edge/pkg/bus/memory/event_dispatcher.go

package memory

import (
	"context"
	"sync"
	"time"

	"forge.cadoles.com/arcad/edge/pkg/bus"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type eventDispatcherSet struct {
	mutex sync.Mutex
	items map[*eventDispatcher]struct{}
}

func (s *eventDispatcherSet) Add(d *eventDispatcher) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	s.items[d] = struct{}{}
}

func (s *eventDispatcherSet) Remove(d *eventDispatcher) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	d.close()
	delete(s.items, d)
}

func (s *eventDispatcherSet) RemoveByOutChannel(out <-chan bus.Message) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	for d := range s.items {
		if d.IsOut(out) {
			d.close()
			delete(s.items, d)
		}
	}
}

func (s *eventDispatcherSet) List() []*eventDispatcher {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	dispatchers := make([]*eventDispatcher, 0, len(s.items))

	for d := range s.items {
		dispatchers = append(dispatchers, d)
	}

	return dispatchers
}

func newEventDispatcherSet() *eventDispatcherSet {
	return &eventDispatcherSet{
		items: make(map[*eventDispatcher]struct{}),
	}
}

type eventDispatcher struct {
	in     chan bus.Message
	out    chan bus.Message
	mutex  sync.RWMutex
	closed bool
}

func (d *eventDispatcher) Closed() bool {
	d.mutex.RLock()
	defer d.mutex.RUnlock()

	return d.closed
}

func (d *eventDispatcher) Close() {
	d.mutex.Lock()
	defer d.mutex.Unlock()

	d.close()
}

func (d *eventDispatcher) close() {
	if d.closed {
		return
	}

	close(d.in)
	d.closed = true
}

func (d *eventDispatcher) In(msg bus.Message) (err error) {
	d.mutex.RLock()
	defer d.mutex.RUnlock()

	if d.closed {
		return
	}

	d.in <- msg

	return nil
}

func (d *eventDispatcher) Out() <-chan bus.Message {
	return d.out
}

func (d *eventDispatcher) IsOut(out <-chan bus.Message) bool {
	return d.out == out
}

func (d *eventDispatcher) Run(ctx context.Context) {
	defer func() {
		for {
			logger.Debug(ctx, "closing dispatcher, flushing out incoming messages")

			close(d.out)

			// Flush all incoming messages
			for {
				_, ok := <-d.in
				if !ok {
					return
				}
			}
		}
	}()

	for {
		msg, ok := <-d.in
		if !ok {
			return
		}

		timeout := time.After(time.Second)

		select {
		case d.out <- msg:
		case <-timeout:
			logger.Error(
				ctx,
				"out message channel timeout",
				logger.F("message", msg),
			)

			return

		case <-ctx.Done():
			logger.Error(
				ctx,
				"message subscription context canceled",
				logger.F("message", msg),
				logger.CapturedE(errors.WithStack(ctx.Err())),
			)

			return
		}
	}
}

func newEventDispatcher(bufferSize int64) *eventDispatcher {
	return &eventDispatcher{
		in:     make(chan bus.Message, bufferSize),
		out:    make(chan bus.Message, bufferSize),
		closed: false,
	}
}