From 36c89315fad651b3b8ce1f8e25310db3ea668fae Mon Sep 17 00:00:00 2001
From: Alexander Batischev <eual.jp@gmail.com>
Date: Sun, 25 Apr 2021 18:29:19 +0300
Subject: Expose fallibility of individual SQL results

`LocalGeneration::sql::files()` runs an SQL query, iterates over the
results and collects the rows into a `Vec`. This can fail at any step:
the query might fail to run, or one of the rows might fail to be fetched
or processed.

Right now, we lump all those failures into a `Result` that wraps the
whole return value. This is only possible because we process each row
before returning. Once `Vec` is replaced by an iterator, we won't have
that luxury anymore, so we now wrap each individual element into its own
`Result` (as well as wrapping the whole vector into a `Result` of its
own).
---
 src/cmd/list_files.rs |  1 +
 src/cmd/restore.rs    |  2 ++
 src/cmd/show_gen.rs   | 17 ++++++++++-------
 src/generation.rs     | 20 ++++++++++++++------
 4 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/src/cmd/list_files.rs b/src/cmd/list_files.rs
index 22b102e..7f0cfed 100644
--- a/src/cmd/list_files.rs
+++ b/src/cmd/list_files.rs
@@ -23,6 +23,7 @@ impl ListFiles {
 
         let gen = client.fetch_generation(&gen_id, temp.path())?;
         for file in gen.files()? {
+            let file = file?;
             println!("{}", format_entry(&file.entry(), file.reason()));
         }
 
diff --git a/src/cmd/restore.rs b/src/cmd/restore.rs
index a321e80..f8bbaf4 100644
--- a/src/cmd/restore.rs
+++ b/src/cmd/restore.rs
@@ -41,6 +41,7 @@ impl Restore {
         info!("restoring {} files", gen.file_count()?);
         let progress = create_progress_bar(gen.file_count()?, true);
         for file in gen.files()? {
+            let file = file?;
             match file.reason() {
                 Reason::FileError => (),
                 _ => restore_generation(
@@ -54,6 +55,7 @@ impl Restore {
             }
         }
         for file in gen.files()? {
+            let file = file?;
             if file.entry().is_dir() {
                 restore_directory_metadata(file.entry(), &self.to)?;
             }
diff --git a/src/cmd/show_gen.rs b/src/cmd/show_gen.rs
index ba39809..7dc52cf 100644
--- a/src/cmd/show_gen.rs
+++ b/src/cmd/show_gen.rs
@@ -23,14 +23,17 @@ impl ShowGeneration {
         let gen = client.fetch_generation(&gen_id, temp.path())?;
         let files = gen.files()?;
 
-        let total_bytes = files.iter().fold(0, |acc, file| {
-            let e = file.entry();
-            if e.kind() == FilesystemKind::Regular {
-                acc + file.entry().len()
-            } else {
-                acc
-            }
+        let total_bytes = files.into_iter().try_fold(0, |acc, file| {
+            file.map(|file| {
+                let e = file.entry();
+                if e.kind() == FilesystemKind::Regular {
+                    acc + e.len()
+                } else {
+                    acc
+                }
+            })
         });
+        let total_bytes = total_bytes?;
 
         println!("generation-id: {}", gen_id);
         println!("file-count: {}", gen.file_count()?);
diff --git a/src/generation.rs b/src/generation.rs
index 1d0ee52..a780203 100644
--- a/src/generation.rs
+++ b/src/generation.rs
@@ -196,7 +196,7 @@ impl LocalGeneration {
         sql::file_count(&self.conn)
     }
 
-    pub fn files(&self) -> LocalGenerationResult<Vec<BackedUpFile>> {
+    pub fn files(&self) -> LocalGenerationResult<Vec<LocalGenerationResult<BackedUpFile>>> {
         sql::files(&self.conn)
     }
 
@@ -289,14 +289,22 @@ mod sql {
         Ok(count)
     }
 
-    pub fn files(conn: &Connection) -> LocalGenerationResult<Vec<BackedUpFile>> {
+    pub fn files(
+        conn: &Connection,
+    ) -> LocalGenerationResult<Vec<LocalGenerationResult<BackedUpFile>>> {
         let mut stmt = conn.prepare("SELECT * FROM files")?;
         let iter = stmt.query_map(params![], |row| row_to_entry(row))?;
-        let mut files = vec![];
+        let mut files: Vec<LocalGenerationResult<BackedUpFile>> = vec![];
         for x in iter {
-            let (fileno, json, reason) = x?;
-            let entry = serde_json::from_str(&json)?;
-            files.push(BackedUpFile::new(fileno, entry, &reason));
+            match x {
+                Ok((fileno, json, reason)) => {
+                    let result = serde_json::from_str(&json)
+                        .map(|entry| BackedUpFile::new(fileno, entry, &reason))
+                        .map_err(|e| e.into());
+                    files.push(result)
+                }
+                Err(e) => files.push(Err(e.into())),
+            }
         }
         Ok(files)
     }
-- 
cgit v1.2.1