Struct async_nats::jetstream::consumer::Consumer

source · 
pub struct Consumer<T: IntoConsumerConfig> { /* private fields */ }

Implementations§

Returns a stream of messages for Pull Consumer.

Example
use futures::StreamExt;
use futures::TryStreamExt;

let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let stream = jetstream.get_or_create_stream(async_nats::jetstream::stream::Config {
    name: "events".to_string(),
    max_messages: 10_000,
    ..Default::default()
}).await?;

jetstream.publish("events".to_string(), "data".into()).await?;

let consumer = stream.get_or_create_consumer("consumer", async_nats::jetstream::consumer::pull::Config {
    durable_name: Some("consumer".to_string()),
    ..Default::default()
}).await?;

let mut messages = consumer.messages().await?.take(100);
while let Some(Ok(message)) = messages.next().await {
  println!("got message {:?}", message);
  message.ack().await?;
}
Ok(())

Enables customization of Stream by setting timeouts, heartbeats, maximum number of messages or bytes buffered.

Examples
use futures::StreamExt;
use async_nats::jetstream::consumer::PullConsumer;
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.stream()
    .max_messages_per_batch(100)
    .max_bytes_per_batch(1024)
    .messages().await?;

while let Some(message) = messages.next().await {
    let message = message?;
    println!("message: {:?}", message);
    message.ack().await?;
}

Returns a batch of specified number of messages, or if there are less messages on the Stream than requested, returns all available messages.

Example
use futures::StreamExt;
use futures::TryStreamExt;

let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let stream = jetstream.get_or_create_stream(async_nats::jetstream::stream::Config {
    name: "events".to_string(),
    max_messages: 10_000,
    ..Default::default()
}).await?;

jetstream.publish("events".to_string(), "data".into()).await?;

let consumer = stream.get_or_create_consumer("consumer", async_nats::jetstream::consumer::pull::Config {
    durable_name: Some("consumer".to_string()),
    ..Default::default()
}).await?;

for _ in 0..100 {
    jetstream.publish("events".to_string(), "data".into()).await?;
}

let mut messages = consumer.fetch().max_messages(200).messages().await?;
// will finish after 100 messages, as that is the number of messages available on the
// stream.
while let Some(Ok(message)) = messages.next().await {
  println!("got message {:?}", message);
  message.ack().await?;
}
Ok(())

Returns a batch of specified number of messages unless timeout happens first.

Example
use futures::StreamExt;
use futures::TryStreamExt;

let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let stream = jetstream.get_or_create_stream(async_nats::jetstream::stream::Config {
    name: "events".to_string(),
    max_messages: 10_000,
    ..Default::default()
}).await?;

jetstream.publish("events".to_string(), "data".into()).await?;

let consumer = stream.get_or_create_consumer("consumer", async_nats::jetstream::consumer::pull::Config {
    durable_name: Some("consumer".to_string()),
    ..Default::default()
}).await?;

let mut messages = consumer.batch().max_messages(100).messages().await?;
while let Some(Ok(message)) = messages.next().await {
  println!("got message {:?}", message);
  message.ack().await?;
}
Ok(())

Returns a sequence of Batches allowing for iterating over batches, and then over messages in those batches.

Example
use futures::StreamExt;
use futures::TryStreamExt;

let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let stream = jetstream.get_or_create_stream(async_nats::jetstream::stream::Config {
    name: "events".to_string(),
    max_messages: 10_000,
    ..Default::default()
}).await?;

jetstream.publish("events".to_string(), "data".into()).await?;

let consumer = stream.get_or_create_consumer("consumer", async_nats::jetstream::consumer::pull::Config {
    durable_name: Some("consumer".to_string()),
    ..Default::default()
}).await?;

let mut iter = consumer.sequence(50).unwrap().take(10);
while let Ok(Some(mut batch)) = iter.try_next().await {
    while let Ok(Some(message)) = batch.try_next().await {
        println!("message received: {:?}", message);
    }
}
Ok(())

Returns a stream of messages for Push Consumer.

