cache and asyncify web module loading

Author: rmorshea

README.md

@@ -103,6 +103,18 @@ You may configure additional options as well:
 ```python
 # the base URL for all IDOM-releated resources
 IDOM_BASE_URL: str = "_idom/"
+
+# Set cache size limit for loading JS files for IDOM.
+# Only applies when not using Django's caching framework (see below).
+IDOM_WEB_MODULE_LRU_CACHE_SIZE: int | None = None
+
+# Configure a cache for loading JS files
+CACHES = {
+  # Configure a cache for loading JS files for IDOM
+  "idom_web_modules": {"BACKEND": ...},
+  # If the above cache is not configured, then we'll use the "default" instead
+  "default": {"BACKEND": ...},
+}
 ```
 
 ## `urls.py`

noxfile.py

@@ -15,17 +15,12 @@
 
 
 @nox.session(reuse_venv=True)
-def test_app(session: Session) -> None:
+def manage(session: Session) -> None:
     """Run a manage.py command for tests/test_app"""
-    session.install("-r", "requirements.txt")
+    session.install("-r", "requirements/test-env.txt")
     session.install("idom[stable]")
     session.install("-e", ".")
     session.chdir("tests")
-
-    build_js_on_commands = ["runserver"]
-    if set(session.posargs).intersection(build_js_on_commands):
-        session.run("python", "manage.py", "build_js")
-
     session.run("python", "manage.py", *session.posargs)
 
 

src/django_idom/config.py

@@ -2,10 +2,26 @@
 
 from django.conf import settings
 from idom.core.proto import ComponentConstructor
+from django.core.cache import DEFAULT_CACHE_ALIAS
 
 
 IDOM_REGISTERED_COMPONENTS: Dict[str, ComponentConstructor] = {}
 
 IDOM_BASE_URL = getattr(settings, "IDOM_BASE_URL", "_idom/")
 IDOM_WEBSOCKET_URL = IDOM_BASE_URL + "websocket/"
 IDOM_WEB_MODULES_URL = IDOM_BASE_URL + "web_module/"
+
+_CACHES = getattr(settings, "CACHES", {})
+if _CACHES:
+    if "idom_web_modules" in getattr(settings, "CACHES", {}):
+        IDOM_WEB_MODULE_CACHE = "idom_web_modules"
+    else:
+        IDOM_WEB_MODULE_CACHE = DEFAULT_CACHE_ALIAS
+else:
+    IDOM_WEB_MODULE_CACHE = None
+
+
+# the LRU cache size for the route serving IDOM_WEB_MODULES_DIR files
+IDOM_WEB_MODULE_LRU_CACHE_SIZE = getattr(
+    settings, "IDOM_WEB_MODULE_LRU_CACHE_SIZE", None
+)

src/django_idom/templates/idom/view.html

@@ -1,7 +1,7 @@
 {% load static %}
 <div id="{{ idom_mount_uuid }}"></div>
 <script type="module" crossorigin="anonymous">
-  import { mountViewToElement } from "{% static 'js/idom.js' %}";
+  import { mountViewToElement } from "{% static 'js/django-idom-client.js' %}";
   const mountPoint = document.getElementById("{{ idom_mount_uuid }}");
   mountViewToElement(
     mountPoint,

src/django_idom/views.py

@@ -1,7 +1,44 @@
+import os
+import asyncio
+import functools
+
 from django.http import HttpRequest, HttpResponse
 from idom.config import IDOM_WED_MODULES_DIR
+from django.core.cache import caches
+
+from .config import IDOM_WEB_MODULE_CACHE, IDOM_WEB_MODULE_LRU_CACHE_SIZE
+
+
+if IDOM_WEB_MODULE_CACHE is None:
+
+    def async_lru_cache(*lru_cache_args, **lru_cache_kwargs):
+        def async_lru_cache_decorator(async_function):
+            @functools.lru_cache(*lru_cache_args, **lru_cache_kwargs)
+            def cached_async_function(*args, **kwargs):
+                coroutine = async_function(*args, **kwargs)
+                return asyncio.ensure_future(coroutine)
+
+            return cached_async_function
+
+        return async_lru_cache_decorator
+
+    @async_lru_cache(IDOM_WEB_MODULE_LRU_CACHE_SIZE)
+    async def web_modules_file(request: HttpRequest, file: str) -> HttpResponse:
+        file_path = IDOM_WED_MODULES_DIR.current.joinpath(*file.split("/"))
+        return HttpResponse(file_path.read_text(), content_type="text/javascript")
+
+
+else:
+    _web_module_cache = caches[IDOM_WEB_MODULE_CACHE]
+
+    async def web_modules_file(request: HttpRequest, file: str) -> HttpResponse:
+        file = IDOM_WED_MODULES_DIR.current.joinpath(*file.split("/")).absolute()
+        last_modified_time = os.stat(file).st_mtime
+        cache_key = f"{file}:{last_modified_time}"
 
+        response = _web_module_cache.get(cache_key)
+        if response is None:
+            response = HttpResponse(file.read_text(), content_type="text/javascript")
+            _web_module_cache.set(cache_key, response, timeout=None)
 
-def web_modules_file(request: HttpRequest, file: str) -> HttpResponse:
-    file_path = IDOM_WED_MODULES_DIR.current.joinpath(*file.split("/"))
-    return HttpResponse(file_path.read_text(), content_type="text/javascript")
+        return response

src/js/rollup.config.js

@@ -7,7 +7,7 @@ const { PRODUCTION } = process.env;
 export default {
   input: "src/index.js",
   output: {
-    file: "../django_idom/static/js/idom.js",
+    file: "../django_idom/static/js/django-idom-client.js",
     format: "esm",
   },
   plugins: [