From da1c2592111947a41f1648cc3b34fbd0e5acd5b7 Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Sun, 26 Feb 2023 12:15:27 -0800
Subject: [PATCH] index_store: use custom error type for write errors

Public APIs should use custom error types (not `io::Error` as
here). The caller isn't affected by this commit because it just
unwraps the error.
---
 lib/src/index_store.rs | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/src/index_store.rs b/lib/src/index_store.rs
index e4311c0f2..6d5f32033 100644
--- a/lib/src/index_store.rs
+++ b/lib/src/index_store.rs
@@ -21,6 +21,7 @@ use std::sync::Arc;
 
 use itertools::Itertools;
 use tempfile::NamedTempFile;
+use thiserror::Error;
 
 use crate::backend::CommitId;
 use crate::commit::Commit;
@@ -31,6 +32,12 @@ use crate::op_store::OperationId;
 use crate::operation::Operation;
 use crate::store::Store;
 
+#[derive(Debug, Error)]
+pub enum IndexWriteError {
+    #[error("{0}")]
+    Other(String),
+}
+
 pub struct IndexStore {
     dir: PathBuf,
 }
@@ -79,9 +86,16 @@ impl IndexStore {
         &self,
         index: MutableIndex,
         op_id: &OperationId,
-    ) -> io::Result<Arc<ReadonlyIndex>> {
-        let index = index.save_in(self.dir.clone())?;
-        self.associate_file_with_operation(&index, op_id)?;
+    ) -> Result<Arc<ReadonlyIndex>, IndexWriteError> {
+        let index = index.save_in(self.dir.clone()).map_err(|err| {
+            IndexWriteError::Other(format!("Failed to write commit index file: {err:?}"))
+        })?;
+        self.associate_file_with_operation(&index, op_id)
+            .map_err(|err| {
+                IndexWriteError::Other(format!(
+                    "Failed to associate commit index file with a operation {op_id:?}: {err:?}"
+                ))
+            })?;
         Ok(index)
     }