async_nats/lib.rs
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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.
//! A Rust asynchronous client for the NATS.io ecosystem.
//!
//! To access the repository, you can clone it by running:
//!
//! ```bash
//! git clone https://github.com/nats-io/nats.rs
//! ````
//! NATS.io is a simple, secure, and high-performance open-source messaging
//! system designed for cloud-native applications, IoT messaging, and microservices
//! architectures.
//!
//! **Note**: The synchronous NATS API is deprecated and no longer actively maintained. If you need to use the deprecated synchronous API, you can refer to:
//! <https://crates.io/crates/nats>
//!
//! For more information on NATS.io visit: <https://nats.io>
//!
//! ## Examples
//!
//! Below, you can find some basic examples on how to use this library.
//!
//! For more details, please refer to the specific methods and structures documentation.
//!
//! ### Complete example
//!
//! Connect to the NATS server, publish messages and subscribe to receive messages.
//!
//! ```no_run
//! use bytes::Bytes;
//! use futures::StreamExt;
//!
//! #[tokio::main]
//! async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//!
//! // Subscribe to the "messages" subject
//! let mut subscriber = client.subscribe("messages").await?;
//!
//! // Publish messages to the "messages" subject
//! for _ in 0..10 {
//! client.publish("messages", "data".into()).await?;
//! }
//!
//! // Receive and process messages
//! while let Some(message) = subscriber.next().await {
//! println!("Received message {:?}", message);
//! }
//!
//! Ok(())
//! }
//! ```
//!
//! ### Publish
//!
//! Connect to the NATS server and publish messages to a subject.
//!
//! ```
//! # use bytes::Bytes;
//! # use std::error::Error;
//! # use std::time::Instant;
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//!
//! // Prepare the subject and data
//! let subject = "foo";
//! let data = Bytes::from("bar");
//!
//! // Publish messages to the NATS server
//! for _ in 0..10 {
//! client.publish(subject, data.clone()).await?;
//! }
//!
//! // Flush internal buffer before exiting to make sure all messages are sent
//! client.flush().await?;
//!
//! # Ok(())
//! # }
//! ```
//!
//! ### Subscribe
//!
//! Connect to the NATS server, subscribe to a subject and receive messages.
//!
//! ```no_run
//! # use bytes::Bytes;
//! # use futures::StreamExt;
//! # use std::error::Error;
//! # use std::time::Instant;
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//!
//! // Subscribe to the "foo" subject
//! let mut subscriber = client.subscribe("foo").await.unwrap();
//!
//! // Receive and process messages
//! while let Some(message) = subscriber.next().await {
//! println!("Received message {:?}", message);
//! }
//! # Ok(())
//! # }
//! ```
//!
//! ### JetStream
//!
//! To access JetStream API, create a JetStream [jetstream::Context].
//!
//! ```no_run
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//! // Create a JetStream context.
//! let jetstream = async_nats::jetstream::new(client);
//!
//! // Publish JetStream messages, manage streams, consumers, etc.
//! jetstream.publish("foo", "bar".into()).await?;
//! # Ok(())
//! # }
//! ```
//!
//! ### Key-value Store
//!
//! Key-value [Store][jetstream::kv::Store] is accessed through [jetstream::Context].
//!
//! ```no_run
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//! // Create a JetStream context.
//! let jetstream = async_nats::jetstream::new(client);
//! // Access an existing key-value.
//! let kv = jetstream.get_key_value("store").await?;
//! # Ok(())
//! # }
//! ```
//! ### Object Store store
//!
//! Object [Store][jetstream::object_store::ObjectStore] is accessed through [jetstream::Context].
//!
//! ```no_run
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//! // Create a JetStream context.
//! let jetstream = async_nats::jetstream::new(client);
//! // Access an existing key-value.
//! let kv = jetstream.get_object_store("store").await?;
//! # Ok(())
//! # }
//! ```
//! ### Service API
//!
//! [Service API][service::Service] is accessible through [Client] after importing its trait.
//!
//! ```no_run
//! # #[tokio::main]
//! # async fn main() -> Result<(), async_nats::Error> {
//! use async_nats::service::ServiceExt;
//! // Connect to the NATS server
//! let client = async_nats::connect("demo.nats.io").await?;
//! let mut service = client
//! .service_builder()
//! .description("some service")
//! .stats_handler(|endpoint, stats| serde_json::json!({ "endpoint": endpoint }))
//! .start("products", "1.0.0")
//! .await?;
//! # Ok(())
//! # }
//! ```
#![deny(unreachable_pub)]
#![deny(rustdoc::broken_intra_doc_links)]
#![deny(rustdoc::private_intra_doc_links)]
#![deny(rustdoc::invalid_codeblock_attributes)]
#![deny(rustdoc::invalid_rust_codeblocks)]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
use thiserror::Error;
use futures::stream::Stream;
use tokio::io::AsyncWriteExt;
use tokio::sync::oneshot;
use tracing::{debug, error};
use core::fmt;
use std::collections::HashMap;
use std::fmt::Display;
use std::future::Future;
use std::iter;
use std::mem;
use std::net::SocketAddr;
use std::option;
use std::pin::Pin;
use std::slice;
use std::str::{self, FromStr};
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::Ordering;
use std::sync::Arc;
use std::task::{Context, Poll};
use tokio::io::ErrorKind;
use tokio::time::{interval, Duration, Interval, MissedTickBehavior};
use url::{Host, Url};
use bytes::Bytes;
use serde::{Deserialize, Serialize};
use serde_repr::{Deserialize_repr, Serialize_repr};
use tokio::io;
use tokio::sync::mpsc;
use tokio::task;
pub type Error = Box<dyn std::error::Error + Send + Sync + 'static>;
const VERSION: &str = env!("CARGO_PKG_VERSION");
const LANG: &str = "rust";
const MAX_PENDING_PINGS: usize = 2;
const MULTIPLEXER_SID: u64 = 0;
/// A re-export of the `rustls` crate used in this crate,
/// for use in cases where manual client configurations
/// must be provided using `Options::tls_client_config`.
