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// Copyright 2020-2022 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use core::pin::Pin;
use core::task::{Context, Poll};
use crate::connection::State;
use crate::subject::ToSubject;
use crate::{PublishMessage, ServerInfo};
use super::{header::HeaderMap, status::StatusCode, Command, Message, Subscriber};
use crate::error::Error;
use bytes::Bytes;
use futures::future::TryFutureExt;
use futures::{Sink, SinkExt as _, StreamExt};
use once_cell::sync::Lazy;
use portable_atomic::AtomicU64;
use regex::Regex;
use std::fmt::Display;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::time::Duration;
use thiserror::Error;
use tokio::sync::{mpsc, oneshot};
use tokio_util::sync::PollSender;
use tracing::trace;
static VERSION_RE: Lazy<Regex> =
Lazy::new(|| Regex::new(r"\Av?([0-9]+)\.?([0-9]+)?\.?([0-9]+)?").unwrap());
/// An error returned from the [`Client::publish`], [`Client::publish_with_headers`],
/// [`Client::publish_with_reply`] or [`Client::publish_with_reply_and_headers`] functions.
pub type PublishError = Error<PublishErrorKind>;
impl From<tokio::sync::mpsc::error::SendError<Command>> for PublishError {
fn from(err: tokio::sync::mpsc::error::SendError<Command>) -> Self {
PublishError::with_source(PublishErrorKind::Send, err)
}
}
impl From<tokio_util::sync::PollSendError<Command>> for PublishError {
fn from(err: tokio_util::sync::PollSendError<Command>) -> Self {
PublishError::with_source(PublishErrorKind::Send, err)
}
}
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum PublishErrorKind {
MaxPayloadExceeded,
Send,
}
impl Display for PublishErrorKind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
PublishErrorKind::MaxPayloadExceeded => write!(f, "max payload size exceeded"),
PublishErrorKind::Send => write!(f, "failed to send message"),
}
}
}
/// Client is a `Cloneable` handle to NATS connection.
/// Client should not be created directly. Instead, one of two methods can be used:
/// [crate::connect] and [crate::ConnectOptions::connect]
#[derive(Clone, Debug)]
pub struct Client {
info: tokio::sync::watch::Receiver<ServerInfo>,
pub(crate) state: tokio::sync::watch::Receiver<State>,
pub(crate) sender: mpsc::Sender<Command>,
poll_sender: PollSender<Command>,
next_subscription_id: Arc<AtomicU64>,
subscription_capacity: usize,
inbox_prefix: Arc<str>,
request_timeout: Option<Duration>,
max_payload: Arc<AtomicUsize>,
}
impl Sink<PublishMessage> for Client {
type Error = PublishError;
fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.poll_sender.poll_ready_unpin(cx).map_err(Into::into)
}
fn start_send(mut self: Pin<&mut Self>, msg: PublishMessage) -> Result<(), Self::Error> {
self.poll_sender
.start_send_unpin(Command::Publish(msg))
.map_err(Into::into)
}
fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.poll_sender.poll_flush_unpin(cx).map_err(Into::into)
}
fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.poll_sender.poll_close_unpin(cx).map_err(Into::into)
}
}
impl Client {
pub(crate) fn new(
info: tokio::sync::watch::Receiver<ServerInfo>,
state: tokio::sync::watch::Receiver<State>,
sender: mpsc::Sender<Command>,
capacity: usize,
inbox_prefix: String,
request_timeout: Option<Duration>,
max_payload: Arc<AtomicUsize>,
) -> Client {
let poll_sender = PollSender::new(sender.clone());
Client {
info,
state,
sender,
poll_sender,
next_subscription_id: Arc::new(AtomicU64::new(1)),
subscription_capacity: capacity,
inbox_prefix: inbox_prefix.into(),
request_timeout,
max_payload,
}
}
/// Returns last received info from the server.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main () -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// println!("info: {:?}", client.server_info());
/// # Ok(())
/// # }
/// ```
pub fn server_info(&self) -> ServerInfo {
// We ignore notifying the watcher, as that requires mutable client reference.
self.info.borrow().to_owned()
}
/// Returns true if the server version is compatible with the version components.
