Transaction Manager
===================

The Transaction Manager handles buffering transactions to Redis, managing state, implementing retry logic, and coordinating with the background processor.

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

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

Key code from ``transaction_manager.py``:

.. literalinclude:: ../../../ccat_ops_db_api/transaction_buffering/transaction_manager.py
   :language: python
   :lines: 23-78
   :emphasize-lines: 20-28

Key Responsibilities
--------------------

1. **Buffer transactions** to Redis queue (LPUSH)
2. **Track transaction status** with TTL
3. **Implement write-through cache** for generated IDs
4. **Cache buffered data** for smart queries
5. **Manage retry logic** with exponential backoff
6. **Handle failed transactions** (dead-letter queue)

Buffering Flow
--------------

.. code-block:: python

   # Buffer a transaction
   async def buffer_transaction(transaction):
       # 1. Add to queue
       await redis.lpush(buffer_key, transaction.model_dump_json())
       
       # 2. Store status
       await redis.setex(status_key, 3600, transaction.model_dump_json())
       
       # 3. Write-through cache
       await _cache_generated_ids(transaction)
       
       # 4. Cache buffered data
       await _cache_buffered_data(transaction)
       
       return transaction.transaction_id

Redis Key Structure
-------------------

**Transaction Buffer** (List):

.. code-block:: text

   Key: site:{site_name}:transaction_buffer
   Operations: LPUSH (add), RPOP (process)
   
**Transaction Status** (String):

.. code-block:: text

   Key: site:{site_name}:transaction:{transaction_id}
   TTL: 3600 seconds
   Value: JSON transaction

**Write-Through Cache** (String):

.. code-block:: text

   Key: site:{site_name}:cache:ids:{model}:{id}
   TTL: Extended until replicated
   Value: JSON record data

**Buffered Data Cache** (String):

.. code-block:: text

   Key: site:{site_name}:buffered:{model}:{id}
   TTL: Extended until replicated
   Value: JSON record data

See :doc:`../../development/redis-inspection` for debugging commands.

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

* :doc:`background-processor` - Processing buffered transactions
* :doc:`lsn-tracking` - Replication confirmation