Simplify custom serializer interface

README.rst

@@ -76,10 +76,6 @@ Setup redis connection and enable caching for desired models:
     # should be compatible or subclass cacheops.redis.CacheopsRedis
     CACHEOPS_CLIENT_CLASS = 'your.redis.ClientClass'
 
-    # To use your own serializer class,
-    # should be compatible or subclass cacheops.serializers.PickleSerializer
-    CACHEOPS_SERIALIZER = 'your.serializers.ClientClass'
-
     CACHEOPS = {
         # Automatically cache any User.objects.get() calls for 15 minutes
         # This also includes .first() and .last() calls,
@@ -666,44 +662,25 @@ A ``query`` object passed to callback also enables reflection on used databases
 **NOTE:** prefix is not used in simple and file cache. This might change in future cacheops.
 
 
-Pickle serializer
------------------
+Custom serialization
+--------------------
 
-Cacheops by default using serializer build on ``pickle`` lib:
+Cacheops uses ``pickle`` by default, employing it's default protocol. But you can specify your own
+it might be any module or a class having `.dumps()` and `.loads()` functions. For example you can use ``dill`` instead, which can serialize more things like anonymous functions:
 
 .. code:: python
 
-    import pickle
-
-    class PickleSerializer:
-        # properties
-        PickleError = pickle.PickleError
-        HIGHEST_PROTOCOL = pickle.HIGHEST_PROTOCOL
-
-        # methods
-        dumps = pickle.dumps
-        loads = pickle.loads
-
-You can overwrite it to any own pickle serializer in two step (for ``dill`` lib):
+    CACHEOPS_SERIALIZER = 'dill'
 
-* setup in settings ``CACHEOPS_SERIALIZER = 'your.serializers.DillSerializer'``
-* write own serializer like this:
+One less obvious use is to fix pickle protocol, to use cacheops cache across python versions:
 
 .. code:: python
 
-    import dill
-
-    class DillSerializer:
-        # properties
-        PickleError = dill.PicklingError
-        HIGHEST_PROTOCOL = dill.HIGHEST_PROTOCOL
-
-        # methods
-        dumps = dill.dumps
-        loads = dill.loads
-
+    import pickle
 
-**NOTE:** this can be helpful on raises like: "AttributeError: Can't pickle local object 'curry.<locals>._curried'".
+    class CACHEOPS_SERIALIZER:
+        dumps = lambda data: pickle.dumps(data, 3)
+        loads = pickle.loads
 
 
 Using memory limit

cacheops/conf.py

@@ -1,9 +1,9 @@
+from importlib import import_module
 from funcy import memoize, merge
 
 from django.conf import settings as base_settings
 from django.core.exceptions import ImproperlyConfigured
 from django.core.signals import setting_changed
-from django.utils.module_loading import import_string
 
 
 ALL_OPS = {'get', 'fetch', 'count', 'aggregate', 'exists'}
@@ -23,7 +23,7 @@ class Defaults:
     #       and one should not filter by their equality anyway.
     CACHEOPS_SKIP_FIELDS = "FileField", "TextField", "BinaryField", "JSONField"
     CACHEOPS_LONG_DISJUNCTION = 8
-    CACHEOPS_SERIALIZER = 'cacheops.serializers.PickleSerializer'
+    CACHEOPS_SERIALIZER = 'pickle'
 
     FILE_CACHE_DIR = '/tmp/cacheops_file_cache'
     FILE_CACHE_TIMEOUT = 60*60*24*30
@@ -33,7 +33,7 @@ class Settings(object):
     def __getattr__(self, name):
         res = getattr(base_settings, name, getattr(Defaults, name))
         if name in ['CACHEOPS_PREFIX', 'CACHEOPS_SERIALIZER']:
-            res = res if callable(res) else import_string(res)
+            res = import_string(res) if isinstance(res, str) else res
 