///
/// This has to be used with caution, as it is not guaranteed that the server
/// that client is connected to is the same version that the one that is
/// a JetStream meta/stream/consumer leader, especially across leafnodes.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// assert!(client.is_server_compatible(2, 8, 4));
/// # Ok(())
/// # }
/// ```
pub fn is_server_compatible(&self, major: i64, minor: i64, patch: i64) -> bool {
let info = self.server_info();
let server_version_captures = match VERSION_RE.captures(&info.version) {
Some(captures) => captures,
None => return false,
};
let server_major = server_version_captures
.get(1)
.map(|m| m.as_str().parse::<i64>().unwrap())
.unwrap();
let server_minor = server_version_captures
.get(2)
.map(|m| m.as_str().parse::<i64>().unwrap())
.unwrap();
let server_patch = server_version_captures
.get(3)
.map(|m| m.as_str().parse::<i64>().unwrap())
.unwrap();
if server_major < major
|| (server_major == major && server_minor < minor)
|| (server_major == major && server_minor == minor && server_patch < patch)
{
return false;
}
true
}
/// Publish a [Message] to a given subject.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// client.publish("events.data", "payload".into()).await?;
/// # Ok(())
/// # }
/// ```
pub async fn publish<S: ToSubject>(
&self,
subject: S,
payload: Bytes,
) -> Result<(), PublishError> {
let subject = subject.to_subject();
let max_payload = self.max_payload.load(Ordering::Relaxed);
if payload.len() > max_payload {
return Err(PublishError::with_source(
PublishErrorKind::MaxPayloadExceeded,
format!(
"Payload size limit of {} exceeded by message size of {}",
payload.len(),
max_payload
),
));
}
self.sender
.send(Command::Publish(PublishMessage {
subject,
payload,
reply: None,
headers: None,
}))
.await?;
Ok(())
}
/// Publish a [Message] with headers to a given subject.
///
/// # Examples
/// ```
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use std::str::FromStr;
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut headers = async_nats::HeaderMap::new();
/// headers.insert(
/// "X-Header",
/// async_nats::HeaderValue::from_str("Value").unwrap(),
/// );
/// client
/// .publish_with_headers("events.data", headers, "payload".into())
/// .await?;
/// # Ok(())
/// # }
/// ```
pub async fn publish_with_headers<S: ToSubject>(
&self,
subject: S,
headers: HeaderMap,
payload: Bytes,
) -> Result<(), PublishError> {
let subject = subject.to_subject();
self.sender
.send(Command::Publish(PublishMessage {
subject,
payload,
reply: None,
headers: Some(headers),
}))
.await?;
Ok(())
}
/// Publish a [Message] to a given subject, with specified response subject
/// to which the subscriber can respond.
/// This method does not await for the response.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// client
/// .publish_with_reply("events.data", "reply_subject", "payload".into())
/// .await?;
/// # Ok(())
/// # }
/// ```
pub async fn publish_with_reply<S: ToSubject, R: ToSubject>(
&self,
subject: S,
reply: R,
payload: Bytes,
) -> Result<(), PublishError> {
let subject = subject.to_subject();
let reply = reply.to_subject();
self.sender
.send(Command::Publish(PublishMessage {
subject,
payload,
reply: Some(reply),
headers: None,
}))
.await?;
Ok(())
}
/// Publish a [Message] to a given subject with headers and specified response subject
/// to which the subscriber can respond.
/// This method does not await for the response.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use std::str::FromStr;
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut headers = async_nats::HeaderMap::new();
/// client
/// .publish_with_reply_and_headers("events.data", "reply_subject", headers, "payload".into())
/// .await?;
/// # Ok(())
/// # }
/// ```
pub async fn publish_with_reply_and_headers<S: ToSubject, R: ToSubject>(
&self,
subject: S,
reply: R,
headers: HeaderMap,
payload: Bytes,
) -> Result<(), PublishError> {
let subject = subject.to_subject();
let reply = reply.to_subject();
self.sender
.send(Command::Publish(PublishMessage {
subject,
payload,
reply: Some(reply),
headers: Some(headers),
}))
.await?;
Ok(())
}
/// Sends the request with headers.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let response = client.request("service", "data".into()).await?;
/// # Ok(())
/// # }
/// ```
pub async fn request<S: ToSubject>(
&self,
subject: S,
payload: Bytes,
) -> Result<Message, RequestError> {
let subject = subject.to_subject();
trace!(
"request sent to subject: {} ({})",
subject.as_ref(),
payload.len()
);
let request = Request::new().payload(payload);
self.send_request(subject, request).await
}
/// Sends the request with headers.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut headers = async_nats::HeaderMap::new();
/// headers.insert("Key", "Value");
/// let response = client
/// .request_with_headers("service", headers, "data".into())
/// .await?;
/// # Ok(())
/// # }
/// ```
pub async fn request_with_headers<S: ToSubject>(
&self,
subject: S,
headers: HeaderMap,
payload: Bytes,
) -> Result<Message, RequestError> {
let subject = subject.to_subject();
let request = Request::new().headers(headers).payload(payload);
self.send_request(subject, request).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", request).await?;
/// # Ok(())
/// # }
/// ```
pub async fn send_request<S: ToSubject>(
&self,
subject: S,
request: Request,
) -> Result<Message, RequestError> {
let subject = subject.to_subject();
if let Some(inbox) = request.inbox {
let timeout = request.timeout.unwrap_or(self.request_timeout);
let mut subscriber = self.subscribe(inbox.clone()).await?;
let payload: Bytes = request.payload.unwrap_or_default();
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?,
}
let request = match timeout {
Some(timeout) => {
tokio::time::timeout(timeout, subscriber.next())
.map_err(|err| RequestError::with_source(RequestErrorKind::TimedOut, err))
.await?
