Merge pull request #72 from AltSchool/feature/global-serializer-cache

global serializer cache

.isort.cfg

@@ -1,2 +1,3 @@
 [settings]
 multi_line_output=3
+known_third_party=django,pylru,rest_framework

dynamic_rest/conf.py

@@ -32,7 +32,11 @@
 
     # PAGE_SIZE_QUERY_PARAM: global setting for the page size query parameter.
     # Can be overriden at the viewset level.
-    'PAGE_SIZE_QUERY_PARAM': 'per_page'
+    'PAGE_SIZE_QUERY_PARAM': 'per_page',
+
+    # SERIALIZER_CACHE_MAX_COUNT: maximum number of serializers to cache
+    'SERIALIZER_CACHE_MAX_COUNT': 1000,
+
 }
 
 

dynamic_rest/fields.py

@@ -3,6 +3,7 @@
 import importlib
 import pickle
 
+import pylru
 from django.utils import six
 from django.utils.functional import cached_property
 from rest_framework import fields
@@ -13,6 +14,10 @@
 from dynamic_rest.conf import settings
 from dynamic_rest.meta import is_field_remote
 
+serializer_cache = pylru.lrucache(
+    settings.SERIALIZER_CACHE_MAX_COUNT
+)
+
 
 class DynamicField(fields.Field):
 
@@ -164,18 +169,10 @@ def root_serializer(self):
     def _get_cached_serializer(self, args, init_args):
         enabled = settings.ENABLE_SERIALIZER_CACHE
 
-        root = self.root_serializer
-        if not root or not self.field_name or not enabled:
+        if not self.parent or not self.field_name or not enabled:
             # Not enough info to use cache.
             return self.serializer_class(*args, **init_args)
 
-        if not hasattr(root, '_descendant_serializer_cache'):
-            # Initialize dict to use as cache on root serializer.
-            # Arguably this is a Serializer concern, but we'll do it
-            # here so it's agnostic to the exact type of the root
-            # serializer (i.e. it could be a DRF serializer).
-            root._descendant_serializer_cache = {}
-
         key_dict = {
             'parent': self.parent.__class__.__name__,
             'field': self.field_name,
@@ -184,14 +181,14 @@ def _get_cached_serializer(self, args, init_args):
         }
         cache_key = hash(pickle.dumps(key_dict))
 
-        if cache_key not in root._descendant_serializer_cache:
+        if cache_key not in serializer_cache:
             szr = self.serializer_class(
                 *args,
                 **init_args
             )
-            root._descendant_serializer_cache[cache_key] = szr
+            serializer_cache[cache_key] = szr
 
-        return root._descendant_serializer_cache[cache_key]
+        return serializer_cache[cache_key]
 
     def _get_request_fields_from_parent(self):
         """Get request fields from the parent serializer."""

install_requires.txt

@@ -1,2 +1,3 @@
 Django>=1.7,<=1.9
 djangorestframework>=3.1.0,<=3.3.0
+pylru==1.0.9

tests/test_serializers.py

@@ -647,18 +647,18 @@ def test_same_serializer_class_different_fields(self):
             )
         )
 
-    def test_different_roots(self):
+    def test_different_roots_share_cache(self):
         serializer2 = CatSerializer(
             request_fields={'home': {}, 'backup_home': {}}
         )
 
         home1 = self.serializer.fields['home']
         home2 = serializer2.fields['home']
 
-        self.assertIsNot(
+        self.assertIs(
             home1.serializer,
             home2.serializer,
-            'Different root serializers should yield different instances.'
+            'Different root serializers should share instances.'
         )
 
     def test_root_serializer_cycle_busting(self):