the coordination driver semantics and required API(s). It **is**
missing some functionality but in the future these not implemented API(s)
will be filled in.
.. _PostgreSQL: http://www.postgresql.org/
"""
CHARACTERISTICS = (
coordination.Characteristics.NON_TIMEOUT_BASED,
coordination.Characteristics.DISTRIBUTED_ACROSS_THREADS,
coordination.Characteristics.DISTRIBUTED_ACROSS_PROCESSES,
coordination.Characteristics.DISTRIBUTED_ACROSS_HOSTS,
)
"""
Tuple of :py:class:`~tooz.coordination.Characteristics` introspectable
enum member(s) that can be used to interogate how this driver works.
"""
def __init__(self, member_id, parsed_url, options):
"""Initialize the PostgreSQL driver."""
super(PostgresDriver, self).__init__()
self._parsed_url = parsed_url
self._options = utils.collapse(options)
def _start(self):
self._conn = PostgresDriver.get_connection(self._parsed_url,
self._options)
def _stop(self):
self._conn.close()
def get_lock(self, name):
return PostgresLock(name, self._parsed_url, self._options)
@staticmethod
def watch_join_group(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def unwatch_join_group(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def watch_leave_group(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def unwatch_leave_group(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def watch_elected_as_leader(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def unwatch_elected_as_leader(group_id, callback):
raise tooz.NotImplemented
@staticmethod
def get_connection(parsed_url, options):
host = options.get("host") or parsed_url.hostname
port = options.get("port") or parsed_url.port
dbname = options.get("dbname") or parsed_url.path[1:]
username = parsed_url.username
password = parsed_url.password
try:
return psycopg2.connect(host=host,
port=port,
user=username,
password=password,
database=dbname)
except psycopg2.Error as e:
coordination.raise_with_cause(coordination.ToozConnectionError,
_format_exception(e),
cause=e)
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