fetch: Prune remotes with sigrefs failures

Previously, trying to load `SignedRefs` for any given remote would
result in a fetch failure.

Teach the fetch to be more resilient by pruning remotes that result in
an error when loading `SignedRefs`, and add the error to the
validation failures.

crates/radicle-fetch/src/sigrefs.rs

@@ -1,5 +1,5 @@
 use std::collections::{BTreeMap, BTreeSet};
-use std::ops::{Deref, Not as _};
+use std::ops::Not as _;
 
 use radicle::storage::git::Repository;
 pub use radicle::storage::refs::SignedRefsAt;
@@ -36,13 +36,6 @@ pub(crate) enum DelegateStatus<T = ()> {
     NonDelegate { remote: PublicKey, data: T },
 }
 
-impl DelegateStatus {
-    /// Construct a `DelegateStatus` without any data.
-    pub fn empty(remote: PublicKey, delegates: &BTreeSet<PublicKey>) -> Self {
-        Self::new((), remote, delegates)
-    }
-}
-
 impl<T> DelegateStatus<T> {
     pub fn new(data: T, remote: PublicKey, delegates: &BTreeSet<PublicKey>) -> Self {
         if delegates.contains(&remote) {
@@ -51,42 +44,6 @@ impl<T> DelegateStatus<T> {
             Self::NonDelegate { remote, data }
         }
     }
-
-    /// Construct a `DelegateStatus` with [`SignedRefsAt`] signed reference
-    /// data, if it can be found in `repo`.
-    pub fn load<R, S>(
-        self,
-        cached: &Cached<R, S>,
-    ) -> Result<
-        DelegateStatus<Option<SignedRefsAt>>,
-        radicle::storage::refs::sigrefs::read::error::Read,
-    >
-    where
-        R: AsRef<Repository>,
-    {
-        let remote = *self.remote();
-        self.traverse(|_| cached.load(&remote))
-    }
-
-    fn remote(&self) -> &PublicKey {
-        match self {
-            Self::Delegate { remote, .. } => remote,
-            Self::NonDelegate { remote, .. } => remote,
-        }
-    }
-
-    fn traverse<U, E>(self, f: impl FnOnce(T) -> Result<U, E>) -> Result<DelegateStatus<U>, E> {
-        match self {
-            Self::Delegate { remote, data } => Ok(DelegateStatus::Delegate {
-                remote,
-                data: f(data)?,
-            }),
-            Self::NonDelegate { remote, data } => Ok(DelegateStatus::NonDelegate {
-                remote,
-                data: f(data)?,
-            }),
-        }
-    }
 }
 
 pub(crate) fn validate(
@@ -102,45 +59,52 @@ pub(crate) fn validate(
 ///
 /// Construct using [`RemoteRefs::load`].
 #[derive(Debug, Default)]
-pub struct RemoteRefs(BTreeMap<PublicKey, SignedRefsAt>);
+pub struct RemoteRefs(
+    pub(super)  BTreeMap<
+        PublicKey,
+        Result<Option<SignedRefsAt>, radicle::storage::refs::sigrefs::read::error::Read>,
+    >,
+);
 
 impl RemoteRefs {
     /// Load the sigrefs for each remote in `remotes`.
-    ///
-    /// If the sigrefs are missing for a given remote, regardless of delegate
-    /// status, then that remote is filtered out.
     pub(crate) fn load<'a, R, S>(
         cached: &Cached<R, S>,
         remotes: impl Iterator<Item = &'a PublicKey>,
-    ) -> Result<Self, error::RemoteRefs>
+    ) -> Self
     where
         R: AsRef<Repository>,
     {
-        remotes
-            .filter_map(|id| match cached.load(id) {
-                Ok(None) => None,
-                Ok(Some(sr)) => Some(Ok((id, sr))),
-                Err(e) => Some(Err(e)),
-            })
-            .try_fold(RemoteRefs::default(), |mut acc, remote_refs| {
-                let (id, sigrefs) = remote_refs?;
-                acc.0.insert(*id, sigrefs);
-                Ok(acc)
-            })
+        Self(
+            remotes
+                .map(|remote| (*remote, cached.load(remote)))
+                .collect(),
+        )
     }
-}
 
-impl Deref for RemoteRefs {
-    type Target = BTreeMap<PublicKey, SignedRefsAt>;
+    pub(crate) fn len(&self) -> usize {
+        self.0.len()
+    }
 