}
None => subscriber.next().await,
};
match request {
Some(message) => {
if message.status == Some(StatusCode::NO_RESPONDERS) {
return Err(RequestError::with_source(
RequestErrorKind::NoResponders,
"no responders",
));
}
Ok(message)
}
None => Err(RequestError::with_source(
RequestErrorKind::Other,
"broken pipe",
)),
}
} else {
let (sender, receiver) = oneshot::channel();
let payload = request.payload.unwrap_or_default();
let respond = self.new_inbox().into();
let headers = request.headers;
self.sender
.send(Command::Request {
subject,
payload,
respond,
headers,
sender,
})
.map_err(|err| RequestError::with_source(RequestErrorKind::Other, err))
.await?;
let timeout = request.timeout.unwrap_or(self.request_timeout);
let request = match timeout {
Some(timeout) => {
tokio::time::timeout(timeout, receiver)
.map_err(|err| RequestError::with_source(RequestErrorKind::TimedOut, err))
.await?
}
None => receiver.await,
};
match request {
Ok(message) => {
if message.status == Some(StatusCode::NO_RESPONDERS) {
return Err(RequestError::with_source(
RequestErrorKind::NoResponders,
"no responders",
));
}
Ok(message)
}
Err(err) => Err(RequestError::with_source(RequestErrorKind::Other, err)),
}
}
}
/// Create a new globally unique inbox which can be used for replies.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// # let mut nc = async_nats::connect("demo.nats.io").await?;
/// let reply = nc.new_inbox();
/// let rsub = nc.subscribe(reply).await?;
/// # Ok(())
/// # }
/// ```
pub fn new_inbox(&self) -> String {
format!("{}.{}", self.inbox_prefix, nuid::next())
}
/// Subscribes to a subject to receive [messages][Message].
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use futures::StreamExt;
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut subscription = client.subscribe("events.>").await?;
/// while let Some(message) = subscription.next().await {
/// println!("received message: {:?}", message);
/// }
/// # Ok(())
/// # }
/// ```
pub async fn subscribe<S: ToSubject>(&self, subject: S) -> Result<Subscriber, SubscribeError> {
let subject = subject.to_subject();
let sid = self.next_subscription_id.fetch_add(1, Ordering::Relaxed);
let (sender, receiver) = mpsc::channel(self.subscription_capacity);
self.sender
.send(Command::Subscribe {
sid,
subject,
queue_group: None,
sender,
})
.await?;
Ok(Subscriber::new(sid, self.sender.clone(), receiver))
}
/// Subscribes to a subject with a queue group to receive [messages][Message].
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use futures::StreamExt;
/// let client = async_nats::connect("demo.nats.io").await?;
/// let mut subscription = client.queue_subscribe("events.>", "queue".into()).await?;
/// while let Some(message) = subscription.next().await {
/// println!("received message: {:?}", message);
/// }
/// # Ok(())
/// # }
/// ```
pub async fn queue_subscribe<S: ToSubject>(
&self,
subject: S,
queue_group: String,
) -> Result<Subscriber, SubscribeError> {
let subject = subject.to_subject();
let sid = self.next_subscription_id.fetch_add(1, Ordering::Relaxed);
let (sender, receiver) = mpsc::channel(self.subscription_capacity);
self.sender
.send(Command::Subscribe {
sid,
subject,
queue_group: Some(queue_group),
sender,
})
.await?;
Ok(Subscriber::new(sid, self.sender.clone(), receiver))
}
/// Flushes the internal buffer ensuring that all messages are sent.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// client.flush().await?;
/// # Ok(())
/// # }
/// ```
pub async fn flush(&self) -> Result<(), FlushError> {
let (tx, rx) = tokio::sync::oneshot::channel();
self.sender
.send(Command::Flush { observer: tx })
.await
.map_err(|err| FlushError::with_source(FlushErrorKind::SendError, err))?;
rx.await
.map_err(|err| FlushError::with_source(FlushErrorKind::FlushError, err))?;
Ok(())
}
/// Returns the current state of the connection.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// println!("connection state: {}", client.connection_state());
/// # Ok(())
/// # }
/// ```
pub fn connection_state(&self) -> State {
self.state.borrow().to_owned()
}
/// Forces the client to reconnect.
