_invalidate_table() - Code Metrics - Inspection of "Stops automatically invalidating other caches than..." - noripyt/django-cachalot - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( eb64d1...f6cfeb )

by Bertrand

created 2016-09-29 17:11 UTC

_invalidate_table() A

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Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes	2
Bugs	0	Features	0

Metric	Value
cc	3
c	2
b	0
f	0
dl	0
loc	11
rs	9.4285

# coding: utf-8

from __future__ import unicode_literals
import datetime
from decimal import Decimal
from hashlib import sha1
from time import time
from uuid import UUID

from django import VERSION as django_version
from django.db import connections
from django.db.models.sql import Query
from django.db.models.sql.where import ExtraWhere, SubqueryConstraint
from django.utils.module_loading import import_string
from django.utils.six import text_type, binary_type

from .settings import cachalot_settings
from .transaction import AtomicCache


DJANGO_GTE_1_9 = django_version[:2] >= (1, 9)


class UncachableQuery(Exception):
    pass


TUPLE_OR_LIST = {tuple, list}

CACHABLE_PARAM_TYPES = {
    bool, int, float, Decimal, binary_type, text_type, type(None),
    datetime.date, datetime.time, datetime.datetime, datetime.timedelta, UUID,
}

UNCACHABLE_FUNCS = set()
if DJANGO_GTE_1_9:
    from django.db.models.functions import Now
    from django.contrib.postgres.functions import TransactionNow
    UNCACHABLE_FUNCS.update((Now, TransactionNow))

try:
    from psycopg2.extras import (
        NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json)
except ImportError:
    pass
else:
    CACHABLE_PARAM_TYPES.update((
        NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json))


def check_parameter_types(params):
    for p in params:
        cl = p.__class__
        if cl not in CACHABLE_PARAM_TYPES:
            if cl in TUPLE_OR_LIST:
                check_parameter_types(p)
            elif cl is dict:
                check_parameter_types(p.items())
            else:
                raise UncachableQuery


def get_query_cache_key(compiler):
    """
    Generates a cache key from a SQLCompiler.

    This cache key is specific to the SQL query and its context
    (which database is used).  The same query in the same context
    (= the same database) must generate the same cache key.

    :arg compiler: A SQLCompiler that will generate the SQL query
    :type compiler: django.db.models.sql.compiler.SQLCompiler
    :return: A cache key
    :rtype: int
    """
    sql, params = compiler.as_sql()
    check_parameter_types(params)
    cache_key = '%s:%s:%s' % (compiler.using, sql, params)
    return sha1(cache_key.encode('utf-8')).hexdigest()


def get_table_cache_key(db_alias, table):
    """
    Generates a cache key from a SQL table.

    :arg db_alias: Alias of the used database
    :type db_alias: str or unicode
    :arg table: Name of the SQL table
    :type table: str or unicode
    :return: A cache key
    :rtype: int
    """
    cache_key = '%s:%s' % (db_alias, table)
    return sha1(cache_key.encode('utf-8')).hexdigest()


def _get_query_cache_key(compiler):
    return import_string(cachalot_settings.CACHALOT_QUERY_KEYGEN)(compiler)


def _get_table_cache_key(db_alias, table):
    return import_string(cachalot_settings.CACHALOT_TABLE_KEYGEN)(db_alias, table)


def _get_tables_from_sql(connection, lowercased_sql):
    return [t for t in connection.introspection.django_table_names()
            if t in lowercased_sql]


def _find_subqueries(children):
    for child in children:
        if child.__class__ is SubqueryConstraint:
            if child.query_object.__class__ is Query:
                yield child.query_object
            else:
                yield child.query_object.query
        else:
            rhs = None
            if hasattr(child, 'rhs'):
                rhs = child.rhs
            rhs_class = rhs.__class__
            if rhs_class is Query:
                yield rhs
            elif hasattr(rhs, 'query'):
                yield rhs.query
            elif rhs_class in UNCACHABLE_FUNCS:
                raise UncachableQuery
        if hasattr(child, 'children'):
            for grand_child in _find_subqueries(child.children):
                yield grand_child