Example
use futures::StreamExt;
use futures::TryStreamExt;
use async_nats::jetstream::consumer::PushConsumer;

let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let stream = jetstream.get_or_create_stream(async_nats::jetstream::stream::Config {
    name: "events".to_string(),
    max_messages: 10_000,
    ..Default::default()
}).await?;

jetstream.publish("events".to_string(), "data".into()).await?;

let consumer: PushConsumer = stream.get_or_create_consumer("consumer", async_nats::jetstream::consumer::push::Config {
    durable_name: Some("consumer".to_string()),
    deliver_subject: "deliver".to_string(),
    ..Default::default()
}).await?;

let mut messages = consumer.messages().await?.take(100);
while let Some(Ok(message)) = messages.next().await {
  println!("got message {:?}", message);
  message.ack().await?;
}
Ok(())
Examples found in repository?
src/jetstream/object_store/mod.rs (line 127)
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    pub async fn get<T: AsRef<str>>(&self, object_name: T) -> Result<Object<'_>, Error> {
        let object_info = self.info(object_name).await?;
        // if let Some(link) = object_info.link {
        //     return self.get(link.name).await;
        // }

        let chunk_subject = format!("$O.{}.C.{}", self.name, object_info.nuid);

        let subscription = self
            .stream
            .create_consumer(crate::jetstream::consumer::push::OrderedConfig {
                filter_subject: chunk_subject,
                deliver_subject: self.stream.context.client.new_inbox(),
                ..Default::default()
            })
            .await?
            .messages()
            .await?;

        Ok(Object::new(subscription, object_info))
    }

    /// Gets an [Object] from the [ObjectStore].
    ///
    /// [Object] implements [tokio::io::AsyncRead] that allows
    /// to read the data from Object Store.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// let client = async_nats::connect("demo.nats.io").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let bucket = jetstream.get_object_store("store").await?;
    /// bucket.delete("FOO").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn delete<T: AsRef<str>>(&self, object_name: T) -> Result<(), Error> {
        let object_name = object_name.as_ref();
        let mut object_info = self.info(object_name).await?;
        object_info.chunks = 0;
        object_info.size = 0;
        object_info.deleted = true;

        let data = serde_json::to_vec(&object_info)?;

        let mut headers = HeaderMap::default();
        headers.insert(NATS_ROLLUP, HeaderValue::from_str(ROLLUP_SUBJECT)?);

        let subject = format!("$O.{}.M.{}", &self.name, encode_object_name(object_name));

        self.stream
            .context
            .publish_with_headers(subject, headers, data.into())
            .await?;

        let chunk_subject = format!("$O.{}.C.{}", self.name, object_info.nuid);

        self.stream.purge_subject(&chunk_subject).await?;

        Ok(())
    }

    /// Retrieves [Object] [ObjectInfo].
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// let client = async_nats::connect("demo.nats.io").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let bucket = jetstream.get_object_store("store").await?;
    /// let info = bucket.info("FOO").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn info<T: AsRef<str>>(&self, object_name: T) -> Result<ObjectInfo, Error> {
        let object_name = object_name.as_ref();
        let object_name = encode_object_name(object_name);
        if !is_valid_object_name(&object_name) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid object name",
            )));
        }

        // Grab last meta value we have.
        let subject = format!("$O.{}.M.{}", &self.name, &object_name);

        let message = self
            .stream
            .get_last_raw_message_by_subject(subject.as_str())
            .await?;
        let decoded_payload = base64::decode(message.payload)
            .map_err(|err| Box::new(std::io::Error::new(ErrorKind::Other, err)))?;
        let object_info = serde_json::from_slice::<ObjectInfo>(&decoded_payload)?;

        Ok(object_info)
    }

    /// Puts an [Object] into the [ObjectStore].
    /// This method implements `tokio::io::AsyncRead`.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// let client = async_nats::connect("demo.nats.io").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let bucket = jetstream.get_object_store("store").await?;
    /// let mut file = tokio::fs::File::open("foo.txt").await?;
    /// bucket.put("file", &mut file).await.unwrap();
    /// # Ok(())
    /// # }
    /// ```
    pub async fn put<T>(
        &self,
        meta: T,
        data: &mut (impl tokio::io::AsyncRead + std::marker::Unpin),
    ) -> Result<ObjectInfo, Error>
    where
        ObjectMeta: From<T>,
    {
        let object_meta: ObjectMeta = meta.into();

