Broken!!!!!

src/concurrent_processor.rs

@@ -1,172 +0,0 @@
-use crate::{
-    details::Details,
-    error::{Error, UploadError},
-    repo::Hash,
-};
-
-use dashmap::{mapref::entry::Entry, DashMap};
-use flume::{r#async::RecvFut, Receiver, Sender};
-use std::{
-    future::Future,
-    path::PathBuf,
-    pin::Pin,
-    sync::Arc,
-    task::{Context, Poll},
-};
-use tracing::Span;
-
-type OutcomeReceiver = Receiver<(Details, Arc<str>)>;
-
-type ProcessMapKey = (Hash, PathBuf);
-
-type ProcessMapInner = DashMap<ProcessMapKey, OutcomeReceiver>;
-
-#[derive(Debug, Default, Clone)]
-pub(crate) struct ProcessMap {
-    process_map: Arc<ProcessMapInner>,
-}
-
-impl ProcessMap {
-    pub(super) fn new() -> Self {
-        Self::default()
-    }
-
-    pub(super) async fn process<Fut>(
-        &self,
-        hash: Hash,
-        path: PathBuf,
-        fut: Fut,
-    ) -> Result<(Details, Arc<str>), Error>
-    where
-        Fut: Future<Output = Result<(Details, Arc<str>), Error>>,
-    {
-        let key = (hash.clone(), path.clone());
-
-        let (sender, receiver) = flume::bounded(1);
-
-        let entry = self.process_map.entry(key.clone());
-
-        let (state, span) = match entry {
-            Entry::Vacant(vacant) => {
-                vacant.insert(receiver);
-
-                let span = tracing::info_span!(
-                    "Processing image",
-                    hash = ?hash,
-                    path = ?path,
-                    completed = &tracing::field::Empty,
-                );
-
-                metrics::counter!(crate::init_metrics::PROCESS_MAP_INSERTED).increment(1);
-
-                (CancelState::Sender { sender }, span)
-            }
-            Entry::Occupied(receiver) => {
-                let span = tracing::info_span!(
-                    "Waiting for processed image",
-                    hash = ?hash,
-                    path = ?path,
-                );
-
-                let receiver = receiver.get().clone().into_recv_async();
-
-                (CancelState::Receiver { receiver }, span)
-            }
-        };
-
-        CancelSafeProcessor {
-            cancel_token: CancelToken {
-                span,
-                key,
-                state,
-                process_map: self.clone(),
-            },
-            fut,
-        }
-        .await
-    }
-
-    fn remove(&self, key: &ProcessMapKey) -> Option<OutcomeReceiver> {
-        self.process_map.remove(key).map(|(_, v)| v)
-    }
-}
-
-struct CancelToken {
-    span: Span,
-    key: ProcessMapKey,
-    state: CancelState,
-    process_map: ProcessMap,
-}
-
-enum CancelState {
-    Sender {
-        sender: Sender<(Details, Arc<str>)>,
-    },
-    Receiver {
-        receiver: RecvFut<'static, (Details, Arc<str>)>,
-    },
-}
-
-impl CancelState {
-    const fn is_sender(&self) -> bool {
-        matches!(self, Self::Sender { .. })
-    }
-}
-
-pin_project_lite::pin_project! {
-    struct CancelSafeProcessor<F> {
-        cancel_token: CancelToken,
-
-        #[pin]
-        fut: F,
-    }
-}
-
-impl<F> Future for CancelSafeProcessor<F>
-where
-    F: Future<Output = Result<(Details, Arc<str>), Error>>,
-{
-    type Output = Result<(Details, Arc<str>), Error>;
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let this = self.as_mut().project();
-
-        let span = &this.cancel_token.span;
-        let process_map = &this.cancel_token.process_map;
-        let state = &mut this.cancel_token.state;
-        let key = &this.cancel_token.key;
-        let fut = this.fut;
-
-        span.in_scope(|| match state {
-            CancelState::Sender { sender } => {
-                let res = std::task::ready!(fut.poll(cx));
-
-                if process_map.remove(key).is_some() {
-                    metrics::counter!(crate::init_metrics::PROCESS_MAP_REMOVED).increment(1);
-                }
-
-                if let Ok(tup) = &res {
-                    let _ = sender.try_send(tup.clone());
-                }
-
-                Poll::Ready(res)
-            }
-            CancelState::Receiver { ref mut receiver } => Pin::new(receiver)
-                .poll(cx)
-                .map(|res| res.map_err(|_| UploadError::Canceled.into())),
-        })
-    }
-}
-
-impl Drop for CancelToken {
-    fn drop(&mut self) {
-        if self.state.is_sender() {
-            let completed = self.process_map.remove(&self.key).is_none();
-            self.span.record("completed", completed);
-
-            if !completed {
-                metrics::counter!(crate::init_metrics::PROCESS_MAP_REMOVED).increment(1);
-            }
-        }
-    }
-}