-    fn deref(&self) -> &Self::Target {
-        &self.0
+    pub(crate) fn into_inner(
+        self,
+    ) -> BTreeMap<
+        PublicKey,
+        Result<Option<SignedRefsAt>, radicle::storage::refs::sigrefs::read::error::Read>,
+    > {
+        self.0
     }
 }
 
 impl<'a> IntoIterator for &'a RemoteRefs {
-    type Item = <&'a BTreeMap<PublicKey, SignedRefsAt> as IntoIterator>::Item;
-    type IntoIter = <&'a BTreeMap<PublicKey, SignedRefsAt> as IntoIterator>::IntoIter;
+    type Item = <&'a BTreeMap<
+        PublicKey,
+        Result<Option<SignedRefsAt>, radicle::storage::refs::sigrefs::read::error::Read>,
+    > as IntoIterator>::Item;
+    type IntoIter = <&'a BTreeMap<
+        PublicKey,
+        Result<Option<SignedRefsAt>, radicle::storage::refs::sigrefs::read::error::Read>,
+    > as IntoIterator>::IntoIter;
 
     fn into_iter(self) -> Self::IntoIter {
         self.0.iter()

crates/radicle-fetch/src/stage.rs

@@ -45,7 +45,7 @@ use radicle::storage::ReadRepository;
 use crate::git::refs::{Policy, Update, Updates};
 use crate::policy::BlockList;
 use crate::refs::{ReceivedRef, ReceivedRefname};
-use crate::sigrefs;
+use crate::sigrefs::RemoteRefs;
 use crate::state::FetchState;
 use crate::transport::WantsHaves;
 use crate::{policy, refs};
@@ -482,12 +482,18 @@ pub struct DataRefs {
     pub remote: PublicKey,
     /// The set of signed references from each remote that was
     /// fetched.
-    pub remotes: sigrefs::RemoteRefs,
+    pub remotes: RemoteRefs,
     /// The data limit for this stage of fetching.
     #[allow(dead_code)]
     pub limit: u64,
 }
 
+impl DataRefs {
+    pub(crate) fn into_remote_refs(self) -> RemoteRefs {
+        self.remotes
+    }
+}
+
 impl ProtocolStage for DataRefs {
     // We don't need to ask for refs since we have all reference names
     // and `Oid`s in `rad/sigrefs`.
@@ -514,10 +520,13 @@ impl ProtocolStage for DataRefs {
     ) -> Result<WantsHaves, error::WantsHaves> {
         let mut wants_haves = WantsHaves::default();
 
-        for (remote, loaded) in &self.remotes {
+        for (remote, result) in self.remotes.into_iter() {
+            let Ok(Some(refs)) = result else {
+                continue;
+            };
             wants_haves.add(
                 refdb,
-                loaded.refs().iter().filter_map(|(refname, tip)| {
+                refs.iter().filter_map(|(refname, tip)| {
                     let refname = Qualified::from_refstr(refname)
                         .map(|refname| refname.with_namespace(Component::from(remote)))?;
                     Some((refname, *tip))
@@ -536,7 +545,10 @@ impl ProtocolStage for DataRefs {
     ) -> Result<Updates<'a>, error::Prepare> {
         let mut updates = Updates::default();
 
-        for (remote, refs) in &self.remotes {
+        for (remote, result) in &self.remotes {
+            let Ok(Some(refs)) = result else {
+                continue;
+            };
             let mut signed = HashSet::with_capacity(refs.refs().len());
             for (name, tip) in refs.iter() {
                 let tracking: Namespaced<'_> = Qualified::from_refstr(name)

crates/radicle-fetch/src/state.rs

@@ -313,7 +313,7 @@ impl FetchState {
                 self.run_stage(handle, handshake, &sigrefs_at)?;
                 let remotes = refs_at.iter().map(|r| &r.remote);
 
