remote/datasette
1
0
Fork 0
mirror of https://github.com/simonw/datasette.git synced 2026-09-29 13:24:07 +02:00
Code Issues Projects Releases Packages Wiki Activity

Run startup via ASGI lifespan instead of waiting for the first request (#2887)

Browse source 
* Run startup via ASGI lifespan instead of waiting for the first request
* Ensure immutable table counts still precompute when startup ran first
This commit is contained in:
Alex Garcia 2026-09-01 09:39:25 -07:00 • committed by GitHub
commit 3e018bb1b5
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
4 changed files with 337 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

42
datasette/utils/asgi.py
View file

@ -1,3 +1,4 @@
import asyncio
import json
import re
from http.cookies import Morsel, SimpleCookie
@ -300,12 +301,24 @@ class AsgiLifespan:
while True:
message = await receive()
if message["type"] == "lifespan.startup":
for fn in self.on_startup:
await fn()
try:
for fn in self.on_startup:
await fn()
except Exception as e: # noqa: BLE001
await send(
{"type": "lifespan.startup.failed", "message": str(e)}
)
return
await send({"type": "lifespan.startup.complete"})
elif message["type"] == "lifespan.shutdown":
for fn in self.on_shutdown:
await fn()
try:
for fn in self.on_shutdown:
await fn()
except Exception as e: # noqa: BLE001
await send(
{"type": "lifespan.shutdown.failed", "message": str(e)}
)
return
await send({"type": "lifespan.shutdown.complete"})
return
else:
@ -624,10 +637,23 @@ class AsgiRunOnFirstRequest:
self.asgi = asgi
self.on_startup = on_startup
self._started = False
# Guards against concurrent early requests interleaving with startup:
# without this, several requests could all observe `_started is
# False` and proceed before any of them finish running the hooks.
self._lock = asyncio.Lock()
async def __call__(self, scope, receive, send):
if not self._started:
self._started = True
for hook in self.on_startup:
await hook()
# Leave "lifespan" scope events alone - this shim only exists as a
# fallback for hosts that never send them. It wraps AsgiLifespan, so
# if it ran on_startup here too, a startup exception would escape
# before AsgiLifespan's own try/except got a chance to turn it into
# a lifespan.startup.failed message.
if scope["type"] != "lifespan" and not self._started:
async with self._lock:
# Re-check: another request may have finished startup while
# we were waiting for the lock.
if not self._started:
for hook in self.on_startup:
await hook()
self._started = True
return await self.asgi(scope, receive, send)