src/generate.rs

@@ -2,7 +2,6 @@ mod ffmpeg;
 mod magick;
 
 use crate::{
-    concurrent_processor::ProcessMap,
     details::Details,
     error::{Error, UploadError},
     formats::{ImageFormat, InputProcessableFormat, InternalVideoFormat, ProcessableFormat},
@@ -13,6 +12,7 @@ use crate::{
 };
 
 use std::{
+    future::Future,
     path::PathBuf,
     sync::Arc,
     time::{Duration, Instant},
@@ -48,10 +48,9 @@ impl Drop for MetricsGuard {
     }
 }
 
-#[tracing::instrument(skip(state, process_map, original_details, hash))]
+#[tracing::instrument(skip(state, original_details, hash))]
 pub(crate) async fn generate<S: Store + 'static>(
     state: &State<S>,
-    process_map: &ProcessMap,
     format: InputProcessableFormat,
     thumbnail_path: PathBuf,
     thumbnail_args: Vec<String>,
@@ -67,33 +66,97 @@ pub(crate) async fn generate<S: Store + 'static>(
 
         Ok((original_details.clone(), identifier))
     } else {
-        let process_fut = process(
+        let variant = thumbnail_path.to_string_lossy().to_string();
+
+        let mut attempts = 0;
+        let (details, identifier) = loop {
+            if attempts > 4 {
+                todo!("return error");
+            }
+
+            match state
+                .repo
+                .claim_variant_processing_rights(hash.clone(), variant.clone())
+                .await?
+            {
+                Ok(()) => {
+                    // process
+                    let process_future = process(
                         state,
                         format,
-            thumbnail_path.clone(),
+                        variant.clone(),
                         thumbnail_args,
                         original_details,
                         hash.clone(),
                     )
                     .with_poll_timer("process-future");
 
-        let (details, identifier) = process_map
+                    let tuple = heartbeat(state, hash.clone(), variant.clone(), process_future)
-            .process(hash, thumbnail_path, process_fut)
+                        .with_poll_timer("heartbeat-future")
-            .with_poll_timer("process-map-future")
+                        .await??;
-            .with_timeout(Duration::from_secs(state.config.media.process_timeout * 4))
+
-            .with_metrics(crate::init_metrics::GENERATE_PROCESS)
+                    break tuple;
-            .await
+                }
-            .map_err(|_| UploadError::ProcessTimeout)??;
+                Err(_) => match state
+                    .repo
+                    .await_variant(hash.clone(), variant.clone())
+                    .await?
+                {
+                    Some(identifier) => {
+                        let details = crate::ensure_details_identifier(state, &identifier).await?;
+
+                        break (details, identifier);
+                    }
+                    None => {
+                        attempts += 1;
+                        continue;
+                    }
+                },
+            }
+        };
 
