fix(events): keep registration status reads nonblocking

config/api_errors.py

@@ -0,0 +1,18 @@
+"""HTTP handling for recoverable database errors."""
+
+from django.http import JsonResponse
+
+
+def handle_database_operational_error(request, error):
+    """Return a retryable response when PostgreSQL rejects a lock wait."""
+    cause = error.__cause__
+    while cause is not None:
+        if getattr(cause, "sqlstate", None) == "55P03" or getattr(cause, "pgcode", None) == "55P03":
+            response = JsonResponse(
+                {"detail": "درخواست به‌دلیل شلوغی موقت پایگاه داده انجام نشد؛ کمی بعد دوباره تلاش کنید."},
+                status=503,
+            )
+            response["Retry-After"] = "2"
+            return response
+        cause = cause.__cause__
+    raise error

config/services/celery.py

@@ -48,6 +48,11 @@ app.conf.beat_schedule = {
         'schedule': crontab(minute='*'),
         'description': 'Releases seats from paid checkouts after their 15-minute window.',
     },
+    'deliver-registration-notifications': {
+        'task': 'apps.events.deliver_pending_registration_notifications',
+        'schedule': crontab(minute='*'),
+        'description': 'Retries committed registration notifications.',
+    },
     'sweep-pending-refunds': {
         'task': 'apps.payments.sweep_pending_refunds',
         'schedule': crontab(minute='*/5'),

config/settings/base.py

@@ -249,6 +249,15 @@ BLOG_ASSET_MAX_SIZE_MB = config('BLOG_ASSET_MAX_SIZE_MB', default=50, cast=int)
 BLOG_IMAGE_ASSET_MAX_SIZE_MB = config('BLOG_IMAGE_ASSET_MAX_SIZE_MB', default=10, cast=int)
 
 if DATABASES["default"]["ENGINE"] == "django.db.backends.postgresql":
+    lock_timeout_ms = config("DB_LOCK_TIMEOUT_MS", default=5000, cast=int)
+    idle_transaction_timeout_ms = config("DB_IDLE_TRANSACTION_TIMEOUT_MS", default=60000, cast=int)
+    database_options = DATABASES["default"].setdefault("OPTIONS", {})
+    existing_options = database_options.get("options") or ""
+    timeout_options = (
+        f"-c lock_timeout={lock_timeout_ms}ms "
+        f"-c idle_in_transaction_session_timeout={idle_transaction_timeout_ms}ms"
+    )
+    database_options["options"] = f"{existing_options} {timeout_options}".strip()
     DATABASES["default"]["ENGINE"] = "django_prometheus.db.backends.postgresql"
 
 from config.services.unfold import *

config/tests/unit/test_api_errors.py

@@ -0,0 +1,35 @@
+import json
+
+import pytest
+from django.db import OperationalError
+
+from config.api_errors import handle_database_operational_error
+
+pytestmark = pytest.mark.unit
+
+
+class PostgresError(Exception):
+    def __init__(self, sqlstate):
+        super().__init__(sqlstate)
+        self.sqlstate = sqlstate
+
+
+def test_database_lock_timeout_returns_retryable_service_unavailable():
+    error = OperationalError("canceling statement due to lock timeout")
+    error.__cause__ = PostgresError("55P03")
+
+    response = handle_database_operational_error(None, error)
+
+    assert response.status_code == 503
+    assert response["Retry-After"] == "2"
+    assert json.loads(response.content) == {
+        "detail": "درخواست به‌دلیل شلوغی موقت پایگاه داده انجام نشد؛ کمی بعد دوباره تلاش کنید."
+    }
+
+
+def test_unrelated_database_operational_error_is_not_hidden():
+    error = OperationalError("database unavailable")
+    error.__cause__ = PostgresError("08006")
+
+    with pytest.raises(OperationalError, match="database unavailable"):
+        handle_database_operational_error(None, error)

config/urls.py

@@ -1,16 +1,19 @@
 from django.contrib import admin
+from django.db import OperationalError
 from django.urls import path, include
 from django.conf import settings
 from django.conf.urls.static import static
 from ninja import NinjaAPI
 from apps.notifications.api.views import NotificationStreamView
 from config.api import router as api_router
+from config.api_errors import handle_database_operational_error
 
 api = NinjaAPI(
     title="CS Association API",
     version="1.0.0",
     description="API for University Computer Science Association",
 )
+api.add_exception_handler(OperationalError, handle_database_operational_error)
 
 api.add_router("", api_router)