Merge pull request #1998 from subspace/gemini-3f-backport-fix-last-ar…

…chived-segment-search

Gemini 3f backport: Fix last archived segment search

crates/sc-consensus-subspace/src/archiver.rs

@@ -40,6 +40,7 @@ use sp_consensus::SyncOracle;
 use sp_consensus_subspace::{FarmerPublicKey, SubspaceApi};
 use sp_objects::ObjectsApi;
 use sp_runtime::traits::{Block as BlockT, CheckedSub, Header, NumberFor, One, Zero};
+use sp_runtime::Saturating;
 use std::error::Error;
 use std::future::Future;
 use std::slice;
@@ -209,6 +210,7 @@ pub(crate) const FINALIZATION_DEPTH_IN_SEGMENTS: usize = 5;
 fn find_last_archived_block<Block, Client, AS>(
     client: &Client,
     segment_headers_store: &SegmentHeadersStore<AS>,
+    best_block_to_archive: NumberFor<Block>,
 ) -> sp_blockchain::Result<Option<(SegmentHeader, Block, BlockObjectMapping)>>
 where
     Block: BlockT,
@@ -230,6 +232,12 @@ where
         .filter_map(|segment_index| segment_headers_store.get_segment_header(segment_index))
     {
         let last_archived_block_number = segment_header.last_archived_block().number;
+        if NumberFor::<Block>::from(last_archived_block_number) > best_block_to_archive {
+            // Last archived block in segment header it too high for current stat of the chain
+            // (segment headers store may know about more blocks in existence than is currently
+            // imported)
+            continue;
+        }
         let Some(last_archived_block_hash) = client.hash(last_archived_block_number.into())? else {
             // This block number is not in our chain yet (segment headers store may know about more
             // blocks in existence than is currently imported)
@@ -358,7 +366,11 @@ where
         .expect("Must always be able to get chain constants")
         .confirmation_depth_k();
 
-    let maybe_last_archived_block = find_last_archived_block(client, segment_headers_store)?;
+    let maybe_last_archived_block = find_last_archived_block(
+        client,
+        segment_headers_store,
+        best_block_number.saturating_sub(confirmation_depth_k.into()),
+    )?;
     let have_last_segment_header = maybe_last_archived_block.is_some();
     let mut best_archived_block = None;