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//! The [`Producer`] handle (WP-5.4): send messages on a sender link.
use std::sync::Arc;
use bytes::Bytes;
use tokio::sync::{Semaphore, mpsc, oneshot};
use crate::api::lifecycle::detach_on_drop;
use crate::codec::to_bytes;
use crate::error::{ErrorKind, LinkError, SendError};
use crate::ids::{ChannelId, Handle};
use crate::proto::{DriverCommand, LinkEvent};
use crate::types::messaging::{DeliveryState, Message};
/// A handle for sending on an attached sender link.
#[derive(Debug)]
pub struct Producer {
commands: mpsc::Sender<DriverCommand>,
channel: ChannelId,
handle: Handle,
#[allow(dead_code)]
events: mpsc::Receiver<LinkEvent>,
/// Bounds buffered fire-and-forget sends: one permit per unwritten
/// [`send_settled`](Self::send_settled) message, released when the driver
/// writes it. `None` = unbounded (`max_outbox == 0`).
outbox: Option<Arc<Semaphore>>,
}
impl Producer {
pub(crate) fn new(
commands: mpsc::Sender<DriverCommand>,
channel: ChannelId,
handle: Handle,
events: mpsc::Receiver<LinkEvent>,
max_outbox: usize,
) -> Self {
Producer {
commands,
channel,
handle,
events,
outbox: (max_outbox > 0).then(|| Arc::new(Semaphore::new(max_outbox))),
}
}
/// The link handle.
pub fn handle(&self) -> Handle {
self.handle
}
/// Send a message and await its terminal delivery state (the outcome the
/// peer settled with — `Accepted`, `Rejected`, …).
///
/// # Examples
/// ```no_run
/// # async fn ex(producer: &ramqp::Producer) -> Result<(), Box<dyn std::error::Error>> {
/// use ramqp::{Message, types::messaging::DeliveryState};
///
/// match producer.send(Message::text("order-42")).await? {
/// DeliveryState::Accepted(_) => println!("durably enqueued"),
/// other => eprintln!("broker did not accept: {other:?}"),
/// }
/// # Ok(()) }
/// ```
pub async fn send(&self, message: Message) -> Result<DeliveryState, SendError> {
self.send_bytes(to_bytes(&message).freeze(), false).await
}
/// Send a message carrying an explicit delivery `state` and await its outcome.
///
/// The primary use is enlisting a message in a transaction: pass the
/// `transactional-state` built from a declared `txn-id` (see
/// [`txn::transactional_state`](crate::txn::transactional_state) under the
/// `transaction` feature).
pub async fn send_with_state(
&self,
message: Message,
state: DeliveryState,
) -> Result<DeliveryState, SendError> {
self.send_bytes_with_state(to_bytes(&message).freeze(), false, Some(state))
.await
}
/// Send a pre-encoded body and await its outcome.
pub async fn send_bytes(&self, body: Bytes, settled: bool) -> Result<DeliveryState, SendError> {
self.send_bytes_with_state(body, settled, None).await
}
async fn send_bytes_with_state(
&self,
body: Bytes,
settled: bool,
state: Option<DeliveryState>,
) -> Result<DeliveryState, SendError> {
let (reply_tx, reply_rx) = oneshot::channel();
self.commands
.send(DriverCommand::SendTransfer {
channel: self.channel,
handle: self.handle,
body,
settled,
message_format: 0,
state,
reply: Some(reply_tx),
})
.await
.map_err(|_| SendError::msg(ErrorKind::NotConnected, "connection closed"))?;
reply_rx
.await
.map_err(|_| SendError::msg(ErrorKind::Cancelled, "driver dropped"))?
}
/// Send a message pre-settled (fire-and-forget; no disposition awaited).
///
/// This trades the disposition round-trip for throughput, but is bounded:
/// at most `max_outbox` (see [`LinkConfig`](crate::config::LinkConfig))
/// unwritten messages may be buffered while awaiting broker credit, after
/// which the call back-pressures (awaits an outbox slot) rather than growing
/// memory unbounded. Set `max_outbox = 0` to opt back into unbounded
/// buffering. Use [`send`](Producer::send) when you need the full
/// credit→disposition loop and the broker's terminal outcome.
///
/// # Examples
/// ```no_run
/// # async fn ex(producer: &ramqp::Producer) -> Result<(), Box<dyn std::error::Error>> {
/// use ramqp::Message;
/// // Fire a burst; the bounded outbox back-pressures instead of buffering forever.
/// for i in 0..1000 {
/// producer.send_settled(Message::text(format!("event-{i}"))).await?;
/// }
/// # Ok(()) }
/// ```
pub async fn send_settled(&self, message: Message) -> Result<(), SendError> {
let body = to_bytes(&message).freeze();
match &self.outbox {
// Bounded: hold a permit until the driver confirms the write.
Some(sem) => {
let permit = sem
.clone()
.acquire_owned()
.await
.map_err(|_| SendError::msg(ErrorKind::Cancelled, "producer closed"))?;
let (reply_tx, reply_rx) = oneshot::channel();
self.commands
.send(DriverCommand::SendTransfer {
channel: self.channel,
handle: self.handle,
body,
settled: true,
message_format: 0,
state: None,
reply: Some(reply_tx),
})
.await
.map_err(|_| SendError::msg(ErrorKind::NotConnected, "connection closed"))?;
// Free the slot once the message is written (or the link drops).
tokio::spawn(async move {
let _ = reply_rx.await;
drop(permit);
});
Ok(())
}
// Unbounded (opt-in): pure fire-and-forget, no completion tracked.
None => self
.commands
.send(DriverCommand::SendTransfer {
channel: self.channel,
handle: self.handle,
body,
settled: true,
message_format: 0,
state: None,
reply: None,
})
.await
.map_err(|_| SendError::msg(ErrorKind::NotConnected, "connection closed")),
}
}
/// Detach the link and await completion.
pub async fn detach(mut self) -> Result<(), LinkError> {
let (tx, rx) = oneshot::channel();
let commands = self.commands.clone();
// Prevent the Drop impl from also detaching.
let handle = std::mem::replace(&mut self.handle, Handle(u32::MAX));
commands
.send(DriverCommand::DetachLink {
channel: self.channel,
handle,
closed: true,
error: None,
reply: tx,
})
.await
.map_err(|_| LinkError::msg(ErrorKind::NotConnected, "connection closed"))?;
rx.await
.map_err(|_| LinkError::msg(ErrorKind::Cancelled, "driver dropped"))?
}
}
impl Drop for Producer {
fn drop(&mut self) {
if self.handle != Handle(u32::MAX) {
detach_on_drop(&self.commands, self.channel, self.handle);
}
}
}