        let encoded_object_name = encode_object_name(&object_meta.name);
        if !is_valid_object_name(&encoded_object_name) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid object name",
            )));
        }
        // Fetch any existing object info, if there is any for later use.
        let maybe_existing_object_info = match self.info(&encoded_object_name).await {
            Ok(object_info) => Some(object_info),
            Err(_) => None,
        };

        let object_nuid = nuid::next();
        let chunk_subject = format!("$O.{}.C.{}", &self.name, &object_nuid);

        let mut object_chunks = 0;
        let mut object_size = 0;

        let mut buffer = Box::new([0; DEFAULT_CHUNK_SIZE]);
        let mut context = ring::digest::Context::new(&SHA256);

        loop {
            let n = data.read(&mut *buffer).await?;

            if n == 0 {
                break;
            }
            context.update(&buffer[..n]);

            object_size += n;
            object_chunks += 1;

            // FIXME: this is ugly
            let payload = bytes::Bytes::from(buffer[..n].to_vec());

            self.stream
                .context
                .publish(chunk_subject.clone(), payload)
                .await?;
        }
        let digest = context.finish();
        let subject = format!("$O.{}.M.{}", &self.name, &encoded_object_name);
        let object_info = ObjectInfo {
            name: object_meta.name,
            description: object_meta.description,
            link: object_meta.link,
            bucket: self.name.clone(),
            nuid: object_nuid,
            chunks: object_chunks,
            size: object_size,
            digest: format!(
                "SHA-256={}",
                base64::encode_config(digest, base64::URL_SAFE)
            ),
            modified: OffsetDateTime::now_utc(),
            deleted: false,
        };

        let mut headers = HeaderMap::new();
        headers.insert(NATS_ROLLUP, ROLLUP_SUBJECT.parse::<HeaderValue>()?);
        let data = serde_json::to_vec(&object_info)?;

        // publish meta.
        self.stream
            .context
            .publish_with_headers(subject, headers, data.into())
            .await?;

        // Purge any old chunks.
        if let Some(existing_object_info) = maybe_existing_object_info {
            let chunk_subject = format!("$O.{}.C.{}", &self.name, &existing_object_info.nuid);

            self.stream.purge_subject(&chunk_subject).await?;
        }

        Ok(object_info)
    }

    /// Creates a [Watch] stream over changes in the [ObjectStore].
    ///
    /// # 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 jetstream = async_nats::jetstream::new(client);
    ///
    /// let bucket = jetstream.get_object_store("store").await?;
    /// let mut watcher = bucket.watch().await.unwrap();
    /// while let Some(object) = watcher.next().await {
    ///     println!("detected changes in {:?}", object?);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn watch(&self) -> Result<Watch<'_>, Error> {
        let subject = format!("$O.{}.M.>", self.name);
        let ordered = self
            .stream
            .create_consumer(crate::jetstream::consumer::push::OrderedConfig {
                deliver_policy: super::consumer::DeliverPolicy::New,
                deliver_subject: self.stream.context.client.new_inbox(),
                description: Some("object store watcher".to_string()),
                filter_subject: subject,
                ..Default::default()
            })
            .await?;
        Ok(Watch {
            subscription: ordered.messages().await?,
        })
    }

    /// Returns a [List] stream with all not deleted [Objects][Object] in the [ObjectStore].
    ///
    /// # 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 jetstream = async_nats::jetstream::new(client);
    ///
    /// let bucket = jetstream.get_object_store("store").await?;
    /// let mut list = bucket.list().await.unwrap();
    /// while let Some(object) = list.next().await {
    ///     println!("object {:?}", object?);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn list(&self) -> Result<List<'_>, Error> {
        trace!("starting Object List");
        let subject = format!("$O.{}.M.>", self.name);
        let ordered = self
            .stream
            .create_consumer(crate::jetstream::consumer::push::OrderedConfig {
                deliver_policy: super::consumer::DeliverPolicy::All,
                deliver_subject: self.stream.context.client.new_inbox(),
                description: Some("object store list".to_string()),
                filter_subject: subject,
                ..Default::default()
            })
            .await?;
        Ok(List {
            done: ordered.info.num_pending == 0,
            subscription: ordered.messages().await?,
        })
    }
More examples
Hide additional examples
src/jetstream/kv/mod.rs (line 407)
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    pub async fn watch<T: AsRef<str>>(&self, key: T) -> Result<Watch<'_>, Error> {
        let subject = format!("{}{}", self.prefix.as_str(), key.as_ref());

