mirror of
https://github.com/jointakahe/takahe.git
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294 lines
10 KiB
Python
294 lines
10 KiB
Python
import datetime
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import os
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import signal
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import time
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import traceback
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import uuid
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from concurrent.futures import Future, ThreadPoolExecutor
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from django.conf import settings
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from django.db import close_old_connections
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from django.utils import timezone
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from core import exceptions, sentry
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from core.models import Config
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from stator.models import StatorModel, Stats
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class LoopingTimer:
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"""
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Triggers check() to be true once every `interval`.
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"""
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next_run: float | None = None
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def __init__(self, interval: float, trigger_at_start=True):
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self.interval = interval
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self.trigger_at_start = trigger_at_start
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def check(self) -> bool:
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# See if it's our first time being called
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if self.next_run is None:
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# Set up the next call based on trigger_at_start
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if self.trigger_at_start:
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self.next_run = time.monotonic()
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else:
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self.next_run = time.monotonic() + self.interval
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# See if it's time to run the next call
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if time.monotonic() >= self.next_run:
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self.next_run = time.monotonic() + self.interval
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return True
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return False
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class StatorRunner:
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"""
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Runs tasks on models that are looking for state changes.
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Designed to run either indefinitely, or just for a few seconds.
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"""
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def __init__(
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self,
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models: list[type[StatorModel]],
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concurrency: int = getattr(settings, "STATOR_CONCURRENCY", 30),
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concurrency_per_model: int = getattr(
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settings, "STATOR_CONCURRENCY_PER_MODEL", 15
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),
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liveness_file: str | None = None,
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schedule_interval: int = 60,
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delete_interval: int = 30,
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lock_expiry: int = 300,
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run_for: int = 0,
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):
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self.models = models
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self.runner_id = uuid.uuid4().hex
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self.concurrency = concurrency
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self.concurrency_per_model = concurrency_per_model
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self.liveness_file = liveness_file
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self.schedule_interval = schedule_interval
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self.delete_interval = delete_interval
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self.lock_expiry = lock_expiry
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self.run_for = run_for
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self.minimum_loop_delay = 0.5
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self.maximum_loop_delay = 5
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self.tasks: dict[tuple[str, str], Future] = {}
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# Set up SIGALRM handler
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signal.signal(signal.SIGALRM, self.alarm_handler)
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def run(self):
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sentry.set_takahe_app("stator")
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self.handled = {}
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self.started = time.monotonic()
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self.executor = ThreadPoolExecutor(max_workers=self.concurrency)
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self.loop_delay = self.minimum_loop_delay
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self.scheduling_timer = LoopingTimer(self.schedule_interval)
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self.deletion_timer = LoopingTimer(self.delete_interval)
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# For the first time period, launch tasks
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print("Running main task loop")
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try:
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with sentry.configure_scope() as scope:
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while True:
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# See if we need to run cleaning
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if self.scheduling_timer.check():
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# Set up the watchdog timer (each time we do this the previous one is cancelled)
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signal.alarm(self.schedule_interval * 2)
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# Write liveness file if configured
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if self.liveness_file:
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with open(self.liveness_file, "w") as fh:
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fh.write(str(int(time.time())))
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# Refresh the config
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self.load_config()
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# Do scheduling (stale lock deletion and stats gathering)
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self.run_scheduling()
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# Clear the cleaning breadcrumbs/extra for the main part of the loop
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sentry.scope_clear(scope)
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self.clean_tasks()
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# See if we need to add deletion tasks
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if self.deletion_timer.check():
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self.add_deletion_tasks()
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# Fetch and run any new handlers we can fit
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self.add_transition_tasks()
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# Are we in limited run mode?
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if (
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self.run_for
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and (time.monotonic() - self.started) > self.run_for
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):
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break
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# Prevent busylooping, but also back off delay if we have
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# no tasks
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if self.tasks:
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self.loop_delay = self.minimum_loop_delay
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else:
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self.loop_delay = min(
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self.loop_delay * 1.5,
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self.maximum_loop_delay,
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)
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time.sleep(self.loop_delay)
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# Clear the Sentry breadcrumbs and extra for next loop
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sentry.scope_clear(scope)
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except KeyboardInterrupt:
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pass
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# Wait for tasks to finish
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print("Waiting for tasks to complete")
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self.executor.shutdown()
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# We're done
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print("Complete")
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def alarm_handler(self, signum, frame):
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"""
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Called when SIGALRM fires, which means we missed a schedule loop.
