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takahe/miniq/views.py
2022-11-05 22:49:25 -06:00

69 lines
2.4 KiB
Python

import asyncio
import time
import traceback
import uuid
from asgiref.sync import sync_to_async
from django.http import HttpResponse
from django.views import View
from miniq.models import Task
from users.models import Identity
class QueueProcessor(View):
"""
A view that takes some items off the queue and processes them.
Tries to limit its own runtime so it's within HTTP timeout limits.
"""
START_TIMEOUT = 30
TOTAL_TIMEOUT = 60
MAX_TASKS = 10
async def get(self, request):
start_time = time.monotonic()
processor_id = uuid.uuid4().hex
handled = 0
self.tasks = []
# For the first time period, launch tasks
while (time.monotonic() - start_time) < self.START_TIMEOUT:
# Remove completed tasks
self.tasks = [t for t in self.tasks if not t.done()]
# See if there's a new task
if len(self.tasks) < self.MAX_TASKS:
# Pop a task off the queue and run it
task = await sync_to_async(Task.get_one_available)(processor_id)
if task is not None:
self.tasks.append(asyncio.create_task(self.run_task(task)))
handled += 1
# Prevent busylooping
await asyncio.sleep(0.01)
# Then wait for tasks to finish
while (time.monotonic() - start_time) < self.TOTAL_TIMEOUT:
# Remove completed tasks
self.tasks = [t for t in self.tasks if not t.done()]
if not self.tasks:
break
# Prevent busylooping
await asyncio.sleep(1)
return HttpResponse(f"{handled} tasks handled")
async def run_task(self, task):
try:
print(f"Task {task}: Starting")
handler = getattr(self, f"handle_{task.type}", None)
if handler is None:
raise ValueError(f"Cannot handle type {task.type}")
await handler(task.subject, task.payload)
await task.complete()
print(f"Task {task}: Complete")
except BaseException as e:
print(f"Task {task}: Error {e}")
traceback.print_exc()
await task.fail(f"{e}\n\n" + traceback.format_exc())
async def handle_identity_fetch(self, subject, payload):
identity = await sync_to_async(Identity.by_handle)(subject)
await identity.fetch_details()