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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 wrapped `crate::Message` with `JetStream` related methods.
use super::context::Context;
use crate::{error, header, Error};
use crate::{subject::Subject, HeaderMap};
use bytes::Bytes;
use futures::future::TryFutureExt;
use futures::StreamExt;
use std::fmt::Display;
use std::{mem, time::Duration};
use time::format_description::well_known::Rfc3339;
use time::OffsetDateTime;
/// A message received directly from the stream, without leveraging a consumer.
#[derive(Debug, Clone)]
pub struct StreamMessage {
pub subject: Subject,
pub sequence: u64,
pub headers: HeaderMap,
pub payload: Bytes,
pub time: OffsetDateTime,
}
#[derive(Clone, Debug)]
pub struct Message {
pub message: crate::Message,
pub context: Context,
}
impl TryFrom<crate::Message> for StreamMessage {
type Error = StreamMessageError;
fn try_from(message: crate::Message) -> Result<Self, Self::Error> {
let headers = message.headers.ok_or_else(|| {
StreamMessageError::with_source(StreamMessageErrorKind::MissingHeader, "no headers")
})?;
let sequence = headers
.get_last(header::NATS_SEQUENCE)
.ok_or_else(|| {
StreamMessageError::with_source(StreamMessageErrorKind::MissingHeader, "sequence")
})
.and_then(|seq| {
seq.as_str().parse().map_err(|err| {
StreamMessageError::with_source(
StreamMessageErrorKind::ParseError,
format!("could not parse sequence header: {}", err),
)
})
})?;
let time = headers
.get_last(header::NATS_TIME_STAMP)
.ok_or_else(|| {
StreamMessageError::with_source(StreamMessageErrorKind::MissingHeader, "timestamp")
})
.and_then(|time| {
OffsetDateTime::parse(time.as_str(), &Rfc3339).map_err(|err| {
StreamMessageError::with_source(
StreamMessageErrorKind::ParseError,
format!("could not parse timestamp header: {}", err),
)
})
})?;
let subject = headers
.get_last(header::NATS_SUBJECT)
.ok_or_else(|| {
StreamMessageError::with_source(StreamMessageErrorKind::MissingHeader, "subject")
})?
.as_str()
.into();
Ok(StreamMessage {
subject,
sequence,
headers,
payload: message.payload,
time,
})
}
}
#[derive(Debug, Clone, PartialEq)]
pub enum StreamMessageErrorKind {
MissingHeader,
ParseError,
}
/// Error returned when library is unable to parse message got directly from the stream.
pub type StreamMessageError = error::Error<StreamMessageErrorKind>;
impl Display for StreamMessageErrorKind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
StreamMessageErrorKind::MissingHeader => write!(f, "missing message header"),
StreamMessageErrorKind::ParseError => write!(f, "parse error"),
}
}
}
impl std::ops::Deref for Message {
type Target = crate::Message;
fn deref(&self) -> &Self::Target {
&self.message
}
}
impl From<Message> for crate::Message {
fn from(source: Message) -> crate::Message {
source.message
}
}
impl Message {
/// Splits [Message] into [Acker] and [crate::Message].
/// This can help reduce memory footprint if [Message] can be dropped before acking,
/// for example when it's transformed into another structure and acked later
pub fn split(mut self) -> (crate::Message, Acker) {
let reply = mem::take(&mut self.message.reply);
(
self.message,
Acker {
context: self.context,
reply,
},
)
}
/// Acknowledges a message delivery by sending `+ACK` to the server.
///
/// If [AckPolicy][crate::jetstream::consumer::AckPolicy] is set to `All` or `Explicit`, messages has to be acked.
/// Otherwise redeliveries will occur and [Consumer][crate::jetstream::consumer::Consumer] will not be able to advance.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::jetstream::consumer::PullConsumer;
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer: PullConsumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// message?.ack().await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn ack(&self) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
self.context
.client
.publish(reply.clone(), "".into())
.map_err(Error::from)
.await
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
/// Acknowledges a message delivery by sending a chosen [AckKind] variant to the server.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::jetstream::consumer::PullConsumer;
/// use async_nats::jetstream::AckKind;
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer: PullConsumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// message?.ack_with(AckKind::Nak(None)).await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn ack_with(&self, kind: AckKind) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
self.context
.client
.publish(reply.to_owned(), kind.into())
.map_err(Error::from)
.await
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
/// Acknowledges a message delivery by sending `+ACK` to the server
/// and awaits for confirmation for the server that it received the message.
/// Useful if user wants to ensure `exactly once` semantics.
///
/// If [AckPolicy][crate::jetstream::consumer::AckPolicy] is set to `All` or `Explicit`, messages has to be acked.
