func()

in pkg/events/events.go [113:159]

• 34 lines of code
• 4 McCabe index (conditional complexity)

func (ev *events) setupRingBuffer(mapFD int, maxEntries uint32) (chan []byte, error) {
	ringbuffer := &RingBuffer{
		RingBufferMapFD: mapFD,
		Mask:            uint64(maxEntries - 1),
	}

	// [Consumer page - 4k][Producer page - 4k][Data section - twice the size of max entries]
	// Refer kernel code, twice the size of max entries will help in boundary scenarios
	// https://github.com/torvalds/linux/blob/master/kernel/bpf/ringbuf.c#L125

	consumer, err := unix.Mmap(mapFD, 0, ev.PageSize, unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
	if err != nil {
		return nil, fmt.Errorf("failed to create Mmap for consumer -> %d: %s", mapFD, err)
	}

	ringbuffer.Consumerpos = unsafe.Pointer(&consumer[0])
	ringbuffer.Consumer = consumer

	mmap_sz := uint32(ev.PageSize) + 2*maxEntries
	producer, err := unix.Mmap(mapFD, int64(ev.PageSize), int(mmap_sz), unix.PROT_READ, unix.MAP_SHARED)
	if err != nil {
		unix.Munmap(producer)
		return nil, fmt.Errorf("failed to create Mmap for producer -> %d: %s", mapFD, err)
	}

	ringbuffer.Producerpos = unsafe.Pointer(&producer[0])
	ringbuffer.Producer = producer
	ringbuffer.Data = unsafe.Pointer(uintptr(unsafe.Pointer(&producer[0])) + uintptr(ev.PageSize))

	ev.RingBuffers = append(ev.RingBuffers, ringbuffer)

	err = ev.epoller.AddEpollCtl(mapFD, ev.EventFdCnt)
	if err != nil {
		unix.Munmap(producer)
		return nil, fmt.Errorf("failed to Epoll event: %s", err)
	}
	ev.RingCnt++
	ev.EventFdCnt++

	//Start channels read
	ev.eventsStopChannel = make(chan struct{})
	ev.eventsDataChannel = make(chan []byte)

	ev.wg.Add(1)
	go ev.reconcileEventsDataChannel()
	return ev.eventsDataChannel, nil
}