def is_cachable(table):
    whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
    if whitelist and table not in whitelist:
        return False
    return table not in cachalot_settings.CACHALOT_UNCACHABLE_TABLES


def are_all_cachable(tables):
    whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
    if whitelist and not tables.issubset(whitelist):
        return False
    return tables.isdisjoint(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)


def filter_cachable(tables):
    whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
    tables = tables.difference(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
    if whitelist:
        return tables.intersection(whitelist)
    return tables


def _get_tables(query, db_alias):
    if ('?' in query.order_by and not cachalot_settings.CACHALOT_CACHE_RANDOM) \
            or query.select_for_update:
        raise UncachableQuery

    tables = set(query.table_map)
    tables.add(query.get_meta().db_table)
    subquery_constraints = _find_subqueries(query.where.children)
    for subquery in subquery_constraints:
        tables.update(_get_tables(subquery, db_alias))
    if query.extra_select or hasattr(query, 'subquery') \
            or any(c.__class__ is ExtraWhere for c in query.where.children):
        sql = query.get_compiler(db_alias).as_sql()[0].lower()
        additional_tables = _get_tables_from_sql(connections[db_alias], sql)
        tables.update(additional_tables)

    if not are_all_cachable(tables):
        raise UncachableQuery
    return tables


def _get_table_cache_keys(compiler):
    db_alias = compiler.using
    return [_get_table_cache_key(db_alias, t)
            for t in _get_tables(compiler.query, db_alias)]


def _invalidate_tables(cache, db_alias, tables):
    tables = filter_cachable(set(tables))
    if not tables:
        return
    now = time()
    cache.set_many(
        {_get_table_cache_key(db_alias, t): now for t in tables},
        cachalot_settings.CACHALOT_TIMEOUT)

    if isinstance(cache, AtomicCache):
        cache.to_be_invalidated.update(tables)