         Ok((details, identifier))
     }
 }
 
+async fn heartbeat<S, O>(
+    state: &State<S>,
+    hash: Hash,
+    variant: String,
+    future: impl Future<Output = O>,
+) -> Result<O, Error> {
+    let repo = state.repo.clone();
+
+    let handle = crate::sync::abort_on_drop(crate::sync::spawn("heartbeat-task", async move {
+        let mut interval = tokio::time::interval(Duration::from_secs(5));
+
+        loop {
+            interval.tick().await;
+
+            if let Err(e) = repo.variant_heartbeat(hash.clone(), variant.clone()).await {
+                break Error::from(e);
+            }
+        }
+    }));
+
+    let future = std::pin::pin!(future);
+
+    tokio::select! {
+        biased;
+        output = future => {
+            Ok(output)
+        }
+        res = handle => {
+            Err(res.map_err(|_| UploadError::Canceled)?)
+        }
+    }
+}
+
 #[tracing::instrument(skip(state, hash))]
 async fn process<S: Store + 'static>(
     state: &State<S>,
     output_format: InputProcessableFormat,
-    thumbnail_path: PathBuf,
+    variant: String,
     thumbnail_args: Vec<String>,
     original_details: &Details,
     hash: Hash,
@@ -142,19 +205,21 @@ async fn process<S: Store + 'static>(
         )
         .await?;
 
-    if let Err(VariantAlreadyExists) = state
+    let identifier = if let Err(VariantAlreadyExists) = state
         .repo
-        .relate_variant_identifier(
+        .relate_variant_identifier(hash.clone(), variant.clone(), &identifier)
-            hash,
-            thumbnail_path.to_string_lossy().to_string(),
-            &identifier,
-        )
         .await?
     {
         state.store.remove(&identifier).await?;
-    }
+        state
-
+            .repo
+            .variant_identifier(hash, variant)
+            .await?
+            .ok_or(UploadError::MissingIdentifier)?
+    } else {
         state.repo.relate_details(&identifier, &details).await?;
+        identifier
+    };
 
     guard.disarm();
 

src/lib.rs

@@ -1,7 +1,6 @@
 mod backgrounded;
 mod blurhash;
 mod bytes_stream;
-mod concurrent_processor;
 mod config;
 mod details;
 mod discover;
@@ -71,7 +70,6 @@ use tracing_actix_web::TracingLogger;
 
 use self::{
     backgrounded::Backgrounded,
-    concurrent_processor::ProcessMap,
     config::{Configuration, Operation},
     details::Details,
     either::Either,
@@ -848,13 +846,12 @@ async fn not_found_hash(repo: &ArcRepo) -> Result<Option<(Alias, Hash)>, Error>
 }
 
 /// Process files
-#[tracing::instrument(name = "Serving processed image", skip(state, process_map))]
+#[tracing::instrument(name = "Serving processed image", skip(state))]
 async fn process<S: Store + 'static>(
     range: Option<web::Header<Range>>,
     web::Query(ProcessQuery { source, operations }): web::Query<ProcessQuery>,
     ext: web::Path<String>,
     state: web::Data<State<S>>,
-    process_map: web::Data<ProcessMap>,
 ) -> Result<HttpResponse, Error> {
     let alias = proxy_alias_from_query(source.into(), &state).await?;
 
@@ -898,7 +895,6 @@ async fn process<S: Store + 'static>(
 
         generate::generate(
             &state,
-            &process_map,
             format,
             thumbnail_path,
             thumbnail_args,
@@ -1591,14 +1587,12 @@ fn json_config() -> web::JsonConfig {
 fn configure_endpoints<S: Store + 'static, F: Fn(&mut web::ServiceConfig)>(
     config: &mut web::ServiceConfig,
     state: State<S>,
-    process_map: ProcessMap,
     extra_config: F,
 ) {
     config
         .app_data(query_config())
         .app_data(json_config())
         .app_data(web::Data::new(state.clone()))
-        .app_data(web::Data::new(process_map.clone()))
         .route("/healthz", web::get().to(healthz::<S>))
         .service(
             web::scope("/image")
@@ -1706,12 +1700,12 @@ fn spawn_cleanup<S>(state: State<S>) {
     });
 }
 
