Introduce marshal ancestry stream alias

Author: clabby

consensus/src/lib.rs

@@ -237,7 +237,7 @@ stability_scope!(ALPHA {
 });
 stability_scope!(ALPHA, cfg(not(target_arch = "wasm32")) {
     use commonware_cryptography::certificate::Scheme;
-    use futures::Stream;
+    use crate::marshal::ancestry::Ancestry;
     use commonware_runtime::{Clock, Metrics, Spawner};
     use rand::Rng;
 
@@ -272,7 +272,7 @@ stability_scope!(ALPHA, cfg(not(target_arch = "wasm32")) {
         fn propose(
             &mut self,
             context: (E, Self::Context),
-            ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+            ancestry: impl Ancestry<Self::Block>,
         ) -> impl Future<Output = Option<Self::Block>> + Send;
 
         /// Verify a block produced by the application's proposer, relative to its ancestry.
@@ -287,7 +287,7 @@ stability_scope!(ALPHA, cfg(not(target_arch = "wasm32")) {
         fn verify(
             &mut self,
             context: (E, Self::Context),
-            ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+            ancestry: impl Ancestry<Self::Block>,
         ) -> impl Future<Output = bool> + Send;
     }
 });

consensus/src/marshal/ancestry.rs

@@ -13,6 +13,16 @@ use std::{
     task::{Context, Poll},
 };
 
+/// A stream of blocks used by application propose and verify calls.
+pub trait Ancestry<B: Block>: Stream<Item = B> + Send + Unpin + 'static {}
+
+impl<T, B> Ancestry<B> for T
+where
+    T: Stream<Item = B> + Send + Unpin + 'static,
+    B: Block,
+{
+}
+
 /// An interface for providing blocks.
 pub trait BlockProvider: Clone + Send + 'static {
     /// The block type the provider walks.

consensus/src/marshal/mocks/verifying.rs

@@ -4,13 +4,12 @@
 //! `Application` trait, suitable for testing the `Marshaled` wrapper in
 //! both standard and coding variants.
 
-use crate::{CertifiableBlock, Epochable};
+use crate::{marshal::ancestry::Ancestry, CertifiableBlock, Epochable};
 use commonware_runtime::deterministic;
 use commonware_utils::{
     channel::{fallible::OneshotExt, oneshot},
     sync::Mutex,
 };
-use futures::Stream;
 use std::{marker::PhantomData, sync::Arc};
 
 /// A mock application that implements `Application` for testing.
@@ -75,15 +74,15 @@ where
     async fn propose(
         &mut self,
         _context: (deterministic::Context, Self::Context),
-        _ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+        _ancestry: impl Ancestry<Self::Block>,
     ) -> Option<Self::Block> {
         self.propose_result.clone()
     }
 
     async fn verify(
         &mut self,
         _context: (deterministic::Context, Self::Context),
-        _ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+        _ancestry: impl Ancestry<Self::Block>,
     ) -> bool {
         self.verify_result
     }
@@ -136,15 +135,15 @@ where
     async fn propose(
         &mut self,
         _context: (deterministic::Context, Self::Context),
-        _ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+        _ancestry: impl Ancestry<Self::Block>,
     ) -> Option<Self::Block> {
         None
     }
 
     async fn verify(
         &mut self,
         _context: (deterministic::Context, Self::Context),
-        _ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+        _ancestry: impl Ancestry<Self::Block>,
     ) -> bool {
         if let Some(started) = self.started.lock().take() {
             started.send_lossy(());

examples/reshare/src/application/core.rs

@@ -5,6 +5,7 @@ use crate::{
     dkg,
 };
 use commonware_consensus::{
+    marshal::ancestry::Ancestry,
     simplex::types::Context,
     types::{Epoch, Round, View},
     Heightable,
@@ -14,7 +15,7 @@ use commonware_cryptography::{
     Signer,
 };
 use commonware_runtime::{Clock, Metrics, Spawner};
-use futures::{Stream, StreamExt};
+use futures::StreamExt;
 use rand::Rng;
 use std::marker::PhantomData;
 
@@ -88,7 +89,7 @@ where
     async fn propose(
         &mut self,
         (_, context): (E, Self::Context),
-        mut ancestry: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
+        mut ancestry: impl Ancestry<Self::Block>,
     ) -> Option<Self::Block> {
         // Fetch the parent block from the ancestry stream.
         let parent_block = ancestry.next().await?;
@@ -110,11 +111,7 @@ where
         ))
     }
 
-    async fn verify(
-        &mut self,
-        _: (E, Self::Context),
-        _: impl Stream<Item = Self::Block> + Send + Unpin + 'static,
-    ) -> bool {
+    async fn verify(&mut self, _: (E, Self::Context), _: impl Ancestry<Self::Block>) -> bool {
         // We wrap this application with `Marshaled`, which handles ancestry
         // verification (parent commitment and height contiguity).
         //