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import asyncio
import logging
from asyncio import Queue
from typing import Any, Dict, Union
from uvicorn import Config
from uvicorn._types import (
LifespanScope,
LifespanShutdownCompleteEvent,
LifespanShutdownEvent,
LifespanShutdownFailedEvent,
LifespanStartupCompleteEvent,
LifespanStartupEvent,
LifespanStartupFailedEvent,
)
LifespanReceiveMessage = Union[LifespanStartupEvent, LifespanShutdownEvent]
LifespanSendMessage = Union[
LifespanStartupFailedEvent,
LifespanShutdownFailedEvent,
LifespanStartupCompleteEvent,
LifespanShutdownCompleteEvent,
]
STATE_TRANSITION_ERROR = "Got invalid state transition on lifespan protocol."
class LifespanOn:
def __init__(self, config: Config) -> None:
if not config.loaded:
config.load()
self.config = config
self.logger = logging.getLogger("uvicorn.error")
self.startup_event = asyncio.Event()
self.shutdown_event = asyncio.Event()
self.receive_queue: "Queue[LifespanReceiveMessage]" = asyncio.Queue()
self.error_occured = False
self.startup_failed = False
self.shutdown_failed = False
self.should_exit = False
self.state: Dict[str, Any] = {}
async def startup(self) -> None:
self.logger.info("Waiting for application startup.")
loop = asyncio.get_event_loop()
main_lifespan_task = loop.create_task(self.main()) # noqa: F841
# Keep a hard reference to prevent garbage collection
# See https://github.com/encode/uvicorn/pull/972
startup_event: LifespanStartupEvent = {"type": "lifespan.startup"}
await self.receive_queue.put(startup_event)
await self.startup_event.wait()
if self.startup_failed or (self.error_occured and self.config.lifespan == "on"):
self.logger.error("Application startup failed. Exiting.")
self.should_exit = True
else:
self.logger.info("Application startup complete.")
async def shutdown(self) -> None:
if self.error_occured:
return
self.logger.info("Waiting for application shutdown.")
shutdown_event: LifespanShutdownEvent = {"type": "lifespan.shutdown"}
await self.receive_queue.put(shutdown_event)
await self.shutdown_event.wait()
if self.shutdown_failed or (
self.error_occured and self.config.lifespan == "on"
):
self.logger.error("Application shutdown failed. Exiting.")
self.should_exit = True
else:
self.logger.info("Application shutdown complete.")
async def main(self) -> None:
try:
app = self.config.loaded_app
scope: LifespanScope = {
"type": "lifespan",
"asgi": {"version": self.config.asgi_version, "spec_version": "2.0"},
"state": self.state,
}
await app(scope, self.receive, self.send)
except BaseException as exc:
self.asgi = None
self.error_occured = True
if self.startup_failed or self.shutdown_failed:
return
if self.config.lifespan == "auto":
msg = "ASGI 'lifespan' protocol appears unsupported."
self.logger.info(msg)
else:
msg = "Exception in 'lifespan' protocol\n"
self.logger.error(msg, exc_info=exc)
finally:
self.startup_event.set()
self.shutdown_event.set()
async def send(self, message: "LifespanSendMessage") -> None:
assert message["type"] in (
"lifespan.startup.complete",
"lifespan.startup.failed",
"lifespan.shutdown.complete",
"lifespan.shutdown.failed",
)
if message["type"] == "lifespan.startup.complete":
assert not self.startup_event.is_set(), STATE_TRANSITION_ERROR
assert not self.shutdown_event.is_set(), STATE_TRANSITION_ERROR
self.startup_event.set()
elif message["type"] == "lifespan.startup.failed":
assert not self.startup_event.is_set(), STATE_TRANSITION_ERROR
assert not self.shutdown_event.is_set(), STATE_TRANSITION_ERROR
self.startup_event.set()
self.startup_failed = True
if message.get("message"):
self.logger.error(message["message"])
elif message["type"] == "lifespan.shutdown.complete":
assert self.startup_event.is_set(), STATE_TRANSITION_ERROR
assert not self.shutdown_event.is_set(), STATE_TRANSITION_ERROR
self.shutdown_event.set()
elif message["type"] == "lifespan.shutdown.failed":
assert self.startup_event.is_set(), STATE_TRANSITION_ERROR
assert not self.shutdown_event.is_set(), STATE_TRANSITION_ERROR
self.shutdown_event.set()
self.shutdown_failed = True
if message.get("message"):
self.logger.error(message["message"])
async def receive(self) -> "LifespanReceiveMessage":
return await self.receive_queue.get()
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