-fn spawn_workers<S>(state: State<S>, process_map: ProcessMap)
+fn spawn_workers<S>(state: State<S>)
 where
     S: Store + 'static,
 {
     crate::sync::spawn("cleanup-worker", queue::process_cleanup(state.clone()));
-    crate::sync::spawn("process-worker", queue::process_images(state, process_map));
+    crate::sync::spawn("process-worker", queue::process_images(state));
 }
 
 fn watch_keys(tls: Tls, sender: ChannelSender) -> DropHandle<()> {
@@ -1737,8 +1731,6 @@ async fn launch<
     state: State<S>,
     extra_config: F,
 ) -> color_eyre::Result<()> {
-    let process_map = ProcessMap::new();
-
     let address = state.config.server.address;
 
     let tls = Tls::from_config(&state.config);
@@ -1748,18 +1740,15 @@ async fn launch<
     let server = HttpServer::new(move || {
         let extra_config = extra_config.clone();
         let state = state.clone();
-        let process_map = process_map.clone();
 
-        spawn_workers(state.clone(), process_map.clone());
+        spawn_workers(state.clone());
 
         App::new()
             .wrap(TracingLogger::default())
             .wrap(Deadline)
             .wrap(Metrics)
             .wrap(Payload::new())
-            .configure(move |sc| {
+            .configure(move |sc| configure_endpoints(sc, state.clone(), extra_config))
-                configure_endpoints(sc, state.clone(), process_map.clone(), extra_config)
-            })
     });
 
     if let Some(tls) = tls {

src/queue.rs

@@ -1,5 +1,4 @@
 use crate::{
-    concurrent_processor::ProcessMap,
     error::{Error, UploadError},
     formats::InputProcessableFormat,
     future::{LocalBoxFuture, WithPollTimer},
@@ -196,8 +195,8 @@ pub(crate) async fn process_cleanup<S: Store + 'static>(state: State<S>) {
     process_jobs(state, CLEANUP_QUEUE, cleanup::perform).await
 }
 
-pub(crate) async fn process_images<S: Store + 'static>(state: State<S>, process_map: ProcessMap) {
+pub(crate) async fn process_images<S: Store + 'static>(state: State<S>) {
-    process_image_jobs(state, process_map, PROCESS_QUEUE, process::perform).await
+    process_jobs(state, PROCESS_QUEUE, process::perform).await
 }
 
 struct MetricsGuard {
@@ -357,7 +356,7 @@ where
             let (job_id, job) = state
                 .repo
                 .pop(queue, worker_id)
-                .with_poll_timer("pop-cleanup")
+                .with_poll_timer("pop-job")
                 .await?;
 
             let guard = MetricsGuard::guard(worker_id, queue);
@@ -369,99 +368,13 @@ where
                 job_id,
                 (callback)(state, job),
             )
-            .with_poll_timer("cleanup-job-and-heartbeat")
+            .with_poll_timer("job-and-heartbeat")
-            .await;
-
-            state
-                .repo
-                .complete_job(queue, worker_id, job_id, job_result(&res))
-                .with_poll_timer("cleanup-job-complete")
-                .await?;
-
-            res?;
-
-            guard.disarm();
-
-            Ok(()) as Result<(), Error>
-        }
-        .instrument(tracing::info_span!("tick", %queue, %worker_id))
-        .await?;
-    }
-}
-
-async fn process_image_jobs<S, F>(
-    state: State<S>,
-    process_map: ProcessMap,
-    queue: &'static str,
-    callback: F,
-) where
-    S: Store,
-    for<'a> F: Fn(&'a State<S>, &'a ProcessMap, serde_json::Value) -> JobFuture<'a> + Copy,
-{
-    let worker_id = uuid::Uuid::new_v4();
-
-    loop {
-        tracing::trace!("process_image_jobs: looping");
-
-        crate::sync::cooperate().await;
-
-        let res = image_job_loop(&state, &process_map, worker_id, queue, callback)
-            .with_poll_timer("image-job-loop")
-            .await;
-
-        if let Err(e) = res {
-            tracing::warn!("Error processing jobs: {}", format!("{e}"));
-            tracing::warn!("{}", format!("{e:?}"));
-
-            if e.is_disconnected() {
-                tokio::time::sleep(Duration::from_secs(10)).await;
-            }
-
-            continue;
-        }
-
-        break;
-    }
-}
-
-async fn image_job_loop<S, F>(
-    state: &State<S>,
-    process_map: &ProcessMap,
-    worker_id: uuid::Uuid,
-    queue: &'static str,
-    callback: F,
-) -> Result<(), Error>
-where
-    S: Store,
-    for<'a> F: Fn(&'a State<S>, &'a ProcessMap, serde_json::Value) -> JobFuture<'a> + Copy,
-{
-    loop {
-        tracing::trace!("image_job_loop: looping");
-
-        crate::sync::cooperate().await;
-
-        async {
-            let (job_id, job) = state
-                .repo
-                .pop(queue, worker_id)
-                .with_poll_timer("pop-process")
-                .await?;
-
-            let guard = MetricsGuard::guard(worker_id, queue);
-
-            let res = heartbeat(
-                &state.repo,
-                queue,
-                worker_id,
-                job_id,
-                (callback)(state, process_map, job),
-            )
-            .with_poll_timer("process-job-and-heartbeat")
             .await;
 
