Add the Store API and initial documentation.

debug_toolbar/settings.py

@@ -42,6 +42,7 @@
     "SQL_WARNING_THRESHOLD": 500,  # milliseconds
     "OBSERVE_REQUEST_CALLBACK": "debug_toolbar.toolbar.observe_request",
     "TOOLBAR_LANGUAGE": None,
+    "TOOLBAR_STORE_CLASS": "debug_toolbar.store.MemoryStore",
 }
 
 

debug_toolbar/store.py

@@ -0,0 +1,120 @@
+import contextlib
+import json
+from collections import defaultdict, deque
+from typing import Any, Dict, Iterable
+
+from django.core.serializers.json import DjangoJSONEncoder
+from django.utils.module_loading import import_string
+
+from debug_toolbar import settings as dt_settings
+
+
+def serialize(data: Any) -> str:
+    # If this starts throwing an exceptions, consider
+    # Subclassing DjangoJSONEncoder and using force_str to
+    # make it JSON serializable.
+    return json.dumps(data, cls=DjangoJSONEncoder)
+
+
+def deserialize(data: str) -> Any:
+    return json.loads(data)
+
+
+class BaseStore:
+    _config = dt_settings.get_config().copy()
+
+    @classmethod
+    def request_ids(cls) -> Iterable:
+        """The stored request ids"""
+        raise NotImplementedError
+
+    @classmethod
+    def exists(cls, request_id: str) -> bool:
+        """Does the given request_id exist in the store"""
+        raise NotImplementedError
+
+    @classmethod
+    def set(cls, request_id: str):
+        """Set a request_id in the store"""
+        raise NotImplementedError
+
+    @classmethod
+    def clear(cls):
+        """Remove all requests from the request store"""
+        raise NotImplementedError
+
+    @classmethod
+    def delete(cls, request_id: str):
+        """Delete the store for the given request_id"""
+        raise NotImplementedError
+
+    @classmethod
+    def save_panel(cls, request_id: str, panel_id: str, data: Any = None):
+        """Save the panel data for the given request_id"""
+        raise NotImplementedError
+
+    @classmethod
+    def panel(cls, request_id: str, panel_id: str) -> Any:
+        """Fetch the panel data for the given request_id"""
+        raise NotImplementedError
+
+
+class MemoryStore(BaseStore):
+    # ids is the collection of storage ids that have been used.
+    # Use a dequeue to support O(1) appends and pops
+    # from either direction.
+    _request_ids: deque = deque()
+    _request_store: Dict[str, Dict] = defaultdict(dict)
+
+    @classmethod
+    def request_ids(cls) -> Iterable:
+        """The stored request ids"""
+        return cls._request_ids
+
+    @classmethod
+    def exists(cls, request_id: str) -> bool:
+        """Does the given request_id exist in the request store"""
+        return request_id in cls._request_ids
+
+    @classmethod
+    def set(cls, request_id: str):
+        """Set a request_id in the request store"""
+        if request_id not in cls._request_ids:
+            cls._request_ids.append(request_id)
+        for _ in range(len(cls._request_ids) - cls._config["RESULTS_CACHE_SIZE"]):
+            removed_id = cls._request_ids.popleft()
+            cls._request_store.pop(removed_id, None)
+
+    @classmethod
+    def clear(cls):
+        """Remove all requests from the request store"""
+        cls._request_ids.clear()
+        cls._request_store.clear()
+
+    @classmethod
+    def delete(cls, request_id: str):
+        """Delete the stored request for the given request_id"""
+        cls._request_store.pop(request_id, None)
+        # Suppress when request_id doesn't exist in the collection of ids.
+        with contextlib.suppress(ValueError):
+            cls._request_ids.remove(request_id)
+
+    @classmethod
+    def save_panel(cls, request_id: str, panel_id: str, data: Any = None):
+        """Save the panel data for the given request_id"""
+        cls.set(request_id)
+        cls._request_store[request_id][panel_id] = serialize(data)
+
+    @classmethod
+    def panel(cls, request_id: str, panel_id: str) -> Any:
+        """Fetch the panel data for the given request_id"""
+        try:
+            data = cls._request_store[request_id][panel_id]
+        except KeyError:
+            return {}
+        else:
+            return deserialize(data)
+
+
+def get_store():
+    return import_string(dt_settings.get_config()["TOOLBAR_STORE_CLASS"])

docs/changes.rst

@@ -9,10 +9,12 @@ Pending
   <https://beta.ruff.rs/>`__.
 * Converted cookie keys to lowercase. Fixed the ``samesite`` argument to
   ``djdt.cookie.set``.
+* Defines the ``BaseStore`` interface for request storage mechanisms.
+* Added the setting ``TOOLBAR_STORE_CLASS`` to configure the request
+  storage mechanism. Defaults to ``debug_toolbar.store.MemoryStore``.
 
