feat: add batch support

[yordis]

No description provided.

[coderabbitai]

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The pull request is closed.

Walkthrough

Batch event processing support was added to the Commanded event handler infrastructure, introducing the handle_batch/1 callback, batch-specific telemetry, and error handling. Configuration options enforce mutual exclusivity between concurrency and batch size. Extensive tests and supporting modules were added to validate batch processing, state management, telemetry, error handling, and handler reset logic.

Changes

File(s) / Module(s)	Change Summary
lib/commanded/event/handler.ex	Added batch processing: handle_batch/1 callback, batch telemetry, error handling, config validation, and documentation.
lib/commanded/event_store/adapter.ex	Enhanced documentation for ack_event/3 to clarify batch acknowledgment semantics.
lib/commanded/event_store/adapters/in_memory.ex	Added debug logging for event acknowledgment in ack_persistent_subscription_by_pid/3.
test/event/event_handler_batch_state_test.exs, test/event/support/state/stateful_batched_event_handler.ex	Added stateful batch handler and tests for state management and batch processing.
test/event/event_handler_batch_subscribe_to_stream_test.exs	Added test and handler for subscribing to a single stream with batch processing.
test/event/event_handler_batch_telemetry_test.exs	Added tests for batch handler telemetry events (start, stop, exception) under various scenarios.
test/event/event_handler_batch_test.exs, test/event/support/batch_handler.ex, test/event/support/error_handling_batch_handler.ex	Added batch handler, error handling batch handler, and tests for batch processing and error strategies.
test/event/event_handler_macro_test.exs, test/event/handler_config_test.exs	Added tests for config validation: mutual exclusivity of concurrency and batch_size, and compile-time callback checks.
test/event/event_handler_state_test.exs	Ensured handler process termination after each stateful event handler test.
test/event/reset_batch_event_handler_test.exs, test/example_domain/bank_account/bank_account_batch_handler.ex	Added batch handler and tests for handler reset and batch state management in a banking domain scenario.
test/event/support/upcast/batch_event_handler.ex, test/event/upcaster_test.exs	Added batch upcast handler and tests for upcasted event batch processing.
test/event_store/adapters/in_memory/in_memory_test.exs	Added test for single event acknowledgment in the in-memory event store.

Sequence Diagram(s)

sequenceDiagram
    participant EventStore
    participant EventHandler
    participant UserApp

    UserApp->>EventStore: Append batch of events
    EventStore->>EventHandler: Send {:events, events} message
    alt Batch processing enabled
        EventHandler->>EventHandler: handle_batch(events)
        EventHandler->>UserApp: Send batch result/notification
        EventHandler->>EventStore: ack_event for last event in batch
    else Single event processing
        loop For each event
            EventHandler->>EventHandler: handle(event, metadata)
            EventHandler->>UserApp: Send event result/notification
            EventHandler->>EventStore: ack_event for event
        end
    end

Loading

Poem

In the warren, events now hop in a pack,
Batching together, they bound down the track.
Telemetry sings as the handler delights,
With errors and retries on long bunny nights.
No more lone carrots—now bunches are chewed,
Batch logic is here, and the code’s feeling renewed!
🥕🥕🥕

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📥 Commits

Reviewing files that changed from the base of the PR and between 31337cb and 2607718.

📒 Files selected for processing (18)

• lib/commanded/event/handler.ex (24 hunks)
• lib/commanded/event_store/adapter.ex (1 hunks)
• lib/commanded/event_store/adapters/in_memory.ex (2 hunks)
• test/event/event_handler_batch_state_test.exs (1 hunks)
• test/event/event_handler_batch_subscribe_to_stream_test.exs (1 hunks)
• test/event/event_handler_batch_telemetry_test.exs (1 hunks)
• test/event/event_handler_batch_test.exs (1 hunks)
• test/event/event_handler_macro_test.exs (1 hunks)
• test/event/event_handler_state_test.exs (5 hunks)
• test/event/handler_config_test.exs (1 hunks)
• test/event/reset_batch_event_handler_test.exs (1 hunks)
• test/event/support/batch_handler.ex (1 hunks)
• test/event/support/error_handling_batch_handler.ex (1 hunks)
• test/event/support/state/stateful_batched_event_handler.ex (1 hunks)
• test/event/support/upcast/batch_event_handler.ex (1 hunks)
• test/event/upcaster_test.exs (1 hunks)
• test/event_store/adapters/in_memory/in_memory_test.exs (2 hunks)
• test/example_domain/bank_account/bank_account_batch_handler.ex (1 hunks)

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• 📝 Generate Docstrings

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