/// Otherwise redeliveries will occur and [Consumer][crate::jetstream::consumer::Consumer] will not be able to advance.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// message?.double_ack().await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn double_ack(&self) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
let inbox = self.context.client.new_inbox();
let mut subscription = self.context.client.subscribe(inbox.clone()).await?;
self.context
.client
.publish_with_reply(reply.clone(), inbox, AckKind::Ack.into())
.await?;
match tokio::time::timeout(self.context.timeout, subscription.next())
.await
.map_err(|_| {
std::io::Error::new(
std::io::ErrorKind::TimedOut,
"double ack response timed out",
)
})? {
Some(_) => Ok(()),
None => Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"subscription dropped",
))),
}
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
/// Returns the `JetStream` message ID
/// if this is a `JetStream` message.
#[allow(clippy::mixed_read_write_in_expression)]
pub fn info(&self) -> Result<Info<'_>, Error> {
const PREFIX: &str = "$JS.ACK.";
const SKIP: usize = PREFIX.len();
let mut reply: &str = self.reply.as_ref().ok_or_else(|| {
std::io::Error::new(std::io::ErrorKind::NotFound, "did not found reply subject")
})?;
if !reply.starts_with(PREFIX) {
return Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"did not found proper prefix",
)));
}
reply = &reply[SKIP..];
let mut split = reply.split('.');
// we should avoid allocating to prevent
// large performance degradations in
// parsing this.
let mut tokens: [Option<&str>; 10] = [None; 10];
let mut n_tokens = 0;
for each_token in &mut tokens {
if let Some(token) = split.next() {
*each_token = Some(token);
n_tokens += 1;
}
}
let mut token_index = 0;
macro_rules! try_parse {
() => {
match str::parse(try_parse!(str)) {
Ok(parsed) => parsed,
Err(e) => {
return Err(Box::new(e));
}
}
};
(str) => {
if let Some(next) = tokens[token_index].take() {
#[allow(unused)]
{
// this isn't actually unused, but it's
// difficult for the compiler to infer this.
token_index += 1;
}
next
} else {
return Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"too few tokens",
)));
}
};
}
// now we can try to parse the tokens to
// individual types. We use an if-else
// chain instead of a match because it
// produces more optimal code usually,
// and we want to try the 9 (11 - the first 2)
// case first because we expect it to
// be the most common. We use >= to be
// future-proof.
if n_tokens >= 9 {
Ok(Info {
domain: {
let domain: &str = try_parse!(str);
if domain == "_" {
None
} else {
Some(domain)
}
},
acc_hash: Some(try_parse!(str)),
stream: try_parse!(str),
consumer: try_parse!(str),
delivered: try_parse!(),
stream_sequence: try_parse!(),
consumer_sequence: try_parse!(),
published: {
let nanos: i128 = try_parse!();
OffsetDateTime::from_unix_timestamp_nanos(nanos)?
},
pending: try_parse!(),
token: if n_tokens >= 9 {
Some(try_parse!(str))
} else {
None
},
})
} else if n_tokens == 7 {
// we expect this to be increasingly rare, as older
// servers are phased out.
Ok(Info {
domain: None,
acc_hash: None,
stream: try_parse!(str),
consumer: try_parse!(str),
delivered: try_parse!(),
stream_sequence: try_parse!(),
consumer_sequence: try_parse!(),
published: {
let nanos: i128 = try_parse!();
OffsetDateTime::from_unix_timestamp_nanos(nanos)?
},
pending: try_parse!(),
token: None,
})
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"bad token number",
)))
}
}
}
/// A lightweight struct useful for decoupling message contents and the ability to ack it.
pub struct Acker {
context: Context,
reply: Option<Subject>,
}
// TODO(tp): This should be async trait to avoid duplication of code. Will be refactored into one when async traits are available.
// The async-trait crate is not a solution here, as it would mean we're allocating at every ack.
// Creating separate function to ack just to avoid one duplication is not worth it either.
impl Acker {
pub fn new(context: Context, reply: Option<Subject>) -> Self {
Self { context, reply }
}
/// Acknowledges a message delivery by sending `+ACK` to the server.
///
/// If [AckPolicy][crate::jetstream::consumer::AckPolicy] is set to `All` or `Explicit`, messages has to be acked.
/// Otherwise redeliveries will occur and [Consumer][crate::jetstream::consumer::Consumer] will not be able to advance.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::jetstream::consumer::PullConsumer;
/// use async_nats::jetstream::Message;
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer: PullConsumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// let (message, acker) = message.map(Message::split)?;
/// // Do something with the message. Ownership can be taken over `Message`
/// // while retaining ability to ack later.
/// println!("message: {:?}", message);
/// // Ack it. `Message` may be dropped already.