 4.1.0 (2023-05-15)
 ------------------
-
 * Improved SQL statement formatting performance.  Additionally, fixed the
   indentation of ``CASE`` statements and stopped simplifying ``.count()``
   queries.

docs/configuration.rst

@@ -150,6 +150,15 @@ Toolbar options
   the request doesn't originate from the toolbar itself, EG that
   ``is_toolbar_request`` is false for a given request.
 
+.. _TOOLBAR_STORE_CLASS:
+
+* ``TOOLBAR_STORE_CLASS``
+
+  Default: ``"debug_toolbar.store.MemoryStore"``
+
+  The path to the class to be used for storing the toolbar's data per request.
+
+
 .. _TOOLBAR_LANGUAGE:
 
 * ``TOOLBAR_LANGUAGE``

tests/test_store.py

@@ -0,0 +1,114 @@
+from django.test import TestCase
+from django.test.utils import override_settings
+
+from debug_toolbar import store
+
+
+class SerializationTestCase(TestCase):
+    def test_serialize(self):
+        self.assertEqual(
+            store.serialize({"hello": {"foo": "bar"}}),
+            '{"hello": {"foo": "bar"}}',
+        )
+
+    def test_deserialize(self):
+        self.assertEqual(
+            store.deserialize('{"hello": {"foo": "bar"}}'),
+            {"hello": {"foo": "bar"}},
+        )
+
+
+class BaseStoreTestCase(TestCase):
+    def test_methods_are_not_implemented(self):
+        # Find all the non-private and dunder class methods
+        methods = [
+            member for member in vars(store.BaseStore) if not member.startswith("_")
+        ]
+        self.assertEqual(len(methods), 7)
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.request_ids()
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.exists("")
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.set("")
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.clear()
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.delete("")
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.save_panel("", "", None)
+        with self.assertRaises(NotImplementedError):
+            store.BaseStore.panel("", "")
+
+
+class MemoryStoreTestCase(TestCase):
+    @classmethod
+    def setUpTestData(cls) -> None:
+        cls.store = store.MemoryStore
+
+    def tearDown(self) -> None:
+        self.store.clear()
+
+    def test_ids(self):
+        self.store.set("foo")
+        self.store.set("bar")
+        self.assertEqual(list(self.store.request_ids()), ["foo", "bar"])
+
+    def test_exists(self):
+        self.assertFalse(self.store.exists("missing"))
+        self.store.set("exists")
+        self.assertTrue(self.store.exists("exists"))
+
+    def test_set(self):
+        self.store.set("foo")
+        self.assertEqual(list(self.store.request_ids()), ["foo"])
+
+    def test_set_max_size(self):
+        existing = self.store._config["RESULTS_CACHE_SIZE"]
+        self.store._config["RESULTS_CACHE_SIZE"] = 1
+        self.store.save_panel("foo", "foo.panel", "foo.value")
+        self.store.save_panel("bar", "bar.panel", {"a": 1})
+        self.assertEqual(list(self.store.request_ids()), ["bar"])
+        self.assertEqual(self.store.panel("foo", "foo.panel"), {})
+        self.assertEqual(self.store.panel("bar", "bar.panel"), {"a": 1})
+        # Restore the existing config setting since this config is shared.
+        self.store._config["RESULTS_CACHE_SIZE"] = existing
+
+    def test_clear(self):
+        self.store.save_panel("bar", "bar.panel", {"a": 1})
+        self.store.clear()
+        self.assertEqual(list(self.store.request_ids()), [])
+        self.assertEqual(self.store.panel("bar", "bar.panel"), {})
+
+    def test_delete(self):
+        self.store.save_panel("bar", "bar.panel", {"a": 1})
+        self.store.delete("bar")
+        self.assertEqual(list(self.store.request_ids()), [])
+        self.assertEqual(self.store.panel("bar", "bar.panel"), {})
+        # Make sure it doesn't error
+        self.store.delete("bar")
+
+    def test_save_panel(self):
+        self.store.save_panel("bar", "bar.panel", {"a": 1})
+        self.assertEqual(list(self.store.request_ids()), ["bar"])
+        self.assertEqual(self.store.panel("bar", "bar.panel"), {"a": 1})
+
+    def test_panel(self):
+        self.assertEqual(self.store.panel("missing", "missing"), {})
+        self.store.save_panel("bar", "bar.panel", {"a": 1})
+        self.assertEqual(self.store.panel("bar", "bar.panel"), {"a": 1})
+
+
+class StubStore(store.BaseStore):
+    pass
+
+
+class GetStoreTestCase(TestCase):
+    def test_get_store(self):
+        self.assertIs(store.get_store(), store.MemoryStore)
+
+    @override_settings(
+        DEBUG_TOOLBAR_CONFIG={"TOOLBAR_STORE_CLASS": "tests.test_store.StubStore"}
+    )
+    def test_get_store_with_setting(self):
+        self.assertIs(store.get_store(), StubStore)