pub use tokio_rustls::rustls;
use connection::{Connection, State};
use connector::{Connector, ConnectorOptions};
pub use header::{HeaderMap, HeaderName, HeaderValue};
pub use subject::Subject;
mod auth;
pub(crate) mod auth_utils;
pub mod client;
pub mod connection;
mod connector;
mod options;
pub use auth::Auth;
pub use client::{
Client, PublishError, Request, RequestError, RequestErrorKind, Statistics, SubscribeError,
};
pub use options::{AuthError, ConnectOptions};
mod crypto;
pub mod error;
pub mod header;
pub mod jetstream;
pub mod message;
#[cfg(feature = "service")]
pub mod service;
pub mod status;
pub mod subject;
mod tls;
pub use message::Message;
pub use status::StatusCode;
/// Information sent by the server back to this client
/// during initial connection, and possibly again later.
#[derive(Debug, Deserialize, Default, Clone, Eq, PartialEq)]
pub struct ServerInfo {
/// The unique identifier of the NATS server.
#[serde(default)]
pub server_id: String,
/// Generated Server Name.
#[serde(default)]
pub server_name: String,
/// The host specified in the cluster parameter/options.
#[serde(default)]
pub host: String,
/// The port number specified in the cluster parameter/options.
#[serde(default)]
pub port: u16,
/// The version of the NATS server.
#[serde(default)]
pub version: String,
/// If this is set, then the server should try to authenticate upon
/// connect.
#[serde(default)]
pub auth_required: bool,
/// If this is set, then the server must authenticate using TLS.
#[serde(default)]
pub tls_required: bool,
/// Maximum payload size that the server will accept.
#[serde(default)]
pub max_payload: usize,
/// The protocol version in use.
#[serde(default)]
pub proto: i8,
/// The server-assigned client ID. This may change during reconnection.
#[serde(default)]
pub client_id: u64,
/// The version of golang the NATS server was built with.
#[serde(default)]
pub go: String,
/// The nonce used for nkeys.
#[serde(default)]
pub nonce: String,
/// A list of server urls that a client can connect to.
#[serde(default)]
pub connect_urls: Vec<String>,
/// The client IP as known by the server.
#[serde(default)]
pub client_ip: String,
/// Whether the server supports headers.
#[serde(default)]
pub headers: bool,
/// Whether server goes into lame duck mode.
#[serde(default, rename = "ldm")]
pub lame_duck_mode: bool,
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub(crate) enum ServerOp {
Ok,
Info(Box<ServerInfo>),
Ping,
Pong,
Error(ServerError),
Message {
sid: u64,
subject: Subject,
reply: Option<Subject>,
payload: Bytes,
headers: Option<HeaderMap>,
status: Option<StatusCode>,
description: Option<String>,
length: usize,
},
}
/// `PublishMessage` represents a message being published
#[derive(Debug)]
pub struct PublishMessage {
pub subject: Subject,
pub payload: Bytes,
pub reply: Option<Subject>,
pub headers: Option<HeaderMap>,
}
/// `Command` represents all commands that a [`Client`] can handle
#[derive(Debug)]
pub(crate) enum Command {
Publish(PublishMessage),
Request {
subject: Subject,
payload: Bytes,
respond: Subject,
headers: Option<HeaderMap>,
sender: oneshot::Sender<Message>,
},
Subscribe {
sid: u64,
subject: Subject,
queue_group: Option<String>,
sender: mpsc::Sender<Message>,
},
Unsubscribe {
sid: u64,
max: Option<u64>,
},
Flush {
observer: oneshot::Sender<()>,
},
Reconnect,
}
/// `ClientOp` represents all actions of `Client`.
#[derive(Debug)]
pub(crate) enum ClientOp {
Publish {
subject: Subject,
payload: Bytes,
respond: Option<Subject>,
headers: Option<HeaderMap>,
},
Subscribe {
sid: u64,
subject: Subject,
queue_group: Option<String>,
},
Unsubscribe {
sid: u64,
max: Option<u64>,
},
Ping,
Pong,
Connect(ConnectInfo),
}
#[derive(Debug)]
struct Subscription {
subject: Subject,
sender: mpsc::Sender<Message>,
queue_group: Option<String>,
delivered: u64,
max: Option<u64>,
}
#[derive(Debug)]
struct Multiplexer {
subject: Subject,
prefix: Subject,
senders: HashMap<String, oneshot::Sender<Message>>,
}
/// A connection handler which facilitates communication from channels to a single shared connection.
