Background Processor
====================

The Background Processor continuously polls the Redis transaction buffer and executes transactions against the main database.

.. contents:: Table of Contents
   :local:
   :depth: 2

Core Implementation
-------------------

Key code from ``background_processor.py``:

.. literalinclude:: ../../../ccat_ops_db_api/transaction_buffering/background_processor.py
   :language: python
   :lines: 19-100
   :emphasize-lines: 10-20, 71-80

Processing Loop
---------------

1. **Check buffer size** (LLEN)
2. **Check database connectivity**
3. **Pop transaction** (RPOP)
4. **Execute transaction** on main database
5. **Capture LSN** after commit
6. **Track replication** via LSN tracker
7. **Cleanup or extend cache** based on replication

Configuration
-------------

.. code-block:: bash

   BACKGROUND_PROCESSING_INTERVAL=1.0  # seconds
   TRANSACTION_RETRY_ATTEMPTS=3
   TRANSACTION_RETRY_DELAY=5  # seconds

Health Monitoring
-----------------

The processor reports health via ``/health`` endpoint:

.. code-block:: json

   {
     "background_processor": {
       "status": "running",
       "last_run": "2025-01-01T00:00:05Z",
       "transactions_processed": 150
     }
   }

Next Steps
----------

* :doc:`lsn-tracking` - How replication is tracked
* :doc:`../../development/debugging-buffering` - Troubleshooting