[feature] Using cbor2 to read streams asynchronously in an asyncio application

[AndreaCensi]

Hi,

I would like to use cbor2 to read CBOR streams in the context of an asyncio application.

From what I see, it is not possible now. Is that right?

From looking at the code, it looks like one should do the read() function of Decoder async, and then propagate the changes; each

value = self.read(length)

becomes

value = await self.read(length)

So I suppose it is not a quick change to be done, as most things need to become asynchronous.

Regarding the C extension, I am not sure what would be involved.

[Sekenre]

Hi,

This code probably won't run but explains how I would approach the problem.

I haven't used async much, but it should work fine if you read from your stream into a buffer and then try to decode that. e.g.

async def read_cbor(stream, q):
    buf = await stream.read(1024) # or whatever maximum length your objects might be
    if (buf):
        try:
             item = cbor2.loads(buf)
             await q.put(item)
        except (CBORDecodeError, CBOREOFError):
             pass # Actually save the buffered data until you have more

And then later on, write an async function that consumes the decoded objects from the queue.

[Sekenre]

I have written an example asyncio protocol using CBOR as a learning project.

You can have a look at it here: https://repl.it/repls/CoolAlertUpgrades

I will also include this example in a future documentation update.