pub(crate) struct ConnectionHandler {
connection: Connection,
connector: Connector,
subscriptions: HashMap<u64, Subscription>,
multiplexer: Option<Multiplexer>,
pending_pings: usize,
info_sender: tokio::sync::watch::Sender<ServerInfo>,
ping_interval: Interval,
should_reconnect: bool,
flush_observers: Vec<oneshot::Sender<()>>,
}
impl ConnectionHandler {
pub(crate) fn new(
connection: Connection,
connector: Connector,
info_sender: tokio::sync::watch::Sender<ServerInfo>,
ping_period: Duration,
) -> ConnectionHandler {
let mut ping_interval = interval(ping_period);
ping_interval.set_missed_tick_behavior(MissedTickBehavior::Delay);
ConnectionHandler {
connection,
connector,
subscriptions: HashMap::new(),
multiplexer: None,
pending_pings: 0,
info_sender,
ping_interval,
should_reconnect: false,
flush_observers: Vec::new(),
}
}
pub(crate) async fn process<'a>(&'a mut self, receiver: &'a mut mpsc::Receiver<Command>) {
struct ProcessFut<'a> {
handler: &'a mut ConnectionHandler,
receiver: &'a mut mpsc::Receiver<Command>,
recv_buf: &'a mut Vec<Command>,
}
enum ExitReason {
Disconnected(Option<io::Error>),
ReconnectRequested,
Closed,
}
impl<'a> ProcessFut<'a> {
const RECV_CHUNK_SIZE: usize = 16;
#[cold]
fn ping(&mut self) -> Poll<ExitReason> {
self.handler.pending_pings += 1;
if self.handler.pending_pings > MAX_PENDING_PINGS {
debug!(
"pending pings {}, max pings {}. disconnecting",
self.handler.pending_pings, MAX_PENDING_PINGS
);
Poll::Ready(ExitReason::Disconnected(None))
} else {
self.handler.connection.enqueue_write_op(&ClientOp::Ping);
Poll::Pending
}
}
}
impl<'a> Future for ProcessFut<'a> {
type Output = ExitReason;
/// Drives the connection forward.
///
/// Returns one of the following:
///
/// * `Poll::Pending` means that the connection
/// is blocked on all fronts or there are
/// no commands to send or receive
/// * `Poll::Ready(ExitReason::Disconnected(_))` means
/// that an I/O operation failed and the connection
/// is considered dead.
/// * `Poll::Ready(ExitReason::Closed)` means that
/// [`Self::receiver`] was closed, so there's nothing
/// more for us to do than to exit the client.
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
// We need to be sure the waker is registered, therefore we need to poll until we
// get a `Poll::Pending`. With a sane interval delay, this means that the loop
// breaks at the second iteration.
while self.handler.ping_interval.poll_tick(cx).is_ready() {
if let Poll::Ready(exit) = self.ping() {
return Poll::Ready(exit);
}
}
loop {
match self.handler.connection.poll_read_op(cx) {
Poll::Pending => break,
Poll::Ready(Ok(Some(server_op))) => {
self.handler.handle_server_op(server_op);
}
Poll::Ready(Ok(None)) => {
return Poll::Ready(ExitReason::Disconnected(None))
}
Poll::Ready(Err(err)) => {
return Poll::Ready(ExitReason::Disconnected(Some(err)))
}
}
}
// WARNING: after the following loop `handle_command`,
// or other functions which call `enqueue_write_op`,
// cannot be called anymore. Runtime wakeups won't
// trigger a call to `poll_write`
let mut made_progress = true;
loop {
while !self.handler.connection.is_write_buf_full() {
debug_assert!(self.recv_buf.is_empty());
let Self {
recv_buf,
handler,
receiver,
} = &mut *self;
match receiver.poll_recv_many(cx, recv_buf, Self::RECV_CHUNK_SIZE) {
Poll::Pending => break,
Poll::Ready(1..) => {
made_progress = true;
for cmd in recv_buf.drain(..) {
handler.handle_command(cmd);
}
}
// TODO: replace `_` with `0` after bumping MSRV to 1.75
Poll::Ready(_) => return Poll::Ready(ExitReason::Closed),
}
}
// The first round will poll both from
// the `receiver` and the writer, giving
// them both a chance to make progress
// and register `Waker`s.
//
// If writing is `Poll::Pending` we exit.
//
// If writing is completed we can repeat the entire
// cycle as long as the `receiver` doesn't end-up
// `Poll::Pending` immediately.
if !mem::take(&mut made_progress) {
break;
}
match self.handler.connection.poll_write(cx) {
Poll::Pending => {
// Write buffer couldn't be fully emptied
break;
}
Poll::Ready(Ok(())) => {
// Write buffer is empty
continue;
}
Poll::Ready(Err(err)) => {
return Poll::Ready(ExitReason::Disconnected(Some(err)))
}
}
}
if let (ShouldFlush::Yes, _) | (ShouldFlush::No, false) = (
self.handler.connection.should_flush(),
self.handler.flush_observers.is_empty(),
) {
match self.handler.connection.poll_flush(cx) {
Poll::Pending => {}
Poll::Ready(Ok(())) => {
for observer in self.handler.flush_observers.drain(..) {
let _ = observer.send(());
}
}
Poll::Ready(Err(err)) => {
return Poll::Ready(ExitReason::Disconnected(Some(err)))
}
}
}
if mem::take(&mut self.handler.should_reconnect) {
return Poll::Ready(ExitReason::ReconnectRequested);
}
Poll::Pending
}
}
let mut recv_buf = Vec::with_capacity(ProcessFut::RECV_CHUNK_SIZE);
loop {
let process = ProcessFut {
handler: self,
receiver,
recv_buf: &mut recv_buf,
};
match process.await {
ExitReason::Disconnected(err) => {
debug!(?err, "disconnected");
if self.handle_disconnect().await.is_err() {
break;
};
debug!("reconnected");
}
ExitReason::Closed => break,
ExitReason::ReconnectRequested => {
debug!("reconnect requested");
// Should be ok to ingore error, as that means we are not in connected state.
