Replace AsgiLifespan with AsgiRunOnFirstRequest, refs #1955

datasette/app.py

@@ -69,8 +69,6 @@ from .utils import (
     row_sql_params_pks,
 )
 from .utils.asgi import (
-    AsgiLifespan,
-    Base400,
     Forbidden,
     NotFound,
     DatabaseNotFound,
@@ -78,11 +76,10 @@ from .utils.asgi import (
     RowNotFound,
     Request,
     Response,
+    AsgiRunOnFirstRequest,
     asgi_static,
     asgi_send,
     asgi_send_file,
-    asgi_send_html,
-    asgi_send_json,
     asgi_send_redirect,
 )
 from .utils.internal_db import init_internal_db, populate_schema_tables
@@ -1420,7 +1417,7 @@ class Datasette:
 
         async def setup_db():
             # First time server starts up, calculate table counts for immutable databases
-            for dbname, database in self.databases.items():
+            for database in self.databases.values():
                 if not database.is_mutable:
                     await database.table_counts(limit=60 * 60 * 1000)
 
@@ -1434,10 +1431,7 @@ class Datasette:
         )
         if self.setting("trace_debug"):
             asgi = AsgiTracer(asgi)
-        asgi = AsgiLifespan(
+        asgi = AsgiRunOnFirstRequest(asgi, on_startup=[setup_db, self.invoke_startup])
-            asgi,
-            on_startup=setup_db,
-        )
         for wrapper in pm.hook.asgi_wrapper(datasette=self):
             asgi = wrapper(asgi)
         return asgi
@@ -1730,42 +1724,34 @@ class DatasetteClient:
         return path
 
     async def get(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.get(self._fix(path), **kwargs)
 
     async def options(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.options(self._fix(path), **kwargs)
 
     async def head(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.head(self._fix(path), **kwargs)
 
     async def post(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.post(self._fix(path), **kwargs)
 
     async def put(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.put(self._fix(path), **kwargs)
 
     async def patch(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.patch(self._fix(path), **kwargs)
 
     async def delete(self, path, **kwargs):
-        await self.ds.invoke_startup()
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.delete(self._fix(path), **kwargs)
 
     async def request(self, method, path, **kwargs):
-        await self.ds.invoke_startup()
         avoid_path_rewrites = kwargs.pop("avoid_path_rewrites", None)
         async with httpx.AsyncClient(app=self.app) as client:
             return await client.request(

datasette/utils/asgi.py

@@ -156,35 +156,6 @@ class Request:
         return cls(scope, None)
 
 
-class AsgiLifespan:
-    def __init__(self, app, on_startup=None, on_shutdown=None):
-        self.app = app
-        on_startup = on_startup or []
-        on_shutdown = on_shutdown or []
-        if not isinstance(on_startup or [], list):
-            on_startup = [on_startup]
-        if not isinstance(on_shutdown or [], list):
-            on_shutdown = [on_shutdown]
-        self.on_startup = on_startup
-        self.on_shutdown = on_shutdown
-
-    async def __call__(self, scope, receive, send):
-        if scope["type"] == "lifespan":
-            while True:
-                message = await receive()
-                if message["type"] == "lifespan.startup":
-                    for fn in self.on_startup:
-                        await fn()
-                    await send({"type": "lifespan.startup.complete"})
-                elif message["type"] == "lifespan.shutdown":
-                    for fn in self.on_shutdown:
-                        await fn()
-                    await send({"type": "lifespan.shutdown.complete"})
-                    return
-        else:
-            await self.app(scope, receive, send)
-
-
 class AsgiStream:
     def __init__(self, stream_fn, status=200, headers=None, content_type="text/plain"):
         self.stream_fn = stream_fn
@@ -449,3 +420,18 @@ class AsgiFileDownload:
             content_type=self.content_type,
             headers=self.headers,
         )
+
+
+class AsgiRunOnFirstRequest:
+    def __init__(self, asgi, on_startup):
+        assert isinstance(on_startup, list)
+        self.asgi = asgi
+        self.on_startup = on_startup
+        self._started = False
+
+    async def __call__(self, scope, receive, send):
+        if not self._started:
+            self._started = True
+            for hook in self.on_startup:
+                await hook()
+        return await self.asgi(scope, receive, send)

docs/plugin_hooks.rst

@@ -902,13 +902,14 @@ Potential use-cases:
 
 .. note::
 
-   If you are writing :ref:`unit tests <testing_plugins>` for a plugin that uses this hook you will need to explicitly call ``await ds.invoke_startup()`` in your tests. An example:
+   If you are writing :ref:`unit tests <testing_plugins>` for a plugin that uses this hook and doesn't exercise Datasette by sending
+   any simulated requests through it you will need to explicitly call ``await ds.invoke_startup()`` in your tests. An example:
 
    .. code-block:: python
 
         @pytest.mark.asyncio
         async def test_my_plugin():
-            ds = Datasette([], metadata={})
+            ds = Datasette()
             await ds.invoke_startup()
             # Rest of test goes here
 

docs/testing_plugins.rst

@@ -80,7 +80,7 @@ Creating a ``Datasette()`` instance like this as useful shortcut in tests, but t
 
 This method registers any :ref:`plugin_hook_startup` or :ref:`plugin_hook_prepare_jinja2_environment` plugins that might themselves need to make async calls.
 
-If you are using ``await datasette.client.get()`` and similar methods then you don't need to worry about this - those method calls ensure that ``.invoke_startup()`` has been called for you.
+If you are using ``await datasette.client.get()`` and similar methods then you don't need to worry about this - Datasette automatically calls ``invoke_startup()`` the first time it handles a request.
 
 .. _testing_plugins_pdb: