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
|
# cache.py - caching layer for pynslcd
#
# Copyright (C) 2012-2019 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 sqlite3
import sys
# 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): # noqa: N801 (this has an iterator name)
"""Regroup the results in the group column by the key columns.
Get entries from a queryset that has multiple result rows per wanted
entry by combining multiple values. E.g.
1, 2, 3
1, 2, 4
1, 2, 5
into
1, 2, [3, 4, 5]
"""
def __init__(self, results, group_by=None, group_column=None):
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 __next__(self):
return self.next()
def _grouper(self, tgtkey):
"""Generate the group columns."""
try:
while self.currkey == tgtkey:
value = self.currvalue[self.group_column]
if value is not None:
yield value
self.currvalue = next(self.it)
self.currkey = self.keyfunc(self.currvalue)
except StopIteration:
pass
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
|