fix cache busting across all gunicorn/uvicorn workers (#99)

.dockerignore

@@ -1,2 +1,3 @@
 fly.staging.toml
 fly.prod.toml
+cache-watch-dog/

.gitignore

@@ -136,3 +136,4 @@ offsets_db_api/_version.py
 *.sqlite
 *.csv
 *.gz
+cache-watch-dog/

offsets_db_api/cache.py

@@ -1,3 +1,4 @@
+import pathlib
 import typing
 
 from fastapi import Request, Response
@@ -10,6 +11,12 @@
 
 CACHE_NAMESPACE = 'offsets-db'
 
+app_dir = pathlib.Path(__file__).parent.parent
+
+watch_dog_dir = app_dir / 'cache-watch-dog'
+watch_dog_dir.mkdir(parents=True, exist_ok=True)
+watch_dog_file = watch_dog_dir / 'last-db-update.txt'
+
 
 def request_key_builder(
     func: typing.Callable[..., typing.Any],

offsets_db_api/logging.py

@@ -1,13 +1,20 @@
 import logging
+import os
 import sys
 
 
 def get_logger() -> logging.Logger:
     logger = logging.getLogger('offsets-db-api')
+    worker_id = os.environ.get('APP_WORKER_ID', '')
 
     if not logger.handlers:
         handler = logging.StreamHandler(stream=sys.stdout)
-        handler.setFormatter(logging.Formatter('%(levelname)s: %(name)s - %(message)s'))
+        if worker_id != '':
+            handler.setFormatter(
+                logging.Formatter(f'[%(name)s] [worker {worker_id}] [%(levelname)s] %(message)s')
+            )
+        else:
+            handler.setFormatter(logging.Formatter('[%(name)s] [%(levelname)s] %(message)s'))
         logger.addHandler(handler)
 
     logger.setLevel(logging.DEBUG)

offsets_db_api/main.py

@@ -1,19 +1,31 @@
+import asyncio
 import os
+import pathlib
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi_cache import FastAPICache
 from fastapi_cache.backends.inmemory import InMemoryBackend
+from watchdog.events import FileSystemEventHandler
+from watchdog.observers import Observer
 
 from .app_metadata import metadata
-from .cache import request_key_builder
+from .cache import clear_cache, request_key_builder, watch_dog_dir, watch_dog_file
 from .logging import get_logger
 from .routers import charts, clips, credits, files, health, projects
 
 logger = get_logger()
 
 
+class CacheInvalidationHandler(FileSystemEventHandler):
+    def on_modified(self, event):
+        event_path = pathlib.Path(event.src_path).resolve()
+        if event_path == watch_dog_file.resolve():
+            logger.info('🔄 File modified: %s', event_path)
+            asyncio.run(clear_cache())
+
+
 @asynccontextmanager
 async def lifespan_event(app: FastAPI):
     """
@@ -39,11 +51,18 @@ async def lifespan_event(app: FastAPI):
         f'🔥 Cache set up with expiration={expiration:,} seconds | {cache_status_header} cache status header.'
     )
 
+    event_handler = CacheInvalidationHandler()
+    observer = Observer()
+    observer.schedule(event_handler, path=str(watch_dog_dir), recursive=False)
+    observer.start()
+
     yield
 
     logger.info('Application shutdown...')
     logger.info('Clearing cache...')
     FastAPICache.reset()
+    observer.stop()
+    observer.join()
     logger.info('👋 Goodbye!')
 
 

offsets_db_api/tasks.py

@@ -1,10 +1,11 @@
+import datetime
 import traceback
 
 import pandas as pd
 from offsets_db_data.models import clip_schema, credit_schema, project_schema
 from sqlmodel import ARRAY, BigInteger, Boolean, Date, DateTime, String, text
 
-from .cache import clear_cache
+from .cache import watch_dog_file
 from .logging import get_logger
 from .models import File
 
@@ -144,4 +145,8 @@ async def process_files(*, engine, session, files: list[File]):
 
     process_dataframe(clip_projects_df, 'clipproject', engine)
 
-    await clear_cache()
+    # modify the watch_dog_file
+    with open(watch_dog_file, 'w') as f:
+        now = datetime.datetime.utcnow()
+        logger.info(f'✅ Updated watch_dog_file: {watch_dog_file} to {now}')
+        f.write(now.strftime('%Y-%m-%d %H:%M:%S'))

requirements.txt

@@ -17,3 +17,4 @@ ujson
 universal_pathlib
 uvicorn
 fastapi-cache2 @ git+https://github.com/andersy005/fastapi-cache@pydantic-v2-compat # for pydantic v2 compatilibity
+watchdog>=3.0