             state
                 .repo
                 .complete_job(queue, worker_id, job_id, job_result(&res))
+                .with_poll_timer("job-complete")
                 .await?;
 
             res?;

src/queue/process.rs

@@ -2,7 +2,6 @@ use time::Instant;
 use tracing::{Instrument, Span};
 
 use crate::{
-    concurrent_processor::ProcessMap,
     error::{Error, UploadError},
     formats::InputProcessableFormat,
     future::WithPollTimer,
@@ -18,11 +17,7 @@ use std::{path::PathBuf, sync::Arc};
 
 use super::{JobContext, JobFuture, JobResult};
 
-pub(super) fn perform<'a, S>(
+pub(super) fn perform<'a, S>(state: &'a State<S>, job: serde_json::Value) -> JobFuture<'a>
-    state: &'a State<S>,
-    process_map: &'a ProcessMap,
-    job: serde_json::Value,
-) -> JobFuture<'a>
 where
     S: Store + 'static,
 {
@@ -58,7 +53,6 @@ where
             } => {
                 generate(
                     state,
-                    process_map,
                     target_format,
                     Serde::into_inner(source),
                     process_path,
@@ -178,10 +172,9 @@ where
     Ok(())
 }
 
-#[tracing::instrument(skip(state, process_map, process_path, process_args))]
+#[tracing::instrument(skip(state, process_path, process_args))]
 async fn generate<S: Store + 'static>(
     state: &State<S>,
-    process_map: &ProcessMap,
     target_format: InputProcessableFormat,
     source: Alias,
     process_path: PathBuf,
@@ -211,7 +204,6 @@ async fn generate<S: Store + 'static>(
 
     crate::generate::generate(
         state,
-        process_map,
         target_format,
         process_path,
         process_args,

src/repo.rs

@@ -740,6 +740,20 @@ where
 
 #[async_trait::async_trait(?Send)]
 pub(crate) trait VariantRepo: BaseRepo {
+    async fn claim_variant_processing_rights(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Result<(), VariantAlreadyExists>, RepoError>;
+
+    async fn variant_heartbeat(&self, hash: Hash, variant: String) -> Result<(), RepoError>;
+
+    async fn await_variant(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Option<Arc<str>>, RepoError>;
+
     async fn relate_variant_identifier(
         &self,
         hash: Hash,
@@ -763,6 +777,26 @@ impl<T> VariantRepo for Arc<T>
 where
     T: VariantRepo,
 {
+    async fn claim_variant_processing_rights(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Result<(), VariantAlreadyExists>, RepoError> {
+        T::claim_variant_processing_rights(self, hash, variant).await
+    }
+
+    async fn variant_heartbeat(&self, hash: Hash, variant: String) -> Result<(), RepoError> {
+        T::variant_heartbeat(self, hash, variant).await
+    }
+
+    async fn await_variant(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Option<Arc<str>>, RepoError> {
+        T::await_variant(self, hash, variant).await
+    }
+
     async fn relate_variant_identifier(
         &self,
         hash: Hash,

src/repo/postgres.rs

@@ -62,6 +62,7 @@ struct Inner {
     notifier_pool: Pool<AsyncPgConnection>,
     queue_notifications: DashMap<String, Arc<Notify>>,
     upload_notifications: DashMap<UploadId, Weak<Notify>>,
+    keyed_notifications: DashMap<String, Arc<Notify>>,
 }
 
 struct UploadInterest {
@@ -81,6 +82,10 @@ struct UploadNotifierState<'a> {
     inner: &'a Inner,
 }
 
