mirror of
https://github.com/Hopiu/django-cachalot.git
synced 2026-05-09 13:14:44 +00:00
144 lines
4.4 KiB
Python
144 lines
4.4 KiB
Python
# coding: utf-8
|
||
|
||
from __future__ import unicode_literals
|
||
from collections import Iterable
|
||
import re
|
||
|
||
from django.core.cache import cache
|
||
from django.db.models.query import EmptyResultSet
|
||
from django.db.models.sql.compiler import (
|
||
SQLCompiler, SQLAggregateCompiler, SQLDateCompiler, SQLDateTimeCompiler,
|
||
SQLInsertCompiler, SQLUpdateCompiler, SQLDeleteCompiler)
|
||
from django.db.models.sql.where import ExtraWhere
|
||
|
||
|
||
COMPILERS = (SQLCompiler,
|
||
SQLAggregateCompiler, SQLDateCompiler, SQLDateTimeCompiler,
|
||
SQLInsertCompiler, SQLUpdateCompiler, SQLDeleteCompiler)
|
||
WRITE_COMPILERS = (SQLInsertCompiler, SQLUpdateCompiler, SQLDeleteCompiler)
|
||
READ_COMPILERS = [c for c in COMPILERS if c not in WRITE_COMPILERS]
|
||
|
||
|
||
PATCHED = False
|
||
MISS_VALUE = '[[The cache key was missed]]'
|
||
|
||
|
||
def _get_tables(query):
|
||
"""
|
||
Returns a ``set`` of all database table names used by ``query``.
|
||
"""
|
||
tables = set(query.tables)
|
||
tables.add(query.model._meta.db_table)
|
||
return tables
|
||
|
||
|
||
def _get_tables_cache_keys(query):
|
||
return ['%s_queries' % t for t in _get_tables(query)]
|
||
|
||
|
||
def _update_tables_queries(query, cache_key):
|
||
tables_cache_keys = _get_tables_cache_keys(query)
|
||
tables_queries = cache.get_many(tables_cache_keys)
|
||
for k in tables_cache_keys:
|
||
queries = tables_queries.get(k, [])
|
||
queries.append(cache_key)
|
||
tables_queries[k] = queries
|
||
cache.set_many(tables_queries)
|
||
|
||
|
||
def _invalidate_tables(query):
|
||
tables_cache_keys = _get_tables_cache_keys(query)
|
||
tables_queries = cache.get_many(tables_cache_keys)
|
||
queries = []
|
||
for k in tables_cache_keys:
|
||
queries.extend(tables_queries.get(k, []))
|
||
cache.delete_many(queries)
|
||
cache.delete_many(tables_cache_keys)
|
||
|
||
|
||
COLUMN_RE = re.compile(r'^"(?P<table>[\w_]+)"\."(?P<column>[\w_]+)"$')
|
||
|
||
|
||
def _has_extra_select_or_where(query):
|
||
"""
|
||
Returns True if ``query`` contains a ``QuerySet.extra`` with ``select``
|
||
or ``where`` arguments.
|
||
|
||
We also have to check for ``prefetch_related``, as it internally uses a
|
||
``QuerySet.extra(select={'_prefetch_related_val_…': '"table"."column"'})``.
|
||
|
||
For more details on how prefetch_related uses ``QuerySet.extra``, see:
|
||
https://github.com/django/django/blob/1.6.7/django/db/models/fields/related.py#L553-L577
|
||
"""
|
||
|
||
# Checks if there’s an extra where
|
||
if any(isinstance(child, ExtraWhere) for child in query.where.children):
|
||
return True
|
||
|
||
# Checks if there’s an extra select
|
||
if query.extra_select and query.extra_select_mask is None:
|
||
tables = _get_tables(query)
|
||
# Checks if extra subqueries are something else than one or several
|
||
# ``prefetch_related``.
|
||
for subquery, params in query.extra_select.values():
|
||
match = COLUMN_RE.match(subquery)
|
||
return match is None or match.group('table') not in tables
|
||
return False
|
||
|
||
|
||
def _monkey_patch_orm_read():
|
||
def patch_execute_sql(method):
|
||
def inner(compiler, *args, **kwargs):
|
||
if isinstance(compiler, WRITE_COMPILERS):
|
||
return method(compiler, *args, **kwargs)
|
||
|
||
query = compiler.query
|
||
|
||
if _has_extra_select_or_where(query):
|
||
return method(compiler, *args, **kwargs)
|
||
|
||
try:
|
||
cache_key = compiler.as_sql()
|
||
except EmptyResultSet:
|
||
return method(compiler, *args, **kwargs)
|
||
|
||
result = cache.get(cache_key, MISS_VALUE)
|
||
|
||
if result == MISS_VALUE:
|
||
result = method(compiler, *args, **kwargs)
|
||
if isinstance(result, Iterable) \
|
||
and not isinstance(result, (tuple, list)):
|
||
result = list(result)
|
||
|
||
_update_tables_queries(query, cache_key)
|
||
|
||
cache.set(cache_key, result)
|
||
|
||
return result
|
||
|
||
return inner
|
||
|
||
for compiler in READ_COMPILERS:
|
||
compiler.execute_sql = patch_execute_sql(compiler.execute_sql)
|
||
|
||
|
||
def _monkey_patch_orm_write():
|
||
def patch_execute_sql(method):
|
||
def inner(compiler, *args, **kwargs):
|
||
_invalidate_tables(compiler.query)
|
||
return method(compiler, *args, **kwargs)
|
||
return inner
|
||
|
||
for compiler in WRITE_COMPILERS:
|
||
compiler.execute_sql = patch_execute_sql(compiler.execute_sql)
|
||
|
||
|
||
def monkey_patch_orm():
|
||
global PATCHED
|
||
_monkey_patch_orm_write()
|
||
_monkey_patch_orm_read()
|
||
PATCHED = True
|
||
|
||
|
||
def is_patched():
|
||
return PATCHED
|