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Just exit as we're likely deadlocked.
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"""
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print("Watchdog timeout exceeded")
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os._exit(2)
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def load_config(self):
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"""
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Refreshes config from the DB
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"""
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Config.system = Config.load_system()
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def run_scheduling(self):
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"""
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Deletes stale locks for models, and submits their stats.
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"""
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with sentry.start_transaction(op="task", name="stator.run_scheduling"):
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for model in self.models:
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num = self.handled.get(model._meta.label_lower, 0)
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if num or settings.DEBUG:
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print(f"{model._meta.label_lower}: Scheduling ({num} handled)")
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self.submit_stats(model)
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model.transition_clean_locks()
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def submit_stats(self, model: type[StatorModel]):
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"""
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Pop some statistics into the database from our local info for the given model
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"""
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stats_instance = Stats.get_for_model(model)
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if stats_instance.model_label in self.handled:
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stats_instance.add_handled(self.handled[stats_instance.model_label])
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del self.handled[stats_instance.model_label]
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stats_instance.set_queued(model.transition_ready_count())
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stats_instance.trim_data()
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stats_instance.save()
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def add_transition_tasks(self, call_inline=False):
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"""
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Adds a transition thread for as many instances as we can, given capacity
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and batch size limits.
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"""
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# Calculate space left for tasks
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space_remaining = self.concurrency - len(self.tasks)
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# Fetch new tasks
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for model in self.models:
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if space_remaining > 0:
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for instance in model.transition_get_with_lock(
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number=min(space_remaining, self.concurrency_per_model),
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lock_expiry=(
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timezone.now() + datetime.timedelta(seconds=self.lock_expiry)
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),
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):
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key = (model._meta.label_lower, instance.pk)
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# Don't run two threads for the same thing
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if key in self.tasks:
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continue
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if call_inline:
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task_transition(instance, in_thread=False)
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else:
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self.tasks[key] = self.executor.submit(
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task_transition, instance
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)
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self.handled[model._meta.label_lower] = (
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self.handled.get(model._meta.label_lower, 0) + 1
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)
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space_remaining -= 1
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def add_deletion_tasks(self, call_inline=False):
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"""
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Adds a deletion thread for each model
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"""
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# Yes, this potentially goes over the capacity limit - it's fine.
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for model in self.models:
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if model.state_graph.deletion_states:
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if call_inline:
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task_deletion(model, in_thread=False)
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else:
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self.tasks[
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model._meta.label_lower, "__delete__"
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] = self.executor.submit(task_deletion, model)
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def clean_tasks(self):
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"""
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Removes any tasks that are done and handles exceptions if they
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raised them.
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"""
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for key, task in list(self.tasks.items()):
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if task.done():
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del self.tasks[key]
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try:
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task.result()
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except BaseException as e:
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exceptions.capture_exception(e)
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traceback.print_exc()
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def run_single_cycle(self):
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"""
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Testing entrypoint to advance things just one cycle, and allow errors
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to propagate out.
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"""
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self.add_deletion_tasks(call_inline=True)
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self.add_transition_tasks(call_inline=True)
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def task_transition(instance: StatorModel, in_thread: bool = True):
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"""
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Runs one state transition/action.
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"""
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task_name = f"stator.task_transition:{instance._meta.label_lower}#{{id}} from {instance.state}"
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started = time.monotonic()
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with sentry.start_transaction(op="task", name=task_name):
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sentry.set_context(
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"instance",
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{
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"model": instance._meta.label_lower,
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"pk": instance.pk,
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"state": instance.state,
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"state_age": instance.state_age,
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},
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)
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result = instance.transition_attempt()
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duration = time.monotonic() - started
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if result:
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print(
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f"{instance._meta.label_lower}: {instance.pk}: {instance.state} -> {result} ({duration:.2f}s)"
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)
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else:
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print(
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f"{instance._meta.label_lower}: {instance.pk}: {instance.state} unchanged ({duration:.2f}s)"
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)
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if in_thread:
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close_old_connections()
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def task_deletion(model: type[StatorModel], in_thread: bool = True):
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"""
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Runs one model deletion set.
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"""
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# Loop, running deletions every second, until there are no more to do
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while True:
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deleted = model.transition_delete_due()
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if not deleted:
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break
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print(f"{model._meta.label_lower}: Deleted {deleted} stale items")
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time.sleep(1)
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if in_thread:
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close_old_connections()
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