        let consumer = self
            .stream
            .create_consumer(super::consumer::push::OrderedConfig {
                deliver_subject: self.stream.context.client.new_inbox(),
                description: Some("kv watch consumer".to_string()),
                filter_subject: subject,
                replay_policy: super::consumer::ReplayPolicy::Instant,
                deliver_policy: DeliverPolicy::New,
                ..Default::default()
            })
            .await?;

        Ok(Watch {
            subscription: consumer.messages().await?,
            prefix: self.prefix.clone(),
            bucket: self.name.clone(),
        })
    }

    /// Creates a [futures::Stream] over [Entries][Entry] for all keys, which yields
    /// values whenever there are changes in the bucket.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// let mut entries = kv.watch_all().await?;
    /// while let Some(entry) = entries.next().await {
    ///     println!("entry: {:?}", entry);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn watch_all(&self) -> Result<Watch<'_>, Error> {
        self.watch(ALL_KEYS).await
    }

    pub async fn get<T: Into<String>>(&self, key: T) -> Result<Option<Vec<u8>>, Error> {
        match self.entry(key).await {
            Ok(Some(entry)) => match entry.operation {
                Operation::Put => Ok(Some(entry.value)),
                _ => Ok(None),
            },
            Ok(None) => Ok(None),
            Err(err) => Err(err),
        }
    }

    /// Updates a value for a given key, but only if passed `revision` is the last `revision` in
    /// the bucket.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// let revision = kv.put("key", "value".into()).await?;
    /// kv.update("key", "updated".into(), revision).await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn update<T: AsRef<str>>(
        &self,
        key: T,
        value: Bytes,
        revision: u64,
    ) -> Result<u64, Error> {
        if !is_valid_key(key.as_ref()) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid key",
            )));
        }
        let subject = format!("{}{}", self.prefix.as_str(), key.as_ref());

        let mut headers = crate::HeaderMap::default();
        headers.insert(
            header::NATS_EXPECTED_LAST_SUBJECT_SEQUENCE,
            HeaderValue::from(revision),
        );

        self.stream
            .context
            .publish_with_headers(subject, headers, value)
            .await?
            .await
            .map(|publish_ack| publish_ack.sequence)
    }

    /// Deletes a given key. This is a non-destructive operation, which sets a `DELETE` marker.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// kv.put("key", "value".into()).await?;
    /// kv.delete("key").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn delete<T: AsRef<str>>(&self, key: T) -> Result<(), Error> {
        if !is_valid_key(key.as_ref()) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid key",
            )));
        }
        let mut subject = String::new();
        if self.use_jetstream_prefix {
            subject.push_str(&self.stream.context.prefix);
            subject.push('.');
        }
        subject.push_str(self.put_prefix.as_ref().unwrap_or(&self.prefix));
        subject.push_str(key.as_ref());

        let mut headers = crate::HeaderMap::default();
        // TODO: figure out which headers k/v should be where.
        headers.insert(KV_OPERATION, KV_OPERATION_DELETE.parse::<HeaderValue>()?);

        self.stream
            .context
            .publish_with_headers(subject, headers, "".into())
            .await?;
        Ok(())
    }

    /// Purges all the revisions of a entry destructively, leaving behind a single purge entry in-place.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// kv.put("key", "value".into()).await?;
    /// kv.put("key", "another".into()).await?;
    /// kv.purge("key").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn purge<T: AsRef<str>>(&self, key: T) -> Result<(), Error> {
        if !is_valid_key(key.as_ref()) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid key",
            )));
        }

        let subject = format!("{}{}", self.prefix.as_str(), key.as_ref());

        let mut headers = crate::HeaderMap::default();
        headers.insert(KV_OPERATION, HeaderValue::from(KV_OPERATION_PURGE));
        headers.insert(NATS_ROLLUP, HeaderValue::from(ROLLUP_SUBJECT));

        self.stream
            .context
            .publish_with_headers(subject, headers, "".into())
            .await?;
        Ok(())
    }