-                let signed_refs = sigrefs::RemoteRefs::load(&self.as_cached(handle), remotes)?;
+                let signed_refs = sigrefs::RemoteRefs::load(&self.as_cached(handle), remotes);
                 Ok(signed_refs)
             }
             None => {
@@ -333,7 +333,7 @@ impl FetchState {
                 let signed_refs = sigrefs::RemoteRefs::load(
                     &self.as_cached(handle),
                     fetched.iter().chain(delegates.iter()),
-                )?;
+                );
                 Ok(signed_refs)
             }
         }
@@ -418,6 +418,7 @@ impl FetchState {
             remote,
             refs_at,
         )?;
+
         log::debug!(
             "Fetched data for {} remote(s) ({}ms)",
             signed_refs.len(),
@@ -429,10 +430,10 @@ impl FetchState {
             remotes: signed_refs,
             limit: limit.refs,
         };
-        self.run_stage(handle, handshake, &data_refs)?;
+        let fetched = self.run_stage(handle, handshake, &data_refs)?;
         log::debug!(
             "Fetched data refs for {} remotes ({}ms)",
-            data_refs.remotes.len(),
+            fetched.len(),
             start.elapsed().as_millis()
         );
 
@@ -450,7 +451,8 @@ impl FetchState {
         // remotes from the tips, thus not updating the production Git
         // repository.
         let mut failures = sigrefs::Validations::default();
-        let signed_refs = data_refs.remotes;
+
+        let signed_refs = data_refs.into_remote_refs();
 
         // We may prune fetched remotes, so we keep track of
         // non-pruned, fetched remotes here.
@@ -469,21 +471,26 @@ impl FetchState {
 
         // TODO(finto): this might read better if it got its own
         // private function.
-        for remote in signed_refs.keys() {
-            if handle.is_blocked(remote) {
+        for (remote, refs) in signed_refs.into_inner() {
+            if handle.is_blocked(&remote) {
                 log::trace!("Skipping blocked remote {remote}");
                 continue;
             }
 
-            let remote = sigrefs::DelegateStatus::empty(*remote, &delegates)
-                .load(&self.as_cached(handle))?;
+            let remote = sigrefs::DelegateStatus::new(refs, remote, &delegates);
             match remote {
-                sigrefs::DelegateStatus::NonDelegate { remote, data: None } => {
+                sigrefs::DelegateStatus::NonDelegate {
+                    remote,
+                    data: Ok(None),
+                } => {
                     log::debug!("Pruning non-delegate {remote} tips, missing 'rad/sigrefs'");
                     failures.push(sigrefs::Validation::MissingRadSigRefs(remote));
                     self.prune(&remote);
                 }
-                sigrefs::DelegateStatus::Delegate { remote, data: None } => {
+                sigrefs::DelegateStatus::Delegate {
+                    remote,
+                    data: Ok(None),
+                } => {
                     log::debug!("Pruning delegate {remote} tips, missing 'rad/sigrefs'");
                     failures.push(sigrefs::Validation::MissingRadSigRefs(remote));
                     self.prune(&remote);
@@ -495,9 +502,26 @@ impl FetchState {
                     valid_delegates.remove(&remote);
                     failed_delegates.insert(remote);
                 }
+                sigrefs::DelegateStatus::Delegate {
+                    remote,
+                    data: Err(err),
+                }
+                | sigrefs::DelegateStatus::NonDelegate {
+                    remote,
+                    data: Err(err),
+                } => {
+                    log::debug!("Pruning {remote} tips due to: {err}");
+                    self.prune(&remote);
+                    valid_delegates.remove(&remote);
+                    failed_delegates.insert(remote);
+                    failures.push(sigrefs::Validation::Read {
+                        remote,
+                        source: err,
+                    });
+                }
                 sigrefs::DelegateStatus::NonDelegate {
                     remote,
-                    data: Some(sigrefs),
+                    data: Ok(Some(sigrefs)),
                 } => {
                     if let Some(SignedRefsAt { at, .. }) =
                         SignedRefsAt::load(remote, handle.repository())?
@@ -527,7 +551,7 @@ impl FetchState {
                 }
                 sigrefs::DelegateStatus::Delegate {
                     remote,
-                    data: Some(sigrefs),
+                    data: Ok(Some(sigrefs)),
                 } => {
                     if let Some(SignedRefsAt { at, .. }) =
                         SignedRefsAt::load(remote, handle.repository())?

crates/radicle/src/storage/git.rs

@@ -410,6 +410,12 @@ pub enum Validation {
     },
     #[error("missing `refs/namespaces/{0}/refs/rad/sigrefs`")]
     MissingRadSigRefs(RemoteId),
+    #[error("failed to read `refs/namespaces/{remote}/refs/rad/sigrefs`: {source}")]
+    Read {
+        remote: RemoteId,
+        #[source]
+        source: crate::storage::refs::sigrefs::read::error::Read,
+    },
 }
 
 impl Repository {