rename IoConcurrency::{todo=>serial} and remove deprecation warning

pageserver/src/pgdatadir_mapping.rs

@@ -209,7 +209,7 @@ impl Timeline {
                     .get_rel_page_at_lsn_batched(
                         pages.iter().map(|(tag, blknum)| (tag, blknum)),
                         effective_lsn,
-                        IoConcurrency::todo(),
+                        IoConcurrency::serial(),
                         ctx,
                     )
                     .await;

pageserver/src/tenant.rs

@@ -6639,7 +6639,7 @@ mod tests {
             .get_vectored_impl(
                 aux_keyspace.clone(),
                 read_lsn,
-                &mut ValuesReconstructState::new(IoConcurrency::todo()),
+                &mut ValuesReconstructState::new(IoConcurrency::serial()),
                 &ctx,
             )
             .await;
@@ -6787,7 +6787,7 @@ mod tests {
             .get_vectored_impl(
                 read.clone(),
                 current_lsn,
-                &mut ValuesReconstructState::new(IoConcurrency::todo()),
+                &mut ValuesReconstructState::new(IoConcurrency::serial()),
                 &ctx,
             )
             .await?;
@@ -6922,7 +6922,7 @@ mod tests {
                         ranges: vec![child_gap_at_key..child_gap_at_key.next()],
                     },
                     query_lsn,
-                    &mut ValuesReconstructState::new(IoConcurrency::todo()),
+                    &mut ValuesReconstructState::new(IoConcurrency::serial()),
                     &ctx,
                 )
                 .await;
@@ -7421,7 +7421,7 @@ mod tests {
                 .get_vectored_impl(
                     keyspace.clone(),
                     lsn,
-                    &mut ValuesReconstructState::new(IoConcurrency::todo()),
+                    &mut ValuesReconstructState::new(IoConcurrency::serial()),
                     &ctx,
                 )
                 .await?
@@ -7611,7 +7611,7 @@ mod tests {
             lsn: Lsn,
             ctx: &RequestContext,
         ) -> anyhow::Result<(BTreeMap<Key, Result<Bytes, PageReconstructError>>, usize)> {
-            let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+            let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
             let res = tline
                 .get_vectored_impl(keyspace.clone(), lsn, &mut reconstruct_state, ctx)
                 .await?;
@@ -7900,7 +7900,7 @@ mod tests {
         );
 
         // test vectored scan on parent timeline
-        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
         let res = tline
             .get_vectored_impl(
                 KeySpace::single(Key::metadata_key_range()),
@@ -7926,7 +7926,7 @@ mod tests {
         );
 
         // test vectored scan on child timeline
-        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
         let res = child
             .get_vectored_impl(
                 KeySpace::single(Key::metadata_key_range()),
@@ -7964,7 +7964,7 @@ mod tests {
         lsn: Lsn,
         ctx: &RequestContext,
     ) -> Result<Option<Bytes>, GetVectoredError> {
-        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
         let mut res = tline
             .get_vectored_impl(
                 KeySpace::single(key..key.next()),
@@ -10056,7 +10056,7 @@ mod tests {
 
         let keyspace = KeySpace::single(get_key(0)..get_key(10));
         let results = tline
-            .get_vectored(keyspace, delta_layer_end_lsn, IoConcurrency::todo(), &ctx)
+            .get_vectored(keyspace, delta_layer_end_lsn, IoConcurrency::serial(), &ctx)
             .await
             .expect("No vectored errors");
         for (key, res) in results {

pageserver/src/tenant/storage_layer.rs

@@ -203,9 +203,10 @@ impl std::fmt::Debug for SelectedIoConcurrency {
 }
 
 impl IoConcurrency {
-    #[deprecated]
-    pub(crate) fn todo() -> Self {
-        // To test futuresunordered, we can create a gate guard here and Box::leak it
+    /// TODO: over time, work towards removing this method.
+    /// Requires finding a long-lived root for the IoConcurrency and funneling it through
+    /// to the place that does the get_values_reconstruct_data call.
+    pub(crate) fn serial() -> Self {
         Self::spawn(SelectedIoConcurrency::Serial)
     }
     pub(crate) fn spawn_from_env(gate_guard: GateGuard) -> IoConcurrency {

pageserver/src/tenant/storage_layer/layer/tests.rs

@@ -58,7 +58,7 @@ async fn smoke_test() {
     };
 
     let img_before = {
-        let mut data = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut data = ValuesReconstructState::new(IoConcurrency::serial());
         layer
             .get_values_reconstruct_data(
                 controlfile_keyspace.clone(),
@@ -93,7 +93,7 @@ async fn smoke_test() {
 
     // on accesses when the layer is evicted, it will automatically be downloaded.
     let img_after = {
-        let mut data = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut data = ValuesReconstructState::new(IoConcurrency::serial());
         layer
             .get_values_reconstruct_data(
                 controlfile_keyspace.clone(),

pageserver/src/tenant/timeline.rs

@@ -1001,7 +1001,7 @@ impl Timeline {
             ranges: vec![key..key.next()],
         };
 
-        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
 
         let vectored_res = self
             .get_vectored_impl(keyspace.clone(), lsn, &mut reconstruct_state, ctx)
@@ -1135,7 +1135,7 @@ impl Timeline {
             .get_vectored_impl(
                 keyspace.clone(),
                 lsn,
-                &mut ValuesReconstructState::new(IoConcurrency::todo()),
+                &mut ValuesReconstructState::new(IoConcurrency::serial()),
                 ctx,
             )
             .await;
@@ -4174,7 +4174,7 @@ impl Timeline {
                         .get_vectored(
                             key_request_accum.consume_keyspace(),
                             lsn,
-                            IoConcurrency::todo(),
+                            IoConcurrency::serial(),
                             ctx,
                         )
                         .await?;
@@ -4257,7 +4257,7 @@ impl Timeline {
         start: Key,
     ) -> Result<ImageLayerCreationOutcome, CreateImageLayersError> {
         // Metadata keys image layer creation.
-        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::todo());
+        let mut reconstruct_state = ValuesReconstructState::new(IoConcurrency::serial());
         let begin = Instant::now();
         let data = self
             .get_vectored_impl(partition.clone(), lsn, &mut reconstruct_state, ctx)
@@ -5757,7 +5757,7 @@ impl Timeline {
         for layer in guard.layer_map()?.iter_historic_layers() {
             if !layer.is_delta() && layer.image_layer_lsn() == lsn {
                 let layer = guard.get_from_desc(&layer);
-                let mut reconstruct_data = ValuesReconstructState::new(IoConcurrency::todo());
+                let mut reconstruct_data = ValuesReconstructState::new(IoConcurrency::serial());
                 layer
                     .get_values_reconstruct_data(
                         KeySpace::single(Key::MIN..Key::MAX),