_find_subqueries() - Code Metrics - Inspection of "Supports RawSQL." - noripyt/django-cachalot - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( d0ee58...452210 )

by Bertrand

created 2017-06-03 15:59 UTC

_find_subqueries() F

↳ Parent: Project

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes	6
Bugs	0	Features	0

Metric	Value
cc	12
c	6
b	0
f	0
dl	0
loc	26
rs	2.7855

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.expressions import RawSQL
from django.db.models.sql import Query
from django.db.models.sql.where import (
    ExtraWhere, SubqueryConstraint, WhereNode)
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


class UncachableQuery(Exception):
    pass


class IsRawQuery(Exception):
    pass


TUPLE_OR_LIST = {tuple, list}

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

UNCACHABLE_FUNCS = set()
if django_version[:2] >= (1, 9):
    from django.db.models.functions import Now
    from django.contrib.postgres.functions import TransactionNow
    UNCACHABLE_FUNCS.update((Now, TransactionNow))

try:
    from psycopg2 import Binary
    from psycopg2.extras import (
        NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json)
except ImportError:
    pass
else:
    CACHABLE_PARAM_TYPES.update((
        Binary,
        NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json))
    if django_version[:2] >= (1, 11):
        from django.contrib.postgres.fields.jsonb import JsonAdapter
        CACHABLE_PARAM_TYPES.add(JsonAdapter)


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,
                              [text_type(p) for p in 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:
        child_class = child.__class__
        if child_class is WhereNode:
            for grand_child in _find_subqueries(child.children):
                yield grand_child
        elif child_class is SubqueryConstraint:
            if child.query_object.__class__ is Query:
                yield child.query_object
            else:
                yield child.query_object.query
        elif child_class is ExtraWhere:
            raise IsRawQuery
        else:
            rhs = None
            if hasattr(child, 'rhs'):
                rhs = child.rhs
            rhs_class = rhs.__class__
            if rhs_class is RawSQL:
                raise IsRawQuery
            if rhs_class is Query:
                yield rhs
            elif hasattr(rhs, 'query'):
                yield rhs.query
            elif rhs_class in UNCACHABLE_FUNCS:
                raise UncachableQuery


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

    try:
        if query.extra_select or getattr(query, 'subquery', False):
            raise IsRawQuery
        tables = set(query.table_map)
        tables.add(query.get_meta().db_table)
        for subquery in _find_subqueries(query.where.children):
            tables.update(_get_tables(db_alias, subquery))
    except IsRawQuery:
        sql = query.get_compiler(db_alias).as_sql()[0].lower()
        tables = _get_tables_from_sql(connections[db_alias], sql)

    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(db_alias, compiler.query)]


