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Make use of ìnto_future` for requests and messages #782

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Make use of ìnto_future` for requests and messages #782

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c56ac94
Make `Client::publish` return `IntoFuture` builder
caspervonb Dec 1, 2022
e1a30bc
Make `client::request` return an `into_future` based builder
caspervonb Dec 23, 2022
4410ab5
Make `Context::publish` return `IntoFuture` builder
caspervonb Feb 21, 2023
b52bfbf
Make `Context::request` return `IntoFuture` builder
n1ghtmare Feb 22, 2023
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258 changes: 149 additions & 109 deletions async-nats/src/client.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,12 +22,13 @@ use lazy_static::lazy_static;
use regex::Regex;
use std::error;
use std::fmt;
use std::future::{Future, IntoFuture};
use std::pin::Pin;
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::Arc;
use std::time::Duration;
use tokio::io::{self, ErrorKind};
use tokio::sync::mpsc;
use tracing::trace;

lazy_static! {
static ref VERSION_RE: Regex = Regex::new(r#"\Av?([0-9]+)\.?([0-9]+)?\.?([0-9]+)?"#).unwrap();
Expand All @@ -37,6 +38,63 @@ lazy_static! {
/// [`Client::publish_with_reply`] or [`Client::publish_with_reply_and_headers`] functions.
pub struct PublishError(mpsc::error::SendError<Command>);

pub struct Publish {
sender: mpsc::Sender<Command>,
subject: String,
payload: Bytes,
headers: Option<HeaderMap>,
respond: Option<String>,
}

impl Publish {
pub fn new(sender: mpsc::Sender<Command>, subject: String, payload: Bytes) -> Publish {
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Contributor

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Does this need to be public?

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It does not.

Publish {
sender,
subject,
payload,
headers: None,
respond: None,
}
}

pub fn headers(mut self, headers: HeaderMap) -> Publish {
self.headers = Some(headers);
self
}

pub fn reply(mut self, subject: String) -> Publish {
self.respond = Some(subject);
self
}
}

impl IntoFuture for Publish {
type Output = Result<(), PublishError>;
type IntoFuture = Pin<Box<dyn Future<Output = Result<(), PublishError>> + Send>>;

fn into_future(self) -> Self::IntoFuture {
let sender = self.sender.clone();
let subject = self.subject;
let payload = self.payload;
let respond = self.respond;
let headers = self.headers;

Box::pin(async move {
sender
.send(Command::Publish {
subject,
payload,
respond,
headers,
})
.map_err(PublishError)
.await?;

Ok(())
})
}
}

impl fmt::Debug for PublishError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("PublishError").finish_non_exhaustive()
Expand Down Expand Up @@ -154,17 +212,8 @@ impl Client {
/// # Ok(())
/// # }
/// ```
pub async fn publish(&self, subject: String, payload: Bytes) -> Result<(), PublishError> {
self.sender
.send(Command::Publish {
subject,
payload,
respond: None,
headers: None,
})
.map_err(PublishError)
.await?;
Ok(())
pub fn publish(&self, subject: String, payload: Bytes) -> Publish {
Publish::new(self.sender.clone(), subject, payload)
}

/// Publish a [Message] with headers to a given subject.
Expand All @@ -187,15 +236,8 @@ impl Client {
headers: HeaderMap,
payload: Bytes,
) -> Result<(), PublishError> {
self.sender
.send(Command::Publish {
subject,
payload,
respond: None,
headers: Some(headers),
})
.map_err(PublishError)
.await?;
self.publish(subject, payload).headers(headers).await?;

Ok(())
}

Expand All @@ -219,15 +261,8 @@ impl Client {
reply: String,
payload: Bytes,
) -> Result<(), PublishError> {
self.sender
.send(Command::Publish {
subject,
payload,
respond: Some(reply),
headers: None,
})
.map_err(PublishError)
.await?;
self.publish(subject, payload).reply(reply).await?;

Ok(())
}

Expand All @@ -254,15 +289,11 @@ impl Client {
headers: HeaderMap,
payload: Bytes,
) -> Result<(), PublishError> {
self.sender
.send(Command::Publish {
subject,
payload,
respond: Some(reply),
headers: Some(headers),
})
.map_err(PublishError)
self.publish(subject, payload)
.headers(headers)
.reply(reply)
.await?;

Ok(())
}

Expand All @@ -278,10 +309,8 @@ impl Client {
/// # Ok(())
/// # }
/// ```
pub async fn request(&self, subject: String, payload: Bytes) -> Result<Message, Error> {
trace!("request sent to subject: {} ({})", subject, payload.len());
let request = Request::new().payload(payload);
self.send_request(subject, request).await
pub fn request(&self, subject: String, payload: Bytes) -> Request {
Request::new(self.clone(), subject, payload)
}

/// Sends the request with headers.
Expand All @@ -304,59 +333,11 @@ impl Client {
headers: HeaderMap,
payload: Bytes,
) -> Result<Message, Error> {
let request = Request::new().headers(headers).payload(payload);
self.send_request(subject, request).await
}
let message = Request::new(self.clone(), subject, payload)
.headers(headers)
.await?;