/// Keep in mind that client will reconnect automatically if the connection is lost and this
/// method does not have to be used in normal circumstances.
/// However, if you want to force the client to reconnect, for example to re-trigger
/// the `auth-callback`, or manually rebalance connections, this method can be useful.
/// This method does not wait for connection to be re-established.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
/// client.force_reconnect().await?;
/// # Ok(())
/// # }
/// ```
pub async fn force_reconnect(&self) -> Result<(), ReconnectError> {
self.sender
.send(Command::Reconnect)
.await
.map_err(Into::into)
}
}
/// Used for building customized requests.
#[derive(Default)]
pub struct Request {
payload: Option<Bytes>,
headers: Option<HeaderMap>,
timeout: Option<Option<Duration>>,
inbox: Option<String>,
}
impl Request {
pub fn new() -> Request {
Default::default()
}
/// Sets the payload of the request. If not used, empty payload will be sent.
///
/// # 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());
/// client.send_request("service", request).await?;
/// # Ok(())
/// # }
/// ```
pub fn payload(mut self, payload: Bytes) -> Request {
self.payload = Some(payload);
self
}
/// Sets the headers of the requests.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use std::str::FromStr;
/// 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()
/// .headers(headers)
/// .payload("data".into());
/// client.send_request("service", request).await?;
/// # Ok(())
/// # }
/// ```
pub fn headers(mut self, headers: HeaderMap) -> Request {
self.headers = Some(headers);
self
}
/// Sets the custom timeout of the request. Overrides default [Client] timeout.
/// Setting it to [Option::None] disables the timeout entirely which might result in deadlock.
/// To use default timeout, simply do not call this function.
///
/// # 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()
/// .timeout(Some(std::time::Duration::from_secs(15)))
/// .payload("data".into());
/// client.send_request("service", request).await?;
/// # Ok(())
/// # }
/// ```
pub fn timeout(mut self, timeout: Option<Duration>) -> Request {
self.timeout = Some(timeout);
self
}
/// Sets custom inbox for this request. Overrides both customized and default [Client] Inbox.
///
/// # Examples
/// ```no_run
/// # #[tokio::main]
/// # 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()
/// .inbox("custom_inbox".into())
/// .payload("data".into());
/// client.send_request("service", request).await?;
/// # Ok(())
/// # }
/// ```
pub fn inbox(mut self, inbox: String) -> Request {
self.inbox = Some(inbox);
self
}
}
#[derive(Error, Debug)]
#[error("failed to send reconnect: {0}")]
pub struct ReconnectError(#[source] crate::Error);
impl From<tokio::sync::mpsc::error::SendError<Command>> for ReconnectError {
fn from(err: tokio::sync::mpsc::error::SendError<Command>) -> Self {
ReconnectError(Box::new(err))
}
}
#[derive(Error, Debug)]
#[error("failed to send subscribe: {0}")]
pub struct SubscribeError(#[source] crate::Error);
impl From<tokio::sync::mpsc::error::SendError<Command>> for SubscribeError {
fn from(err: tokio::sync::mpsc::error::SendError<Command>) -> Self {
SubscribeError(Box::new(err))
}
}
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum RequestErrorKind {
/// There are services listening on requested subject, but they didn't respond
/// in time.
TimedOut,
/// No one is listening on request subject.
NoResponders,
/// Other errors, client/io related.
Other,
}
impl Display for RequestErrorKind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::TimedOut => write!(f, "request timed out"),
Self::NoResponders => write!(f, "no responders"),
Self::Other => write!(f, "request failed"),
}
}
}
/// Error returned when a core NATS request fails.
/// To be enumerate over the variants, call [RequestError::kind].
pub type RequestError = Error<RequestErrorKind>;
impl From<PublishError> for RequestError {
fn from(e: PublishError) -> Self {
RequestError::with_source(RequestErrorKind::Other, e)
}
}
impl From<SubscribeError> for RequestError {
fn from(e: SubscribeError) -> Self {
RequestError::with_source(RequestErrorKind::Other, e)
}
}
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum FlushErrorKind {
/// Sending the flush failed client side.
SendError,
/// Flush failed.
/// This can happen mostly in case of connection issues
/// that cannot be resolved quickly.
FlushError,
}
impl Display for FlushErrorKind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::SendError => write!(f, "failed to send flush request"),
Self::FlushError => write!(f, "flush failed"),
}
}
}
pub type FlushError = Error<FlushErrorKind>;