self.connection.stream.shutdown().await.ok();
if self.handle_disconnect().await.is_err() {
break;
};
}
}
}
}
fn handle_server_op(&mut self, server_op: ServerOp) {
self.ping_interval.reset();
match server_op {
ServerOp::Ping => {
self.connection.enqueue_write_op(&ClientOp::Pong);
}
ServerOp::Pong => {
debug!("received PONG");
self.pending_pings = self.pending_pings.saturating_sub(1);
}
ServerOp::Error(error) => {
self.connector
.events_tx
.try_send(Event::ServerError(error))
.ok();
}
ServerOp::Message {
sid,
subject,
reply,
payload,
headers,
status,
description,
length,
} => {
self.connector
.connect_stats
.in_messages
.add(1, Ordering::Relaxed);
if let Some(subscription) = self.subscriptions.get_mut(&sid) {
let message: Message = Message {
subject,
reply,
payload,
headers,
status,
description,
length,
};
// if the channel for subscription was dropped, remove the
// subscription from the map and unsubscribe.
match subscription.sender.try_send(message) {
Ok(_) => {
subscription.delivered += 1;
// if this `Subscription` has set `max` value, check if it
// was reached. If yes, remove the `Subscription` and in
// the result, `drop` the `sender` channel.
if let Some(max) = subscription.max {
if subscription.delivered.ge(&max) {
self.subscriptions.remove(&sid);
}
}
}
Err(mpsc::error::TrySendError::Full(_)) => {
self.connector
.events_tx
.try_send(Event::SlowConsumer(sid))
.ok();
}
Err(mpsc::error::TrySendError::Closed(_)) => {
self.subscriptions.remove(&sid);
self.connection
.enqueue_write_op(&ClientOp::Unsubscribe { sid, max: None });
}
}
} else if sid == MULTIPLEXER_SID {
if let Some(multiplexer) = self.multiplexer.as_mut() {
let maybe_token =
subject.strip_prefix(multiplexer.prefix.as_ref()).to_owned();
if let Some(token) = maybe_token {
if let Some(sender) = multiplexer.senders.remove(token) {
let message = Message {
subject,
reply,
payload,
headers,
status,
description,
length,
};
let _ = sender.send(message);
}
}
}
}
}
// TODO: we should probably update advertised server list here too.
ServerOp::Info(info) => {
if info.lame_duck_mode {
self.connector.events_tx.try_send(Event::LameDuckMode).ok();
}
}
_ => {
// TODO: don't ignore.
}
}
}
fn handle_command(&mut self, command: Command) {
self.ping_interval.reset();
match command {
Command::Unsubscribe { sid, max } => {
if let Some(subscription) = self.subscriptions.get_mut(&sid) {
subscription.max = max;
match subscription.max {
Some(n) => {
if subscription.delivered >= n {
self.subscriptions.remove(&sid);
}
}
None => {
self.subscriptions.remove(&sid);
}
}
self.connection
.enqueue_write_op(&ClientOp::Unsubscribe { sid, max });
}
}
Command::Flush { observer } => {
self.flush_observers.push(observer);
}
Command::Subscribe {
sid,
subject,
queue_group,
sender,
} => {
let subscription = Subscription {
sender,
delivered: 0,
max: None,
subject: subject.to_owned(),
queue_group: queue_group.to_owned(),
};
self.subscriptions.insert(sid, subscription);
self.connection.enqueue_write_op(&ClientOp::Subscribe {
sid,
subject,
queue_group,
});
}
Command::Request {
subject,
payload,
respond,
headers,
sender,
} => {
let (prefix, token) = respond.rsplit_once('.').expect("malformed request subject");
let multiplexer = if let Some(multiplexer) = self.multiplexer.as_mut() {
multiplexer
} else {
let prefix = Subject::from(format!("{}.{}.", prefix, nuid::next()));
let subject = Subject::from(format!("{}*", prefix));
self.connection.enqueue_write_op(&ClientOp::Subscribe {
sid: MULTIPLEXER_SID,
subject: subject.clone(),
queue_group: None,
});
self.multiplexer.insert(Multiplexer {
subject,
prefix,
senders: HashMap::new(),
})
};
self.connector
.connect_stats
.out_messages
.add(1, Ordering::Relaxed);
multiplexer.senders.insert(token.to_owned(), sender);
let respond: Subject = format!("{}{}", multiplexer.prefix, token).into();
let pub_op = ClientOp::Publish {
subject,
payload,
respond: Some(respond),
headers,
};
self.connection.enqueue_write_op(&pub_op);
}
Command::Publish(PublishMessage {
subject,
payload,
reply: respond,
headers,
}) => {
self.connector
.connect_stats
.out_messages
.add(1, Ordering::Relaxed);
let header_len = headers
.as_ref()
.map(|headers| headers.len())
.unwrap_or_default();
self.connector.connect_stats.out_bytes.add(
(payload.len()
+ respond.as_ref().map_or_else(|| 0, |r| r.len())
+ subject.len()
+ header_len) as u64,
Ordering::Relaxed,
);
self.connection.enqueue_write_op(&ClientOp::Publish {
subject,
payload,
respond,
headers,
});
}
Command::Reconnect => {
self.should_reconnect = true;
}
}
}
async fn handle_disconnect(&mut self) -> Result<(), ConnectError> {
self.pending_pings = 0;
self.connector.events_tx.try_send(Event::Disconnected).ok();
self.connector.state_tx.send(State::Disconnected).ok();
self.handle_reconnect().await
}
async fn handle_reconnect(&mut self) -> Result<(), ConnectError> {
let (info, connection) = self.connector.connect().await?;
self.connection = connection;
let _ = self.info_sender.send(info);
self.subscriptions
.retain(|_, subscription| !subscription.sender.is_closed());
for (sid, subscription) in &self.subscriptions {
self.connection.enqueue_write_op(&ClientOp::Subscribe {
sid: *sid,
subject: subscription.subject.to_owned(),
queue_group: subscription.queue_group.to_owned(),
});
}
if let Some(multiplexer) = &self.multiplexer {
self.connection.enqueue_write_op(&ClientOp::Subscribe {
sid: MULTIPLEXER_SID,
subject: multiplexer.subject.to_owned(),
queue_group: None,
});
}
Ok(())
}
}
/// Connects to NATS with specified options.
