70 lines
2.3 KiB
Rust
70 lines
2.3 KiB
Rust
use anyhow::Context;
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use tokio::{
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io::{AsyncBufReadExt, AsyncWriteExt, BufReader},
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net::{tcp::OwnedWriteHalf, TcpStream},
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};
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use tokio_stream::{wrappers::LinesStream, StreamExt};
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use crate::{command, event};
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use super::common::{BoxedStream, NEW_LINE};
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/// [EventStream] is a stream of [event::Event]s sent by the server
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///
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/// # Cancel Safety
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///
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/// This stream is cancel-safe, meaning that it can be used in [tokio::select]
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/// without the risk of missing events.
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pub type EventStream = BoxedStream<anyhow::Result<event::Event>>;
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/// [CommandWriter] is a wrapper around a [TcpStream] which writes [command::UserCommand]s to the server
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pub struct CommandWriter {
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writer: OwnedWriteHalf,
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}
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impl CommandWriter {
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pub fn new(writer: OwnedWriteHalf) -> Self {
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Self { writer }
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}
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/// Send a [command::UserCommand] to the backing [TcpStream]
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///
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/// # Cancel Safety
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///
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/// This method is not cancellation safe. If it is used as the event
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/// in a [tokio::select!] statement and some other
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/// branch completes first, then the provided [command::UserCommand] may have been
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/// partially written, but future calls to `write` will start over
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/// from the beginning of the buffer. Causing undefined behaviour.
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pub async fn write(&mut self, command: &command::UserCommand) -> anyhow::Result<()> {
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let mut serialized_bytes = serde_json::to_vec(command)?;
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serialized_bytes.extend_from_slice(NEW_LINE);
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self.writer.write_all(serialized_bytes.as_slice()).await?;
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Ok(())
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}
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}
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/// Splits a TCP stream into a stream of events and a command writer.
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///
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/// # Arguments
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///
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/// - `stream` - A [TcpStream] to split
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pub fn split_tcp_stream(stream: TcpStream) -> (EventStream, CommandWriter) {
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let (reader, writer) = stream.into_split();
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(
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Box::pin(
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LinesStream::new(BufReader::new(reader).lines()).map(|line| {
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line.context("could not read line from the server")
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.and_then(|line| {
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serde_json::from_str::<event::Event>(&line)
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.context("failed to deserialize event from the server")
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})
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}),
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),
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CommandWriter::new(writer),
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)
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}
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