+struct KeyedNotifierState<'a> {
+    inner: &'a Inner,
+}
+
 #[derive(Debug, thiserror::Error)]
 pub(crate) enum ConnectPostgresError {
     #[error("Failed to connect to postgres for migrations")]
@@ -331,6 +336,7 @@ impl PostgresRepo {
             notifier_pool,
             queue_notifications: DashMap::new(),
             upload_notifications: DashMap::new(),
+            keyed_notifications: DashMap::new(),
         });
 
         let handle = crate::sync::abort_on_drop(crate::sync::spawn_sendable(
@@ -363,7 +369,54 @@ impl PostgresRepo {
             .with_poll_timer("postgres-get-notifier-connection")
             .await
     }
+
+    async fn insert_keyed_notifier(
+        &self,
+        input_key: &str,
+    ) -> Result<Result<(), AlreadyInserted>, PostgresError> {
+        use schema::keyed_notifications::dsl::*;
+
+        let mut conn = self.get_connection().await?;
+
+        let res = diesel::insert_into(keyed_notifications)
+            .values((key.eq(input_key)))
+            .execute(&mut conn)
+            .with_timeout(Duration::from_secs(5))
+            .await
+            .map_err(|_| PostgresError::DbTimeout)?;
+
+        match res {
+            Ok(_) => Ok(Ok(())),
+            Err(diesel::result::Error::DatabaseError(
+                diesel::result::DatabaseErrorKind::UniqueViolation,
+                _,
+            )) => Ok(Err(AlreadyInserted)),
+            Err(e) => Err(PostgresError::Diesel(e).into()),
         }
+    }
+
+    async fn listen_on_key(&self, input_key: &str) -> Result<Result<(), TimedOut>, PostgresError> {
+        todo!()
+    }
+
+    async fn clear_keyed_notifier(&self, input_key: &str) -> Result<(), PostgresError> {
+        use schema::keyed_notifications::dsl::*;
+
+        let mut conn = self.get_connection().await?;
+
+        diesel::delete(keyed_notifications)
+            .filter(key.eq(input_key))
+            .execute(&mut conn)
+            .with_timeout(Duration::from_secs(5))
+            .await
+            .map_err(|_| PostgresError::DbTimeout)??;
+
+        Ok(())
+    }
+}
+
+struct TimedOut;
+struct AlreadyInserted;
 
 struct GetConnectionMetricsGuard {
     start: Instant,
@@ -511,6 +564,19 @@ impl<'a> UploadNotifierState<'a> {
     }
 }
 
+impl<'a> KeyedNotifierState<'a> {
+    fn handle(&self, key: &str) {
+        if let Some(notifier) = self
+            .inner
+            .keyed_notifications
+            .remove(key)
+            .and_then(|(_, weak)| weak.upgrade())
+        {
+            notifier.notify_waiters();
+        }
+    }
+}
+
 type BoxFuture<'a, T> = std::pin::Pin<Box<dyn std::future::Future<Output = T> + Send + 'a>>;
 type ConfigFn =
     Box<dyn Fn(&str) -> BoxFuture<'_, ConnectionResult<AsyncPgConnection>> + Send + Sync + 'static>;
@@ -529,6 +595,8 @@ async fn delegate_notifications(
 
     let upload_notifier_state = UploadNotifierState { inner: &inner };
 