         # Convert old list of classes to list of strings
         if name == 'CACHEOPS_SKIP_FIELDS':
@@ -47,6 +47,14 @@ def __getattr__(self, name):
 setting_changed.connect(lambda setting, **kw: settings.__dict__.pop(setting, None), weak=False)
 
 
+def import_string(path):
+    if "." in path:
+        module, attr = path.rsplit(".", 1)
+        return getattr(import_module(module), attr)
+    else:
+        return import_module(path)
+
+
 @memoize
 def prepare_profiles():
     """

cacheops/query.py

@@ -51,7 +51,7 @@ def cache_thing(prefix, cache_key, data, cond_dnfs, timeout, dbs=(), precall_key
     load_script('cache_thing', settings.CACHEOPS_LRU)(
         keys=[prefix, cache_key, precall_key],
         args=[
-            settings.CACHEOPS_SERIALIZER.dumps(data, -1),
+            settings.CACHEOPS_SERIALIZER.dumps(data),
             json.dumps(cond_dnfs, default=str),
             timeout
         ]

cacheops/simple.py

@@ -91,7 +91,7 @@ def get(self, cache_key):
 
     @handle_connection_failure
     def set(self, cache_key, data, timeout=None):
-        pickled_data = settings.CACHEOPS_SERIALIZER.dumps(data, -1)
+        pickled_data = settings.CACHEOPS_SERIALIZER.dumps(data)
         if timeout is not None:
             self.conn.setex(cache_key, timeout, pickled_data)
         else:
@@ -133,7 +133,7 @@ def get(self, key):
 
             with open(filename, 'rb') as f:
                 return settings.CACHEOPS_SERIALIZER.load(f)
-        except (IOError, OSError, EOFError, settings.CACHEOPS_SERIALIZER.PickleError):
+        except (IOError, OSError, EOFError):
             raise CacheMiss
 
     def set(self, key, data, timeout=None):
@@ -150,8 +150,7 @@ def set(self, key, data, timeout=None):
             # Use open with exclusive rights to prevent data corruption
             f = os.open(filename, os.O_EXCL | os.O_WRONLY | os.O_CREAT)
             try:
-                os.write(f, settings.CACHEOPS_SERIALIZER.dumps(
-                    data, settings.CACHEOPS_SERIALIZER.HIGHEST_PROTOCOL))
+                os.write(f, settings.CACHEOPS_SERIALIZER.dumps(data))
             finally:
                 os.close(f)
 

requirements-test.txt

@@ -4,3 +4,4 @@ funcy>=1.8,<2.0
 six>=1.4.0
 before_after==1.0.0
 jinja2>=2.10
+dill

tests/bench.py

@@ -7,10 +7,10 @@
 
 
 posts = list(Post.objects.cache().all())
-posts_pickle = settings.CACHEOPS_SERIALIZER.dumps(posts, -1)
+posts_pickle = settings.CACHEOPS_SERIALIZER.dumps(posts)
 
 def do_pickle():
-    settings.CACHEOPS_SERIALIZER.dumps(posts, -1)
+    settings.CACHEOPS_SERIALIZER.dumps(posts)
 
 def do_unpickle():
     settings.CACHEOPS_SERIALIZER.loads(posts_pickle)

tests/tests.py

@@ -649,7 +649,7 @@ def test_385(self):
 
         invalidate_model(Client)
 
-        with override_settings(CACHEOPS_SERIALIZER='tests.serializers.DillSerializer'):
+        with override_settings(CACHEOPS_SERIALIZER='dill'):
             with self.assertNumQueries(1):
                 Client.objects.filter(name='Client Name').cache().first()
                 Client.objects.filter(name='Client Name').cache().first()

tox.ini

@@ -36,6 +36,7 @@ deps =
     pypy3: psycopg2cffi>=2.7.6
     before_after==1.0.0
     jinja2>=2.10
+    dill
 commands =
     ./run_tests.py []
     env CACHEOPS_PREFIX=1 ./run_tests.py []