Add caching for imagekit (#1472)

main/cache/backends.py

@@ -0,0 +1,46 @@
+from django.core.cache import caches
+from django.core.cache.backends.base import BaseCache
+
+
+class FallbackCache(BaseCache):
+    """
+    Cache backend that supports a list of fallback caches
+
+    This cache backend sets the value in all caches and reads from caches in order
+    until it gets a hit. You'll typically want to configure this with a list of
+    caches with increasing durability.
+
+    For example in settings.py:
+
+    CACHES = {
+        "fallback": {
+            "BACKEND": "main.cache.backends.FallbackCache",
+            "LOCATION": ["in-memory", "redis", "database"],
+        },
+        ...
+    }
+    """
+
+    def __init__(self, cache_names, params):
+        super().__init__(params)
+        self._cache_names = cache_names
+
+    def get(self, key, default=None, version=None):
+        """Get the value from the caches in order"""
+        for cache_name in self._cache_names:
+            cache = caches[cache_name]
+            result = cache.get(key, default=default, version=version)
+            if result:
+                return result
+        return None
+
+    def set(self, key, value, timeout=None, version=None):
+        """Set a value in the caches"""
+        for cache_name in self._cache_names:
+            cache = caches[cache_name]
+            cache.set(
+                key,
+                value,
+                timeout=timeout,
+                version=version,
+            )

main/cache/backends_test.py

@@ -0,0 +1,44 @@
+from django.core.cache.backends.base import BaseCache
+
+from main.cache.backends import FallbackCache
+
+
+def test_fallback_cache_get(mocker, settings):
+    """Test that get() on the fallback cache works correctly"""
+    mock_cache_1 = mocker.Mock(spec=BaseCache)
+    mock_cache_1.get.return_value = 12345
+    mock_cache_2 = mocker.Mock(spec=BaseCache)
+    mock_cache_2.get.return_value = 67890
+
+    mocker.patch.dict(
+        "main.cache.backends.caches", {"dummy1": mock_cache_1, "dummy2": mock_cache_2}
+    )
+
+    cache = FallbackCache(["dummy1", "dummy2"], {})
+
+    assert cache.get("key", default="default", version=1) == 12345
+
+    mock_cache_1.get.return_value = None
+
+    assert cache.get("key", default="default", version=1) == 67890
+
+    mock_cache_2.get.return_value = None
+
+    assert cache.get("key", default="default", version=1) is None
+
+
+def test_fallback_cache_set(mocker, settings):
+    """Test that set() on the fallback cache works correctly"""
+    mock_cache_1 = mocker.Mock(spec=BaseCache)
+    mock_cache_2 = mocker.Mock(spec=BaseCache)
+
+    mocker.patch.dict(
+        "main.cache.backends.caches", {"dummy1": mock_cache_1, "dummy2": mock_cache_2}
+    )
+
+    cache = FallbackCache(["dummy1", "dummy2"], {})
+
+    cache.set("key", "value", timeout=600, version=1)
+
+    mock_cache_1.set.assert_called_once_with("key", "value", timeout=600, version=1)
+    mock_cache_2.set.assert_called_once_with("key", "value", timeout=600, version=1)

main/settings.py

@@ -509,6 +509,7 @@
 
 IMAGEKIT_SPEC_CACHEFILE_NAMER = "imagekit.cachefiles.namers.source_name_dot_hash"
 IMAGEKIT_CACHEFILE_DIR = get_string("IMAGEKIT_CACHEFILE_DIR", "")
+IMAGEKIT_CACHE_BACKEND = "imagekit"
 
 
 # django cache back-ends
@@ -532,6 +533,24 @@
         "LOCATION": CELERY_BROKER_URL,  # noqa: F405
         "OPTIONS": {"CLIENT_CLASS": "django_redis.client.DefaultClient"},
     },
+    # imagekit caching
+    "imagekit": {
+        "BACKEND": "main.cache.backends.FallbackCache",
+        "LOCATION": [
+            "imagekit_in_memory",
+            "imagekit_db",
+        ],
+    },
+    "imagekit_in_memory": {
+        "BACKEND": "django.core.cache.backends.locmem.LocMemCache",
+        "LOCATION": "imagekit_in_memory_cache",
+        "TIMEOUT": None,
+    },
+    "imagekit_db": {
+        "BACKEND": "django.core.cache.backends.db.DatabaseCache",
+        "LOCATION": "imagekit_cache",
+        "TIMEOUT": None,
+    },
 }
 
 # OpenSearch

scripts/run-django-dev.sh

@@ -4,6 +4,7 @@
 
 python3 manage.py collectstatic --noinput --clear
 python3 manage.py migrate --noinput
+python3 manage.py createcachetable
 RUN_DATA_MIGRATIONS=true python3 manage.py migrate --noinput
 
 # load required fixtures on development by default