    /// Returns a [futures::Stream] that allows iterating over all [Operations][Operation] that
    /// happen for given key.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// let mut entries = kv.history("kv").await?;
    /// while let Some(entry) = entries.next().await {
    ///     println!("entry: {:?}", entry);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn history<T: AsRef<str>>(&self, key: T) -> Result<History<'_>, Error> {
        if !is_valid_key(key.as_ref()) {
            return Err(Box::new(io::Error::new(
                io::ErrorKind::InvalidInput,
                "invalid key",
            )));
        }
        let subject = format!("{}{}", self.prefix.as_str(), key.as_ref());

        let consumer = self
            .stream
            .create_consumer(super::consumer::push::OrderedConfig {
                deliver_subject: self.stream.context.client.new_inbox(),
                description: Some("kv history consumer".to_string()),
                filter_subject: subject,
                replay_policy: super::consumer::ReplayPolicy::Instant,
                ..Default::default()
            })
            .await?;

        Ok(History {
            subscription: consumer.messages().await?,
            done: false,
            prefix: self.prefix.clone(),
            bucket: self.name.clone(),
        })
    }

    /// Returns a [futures::Stream] that allows iterating over all keys in the bucket.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use futures::StreamExt;
    /// let client = async_nats::connect("demo.nats.io:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    /// let kv = jetstream.create_key_value(async_nats::jetstream::kv::Config {
    ///     bucket: "kv".to_string(),
    ///     history: 10,
    ///     ..Default::default()
    /// }).await?;
    /// let mut entries = kv.keys().await?;
    /// while let Some(key) = entries.next() {
    ///     println!("key: {:?}", key);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn keys(&self) -> Result<collections::hash_set::IntoIter<String>, Error> {
        let subject = format!("{}>", self.prefix.as_str());

        let consumer = self
            .stream
            .create_consumer(super::consumer::push::OrderedConfig {
                deliver_subject: self.stream.context.client.new_inbox(),
                description: Some("kv history consumer".to_string()),
                filter_subject: subject,
                headers_only: true,
                replay_policy: super::consumer::ReplayPolicy::Instant,
                ..Default::default()
            })
            .await?;

        let mut entries = History {
            done: consumer.info.num_pending == 0,
            subscription: consumer.messages().await?,
            prefix: self.prefix.clone(),
            bucket: self.name.clone(),
        };

        let mut keys = HashSet::new();
        while let Some(entry) = entries.try_next().await? {
            keys.insert(entry.key);
        }
        Ok(keys.into_iter())
    }
Examples found in repository?
src/jetstream/stream.rs (lines 621-625)
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    pub async fn create_consumer<C: IntoConsumerConfig + FromConsumer>(
        &self,
        config: C,
    ) -> Result<Consumer<C>, Error> {
        let config = config.into_consumer_config();

        let subject = {
            if self.context.client.is_server_compatible(2, 9, 0) {
                let filter = if config.filter_subject.is_empty() {
                    "".to_string()
                } else {
                    format!(".{}", config.filter_subject)
                };
                config
                    .name
                    .as_ref()
                    .or(config.durable_name.as_ref())
                    .map(|name| {
                        format!(
                            "CONSUMER.CREATE.{}.{}{}",
                            self.info.config.name, name, filter
                        )
                    })
                    .unwrap_or_else(|| format!("CONSUMER.CREATE.{}", self.info.config.name))
            } else if config.name.is_some() {
                return Err(Box::new(std::io::Error::new(
                    ErrorKind::Other,
                    "can't use consumer name with server below version 2.9",
                )));
            } else if let Some(ref durable_name) = config.durable_name {
                format!(
                    "CONSUMER.DURABLE.CREATE.{}.{}",
                    self.info.config.name, durable_name
                )
            } else {
                format!("CONSUMER.CREATE.{}", self.info.config.name)
            }
        };

        match self
            .context
            .request(
                subject,
                &json!({"stream_name": self.info.config.name.clone(), "config": config}),
            )
            .await?
        {
            Response::Err { error } => Err(Box::new(std::io::Error::new(
                ErrorKind::Other,
                format!(
                    "nats: error while creating stream: {}, {}, {}",
                    error.code, error.status, error.description
                ),
            ))),
            Response::Ok::<consumer::Info>(info) => Ok(Consumer::new(
                FromConsumer::try_from_consumer_config(info.clone().config)?,
                info,
                self.context.clone(),
            )),
        }
    }