///
/// It is generally advised to use [ConnectOptions] instead, as it provides a builder for whole
/// configuration.
///
/// # Examples
/// ```
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let mut nc =
/// async_nats::connect_with_options("demo.nats.io", async_nats::ConnectOptions::new()).await?;
/// nc.publish("test", "data".into()).await?;
/// # Ok(())
/// # }
/// ```
pub async fn connect_with_options<A: ToServerAddrs>(
addrs: A,
options: ConnectOptions,
) -> Result<Client, ConnectError> {
let ping_period = options.ping_interval;
let (events_tx, mut events_rx) = mpsc::channel(128);
let (state_tx, state_rx) = tokio::sync::watch::channel(State::Pending);
// We're setting it to the default server payload size.
let max_payload = Arc::new(AtomicUsize::new(1024 * 1024));
let statistics = Arc::new(Statistics::default());
let mut connector = Connector::new(
addrs,
ConnectorOptions {
tls_required: options.tls_required,
certificates: options.certificates,
client_key: options.client_key,
client_cert: options.client_cert,
tls_client_config: options.tls_client_config,
tls_first: options.tls_first,
auth: options.auth,
no_echo: options.no_echo,
connection_timeout: options.connection_timeout,
name: options.name,
ignore_discovered_servers: options.ignore_discovered_servers,
retain_servers_order: options.retain_servers_order,
read_buffer_capacity: options.read_buffer_capacity,
reconnect_delay_callback: options.reconnect_delay_callback,
auth_callback: options.auth_callback,
max_reconnects: options.max_reconnects,
},
events_tx,
state_tx,
max_payload.clone(),
statistics.clone(),
)
.map_err(|err| ConnectError::with_source(ConnectErrorKind::ServerParse, err))?;
let mut info: ServerInfo = Default::default();
let mut connection = None;
if !options.retry_on_initial_connect {
debug!("retry on initial connect failure is disabled");
let (info_ok, connection_ok) = connector.try_connect().await?;
connection = Some(connection_ok);
info = info_ok;
}
let (info_sender, info_watcher) = tokio::sync::watch::channel(info.clone());
let (sender, mut receiver) = mpsc::channel(options.sender_capacity);
let client = Client::new(
info_watcher,
state_rx,
sender,
options.subscription_capacity,
options.inbox_prefix,
options.request_timeout,
max_payload,
statistics,
);
task::spawn(async move {
while let Some(event) = events_rx.recv().await {
tracing::info!("event: {}", event);
if let Some(event_callback) = &options.event_callback {
event_callback.call(event).await;
}
}
});
task::spawn(async move {
if connection.is_none() && options.retry_on_initial_connect {
let (info, connection_ok) = match connector.connect().await {
Ok((info, connection)) => (info, connection),
Err(err) => {
error!("connection closed: {}", err);
return;
}
};
info_sender.send(info).ok();
connection = Some(connection_ok);
}
let connection = connection.unwrap();
let mut connection_handler =
ConnectionHandler::new(connection, connector, info_sender, ping_period);
connection_handler.process(&mut receiver).await
});
Ok(client)
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Event {
Connected,
Disconnected,
LameDuckMode,
SlowConsumer(u64),
ServerError(ServerError),
ClientError(ClientError),
}
impl fmt::Display for Event {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Event::Connected => write!(f, "connected"),
Event::Disconnected => write!(f, "disconnected"),
Event::LameDuckMode => write!(f, "lame duck mode detected"),
Event::SlowConsumer(sid) => write!(f, "slow consumers for subscription {sid}"),
Event::ServerError(err) => write!(f, "server error: {err}"),
Event::ClientError(err) => write!(f, "client error: {err}"),
}
}
}
/// Connects to NATS with default config.
///
/// Returns cloneable [Client].
///
/// To have customized NATS connection, check [ConnectOptions].