/// acker.ack().await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn ack(&self) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
self.context
.client
.publish(reply.to_owned(), "".into())
.map_err(Error::from)
.await
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
/// Acknowledges a message delivery by sending a chosen [AckKind] variant to the server.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::jetstream::consumer::PullConsumer;
/// use async_nats::jetstream::AckKind;
/// use async_nats::jetstream::Message;
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer: PullConsumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// let (message, acker) = message.map(Message::split)?;
/// // Do something with the message. Ownership can be taken over `Message`.
/// // while retaining ability to ack later.
/// println!("message: {:?}", message);
/// // Ack it. `Message` may be dropped already.
/// acker.ack_with(AckKind::Nak(None)).await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn ack_with(&self, kind: AckKind) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
self.context
.client
.publish(reply.to_owned(), kind.into())
.map_err(Error::from)
.await
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
/// Acknowledges a message delivery by sending `+ACK` to the server
/// and awaits for confirmation for the server that it received the message.
/// Useful if user wants to ensure `exactly once` semantics.
///
/// If [AckPolicy][crate::jetstream::consumer::AckPolicy] is set to `All` or `Explicit`, messages has to be acked.
/// Otherwise redeliveries will occur and [Consumer][crate::jetstream::consumer::Consumer] will not be able to advance.
///
/// # Examples
///
/// ```no_run
/// # #[tokio::main]
/// # async fn main() -> Result<(), async_nats::Error> {
/// use async_nats::jetstream::Message;
/// use futures::StreamExt;
/// let client = async_nats::connect("localhost:4222").await?;
/// let jetstream = async_nats::jetstream::new(client);
///
/// let consumer = jetstream
/// .get_stream("events")
/// .await?
/// .get_consumer("pull")
/// .await?;
///
/// let mut messages = consumer.fetch().max_messages(100).messages().await?;
///
/// while let Some(message) = messages.next().await {
/// let (message, acker) = message.map(Message::split)?;
/// // Do something with the message. Ownership can be taken over `Message`.
/// // while retaining ability to ack later.
/// println!("message: {:?}", message);
/// // Ack it. `Message` may be dropped already.
/// acker.double_ack().await?;
/// }
/// # Ok(())
/// # }
/// ```
pub async fn double_ack(&self) -> Result<(), Error> {
if let Some(ref reply) = self.reply {
let inbox = self.context.client.new_inbox();
let mut subscription = self.context.client.subscribe(inbox.to_owned()).await?;
self.context
.client
.publish_with_reply(reply.to_owned(), inbox, AckKind::Ack.into())
.await?;
match tokio::time::timeout(self.context.timeout, subscription.next())
.await
.map_err(|_| {
std::io::Error::new(
std::io::ErrorKind::TimedOut,
"double ack response timed out",
)
})? {
Some(_) => Ok(()),
None => Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"subscription dropped",
))),
}
} else {
Err(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
"No reply subject, not a JetStream message",
)))
}
}
}
/// The kinds of response used for acknowledging a processed message.
#[derive(Debug, Clone, Copy)]
pub enum AckKind {
/// Acknowledges a message was completely handled.
Ack,
/// Signals that the message will not be processed now
/// and processing can move onto the next message, NAK'd
/// message will be retried.
Nak(Option<Duration>),
/// When sent before the AckWait period indicates that
/// work is ongoing and the period should be extended by
/// another equal to AckWait.
Progress,
/// Acknowledges the message was handled and requests
/// delivery of the next message to the reply subject.
/// Only applies to Pull-mode.
Next,
/// Instructs the server to stop redelivery of a message
/// without acknowledging it as successfully processed.
Term,
}
impl From<AckKind> for Bytes {
fn from(kind: AckKind) -> Self {
use AckKind::*;
match kind {
Ack => Bytes::from_static(b"+ACK"),
Nak(maybe_duration) => match maybe_duration {
None => Bytes::from_static(b"-NAK"),
Some(duration) => format!("-NAK {{\"delay\":{}}}", duration.as_nanos()).into(),
},
Progress => Bytes::from_static(b"+WPI"),
Next => Bytes::from_static(b"+NXT"),
Term => Bytes::from_static(b"+TERM"),
}
}
}
/// Information about a received message
#[derive(Debug, Clone)]
pub struct Info<'a> {
/// Optional domain, present in servers post-ADR-15
pub domain: Option<&'a str>,
/// Optional account hash, present in servers post-ADR-15
pub acc_hash: Option<&'a str>,
/// The stream name
pub stream: &'a str,
/// The consumer name
pub consumer: &'a str,
/// The stream sequence number associated with this message
pub stream_sequence: u64,
/// The consumer sequence number associated with this message
pub consumer_sequence: u64,
/// The number of delivery attempts for this message
pub delivered: i64,
/// the number of messages known by the server to be pending to this consumer
pub pending: u64,
/// the time that this message was received by the server from its publisher
pub published: time::OffsetDateTime,
/// Optional token, present in servers post-ADR-15
pub token: Option<&'a str>,
}