diff --git a/services/backup/src/blob/put_client.rs b/services/backup/src/blob/put_client.rs --- a/services/backup/src/blob/put_client.rs +++ b/services/backup/src/blob/put_client.rs @@ -1,11 +1,14 @@ -use anyhow::Result; +use anyhow::{bail, Result}; use tokio::{ - sync::mpsc::{Receiver, Sender}, + sync::mpsc::{self, Receiver, Sender}, task::JoinHandle, }; -use tracing::instrument; +use tokio_stream::wrappers::ReceiverStream; +use tracing::{instrument, Instrument}; use super::proto; +use crate::constants::MPSC_CHANNEL_BUFFER_CAPACITY; + pub use proto::put_request::Data as PutRequestData; pub use proto::{PutRequest, PutResponse}; @@ -15,23 +18,84 @@ handle: JoinHandle>, } +/// The PutClient instance is a handle holder of a Tokio task running the +/// actual blob client instance. The communication is done via two MPSC +/// channels - one sending requests to the client task, and another for sending +/// responses back to the caller. These messages should go in pairs +/// - one request for one response. +/// The client task can be stopped and awaited for result via the `terminate()` +/// method. impl PutClient { /// Connects to the Blob service and keeps the client connection open /// in a separate Tokio task. #[instrument(name = "put_client")] pub async fn start() -> Result { - todo!() + let service_url = &crate::CONFIG.blob_service_url; + let mut blob_client = + proto::blob_service_client::BlobServiceClient::connect( + service_url.to_string(), + ) + .await?; + let (blob_req_tx, blob_req_rx) = + mpsc::channel(MPSC_CHANNEL_BUFFER_CAPACITY); + let (blob_res_tx, blob_res_rx) = + mpsc::channel(MPSC_CHANNEL_BUFFER_CAPACITY); + let client_thread = async move { + match blob_client + .put(tonic::Request::new(ReceiverStream::new(blob_req_rx))) + .await + { + Ok(response) => { + let mut response_stream = response.into_inner(); + loop { + match response_stream.message().await? { + Some(response_message) => { + // warning: this will produce an error if there's more unread + // responses than MPSC_CHANNEL_BUFFER_CAPACITY + // so you should always read the response MPSC channel + // right after sending a request to dequeue the responses + // and make room for more. + // The PutClient::put() function should take care of that + if let Err(err) = blob_res_tx.try_send(response_message) { + bail!(err); + } + } + // Response stream was closed + None => break, + } + } + } + Err(err) => { + bail!(err.to_string()); + } + }; + Ok(()) + }; + let handle = tokio::spawn(client_thread.in_current_span()); + + Ok(PutClient { + req_tx: blob_req_tx, + res_rx: blob_res_rx, + handle, + }) } /// Sends a [`PutRequest`] to the stream and waits for blob service /// to send a response. After all data is sent, the [`PutClient::terminate`] /// should be called to end the transmission and handle possible errors. pub async fn put(&mut self, req: PutRequest) -> Result { - todo!() + self.req_tx.try_send(req)?; + self + .res_rx + .recv() + .await + .ok_or_else(|| anyhow::anyhow!("Blob client channel closed")) } /// Closes the connection and awaits the blob client task to finish. pub async fn terminate(self) -> Result<()> { - todo!() + drop(self.req_tx); + let thread_result = self.handle.await?; + thread_result } }