cachalot._get_tables() - Code Metrics - Inspection of "Changes __version__ for PEP 396 compliance." - noripyt/django-cachalot - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( f597a7...ef36e5 )

by Bertrand

created 2016-01-11 20:05 UTC

cachalot._get_tables() F

↳ Parent: Project

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Metric	Value
cc	12
dl	0
loc	23
rs	2.9695

How to fix Complexity

# 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 .signals import post_invalidation
from .transaction import AtomicCache


DJANGO_LTE_1_8 = django_version[:2] <= (1, 8)
DJANGO_GTE_1_9 = django_version[:2] >= (1, 9)


class UncachableQuery(Exception):
    pass


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 is list or cl is tuple:
                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: str
    """
    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: str
    """
    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 _get_tables(query, db_alias):
    if '?' in query.order_by and not cachalot_settings.CACHALOT_CACHE_RANDOM:
        raise UncachableQuery

    tables = set(query.table_map)
    tables.add(query.get_meta().db_table)
    subquery_constraints = _find_subqueries(
        query.where.children + query.having.children if DJANGO_LTE_1_8
        else 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)

    whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
    blacklist = cachalot_settings.CACHALOT_UNCACHABLE_TABLES
    if (whitelist and not tables.issubset(whitelist)) \
            or not tables.isdisjoint(blacklist):
        raise UncachableQuery
    return tables


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


def _invalidate_tables(cache, db_alias, tables):
    now = time()
    d = {}
    for table in tables:
        d[_get_table_cache_key(db_alias, table)] = now
    cache.set_many(d, None)

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


def _invalidate_table(cache, db_alias, table):
    cache.set(_get_table_cache_key(db_alias, table), time(), None)

    if isinstance(cache, AtomicCache):
        cache.to_be_invalidated.add(table)
    else:
        post_invalidation.send(table, db_alias=db_alias)


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 .signals import post_invalidation
19			from .transaction import AtomicCache
20
21
22			DJANGO_LTE_1_8 = django_version[:2] <= (1, 8)
23			DJANGO_GTE_1_9 = django_version[:2] >= (1, 9)
24
25
26			class UncachableQuery(Exception):
27			pass
28
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 is list or cl is tuple:
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: str
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: str
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 _get_tables(query, db_alias):
134			if '?' in query.order_by and not cachalot_settings.CACHALOT_CACHE_RANDOM:
135			raise UncachableQuery
136
137			tables = set(query.table_map)
138			tables.add(query.get_meta().db_table)
139			subquery_constraints = _find_subqueries(
140			query.where.children + query.having.children if DJANGO_LTE_1_8
141			else query.where.children)
142			for subquery in subquery_constraints:
143			tables.update(_get_tables(subquery, db_alias))
144			if query.extra_select or hasattr(query, 'subquery') \
145			or any(c.__class__ is ExtraWhere for c in query.where.children):
146			sql = query.get_compiler(db_alias).as_sql()[0].lower()
147			additional_tables = _get_tables_from_sql(connections[db_alias], sql)
148			tables.update(additional_tables)
149
150			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
151			blacklist = cachalot_settings.CACHALOT_UNCACHABLE_TABLES
152			if (whitelist and not tables.issubset(whitelist)) \
153			or not tables.isdisjoint(blacklist):
154			raise UncachableQuery
155			return tables
156
157
158			def _get_table_cache_keys(compiler):
159			db_alias = compiler.using
160			tables = _get_tables(compiler.query, db_alias)
161			return [_get_table_cache_key(db_alias, t) for t in tables]
162
163
164			def _invalidate_tables(cache, db_alias, tables):
165			now = time()
166			d = {}
167			for table in tables:
168			d[_get_table_cache_key(db_alias, table)] = now
169			cache.set_many(d, None)
170
171			if isinstance(cache, AtomicCache):
172			cache.to_be_invalidated.update(tables)
173
174
175			def _invalidate_table(cache, db_alias, table):
176			cache.set(_get_table_cache_key(db_alias, table), time(), None)
177
178			if isinstance(cache, AtomicCache):
179			cache.to_be_invalidated.add(table)
180			else:
181			post_invalidation.send(table, db_alias=db_alias)
182

noripyt / django-cachalot

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cachalot._get_tables() F

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