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.expressions import RawSQL
13			from django.db.models.sql import Query
14			from django.db.models.sql.where import (
15			ExtraWhere, SubqueryConstraint, WhereNode)
16			from django.utils.module_loading import import_string
17			from django.utils.six import text_type, binary_type
18
19			from .settings import cachalot_settings
20			from .transaction import AtomicCache
21
22
23			class UncachableQuery(Exception):
24			pass
25
26
27			class IsRawQuery(Exception):
28			pass
29
30
31			TUPLE_OR_LIST = {tuple, list}
32
33			CACHABLE_PARAM_TYPES = {
34			bool, int, float, Decimal, bytearray, binary_type, text_type, type(None),
35			datetime.date, datetime.time, datetime.datetime, datetime.timedelta, UUID,
36			}
37
38			UNCACHABLE_FUNCS = set()
39			if django_version[:2] >= (1, 9):
40			from django.db.models.functions import Now
41			from django.contrib.postgres.functions import TransactionNow
42			UNCACHABLE_FUNCS.update((Now, TransactionNow))
43
44			try:
45			from psycopg2 import Binary
46			from psycopg2.extras import (
47			NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json)
48			except ImportError:
49			pass
50			else:
51			CACHABLE_PARAM_TYPES.update((
52			Binary,
53			NumericRange, DateRange, DateTimeRange, DateTimeTZRange, Inet, Json))
54			if django_version[:2] >= (1, 11):
55			from django.contrib.postgres.fields.jsonb import JsonAdapter
56			CACHABLE_PARAM_TYPES.add(JsonAdapter)
57
58
59			def check_parameter_types(params):
60			for p in params:
61			cl = p.__class__
62			if cl not in CACHABLE_PARAM_TYPES:
63			if cl in TUPLE_OR_LIST:
64			check_parameter_types(p)
65			elif cl is dict:
66			check_parameter_types(p.items())
67			else:
68			raise UncachableQuery
69
70
71			def get_query_cache_key(compiler):
72			"""
73			Generates a cache key from a SQLCompiler.
74
75			This cache key is specific to the SQL query and its context
76			(which database is used). The same query in the same context
77			(= the same database) must generate the same cache key.
78
79			:arg compiler: A SQLCompiler that will generate the SQL query
80			:type compiler: django.db.models.sql.compiler.SQLCompiler
81			:return: A cache key
82			:rtype: int
83			"""
84			sql, params = compiler.as_sql()
85			check_parameter_types(params)
86			cache_key = '%s:%s:%s' % (compiler.using, sql,
87			[text_type(p) for p in params])
88			return sha1(cache_key.encode('utf-8')).hexdigest()
89
90
91			def get_table_cache_key(db_alias, table):
92			"""
93			Generates a cache key from a SQL table.
94
95			:arg db_alias: Alias of the used database
96			:type db_alias: str or unicode
97			:arg table: Name of the SQL table
98			:type table: str or unicode
99			:return: A cache key
100			:rtype: int
101			"""
102			cache_key = '%s:%s' % (db_alias, table)
103			return sha1(cache_key.encode('utf-8')).hexdigest()
104
105
106			def _get_query_cache_key(compiler):
107			return import_string(cachalot_settings.CACHALOT_QUERY_KEYGEN)(compiler)
108
109
110			def _get_table_cache_key(db_alias, table):
111			return import_string(cachalot_settings.CACHALOT_TABLE_KEYGEN)(db_alias, table)
112
113
114			def _get_tables_from_sql(connection, lowercased_sql):
115			return {t for t in connection.introspection.django_table_names()
116			if t in lowercased_sql}
117
118
119			def _find_subqueries(children):
120			for child in children:
121			child_class = child.__class__
122			if child_class is WhereNode:
123			for grand_child in _find_subqueries(child.children):
124			yield grand_child
125			elif child_class is SubqueryConstraint:
126			if child.query_object.__class__ is Query:
127			yield child.query_object
128			else:
129			yield child.query_object.query
130			elif child_class is ExtraWhere:
131			raise IsRawQuery
132			else:
133			rhs = None
134			if hasattr(child, 'rhs'):
135			rhs = child.rhs
136			rhs_class = rhs.__class__
137			if rhs_class is RawSQL:
138			raise IsRawQuery
139			if rhs_class is Query:
140			yield rhs
141			elif hasattr(rhs, 'query'):
142			yield rhs.query
143			elif rhs_class in UNCACHABLE_FUNCS:
144			raise UncachableQuery
145
146
147			def is_cachable(table):
148			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
149			if whitelist and table not in whitelist:
150			return False
151			return table not in cachalot_settings.CACHALOT_UNCACHABLE_TABLES
152
153
154			def are_all_cachable(tables):
155			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
156			if whitelist and not tables.issubset(whitelist):
157			return False
158			return tables.isdisjoint(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
159
160
161			def filter_cachable(tables):
162			whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
163			tables = tables.difference(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
164			if whitelist:
165			return tables.intersection(whitelist)
166			return tables
167
168
169			def _get_tables(db_alias, query):
170			if query.select_for_update or (
171			'?' in query.order_by
172			and not cachalot_settings.CACHALOT_CACHE_RANDOM):
173			raise UncachableQuery
174
175			try:
176			if query.extra_select or getattr(query, 'subquery', False):
177			raise IsRawQuery
178			tables = set(query.table_map)
179			tables.add(query.get_meta().db_table)
180			for subquery in _find_subqueries(query.where.children):
181			tables.update(_get_tables(db_alias, subquery))
182			except IsRawQuery:
183			sql = query.get_compiler(db_alias).as_sql()[0].lower()
184			tables = _get_tables_from_sql(connections[db_alias], sql)
185
186			if not are_all_cachable(tables):
187			raise UncachableQuery
188			return tables
189
190
191			def _get_table_cache_keys(compiler):
192			db_alias = compiler.using
193			return [_get_table_cache_key(db_alias, t)
194			for t in _get_tables(db_alias, compiler.query)]
195
196
197			def _invalidate_tables(cache, db_alias, tables):
198			tables = filter_cachable(set(tables))
199			if not tables:
200			return
201			now = time()
202			cache.set_many(
203			{_get_table_cache_key(db_alias, t): now for t in tables},
204			cachalot_settings.CACHALOT_TIMEOUT)
205
206			if isinstance(cache, AtomicCache):
207			cache.to_be_invalidated.update(tables)
208

noripyt / django-cachalot

Push — master ( d0ee58...452210 )

_find_subqueries() F

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