service backend

api/pkg/messaging/internal/inprocess/broker.go

@@ -0,0 +1,87 @@
+package inprocess
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/tech/sendico/pkg/merrors"
+	me "github.com/tech/sendico/pkg/messaging/envelope"
+	"github.com/tech/sendico/pkg/mlogger"
+	"github.com/tech/sendico/pkg/model"
+	"github.com/tech/sendico/pkg/mutil/mzap"
+	"go.uber.org/zap"
+)
+
+type MessageBroker struct {
+	logger      mlogger.Logger
+	subscribers map[string][]chan me.Envelope
+	lock        sync.RWMutex
+	bufferSize  int
+}
+
+func (b *MessageBroker) Publish(envelope me.Envelope) error {
+	topic := envelope.GetSignature().ToString()
+	b.logger.Debug("Publishing message", mzap.Envelope(envelope))
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	if subs, ok := b.subscribers[topic]; ok {
+		for _, sub := range subs {
+			select {
+			case sub <- envelope:
+			default:
+			}
+		}
+		return nil
+	}
+	b.logger.Warn("Topic not found", mzap.Envelope(envelope))
+	return merrors.NoMessagingTopic(topic)
+}
+
+func (b *MessageBroker) Subscribe(event model.NotificationEvent) (<-chan me.Envelope, error) {
+	topic := event.ToString()
+	b.logger.Info("New topic subscriber", zap.String("topic", topic))
+	ch := make(chan me.Envelope, b.bufferSize) // Buffered channel to avoid blocking publishers
+	{
+		b.lock.Lock()
+		defer b.lock.Unlock()
+		b.subscribers[topic] = append(b.subscribers[topic], ch)
+	}
+
+	return ch, nil
+}
+
+func (b *MessageBroker) Unsubscribe(event model.NotificationEvent, subChan <-chan me.Envelope) error {
+	topic := event.ToString()
+	b.logger.Info("Unsubscribing topic", zap.String("topic", topic))
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	subs, ok := b.subscribers[topic]
+	if !ok {
+		b.logger.Debug("No subscribers for topic", zap.String("topic", topic))
+		return nil
+	}
+
+	for i, ch := range subs {
+		if ch == subChan {
+			b.subscribers[topic] = append(subs[:i], subs[i+1:]...)
+			close(ch)
+			return nil
+		}
+	}
+
+	b.logger.Warn("No topic found", zap.String("topic", topic))
+	return merrors.NoMessagingTopic(topic)
+}
+
+func NewInProcessBroker(logger mlogger.Logger, bufferSize int) (*MessageBroker, error) {
+	if bufferSize < 1 {
+		return nil, merrors.InvalidArgument(fmt.Sprintf("Invelid buffer size %d. It must be greater than 1", bufferSize))
+	}
+	logger.Info("Created in-process logger", zap.Int("buffer_size", bufferSize))
+	return &MessageBroker{
+		logger:      logger.Named("in_process"),
+		subscribers: make(map[string][]chan me.Envelope),
+		bufferSize:  bufferSize,
+	}, nil
+}

api/pkg/messaging/internal/inprocess/config/config.go

@@ -0,0 +1,5 @@
+package inprocess
+
+type MessagingConfig struct {
+	BufferSize int `mapstructure:"buffer_size" yaml:"buffer_size"`
+}