///
/// # Examples
///
/// ## Single URL
/// ```
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let mut nc = async_nats::connect("demo.nats.io").await?;
/// nc.publish("test", "data".into()).await?;
/// # Ok(())
/// # }
/// ```
///
/// ## Connect with [Vec] of [ServerAddr].
/// ```no_run
/// #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::ServerAddr;
/// let client = async_nats::connect(vec![
/// "demo.nats.io".parse::<ServerAddr>()?,
/// "other.nats.io".parse::<ServerAddr>()?,
/// ])
/// .await
/// .unwrap();
/// # Ok(())
/// # }
/// ```
///
/// ## with [Vec], but parse URLs inside [crate::connect()]
/// ```no_run
/// #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::ServerAddr;
/// let servers = vec!["demo.nats.io", "other.nats.io"];
/// let client = async_nats::connect(
/// servers
/// .iter()
/// .map(|url| url.parse())
/// .collect::<Result<Vec<ServerAddr>, _>>()?,
/// )
/// .await?;
/// # Ok(())
/// # }
/// ```
///
///
/// ## with slice.
/// ```no_run
/// #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::ServerAddr;
/// let client = async_nats::connect(
/// [
/// "demo.nats.io".parse::<ServerAddr>()?,
/// "other.nats.io".parse::<ServerAddr>()?,
/// ]
/// .as_slice(),
/// )
/// .await?;
/// # Ok(())
/// # }
pub async fn connect<A: ToServerAddrs>(addrs: A) -> Result<Client, ConnectError> {
connect_with_options(addrs, ConnectOptions::default()).await
}
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ConnectErrorKind {
/// Parsing the passed server address failed.
ServerParse,
/// DNS related issues.
Dns,
/// Failed authentication process, signing nonce, etc.
Authentication,
/// Server returned authorization violation error.
AuthorizationViolation,
/// Connect timed out.
TimedOut,
/// Erroneous TLS setup.
Tls,
/// Other IO error.
Io,
/// Reached the maximum number of reconnects.
MaxReconnects,
}
impl Display for ConnectErrorKind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::ServerParse => write!(f, "failed to parse server or server list"),
Self::Dns => write!(f, "DNS error"),
Self::Authentication => write!(f, "failed signing nonce"),
Self::AuthorizationViolation => write!(f, "authorization violation"),
Self::TimedOut => write!(f, "timed out"),
Self::Tls => write!(f, "TLS error"),
Self::Io => write!(f, "IO error"),
Self::MaxReconnects => write!(f, "reached maximum number of reconnects"),
}
}
}
/// Returned when initial connection fails.
/// To be enumerate over the variants, call [ConnectError::kind].
pub type ConnectError = error::Error<ConnectErrorKind>;
impl From<io::Error> for ConnectError {
fn from(err: io::Error) -> Self {
ConnectError::with_source(ConnectErrorKind::Io, err)
}
}
/// Retrieves messages from given `subscription` created by [Client::subscribe].
///
/// Implements [futures::stream::Stream] for ergonomic async message processing.
///
/// # Examples
/// ```
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let mut nc = async_nats::connect("demo.nats.io").await?;
/// # nc.publish("test", "data".into()).await?;
/// # Ok(())
/// # }
/// ```
#[derive(Debug)]
pub struct Subscriber {
sid: u64,
receiver: mpsc::Receiver<Message>,
sender: mpsc::Sender<Command>,
}
impl Subscriber {
fn new(
sid: u64,
sender: mpsc::Sender<Command>,
receiver: mpsc::Receiver<Message>,
) -> Subscriber {
Subscriber {
sid,
sender,
receiver,
}
}
/// Unsubscribes from subscription, draining all remaining messages.
///
/// # Examples
/// ```
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
///
/// let mut subscriber = client.subscribe("foo").await?;
///
/// subscriber.unsubscribe().await?;
/// # Ok(())
/// # }
/// ```
pub async fn unsubscribe(&mut self) -> Result<(), UnsubscribeError> {
self.sender
.send(Command::Unsubscribe {
sid: self.sid,
max: None,
})
.await?;
self.receiver.close();
Ok(())
}
/// Unsubscribes from subscription after reaching given number of messages.
/// This is the total number of messages received by this subscription in it's whole
/// lifespan. If it already reached or surpassed the passed value, it will immediately stop.
