Support of non-socket file descriptors like those of a /dev/tty...

[jesskomput]

Hello, my context is mongoose running on a Linux.

Is there already a way to add a device like a /dev/ttyUSB0 to the [poll|select]ed list of mg_connections?.
This would allows to communicate through HTTPS with for example a controller board like Arduino, ESP, ... without the need of multi-threading.

If not, I can suggest some simple source mods in a "feature request" post, my tests seem to work although there may be things missing.

[scaprile]

Could you ellaborate on your use case, please ? I can't follow you.
You can do something like what I think you want to do with the multi-threading example, why can't you use multi-threading in Linux ? You could also just check for serial data in the event handler with MG_EV_POLL.

[jesskomput]

My use case: a web-page with some javascript sending commands/getting-events via a WebSocket connected mongoose server to/from an Arduino-UNO.

I know it's doable with multi-threading, but I was used to be able to add file descriptors got from open() calls to the select in various frameworks hiding the select/poll from the programmer.
So I had a look at the source code and quickly found mg_wrapfd() which I thought would do it.

Some debugging helped to find why this didn't work, and the addition of a flag if_tty in the struct mg_connection plus two conditional calls of read() and write() seemed to solve it.

Again, a mod. just for simplicity, no inter-thread comm, no polling, no second select... (multi-threading is for experienced C developers).

Also, as you suggest, I will look in detail what can be done with MG_EV_POLL, I suspect it's kind of polling.

[scaprile]

So you have a Linux machine running Mongoose as a websocket server and for some reason you connect an 8-bit hardware with a serial port to one of that LInux machine serial ports.
Somehow and for some reason you need to exchange something with the 8-bitter when something happens somewhere.

On every call to mg_mgr_poll(), when the select()/poll() call returns, all outstanding connections are polled and receive an MG_EV_POLL event.
On your websocket connection:

• When it receives an MG_EV_WS_MSG event and you need to exchange something with the 8-bitter, you write to your serial port.
• When it receives an MG_EV_POLL event call, you check your serial port for data from the 8-bitter and read from it.