From cae44c7ed9dfdafabc36459efeda54ca17a759d6 Mon Sep 17 00:00:00 2001
From: Ryo Chijiiwa <ryochiji@gmail.com>
Date: Fri, 5 Feb 2016 23:32:11 -0800
Subject: [PATCH] Revert "global serializer cache"

---
 .isort.cfg                |  1 -
 dynamic_rest/conf.py      |  6 +-----
 dynamic_rest/fields.py    | 21 ++++++++++++---------
 install_requires.txt      |  1 -
 tests/test_serializers.py |  6 +++---
 5 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/.isort.cfg b/.isort.cfg
index 7f3c82de..efc0bdb0 100644
--- a/.isort.cfg
+++ b/.isort.cfg
@@ -1,3 +1,2 @@
 [settings]
 multi_line_output=3
-known_third_party=django,pylru,rest_framework
diff --git a/dynamic_rest/conf.py b/dynamic_rest/conf.py
index 4ad438fa..b5267f5c 100644
--- a/dynamic_rest/conf.py
+++ b/dynamic_rest/conf.py
@@ -32,11 +32,7 @@
 
     # 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',
-
-    # SERIALIZER_CACHE_MAX_COUNT: maximum number of serializers to cache
-    'SERIALIZER_CACHE_MAX_COUNT': 1000,
-
+    'PAGE_SIZE_QUERY_PARAM': 'per_page'
 }
 
 
diff --git a/dynamic_rest/fields.py b/dynamic_rest/fields.py
index 204ae4ca..d2361ad2 100644
--- a/dynamic_rest/fields.py
+++ b/dynamic_rest/fields.py
@@ -3,7 +3,6 @@
 import importlib
 import pickle
 
-import pylru
 from django.utils import six
 from django.utils.functional import cached_property
 from rest_framework import fields
@@ -14,10 +13,6 @@
 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):
 
@@ -169,10 +164,18 @@ def root_serializer(self):
     def _get_cached_serializer(self, args, init_args):
         enabled = settings.ENABLE_SERIALIZER_CACHE
 
-        if not self.parent or not self.field_name or not enabled:
+        root = self.root_serializer
+        if not root 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,
@@ -181,14 +184,14 @@ def _get_cached_serializer(self, args, init_args):
         }
         cache_key = hash(pickle.dumps(key_dict))
 
-        if cache_key not in serializer_cache:
+        if cache_key not in root._descendant_serializer_cache:
             szr = self.serializer_class(
                 *args,
                 **init_args
             )
-            serializer_cache[cache_key] = szr
+            root._descendant_serializer_cache[cache_key] = szr
 
-        return serializer_cache[cache_key]
+        return root._descendant_serializer_cache[cache_key]
 
     def _get_request_fields_from_parent(self):
         """Get request fields from the parent serializer."""
diff --git a/install_requires.txt b/install_requires.txt
index 130a4857..94fb3bae 100644
--- a/install_requires.txt
+++ b/install_requires.txt
@@ -1,3 +1,2 @@
 Django>=1.7,<=1.9
 djangorestframework>=3.1.0,<=3.3.0
-pylru==1.0.9
diff --git a/tests/test_serializers.py b/tests/test_serializers.py
index 4fb00077..f2d13b36 100644
--- a/tests/test_serializers.py
+++ b/tests/test_serializers.py
@@ -647,7 +647,7 @@ def test_same_serializer_class_different_fields(self):
             )
         )
 
-    def test_different_roots_share_cache(self):
+    def test_different_roots(self):
         serializer2 = CatSerializer(
             request_fields={'home': {}, 'backup_home': {}}
         )
@@ -655,10 +655,10 @@ def test_different_roots_share_cache(self):
         home1 = self.serializer.fields['home']
         home2 = serializer2.fields['home']
 
-        self.assertIs(
+        self.assertIsNot(
             home1.serializer,
             home2.serializer,
-            'Different root serializers should share instances.'
+            'Different root serializers should yield different instances.'
         )
 
     def test_root_serializer_cycle_busting(self):