eventbus

Lightweight in-process event bus with wildcard topic matching, middleware support, and observability metrics.

Features

• Dispatch modes: Sync (default), Async (background workers), Parallel (concurrent)
• Wildcard topic matching: user.* (single level), user.> (multi level)
• Middleware: logging, recover, retry with backoff, dead-letter, per-topic metrics
• Built-in metrics: published, delivered, failed, pending, average latency

Key types

• Event -- message with ID, Name, Time, Payload, Headers, Attempt
• Handler -- func(ctx, *Event) error
• Middleware -- func(next Handler) Handler
• Bus -- core interface (Publish, Subscribe, Unsubscribe, Close, Metrics)
• Subscription -- active subscription handle
• Metrics / MetricsCollector -- observability snapshot
• DispatchMode -- Sync, Async, Parallel

Key functions

• NewBus(opts...) -- create an in-memory bus
• New(name, payload) / NewWithSource(name, source, payload) -- create events
• WithDispatchMode, WithMiddleware, WithAsyncBufferSize -- bus options
• LoggingMiddleware, RecoverMiddleware, RetryMiddleware, DeadLetterMiddleware, MetricsMiddleware
• TopicMatches(pattern, name) -- wildcard match helper

Quick start

import (
    "context"
    "github.com/LingByte/ling-base/common/eventbus"
)

bus := eventbus.NewBus()
defer bus.Close()

bus.Subscribe("user.created", func(ctx context.Context, e *eventbus.Event) error {
    log.Printf("user created: %v", e.Payload)
    return nil
})

_ = bus.Publish(ctx, eventbus.New("user.created", "user-123"))

License

MIT