Currently the offsets storage is only accessible from SourceTask to able to initialize properly tasks after a restart, a crash or a reconfiguration request.
To implement more complex connectors that need to track the progression of each task it would helpful to have access to an OffsetStorageReader instance from the SourceConnector.
In that way, we could have a background thread that could request a tasks reconfiguration based on source offsets.
This improvement proposal comes from a customer project that needs to periodically scan directories on a shared storage for detecting and for streaming new files into Kafka.
The connector implementation is pretty straightforward.
The connector uses a background thread to periodically scan directories. When new inputs files are detected a tasks reconfiguration is requested. Then the connector assigns a file subset to each task.
Each task stores sources offsets for the last sent record. The source offsets data are:
- the size of file
- the bytes offset
- the bytes size
Tasks become idle when the assigned files are completed (in : recordBytesOffsets + recordBytesSize = fileBytesSize).
Then, the connector should be able to track offsets for each assigned file.
When all tasks has finished the connector can stop them or assigned new files by requesting tasks reconfiguration.
Moreover, another advantage of monitoring source offsets from the connector is detect slow or failed tasks and if necessary to be able to restart all tasks.
If you think this improvement is OK, I can work a pull request.