# Changelog

All notable changes to this module will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this module adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [0.9.0] - 2026-03-18

### Added

- `Task` type — `func(ctx context.Context) error`; the unit of work dispatched to the pool
- `Config` struct — pool settings loaded from environment variables: `WORKER_POOL_SIZE` (number of concurrent goroutines, default `5`), `WORKER_BUFFER_SIZE` (task queue channel capacity, default `100`), `WORKER_TASK_TIMEOUT` (per-task context deadline; `0` means no deadline, default `0s`), `WORKER_SHUTDOWN_TIMEOUT` (time to wait for workers to drain on stop, default `30s`)
- `Provider` interface — `Dispatch(task Task) bool`; for callers that only dispatch tasks; returns `false` immediately when the queue is full (backpressure, non-blocking)
- `Component` interface — embeds `launcher.Component` and `Provider`; the full lifecycle-managed surface registered with the launcher
- `New(logger logz.Logger, cfg Config) Component` — constructor; applies safe defaults (`PoolSize <= 0` → 5, `BufferSize <= 0` → 100); returns a `Component` ready for `lc.Append`
- `OnInit` — logs pool configuration; initialises the buffered task channel
- `OnStart` — spawns `PoolSize` worker goroutines, each ranging over the task channel
- `OnStop` — closes the task channel (drain signal), cancels the pool context, then waits up to `ShutdownTimeout` for all goroutines to finish; logs an error on timeout but returns `nil` so the launcher continues
- Per-task timeout — when `TaskTimeout > 0`, each worker creates a `context.WithTimeout` child before invoking the task; tasks also receive a cancellation signal when the pool is stopping via the pool context
- Error logging — task errors are logged with the worker ID; errors are not surfaced to the dispatcher

### Design Notes

- A single buffered `chan Task` is shared by all workers; closing it during `OnStop` is the drain signal, avoiding a separate done channel or additional synchronisation primitives.
- `Dispatch` is deliberately non-blocking: a `false` return means the task has been dropped, not queued; the caller owns the retry or overflow decision, keeping backpressure handling out of the pool itself.
- `Provider` / `Component` split follows the framework pattern: inject `Provider` into callers that only dispatch tasks, inject `Component` only at the lifecycle registration site.

[0.9.0]: https://code.nochebuena.dev/go/worker/releases/tag/v0.9.0