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101 lines
3 KiB
Python
101 lines
3 KiB
Python
# coding: utf-8
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from __future__ import unicode_literals
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from hashlib import md5
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from time import time
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import django
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from django.db import connections
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from django.db.models.sql.where import ExtraWhere
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if django.VERSION[:2] >= (1, 7):
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from django.utils.module_loading import import_string
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else:
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from django.utils.module_loading import import_by_path as import_string
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from .settings import cachalot_settings
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def _hash_cache_key(unicode_key):
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return md5(unicode_key.encode('utf-8')).hexdigest()
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def get_query_cache_key(compiler):
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"""
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Generates a cache key from a SQLCompiler.
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This cache key is specific to the SQL query and its context
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(which database is used). The same query in the same context
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(= the same database) must generate the same cache key.
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:arg compiler: A SQLCompiler that will generate the SQL query
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:type compiler: django.db.models.sql.compiler.SQLCompiler
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:return: A cache key
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:rtype: str or unicode
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"""
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sql, params = compiler.as_sql()
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return _hash_cache_key('%s:%s:%s' % (compiler.using, sql, params))
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def get_table_cache_key(db_alias, table):
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"""
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Generates a cache key from a SQL table.
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:arg db_alias: Alias of the used database
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:type db_alias: str or unicode
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:arg table: Name of the SQL table
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:type table: str or unicode
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:return: A cache key
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:rtype: str or unicode
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"""
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return _hash_cache_key('%s:%s' % (db_alias, table))
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def _get_query_cache_key(compiler):
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return import_string(cachalot_settings.CACHALOT_QUERY_KEYGEN)(compiler)
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def _get_table_cache_key(db_alias, table):
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return import_string(cachalot_settings.CACHALOT_TABLE_KEYGEN)(db_alias, table)
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def _get_tables_from_sql(connection, lowercased_sql):
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return [t for t in connection.introspection.django_table_names()
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if t in lowercased_sql]
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def _get_tables(compiler):
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"""
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Returns a ``set`` of all SQL table names used by ``compiler``.
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:arg compiler: A SQLCompiler that will generate the SQL query
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:type compiler: django.db.models.sql.compiler.SQLCompiler
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:return: All the SQL table names
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:rtype: set
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"""
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query = compiler.query
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tables = set(query.tables)
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tables.add(query.model._meta.db_table)
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if query.extra_select or any(isinstance(c, ExtraWhere)
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for c in query.where.children):
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sql, params = compiler.as_sql()
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connection = connections[compiler.using]
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full_sql = (sql % params)
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tables.update(_get_tables_from_sql(connection, full_sql))
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return tables
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def _get_table_cache_keys(compiler):
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using = compiler.using
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return [_get_table_cache_key(using, t) for t in _get_tables(compiler)]
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def _invalidate_table_cache_keys(cache, table_cache_keys):
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if hasattr(cache, 'to_be_invalidated'):
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cache.to_be_invalidated.update(table_cache_keys)
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now = time()
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cache.set_many(dict((k, now) for k in table_cache_keys), None)
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def _invalidate_tables(cache, compiler):
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table_cache_keys = _get_table_cache_keys(compiler)
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_invalidate_table_cache_keys(cache, table_cache_keys)
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