/usr/share/pynslcd/cache.py is in pynslcd 0.9.4-3+deb8u2.
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 | # cache.py - caching layer for pynslcd
#
# Copyright (C) 2012, 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
import datetime
import os
import sys
import sqlite3
# TODO: probably create a config table
# FIXME: have some way to remove stale entries from the cache if all items from LDAP are queried (perhas use TTL from all request)
class regroup(object):
def __init__(self, results, group_by=None, group_column=None):
"""Regroup the results in the group column by the key columns."""
self.group_by = tuple(group_by)
self.group_column = group_column
self.it = iter(results)
self.tgtkey = self.currkey = self.currvalue = object()
def keyfunc(self, row):
return tuple(row[x] for x in self.group_by)
def __iter__(self):
return self
def next(self):
# find a start row
while self.currkey == self.tgtkey:
self.currvalue = next(self.it) # Exit on StopIteration
self.currkey = self.keyfunc(self.currvalue)
self.tgtkey = self.currkey
# turn the result row into a list of columns
row = list(self.currvalue)
# replace the group column
row[self.group_column] = list(self._grouper(self.tgtkey))
return row
def _grouper(self, tgtkey):
"""Generate the group columns."""
while self.currkey == tgtkey:
value = self.currvalue[self.group_column]
if value is not None:
yield value
self.currvalue = next(self.it) # Exit on StopIteration
self.currkey = self.keyfunc(self.currvalue)
class Query(object):
"""Helper class to build an SQL query for the cache."""
def __init__(self, query):
self.query = query
self.wheres = []
self.parameters = []
def add_where(self, where, parameters):
self.wheres.append(where)
self.parameters += parameters
def execute(self, con):
query = self.query
if self.wheres:
query += ' WHERE ' + ' AND '.join(self.wheres)
cursor = con.cursor()
return cursor.execute(query, self.parameters)
class Cache(object):
"""The description of the cache."""
retrieve_sql = None
retrieve_by = dict()
group_by = ()
group_columns = ()
def __init__(self):
self.con = _get_connection()
self.db = sys.modules[self.__module__].__name__
if not hasattr(self, 'tables'):
self.tables = ['%s_cache' % self.db]
self.create()
def create(self):
"""Create the needed tables if neccesary."""
self.con.executescript(self.create_sql)
def store(self, *values):
"""Store the values in the cache for the specified table.
The order of the values is the order returned by the Reques.convert()
function."""
# split the values into simple (flat) values and one-to-many values
simple_values = []
multi_values = []
for v in values:
if isinstance(v, (list, tuple, set)):
multi_values.append(v)
else:
simple_values.append(v)
# insert the simple values
simple_values.append(datetime.datetime.now())
args = ', '.join(len(simple_values) * ('?', ))
self.con.execute('''
INSERT OR REPLACE INTO %s
VALUES
(%s)
''' % (self.tables[0], args), simple_values)
# insert the one-to-many values
for n, vlist in enumerate(multi_values):
self.con.execute('''
DELETE FROM %s
WHERE `%s` = ?
''' % (self.tables[n + 1], self.db), (values[0], ))
self.con.executemany('''
INSERT INTO %s
VALUES
(?, ?)
''' % (self.tables[n + 1]), ((values[0], x) for x in vlist))
def retrieve(self, parameters):
"""Retrieve all items from the cache based on the parameters
supplied."""
query = Query(self.retrieve_sql or '''
SELECT *
FROM %s
''' % self.tables[0])
if parameters:
for k, v in parameters.items():
where = self.retrieve_by.get(k, '`%s`.`%s` = ?' % (self.tables[0], k))
query.add_where(where, where.count('?') * [v])
# group by
# FIXME: find a nice way to turn group_by and group_columns into names
results = query.execute(self.con)
group_by = list(self.group_by + self.group_columns)
for column in self.group_columns[::-1]:
group_by.pop()
results = regroup(results, group_by, column)
# strip the mtime from the results
return (list(x)[:-1] for x in results)
def __enter__(self):
return self.con.__enter__();
def __exit__(self, *args):
return self.con.__exit__(*args);
# the connection to the sqlite database
_connection = None
# FIXME: make tread safe (is this needed the way the caches are initialised?)
def _get_connection():
global _connection
if _connection is None:
filename = '/tmp/pynslcd_cache.sqlite'
dirname = os.path.dirname(filename)
if not os.path.isdir(dirname):
os.mkdir(dirname)
connection = sqlite3.connect(
filename, detect_types=sqlite3.PARSE_DECLTYPES,
check_same_thread=False)
connection.row_factory = sqlite3.Row
# initialise connection properties
connection.executescript('''
-- store temporary tables in memory
PRAGMA temp_store = MEMORY;
-- disable sync() on database (corruption on disk failure)
PRAGMA synchronous = OFF;
-- put journal in memory (corruption if crash during transaction)
PRAGMA journal_mode = MEMORY;
''')
_connection = connection
return _connection
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