# coding: utf-8
from __future__ import unicode_literals
from django.apps import apps
from django.conf import settings
from django.db import connections
from django.utils.six import string_types
from .cache import cachalot_caches
from .settings import cachalot_settings
from .signals import post_invalidation
from .transaction import AtomicCache
from .utils import _invalidate_tables
__all__ = ('invalidate', 'get_last_invalidation')
def _cache_db_tables_iterator(tables, cache_alias, db_alias):
no_tables = not tables
cache_aliases = settings.CACHES if cache_alias is None else (cache_alias,)
db_aliases = settings.DATABASES if db_alias is None else (db_alias,)
for db_alias in db_aliases:
if no_tables:
tables = connections[db_alias].introspection.table_names()
if tables:
for cache_alias in cache_aliases:
yield cache_alias, db_alias, tables
def _get_tables(tables_or_models):
return [(apps.get_model(o)._meta.db_table if '.' in o else o)
if isinstance(o, string_types) else o._meta.db_table
for o in tables_or_models]
[docs]def invalidate(*tables_or_models, **kwargs):
"""
Clears what was cached by django-cachalot implying one or more SQL tables
or models from ``tables_or_models``.
If ``tables_or_models`` is not specified, all tables found in the database
(including those outside Django) are invalidated.
If ``cache_alias`` is specified, it only clears the SQL queries stored
on this cache, otherwise queries from all caches are cleared.
If ``db_alias`` is specified, it only clears the SQL queries executed
on this database, otherwise queries from all databases are cleared.
:arg tables_or_models: SQL tables names, models or models lookups
(or a combination)
:type tables_or_models: tuple of strings or models
:arg cache_alias: Alias from the Django ``CACHES`` setting
:type cache_alias: string or NoneType
:arg db_alias: Alias from the Django ``DATABASES`` setting
:type db_alias: string or NoneType
:returns: Nothing
:rtype: NoneType
"""
# TODO: Replace with positional arguments when we drop Python 2 support.
cache_alias = kwargs.pop('cache_alias', None)
db_alias = kwargs.pop('db_alias', None)
for k in kwargs:
raise TypeError(
"invalidate() got an unexpected keyword argument '%s'" % k)
send_signal = False
invalidated = set()
for cache_alias, db_alias, tables in _cache_db_tables_iterator(
_get_tables(tables_or_models), cache_alias, db_alias):
cache = cachalot_caches.get_cache(cache_alias, db_alias)
if not isinstance(cache, AtomicCache):
send_signal = True
_invalidate_tables(cache, db_alias, tables)
invalidated.update(tables)
if send_signal:
for table in invalidated:
post_invalidation.send(table, db_alias=db_alias)
[docs]def get_last_invalidation(*tables_or_models, **kwargs):
"""
Returns the timestamp of the most recent invalidation of the given
``tables_or_models``. If ``tables_or_models`` is not specified,
all tables found in the database (including those outside Django) are used.
If ``cache_alias`` is specified, it only fetches invalidations
in this cache, otherwise invalidations in all caches are fetched.
If ``db_alias`` is specified, it only fetches invalidations
for this database, otherwise invalidations for all databases are fetched.
:arg tables_or_models: SQL tables names, models or models lookups
(or a combination)
:type tables_or_models: tuple of strings or models
:arg cache_alias: Alias from the Django ``CACHES`` setting
:type cache_alias: string or NoneType
:arg db_alias: Alias from the Django ``DATABASES`` setting
:type db_alias: string or NoneType
:returns: The timestamp of the most recent invalidation
:rtype: float
"""
# TODO: Replace with positional arguments when we drop Python 2 support.
cache_alias = kwargs.pop('cache_alias', None)
db_alias = kwargs.pop('db_alias', None)
for k in kwargs:
raise TypeError("get_last_invalidation() got an unexpected "
"keyword argument '%s'" % k)
last_invalidation = 0.0
for cache_alias, db_alias, tables in _cache_db_tables_iterator(
_get_tables(tables_or_models), cache_alias, db_alias):
get_table_cache_key = cachalot_settings.CACHALOT_TABLE_KEYGEN
table_cache_keys = [get_table_cache_key(db_alias, t) for t in tables]
invalidations = cachalot_caches.get_cache(
cache_alias, db_alias).get_many(table_cache_keys).values()
if invalidations:
current_last_invalidation = max(invalidations)
if current_last_invalidation > last_invalidation:
last_invalidation = current_last_invalidation
return last_invalidation