///
/// # Examples
/// ```
/// # use futures::StreamExt;
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// let client = async_nats::connect("demo.nats.io").await?;
///
/// let mut subscriber = client.subscribe("test").await?;
/// subscriber.unsubscribe_after(3).await?;
///
/// for _ in 0..3 {
/// client.publish("test", "data".into()).await?;
/// }
///
/// while let Some(message) = subscriber.next().await {
/// println!("message received: {:?}", message);
/// }
/// println!("no more messages, unsubscribed");
/// # Ok(())
/// # }
/// ```
pub async fn unsubscribe_after(&mut self, unsub_after: u64) -> Result<(), UnsubscribeError> {
self.sender
.send(Command::Unsubscribe {
sid: self.sid,
max: Some(unsub_after),
})
.await?;
Ok(())
}
}
#[derive(Error, Debug, PartialEq)]
#[error("failed to send unsubscribe")]
pub struct UnsubscribeError(String);
impl From<tokio::sync::mpsc::error::SendError<Command>> for UnsubscribeError {
fn from(err: tokio::sync::mpsc::error::SendError<Command>) -> Self {
UnsubscribeError(err.to_string())
}
}
impl Drop for Subscriber {
fn drop(&mut self) {
self.receiver.close();
tokio::spawn({
let sender = self.sender.clone();
let sid = self.sid;
async move {
sender
.send(Command::Unsubscribe { sid, max: None })
.await
.ok();
}
});
}
}
impl Stream for Subscriber {
type Item = Message;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
self.receiver.poll_recv(cx)
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum CallbackError {
Client(ClientError),
Server(ServerError),
}
impl std::fmt::Display for CallbackError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::Client(error) => write!(f, "{error}"),
Self::Server(error) => write!(f, "{error}"),
}
}
}
impl From<ServerError> for CallbackError {
fn from(server_error: ServerError) -> Self {
CallbackError::Server(server_error)
}
}
impl From<ClientError> for CallbackError {
fn from(client_error: ClientError) -> Self {
CallbackError::Client(client_error)
}
}
#[derive(Clone, Debug, Eq, PartialEq, Error)]
pub enum ServerError {
AuthorizationViolation,
SlowConsumer(u64),
Other(String),
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ClientError {
Other(String),
MaxReconnects,
}
impl std::fmt::Display for ClientError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::Other(error) => write!(f, "nats: {error}"),
Self::MaxReconnects => write!(f, "nats: max reconnects reached"),
}
}
}
impl ServerError {
fn new(error: String) -> ServerError {
match error.to_lowercase().as_str() {
"authorization violation" => ServerError::AuthorizationViolation,
// error messages can contain case-sensitive values which should be preserved
_ => ServerError::Other(error),
}
}
}
impl std::fmt::Display for ServerError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::AuthorizationViolation => write!(f, "nats: authorization violation"),
Self::SlowConsumer(sid) => write!(f, "nats: subscription {sid} is a slow consumer"),
Self::Other(error) => write!(f, "nats: {error}"),
}
}
}
/// Info to construct a CONNECT message.
#[derive(Clone, Debug, Serialize)]
pub struct ConnectInfo {
/// Turns on +OK protocol acknowledgments.
pub verbose: bool,
/// Turns on additional strict format checking, e.g. for properly formed
/// subjects.
pub pedantic: bool,
/// User's JWT.
#[serde(rename = "jwt")]
pub user_jwt: Option<String>,
/// Public nkey.
pub nkey: Option<String>,
/// Signed nonce, encoded to Base64URL.
#[serde(rename = "sig")]
pub signature: Option<String>,
/// Optional client name.
pub name: Option<String>,
/// If set to `true`, the server (version 1.2.0+) will not send originating
/// messages from this connection to its own subscriptions. Clients should
/// set this to `true` only for server supporting this feature, which is
/// when proto in the INFO protocol is set to at least 1.
pub echo: bool,
/// The implementation language of the client.
pub lang: String,
/// The version of the client.
pub version: String,
/// Sending 0 (or absent) indicates client supports original protocol.
/// Sending 1 indicates that the client supports dynamic reconfiguration
/// of cluster topology changes by asynchronously receiving INFO messages
/// with known servers it can reconnect to.
pub protocol: Protocol,
/// Indicates whether the client requires an SSL connection.
pub tls_required: bool,
/// Connection username (if `auth_required` is set)
pub user: Option<String>,
/// Connection password (if auth_required is set)
pub pass: Option<String>,
/// Client authorization token (if auth_required is set)
pub auth_token: Option<String>,
/// Whether the client supports the usage of headers.
pub headers: bool,
/// Whether the client supports no_responders.
pub no_responders: bool,
}
/// Protocol version used by the client.
#[derive(Serialize_repr, Deserialize_repr, PartialEq, Eq, Debug, Clone, Copy)]
#[repr(u8)]
pub enum Protocol {
/// Original protocol.
Original = 0,
/// Protocol with dynamic reconfiguration of cluster and lame duck mode functionality.
Dynamic = 1,
}
/// Address of a NATS server.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct ServerAddr(Url);
impl FromStr for ServerAddr {
type Err = io::Error;
/// Parse an address of a NATS server.
///
/// If not stated explicitly the `nats://` schema and port `4222` is assumed.
fn from_str(input: &str) -> Result<Self, Self::Err> {
let url: Url = if input.contains("://") {
input.parse()
} else {
format!("nats://{input}").parse()
}
.map_err(|e| {
io::Error::new(
ErrorKind::InvalidInput,
format!("NATS server URL is invalid: {e}"),
)
})?;
Self::from_url(url)
}
}
impl ServerAddr {
/// Check if the URL is a valid NATS server address.
pub fn from_url(url: Url) -> io::Result<Self> {
if url.scheme() != "nats" && url.scheme() != "tls" {
return Err(std::io::Error::new(
ErrorKind::InvalidInput,
format!("invalid scheme for NATS server URL: {}", url.scheme()),
));
}
Ok(Self(url))
}
/// Turn the server address into a standard URL.
pub fn into_inner(self) -> Url {
self.0
}
/// Returns if tls is required by the client for this server.
pub fn tls_required(&self) -> bool {
self.0.scheme() == "tls"
}
/// Returns if the server url had embedded username and password.
pub fn has_user_pass(&self) -> bool {
self.0.username() != ""
}
/// Returns the host.
pub fn host(&self) -> &str {
match self.0.host() {
Some(Host::Domain(_)) | Some(Host::Ipv4 { .. }) => self.0.host_str().unwrap(),
// `host_str()` for Ipv6 includes the []s
Some(Host::Ipv6 { .. }) => {
let host = self.0.host_str().unwrap();
&host[1..host.len() - 1]
}
None => "",
}
}
/// Returns the port.
