Lazy load package data to improve import time (#414)

Author: Dreamsorcerer

.mypy.ini

@@ -26,6 +26,3 @@ ignore_missing_imports = True
 
 [mypy-aiohttp_mako.*]
 ignore_missing_imports = True
-
-[mypy-pkg_resources.*]
-ignore_missing_imports = True

aiohttp_debugtoolbar/panels/versions.py

@@ -1,40 +1,21 @@
 import platform
 import sys
 from operator import itemgetter
-
-import pkg_resources  # noqa: I900
+from typing import ClassVar, Dict, List, Optional
 
 from .base import DebugPanel
 
-__all__ = ["VersionDebugPanel"]
-
-
-packages = []
-for distribution in pkg_resources.working_set:
-    name = distribution.project_name
-    dependencies = [d.project_name for d in distribution.requires()]
-
-    # parse home page url
-    metadata_file = distribution.PKG_INFO
-    lines = distribution.get_metadata_lines(metadata_file)
-    url = "#"
-    for line in lines:
-        if line.startswith("Home-page:"):
-            url = line[10:].strip()
-            break
-
-    packages.append(
-        {
-            "version": distribution.version,
-            "lowername": name.lower(),
-            "name": name,
-            "dependencies": dependencies,
-            "url": url,
-        }
-    )
+if sys.version_info >= (3, 8):
+    from importlib.metadata import Distribution, version
+else:
+    Distribution = None
+
+    def version(_v):
+        return ""
 
-packages = sorted(packages, key=itemgetter("lowername"))
-aiohttp_version = pkg_resources.get_distribution("aiohttp").version
+
+__all__ = ("VersionDebugPanel",)
+aiohttp_version = version("aiohttp")
 
 
 class VersionDebugPanel(DebugPanel):
@@ -48,15 +29,43 @@ class VersionDebugPanel(DebugPanel):
     template = "versions.jinja2"
     title = "Versions"
     nav_title = title
+    packages: ClassVar[Optional[List[Dict[str, str]]]] = None
 
     def __init__(self, request):
         super().__init__(request)
         self.data = {
             "platform": self.get_platform(),
-            "packages": packages,
+            "packages": self.get_packages(),
             "aiohttp_version": aiohttp_version,
         }
 
+    @classmethod
+    def get_packages(cls) -> List[Dict[str, str]]:
+        if VersionDebugPanel.packages:
+            return VersionDebugPanel.packages
+
+        if Distribution is None:
+            return ()  # type: ignore[unreachable]
+
+        packages = []
+        for distribution in Distribution.discover():
+            name = distribution.metadata["Name"]
+            dependencies = [d for d in distribution.requires or ()]
+            url = distribution.metadata["Home-page"]
+
+            packages.append(
+                {
+                    "version": distribution.version,
+                    "lowername": name.lower(),
+                    "name": name,
+                    "dependencies": dependencies,
+                    "url": url,
+                }
+            )
+
+        VersionDebugPanel.packages = sorted(packages, key=itemgetter("lowername"))
+        return VersionDebugPanel.packages
+
     def _get_platform_name(self):
         return platform.platform()
 

tests/conftest.py

@@ -5,6 +5,8 @@
 
 from aiohttp_debugtoolbar import setup
 
+pytest_plugins = ("pytester",)
+
 
 @pytest.fixture
 def create_server(unused_tcp_port_factory):

tests/test_imports.py

@@ -0,0 +1,22 @@
+import platform
+import sys
+
+import pytest
+
+
+@pytest.mark.skipif(
+    not sys.platform.startswith("linux") or platform.python_implementation() == "PyPy",
+    reason="Unreliable",
+)
+def test_import_time(pytester: pytest.Pytester) -> None:
+    """Check that importing aiohttp-debugtoolbar doesn't take too long.
+    Obviously, the time may vary on different machines and may need to be adjusted
+    from time to time, but this should provide an early warning if something is
+    added that significantly increases import time.
+    """
+    r = pytester.run(
+        sys.executable, "-We", "-c", "import aiohttp_debugtoolbar", timeout=0.6
+    )
+
+    assert not r.stdout.str()
+    assert not r.stderr.str()

tests/test_middleware.py

@@ -1,3 +1,5 @@
+import asyncio
+
 import aiohttp_jinja2
 import pytest
 from aiohttp import web
@@ -209,14 +211,16 @@ async def handler(request: web.Request) -> web.Response:
     client = await aiohttp_client(app)
 
     # Should be logged
-    r = await client.get("/")
-    assert r.status == 200
+    async with client.get("/") as r:
+        assert r.status == 200
     # Should not be logged
-    r = await client.get("/favicon.ico")
-    assert r.status == 200
-    r = await client.get("/_debugtoolbar/static/img/aiohttp.svg")
-    assert r.status == 200
+    async with client.get("/favicon.ico") as r:
+        assert r.status == 200
+    async with client.get("/_debugtoolbar/static/img/aiohttp.svg") as r:
+        assert r.status == 200
 
     request_history = tuple(app[aiohttp_debugtoolbar.APP_KEY]["request_history"])
     assert len(request_history) == 1
     assert request_history[0][1].request.path == "/"
+
+    await asyncio.sleep(0)  # Workaround, maybe fixed in aiohttp 4.

tests/test_panels_versions.py

@@ -0,0 +1,22 @@
+import sys
+from unittest.mock import create_autospec
+
+import pytest
+from aiohttp import web
+
+from aiohttp_debugtoolbar.panels import VersionDebugPanel
+
+
+@pytest.mark.skipif(sys.version_info < (3, 8), reason="Missing importlib.metadata")
+async def test_packages():
+    request_mock = create_autospec(web.Request)
+    panel = VersionDebugPanel(request_mock)
+
+    jinja2_metadata = {
+        "version": "3.0.3",
+        "lowername": "jinja2",
+        "name": "Jinja2",
+        "dependencies": ["MarkupSafe (>=2.0)", "Babel (>=2.7) ; extra == 'i18n'"],
+        "url": "https://palletsprojects.com/p/jinja/",
+    }
+    assert jinja2_metadata in panel.data["packages"]