    /// Retrieve [Info] about [Consumer] from the server.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use async_nats::jetstream::consumer;
    /// let client = async_nats::connect("localhost:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let stream = jetstream.get_stream("events").await?;
    /// let info = stream.consumer_info("pull").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn consumer_info<T: AsRef<str>>(&self, name: T) -> Result<consumer::Info, Error> {
        let name = name.as_ref();

        let subject = format!("CONSUMER.INFO.{}.{}", self.info.config.name, name);

        match self.context.request(subject, &json!({})).await? {
            Response::Ok(info) => Ok(info),
            Response::Err { error } => Err(Box::new(std::io::Error::new(
                ErrorKind::Other,
                format!(
                    "nats: error while getting consumer info: {}, {}, {}",
                    error.code, error.status, error.description
                ),
            ))),
        }
    }

    /// Get [Consumer] from the the server. [Consumer] iterators can be used to retrieve
    /// [Messages][crate::jetstream::Message] for a given [Consumer].
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use async_nats::jetstream::consumer;
    /// use futures::StreamExt;
    /// let client = async_nats::connect("localhost:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let stream = jetstream.get_stream("events").await?;
    /// let consumer: consumer::PullConsumer = stream.get_consumer("pull").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn get_consumer<T: FromConsumer + IntoConsumerConfig>(
        &self,
        name: &str,
    ) -> Result<Consumer<T>, Error> {
        let info = self.consumer_info(name).await?;

        Ok(Consumer::new(
            T::try_from_consumer_config(info.config.clone())?,
            info,
            self.context.clone(),
        ))
    }

    /// Create a [Consumer] with the given configuration if it is not present on the server. Returns a handle to the [Consumer].
    ///
    /// Note: This does not validate if the [Consumer] on the server is compatible with the configuration passed in except Push/Pull compatibility.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), async_nats::Error> {
    /// use async_nats::jetstream::consumer;
    /// use futures::StreamExt;
    /// let client = async_nats::connect("localhost:4222").await?;
    /// let jetstream = async_nats::jetstream::new(client);
    ///
    /// let stream = jetstream.get_stream("events").await?;
    /// let consumer = stream.get_or_create_consumer("pull", consumer::pull::Config {
    ///     durable_name: Some("pull".to_string()),
    ///     ..Default::default()
    /// }).await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn get_or_create_consumer<T: FromConsumer + IntoConsumerConfig>(
        &self,
        name: &str,
        config: T,
    ) -> Result<Consumer<T>, Error> {
        let subject = format!("CONSUMER.INFO.{}.{}", self.info.config.name, name);

        match self.context.request(subject, &json!({})).await? {
            Response::Err { error } if error.status == 404 => self.create_consumer(config).await,
            Response::Err { error } => Err(Box::new(io::Error::new(
                ErrorKind::Other,
                format!(
                    "nats: error while getting or creating stream: {}, {}, {}",
                    error.code, error.status, error.description
                ),
            ))),
            Response::Ok::<consumer::Info>(info) => Ok(Consumer::new(
                T::try_from_consumer_config(info.config.clone())?,
                info,
                self.context.clone(),
            )),
        }
    }

Retrieves info about Consumer from the server, updates the cached info inside Consumer and returns it.

Examples
use async_nats::jetstream::consumer::PullConsumer;
let client = async_nats::connect("localhost:4222").await?;
let jetstream = async_nats::jetstream::new(client);

let mut consumer: PullConsumer = jetstream
    .get_stream("events").await?
    .get_consumer("pull").await?;

let info = consumer.info().await?;

Returns cached Info for the Consumer. Cache is either from initial creation/retrieval of the Consumer or last call to Info.

Examples
use async_nats::jetstream::consumer::PullConsumer;
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 info = consumer.cached_info();

Trait Implementations§

Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more

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Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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Calls U::from(self).

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