deser-tokio

Read and write deser values with tokio. This connects the stream serializers and stream deserializers of all deser formats (JSON, CBOR, YAML, TOML, ...) to AsyncRead and AsyncWrite, for instance to speak JSON Lines or CBOR sequences over a socket:

use deser::{Deserialize, Serialize};
use deser_json::{DeserializerConfig, Serializer, SerializerConfig, StreamDeserializer, Trailing};
use deser_tokio::{Reader, Writer};
use tokio::net::TcpStream;

const READ_LINES: DeserializerConfig =
    DeserializerConfig::builder().trailing(Trailing::Newline).build();
const WRITE_LINES: SerializerConfig =
    SerializerConfig::builder().trailing(Trailing::Newline).build();

#[derive(Serialize, Deserialize)]
struct Request {
    id: u64,
    method: String,
}

async fn serve(socket: TcpStream) -> Result<(), deser::Error> {
    let (input, output) = socket.into_split();
    let mut requests = Reader::new(input, StreamDeserializer::with_config(READ_LINES));
    let mut responses = Writer::new(output, Serializer::with_config(WRITE_LINES));
    while let Some(request) = requests.read::<Request>().await? {
        responses.write(&request.id).await?;
    }
    Ok(())
}

• Works with every format: the stream deserializers of the formats split streams into values and their serializers write them without doing IO (see deser::stream), this crate only does the IO.
• Bounded memory: values of formats that support it (JSON and CBOR) are deserialized while their input arrives, only incomplete tokens are buffered. Values of other formats are buffered one at a time. Values can also borrow from the buffer (Reader::read_borrowed).
• Multi-threaded runtimes: the futures are Send and can be spawned.
• Cancellation safe reads: a read can be used in tokio::select! without losing data.
• Errors refer to the stream: offsets, lines and columns are relative to the start of the stream.
• tokio-util: with the codec feature, Codec works with FramedRead, FramedWrite and Framed.

For blocking IO use deser::io and the formats' from_reader and to_writer functions instead.