From 43e016a7d12c4f53ec864e5cd18cb3516fa2991e Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Wed, 27 Dec 2023 22:37:13 +0900
Subject: [PATCH] index: add explicit reindexing method that can propagate
 error

---
 cli/src/commands/debug.rs      | 10 ++++------
 lib/src/default_index/store.rs | 13 +++++++++++++
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/cli/src/commands/debug.rs b/cli/src/commands/debug.rs
index 6ce2d2c9d..b86ed84eb 100644
--- a/cli/src/commands/debug.rs
+++ b/cli/src/commands/debug.rs
@@ -20,6 +20,7 @@ use clap::Subcommand;
 use jj_lib::backend::ObjectId;
 use jj_lib::default_index::{AsCompositeIndex as _, DefaultIndexStore, DefaultReadonlyIndex};
 use jj_lib::local_working_copy::LocalWorkingCopy;
+use jj_lib::repo::Repo;
 use jj_lib::revset;
 use jj_lib::working_copy::WorkingCopy;
 
@@ -240,12 +241,9 @@ fn cmd_debug_reindex(
         default_index_store
             .reinit()
             .map_err(|err| CommandError::InternalError(err.to_string()))?;
-        let repo = repo.reload_at(repo.operation())?;
-        let default_index: &DefaultReadonlyIndex = repo
-            .readonly_index()
-            .as_any()
-            .downcast_ref()
-            .expect("Default index should be a DefaultReadonlyIndex");
+        let default_index = default_index_store
+            .build_index_at_operation(repo.operation(), repo.store())
+            .map_err(|err| CommandError::InternalError(err.to_string()))?;
         writeln!(
             ui.stderr(),
             "Finished indexing {:?} commits.",
diff --git a/lib/src/default_index/store.rs b/lib/src/default_index/store.rs
index 6e9f46263..8560fab33 100644
--- a/lib/src/default_index/store.rs
+++ b/lib/src/default_index/store.rs
@@ -119,6 +119,19 @@ impl DefaultIndexStore {
         .map_err(DefaultIndexStoreError::LoadIndex)
     }
 
+    /// Rebuilds index for the given `operation`.
+    ///
+    /// The index to be built will be calculated from one of the ancestor
+    /// operations if exists. Use `reinit()` to rebuild index from scratch.
+    pub fn build_index_at_operation(
+        &self,
+        operation: &Operation,
+        store: &Arc<Store>,
+    ) -> Result<DefaultReadonlyIndex, DefaultIndexStoreError> {
+        let index_segment = self.build_index_segments_at_operation(operation, store)?;
+        Ok(DefaultReadonlyIndex::from_segment(index_segment))
+    }
+
     #[tracing::instrument(skip(self, store))]
     fn build_index_segments_at_operation(
         &self,