pub fn port(&self) -> u16 {
self.0.port().unwrap_or(4222)
}
/// Returns the optional username in the url.
pub fn username(&self) -> Option<&str> {
let user = self.0.username();
if user.is_empty() {
None
} else {
Some(user)
}
}
/// Returns the optional password in the url.
pub fn password(&self) -> Option<&str> {
self.0.password()
}
/// Return the sockets from resolving the server address.
pub async fn socket_addrs(&self) -> io::Result<impl Iterator<Item = SocketAddr> + '_> {
tokio::net::lookup_host((self.host(), self.port())).await
}
}
/// Capability to convert into a list of NATS server addresses.
///
/// There are several implementations ensuring the easy passing of one or more server addresses to
/// functions like [`crate::connect()`].
pub trait ToServerAddrs {
/// Returned iterator over socket addresses which this type may correspond
/// to.
type Iter: Iterator<Item = ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter>;
}
impl ToServerAddrs for ServerAddr {
type Iter = option::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
Ok(Some(self.clone()).into_iter())
}
}
impl ToServerAddrs for str {
type Iter = option::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
self.parse::<ServerAddr>()
.map(|addr| Some(addr).into_iter())
}
}
impl ToServerAddrs for String {
type Iter = option::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
(**self).to_server_addrs()
}
}
impl<T: AsRef<str>> ToServerAddrs for [T] {
type Iter = std::vec::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
self.iter()
.map(AsRef::as_ref)
.map(str::parse)
.collect::<io::Result<_>>()
.map(Vec::into_iter)
}
}
impl<T: AsRef<str>> ToServerAddrs for Vec<T> {
type Iter = std::vec::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
self.as_slice().to_server_addrs()
}
}
impl<'a> ToServerAddrs for &'a [ServerAddr] {
type Iter = iter::Cloned<slice::Iter<'a, ServerAddr>>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
Ok(self.iter().cloned())
}
}
impl ToServerAddrs for Vec<ServerAddr> {
type Iter = std::vec::IntoIter<ServerAddr>;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
Ok(self.clone().into_iter())
}
}
impl<T: ToServerAddrs + ?Sized> ToServerAddrs for &T {
type Iter = T::Iter;
fn to_server_addrs(&self) -> io::Result<Self::Iter> {
(**self).to_server_addrs()
}
}
pub(crate) fn is_valid_subject<T: AsRef<str>>(subject: T) -> bool {
let subject_str = subject.as_ref();
!subject_str.starts_with('.')
&& !subject_str.ends_with('.')
&& subject_str.bytes().all(|c| !c.is_ascii_whitespace())
}
macro_rules! from_with_timeout {
($t:ty, $k:ty, $origin: ty, $origin_kind: ty) => {
impl From<$origin> for $t {
fn from(err: $origin) -> Self {
match err.kind() {
<$origin_kind>::TimedOut => Self::new(<$k>::TimedOut),
_ => Self::with_source(<$k>::Other, err),
}
}
}
};
}
pub(crate) use from_with_timeout;
use crate::connection::ShouldFlush;
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn server_address_ipv6() {
let address = ServerAddr::from_str("nats://[::]").unwrap();
assert_eq!(address.host(), "::")
}
#[test]
fn server_address_ipv4() {
let address = ServerAddr::from_str("nats://127.0.0.1").unwrap();
assert_eq!(address.host(), "127.0.0.1")
}
#[test]
fn server_address_domain() {
let address = ServerAddr::from_str("nats://example.com").unwrap();
assert_eq!(address.host(), "example.com")
}
#[test]
fn to_server_addrs_vec_str() {
let vec = vec!["nats://127.0.0.1", "nats://[::]"];
let mut addrs_iter = vec.to_server_addrs().unwrap();
assert_eq!(addrs_iter.next().unwrap().host(), "127.0.0.1");
assert_eq!(addrs_iter.next().unwrap().host(), "::");
assert_eq!(addrs_iter.next(), None);
}
#[test]
fn to_server_addrs_arr_str() {
let arr = ["nats://127.0.0.1", "nats://[::]"];
let mut addrs_iter = arr.to_server_addrs().unwrap();
assert_eq!(addrs_iter.next().unwrap().host(), "127.0.0.1");
assert_eq!(addrs_iter.next().unwrap().host(), "::");
assert_eq!(addrs_iter.next(), None);
}
#[test]
fn to_server_addrs_vec_string() {
let vec = vec!["nats://127.0.0.1".to_string(), "nats://[::]".to_string()];
let mut addrs_iter = vec.to_server_addrs().unwrap();
assert_eq!(addrs_iter.next().unwrap().host(), "127.0.0.1");
assert_eq!(addrs_iter.next().unwrap().host(), "::");
assert_eq!(addrs_iter.next(), None);
}
#[test]
fn to_server_addrs_arr_string() {
let arr = ["nats://127.0.0.1".to_string(), "nats://[::]".to_string()];
let mut addrs_iter = arr.to_server_addrs().unwrap();
assert_eq!(addrs_iter.next().unwrap().host(), "127.0.0.1");
assert_eq!(addrs_iter.next().unwrap().host(), "::");
assert_eq!(addrs_iter.next(), None);
}
}