gRPC interceptor to manage Django DB connections

interceptor.py

"""
Handling database connections in gRPC server and Django

As explained in the docs -> https://docs.djangoproject.com/en/5.0/ref/databases/#caveats
```
If a connection is created in a long-running process, outside of Django’s request-response cycle, the connection will
remain open until explicitly closed, or timeout occurs.
```

This practically means that all long-running processes are responsible for managing their database connections.
The following interceptor provides such functionality for gRPC servers using the Django framework.
"""

from grpc_interceptor import ServerInterceptor

from django.db import close_old_connections


class CloseOldDBConnectionInterceptor(ServerInterceptor):
    """
    This interceptor is used to close old database connections if they are not usable e.g. reached the timeout or
    broken

    IMPORTANT: Extending `grpc.ServerInterceptor` and implementing the `intercept_service` method
    causes the interceptor to be executed in a separate thread, thus it has no control on the
    connections used by the actual handler

    Using the `grpc_interceptor.ServerInterceptor` and implementing the `intercept` method
    causes the interceptor to be executed in the same thread as the actual handler
    thus it has control on the connections used by the actual handler

    WARNING: Implementing `intercept_service` in the same method causes `intercept` to not be called
    """

    def intercept(self, method, request, context, method_name):
        close_old_connections()
        result = method(request, context)

        return result