/// Sends the request created by the [Request].
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let request = async_nats::Request::new().payload("data".into());
/// let response = client.send_request("service".into(), request).await?;
/// # Ok(())
/// # }
/// ```
pub async fn send_request(&self, subject: String, request: Request) -> Result<Message, Error> {
let inbox = request.inbox.unwrap_or_else(|| self.new_inbox());
let timeout = request.timeout.unwrap_or(self.request_timeout);
let mut sub = self.subscribe(inbox.clone()).await?;
let payload: Bytes = request.payload.unwrap_or_else(Bytes::new);
match request.headers {
Some(headers) => {
self.publish_with_reply_and_headers(subject, inbox, headers, payload)
.await?
}
None => self.publish_with_reply(subject, inbox, payload).await?,
}
self.flush().await?;
let request = match timeout {
Some(timeout) => {
tokio::time::timeout(timeout, sub.next())
.map_err(|_| std::io::Error::new(ErrorKind::TimedOut, "request timed out"))
.await?
}
None => sub.next().await,
};
match request {
Some(message) => {
if message.status == Some(StatusCode::NO_RESPONDERS) {
return Err(Box::new(std::io::Error::new(
ErrorKind::NotFound,
"nats: no responders",
)));
}
Ok(message)
}
None => Err(Box::new(io::Error::new(
ErrorKind::BrokenPipe,
"did not receive any message",
))),
}
Ok(message)
}

/// Create a new globally unique inbox which can be used for replies.
Expand Down Expand Up @@ -480,18 +461,27 @@ impl Client {
}
}

/// Used for building customized requests.
#[derive(Default)]
/// Used for building and sending requests.
#[derive(Debug)]
pub struct Request {
client: Client,
subject: String,
payload: Option<Bytes>,
headers: Option<HeaderMap>,
timeout: Option<Option<Duration>>,
inbox: Option<String>,
}

impl Request {
pub fn new() -> Request {
Default::default()
pub fn new(client: Client, subject: String, payload: Bytes) -> Request {
Request {
client,
subject,
payload: Some(payload),
headers: None,
timeout: None,
inbox: None,
}
}

/// Sets the payload of the request. If not used, empty payload will be sent.
Expand All @@ -501,8 +491,7 @@ impl Request {
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let request = async_nats::Request::new().payload("data".into());
/// client.send_request("service".into(), request).await?;
/// client.request("subject".into(), "data".into()).await?;
/// # Ok(())
/// # }
/// ```
Expand All @@ -521,10 +510,11 @@ impl Request {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut headers = async_nats::HeaderMap::new();
/// headers.insert("X-Example", async_nats::HeaderValue::from_str("Value").unwrap());
/// let request = async_nats::Request::new()
///
/// client.request("subject".into(), "payload".into())
/// .headers(headers)
/// .payload("data".into());
/// client.send_request("service".into(), request).await?;
/// .await?;
///
/// # Ok(())
/// # }
/// ```
Expand All @@ -542,10 +532,10 @@ impl Request {
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let request = async_nats::Request::new()
/// client.request("service".into(), "data".into())
/// .timeout(Some(std::time::Duration::from_secs(15)))
/// .payload("data".into());
/// client.send_request("service".into(), request).await?;
/// .await?;
///
/// # Ok(())
/// # }
/// ```
Expand All @@ -562,15 +552,65 @@ impl Request {
/// # async fn main() -> Result<(), async_nats::Error> {
/// use std::str::FromStr;
/// let client = async_nats::connect("demo.nats.io").await?;
/// let request = async_nats::Request::new()
/// client.request("subject".into(), "payload".into())
/// .inbox("custom_inbox".into())
/// .payload("data".into());
/// client.send_request("service".into(), request).await?;
/// .await?;
/// # Ok(())
/// # }
/// ```
pub fn inbox(mut self, inbox: String) -> Request {
self.inbox = Some(inbox);
self
}

async fn send(self) -> Result<Message, Error> {
let inbox = self.inbox.unwrap_or_else(|| self.client.new_inbox());
let mut subscriber = self.client.subscribe(inbox.clone()).await?;
let mut publish = self
.client
.publish(self.subject, self.payload.unwrap_or_else(Bytes::new));
if let Some(headers) = self.headers {
publish = publish.headers(headers);
}

publish = publish.reply(inbox);
publish.into_future().await?;

self.client.flush().await?;

let period = self.timeout.unwrap_or(self.client.request_timeout);
let message = match period {
Some(period) => {
tokio::time::timeout(period, subscriber.next())
.map_err(|_| std::io::Error::new(ErrorKind::TimedOut, "request timed out"))
.await?
}
None => subscriber.next().await,
};

match message {
Some(message) => {
if message.status == Some(StatusCode::NO_RESPONDERS) {
return Err(Box::new(std::io::Error::new(
ErrorKind::NotFound,
"nats: no responders",
)));
}
Ok(message)
}
None => Err(Box::new(io::Error::new(
ErrorKind::BrokenPipe,
"did not receive any message",
))),
}
}
}

impl IntoFuture for Request {
type Output = Result<Message, Error>;
type IntoFuture = Pin<Box<dyn Future<Output = Result<Message, Error>> + Send>>;

fn into_future(self) -> Self::IntoFuture {
Box::pin(self.send())
}
}
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