Specs

topology(broadway :: atom()) :: [
  {atom(),
   [
     %{
       :name => atom(),
       optional(:concurrency) => pos_integer(),
       optional(:batcher_name) => atom()
     }
   ]}
]

Returns the topology details for a pipeline.

The stages that have the "concurrency" field indicates a list of processes running with that name prefix. Each process has "name" as prefix plus "_" and the index of 0..(concurrency - 1), as atom.

For example, a producer named MyBroadway.Broadway.Producer with concurrency of 1 represents only a process named MyBroadway.Broadway.Producer_0.

Note that Broadway does not accept multiple producers neither multiple processors. But we choose to keep in a list for simplicity and future proof.

Examples

iex> Broadway.topology(MyBroadway)
[
  producers: [%{name: MyBroadway.Broadway.Producer, concurrency: 1}],
  processors: [%{name: MyBroadway.Broadway.Processor_default, concurrency: 10}],
  batchers: [
    %{
      batcher_name: MyBroadway.Broadway.Batcher_default,
      name: MyBroadway.Broadway.BatchProcessor_default,
      concurrency: 5
    },
    %{
      batcher_name: MyBroadway.Broadway.Batcher_s3,
      name: MyBroadway.Broadway.BatchProcessor_s3,
      concurrency: 3
    }
  ]
]