1			# coding: utf-8
2
3			from __future__ import unicode_literals
4			import datetime
5			from decimal import Decimal
6			from hashlib import sha1
7			from time import time
8			from uuid import UUID
9
10			from django import VERSION as django_version
11			from django.db import connections
12			from django.db.models.sql import Query
13			from django.db.models.sql.where import ExtraWhere, SubqueryConstraint
14			from django.utils.module_loading import import_string
15			from django.utils.six import text_type, binary_type
16
17			from .settings import cachalot_settings
18			from .transaction import AtomicCache
19
20
21			DJANGO_GTE_1_9 = django_version[:2] >= (1, 9)
22
23
24			class UncachableQuery(Exception):
25			pass
26
27
28			TUPLE_OR_LIST = {tuple, list}
29
30			CACHABLE_PARAM_TYPES = {
31			bool, int, float, Decimal, binary_type, text_type, type(None),
32			datetime.date, datetime.time, datetime.datetime, datetime.timedelta, UUID,
33			}
34
35			UNCACHABLE_FUNCS = set()
36			if DJANGO_GTE_1_9:
37			from django.db.models.functions import Now
38			from django.contrib.postgres.functions import TransactionNow
39			UNCACHABLE_FUNCS.update((Now, TransactionNow))
40
41			try:
42			from psycopg2.extras import (
43			NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json)
44			except ImportError:
45			pass
46			else:
47			CACHABLE_PARAM_TYPES.update((
48			NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json))
49
50
51			def check_parameter_types(params):
52			for p in params:
53			cl = p.__class__
54			if cl not in CACHABLE_PARAM_TYPES:
55			if cl in TUPLE_OR_LIST:
56			check_parameter_types(p)
57			elif cl is dict:
58			check_parameter_types(p.items())
59			else:
60			raise UncachableQuery
61
62
63			def get_query_cache_key(compiler):
64			"""
65			Generates a cache key from a SQLCompiler.
66
67			This cache key is specific to the SQL query and its context
68			(which database is used). The same query in the same context
69			(= the same database) must generate the same cache key.
70
71			:arg compiler: A SQLCompiler that will generate the SQL query
72			:type compiler: django.db.models.sql.compiler.SQLCompiler
73			:return: A cache key
74			:rtype: int
75			"""
76			sql, params = compiler.as_sql()
77			check_parameter_types(params)
78			cache_key = '%s:%s:%s' % (compiler.using, sql, params)
79			return sha1(cache_key.encode('utf-8')).hexdigest()
80
81
82			def get_table_cache_key(db_alias, table):
83			"""
84			Generates a cache key from a SQL table.
85
86			:arg db_alias: Alias of the used database
87			:type db_alias: str or unicode
88			:arg table: Name of the SQL table
89			:type table: str or unicode
90			:return: A cache key
91			:rtype: int
92			"""
93			cache_key = '%s:%s' % (db_alias, table)
94			return sha1(cache_key.encode('utf-8')).hexdigest()
95
96
97			def _get_query_cache_key(compiler):
98			return import_string(cachalot_settings.CACHALOT_QUERY_KEYGEN)(compiler)
99
100
101			def _get_table_cache_key(db_alias, table):
102			return import_string(cachalot_settings.CACHALOT_TABLE_KEYGEN)(db_alias, table)
103
104
105			def _get_tables_from_sql(connection, lowercased_sql):
106			return [t for t in connection.introspection.django_table_names()
107			if t in lowercased_sql]
108
109
110			def _find_subqueries(children):
111			for child in children:
112			if child.__class__ is SubqueryConstraint:
113			if child.query_object.__class__ is Query:
114			yield child.query_object
115			else:
116			yield child.query_object.query
117			else:
118			rhs = None
119			if hasattr(child, 'rhs'):
120			rhs = child.rhs
121			rhs_class = rhs.__class__
122			if rhs_class is Query:
123			yield rhs
124			elif hasattr(rhs, 'query'):
125			yield rhs.query
126			elif rhs_class in UNCACHABLE_FUNCS:
127			raise UncachableQuery
128			if hasattr(child, 'children'):
129			for grand_child in _find_subqueries(child.children):
130			yield grand_child
131
132
133			def is_cachable(table):
134			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
135			if whitelist and table not in whitelist:
136			return False
137			return table not in cachalot_settings.CACHALOT_UNCACHABLE_TABLES
138
139
140			def are_all_cachable(tables):
141			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
142			if whitelist and not tables.issubset(whitelist):
143			return False
144			return tables.isdisjoint(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
145
146
147			def filter_cachable(tables):
148			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
149			tables = tables.difference(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
150			if whitelist:
151			return tables.intersection(whitelist)
152			return tables
153
154
155			def _get_tables(query, db_alias):
156			if ('?' in query.order_by and not cachalot_settings.CACHALOT_CACHE_RANDOM) \
157			or query.select_for_update:
158			raise UncachableQuery
159
160			tables = set(query.table_map)
161			tables.add(query.get_meta().db_table)
162			subquery_constraints = _find_subqueries(query.where.children)
163			for subquery in subquery_constraints:
164			tables.update(_get_tables(subquery, db_alias))
165			if query.extra_select or hasattr(query, 'subquery') \
166			or any(c.__class__ is ExtraWhere for c in query.where.children):
167			sql = query.get_compiler(db_alias).as_sql()[0].lower()
168			additional_tables = _get_tables_from_sql(connections[db_alias], sql)
169			tables.update(additional_tables)
170
171			if not are_all_cachable(tables):
172			raise UncachableQuery
173			return tables
174
175
176			def _get_table_cache_keys(compiler):
177			db_alias = compiler.using
178			return [_get_table_cache_key(db_alias, t)
179			for t in _get_tables(compiler.query, db_alias)]
180
181
182			def _invalidate_tables(cache, db_alias, tables):
183			tables = filter_cachable(set(tables))
184			if not tables:
185			return
186			now = time()
187			cache.set_many(
188			{_get_table_cache_key(db_alias, t): now for t in tables},
189			cachalot_settings.CACHALOT_TIMEOUT)
190
191			if isinstance(cache, AtomicCache):
192			cache.to_be_invalidated.update(tables)
193

noripyt / django-cachalot

Push — master ( eb64d1...f6cfeb )

_invalidate_table() A

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