+    let keyed_notifier_state = KeyedNotifierState { inner: &inner };
+
     while let Ok(notification) = receiver.recv_async().await {
         tracing::trace!("delegate_notifications: looping");
         metrics::counter!(crate::init_metrics::POSTGRES_NOTIFICATION).increment(1);
@@ -542,6 +610,10 @@ async fn delegate_notifications(
                 // new upload finished
                 upload_notifier_state.handle(notification.payload());
             }
+            "keyed_notification_channel" => {
+                // new keyed notification
+                keyed_notifier_state.handle(notification.payload());
+            }
             channel => {
                 tracing::info!(
                     "Unhandled postgres notification: {channel}: {}",
@@ -981,6 +1053,29 @@ impl HashRepo for PostgresRepo {
 
 #[async_trait::async_trait(?Send)]
 impl VariantRepo for PostgresRepo {
+    #[tracing::instrument(level = "debug", skip(self))]
+    async fn claim_variant_processing_rights(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Result<(), VariantAlreadyExists>, RepoError> {
+        todo!()
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    async fn variant_heartbeat(&self, hash: Hash, variant: String) -> Result<(), RepoError> {
+        todo!()
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    async fn await_variant(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Option<Arc<str>>, RepoError> {
+        todo!()
+    }
+
     #[tracing::instrument(level = "debug", skip(self))]
     async fn relate_variant_identifier(
         &self,

src/repo/postgres/migrations/V0014__add_keyed_notifications.rs

@@ -0,0 +1,50 @@
+use barrel::backend::Pg;
+use barrel::functions::AutogenFunction;
+use barrel::{types, Migration};
+
+pub(crate) fn migration() -> String {
+    let mut m = Migration::new();
+
+    m.create_table("keyed_notifications", |t| {
+        t.add_column(
+            "key",
+            types::text().primary(true).unique(true).nullable(false),
+        );
+        t.add_column(
+            "heartbeat",
+            types::datetime()
+                .nullable(false)
+                .default(AutogenFunction::CurrentTimestamp),
+        );
+
+        t.add_index(
+            "keyed_notifications_heartbeat_index",
+            types::index(["heartbeat"]),
+        );
+    });
+
+    m.inject_custom(
+        r#"
+CREATE OR REPLACE FUNCTION keyed_notify()
+	RETURNS trigger AS
+$$
+BEGIN
+	PERFORM pg_notify('keyed_notification_channel', OLD.key);
+	RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+    "#
+        .trim(),
+    );
+
+    m.inject_custom(
+        r#"
+CREATE TRIGGER keyed_notification_removed
+	AFTER DELETE
+	ON keyed_notifications
+	FOR EACH ROW
+EXECUTE PROCEDURE keyed_notify();
+    "#,
+    );
+    m.make::<Pg>().to_string()
+}

src/repo/postgres/schema.rs

@@ -48,6 +48,13 @@ diesel::table! {
     }
 }
 
+diesel::table! {
+    keyed_notifications (key) {
+        key -> Text,
+        heartbeat -> Timestamp,
+    }
+}
+
 diesel::table! {
     proxies (url) {
         url -> Text,
@@ -109,6 +116,7 @@ diesel::allow_tables_to_appear_in_same_query!(
     details,
     hashes,
     job_queue,
+    keyed_notifications,
     proxies,
     refinery_schema_history,
     settings,

src/repo/sled.rs

@@ -1448,6 +1448,29 @@ impl HashRepo for SledRepo {
 
 #[async_trait::async_trait(?Send)]
 impl VariantRepo for SledRepo {
+    #[tracing::instrument(level = "trace", skip(self))]
+    async fn claim_variant_processing_rights(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Result<(), VariantAlreadyExists>, RepoError> {
+        todo!()
+    }
+
+    #[tracing::instrument(level = "trace", skip(self))]
+    async fn variant_heartbeat(&self, hash: Hash, variant: String) -> Result<(), RepoError> {
+        todo!()
+    }
+
+    #[tracing::instrument(level = "trace", skip(self))]
+    async fn await_variant(
+        &self,
+        hash: Hash,
+        variant: String,
+    ) -> Result<Option<Arc<str>>, RepoError> {
+        todo!()
+    }
+
     #[tracing::instrument(level = "trace", skip(self))]
     async fn relate_variant_identifier(
         &self,