From a2fb42d242864a3db90634edd0209e782cb5eae7 Mon Sep 17 00:00:00 2001
From: Alexander Weiss <alex@weissfam.de>
Date: Mon, 26 Sep 2022 23:21:08 +0200
Subject: [PATCH] REST backend: abort at permanent errors

---
 src/backend/rest.rs | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/src/backend/rest.rs b/src/backend/rest.rs
index 4ff8d3d..37cf8c8 100644
--- a/src/backend/rest.rs
+++ b/src/backend/rest.rs
@@ -2,14 +2,33 @@ use std::time::Duration;
 
 use anyhow::{bail, Result};
 use async_trait::async_trait;
-use backoff::{backoff::Backoff, ExponentialBackoff, ExponentialBackoffBuilder};
+use backoff::{backoff::Backoff, Error, ExponentialBackoff, ExponentialBackoffBuilder};
 use bytes::Bytes;
 use log::*;
-use reqwest::{Client, Url};
+use reqwest::{Client, Response, Url};
 use serde::Deserialize;
 
 use super::{FileType, Id, ReadBackend, WriteBackend};
 
+// trait CheckError to add user-defined methoed check_error on Response
+trait CheckError {
+    fn check_error(self) -> std::result::Result<Response, Error<reqwest::Error>>;
+}
+
+impl CheckError for Response {
+    // Check reqwest Response for error and treat errors as permanent or transient
+    fn check_error(self) -> std::result::Result<Response, Error<reqwest::Error>> {
+        match self.error_for_status() {
+            Ok(t) => Ok(t),
+            Err(err) if err.status().unwrap().is_client_error() => Err(Error::Permanent(err)),
+            Err(err) => Err(Error::Transient {
+                err,
+                retry_after: None,
+            }),
+        }
+    }
+}
+
 #[derive(Clone)]
 struct MaybeBackoff(Option<ExponentialBackoff>);
 
@@ -32,7 +51,6 @@ pub struct RestBackend {
     backoff: MaybeBackoff,
 }
 
-// TODO for backoff: Handle transient vs permanent errors!
 fn notify(err: reqwest::Error, duration: Duration) {
     warn!("Error {err} at {duration:?}, retrying");
 }
@@ -136,7 +154,7 @@ impl ReadBackend for RestBackend {
                     .header("Accept", "application/vnd.x.restic.rest.v2")
                     .send()
                     .await?
-                    .error_for_status()?
+                    .check_error()?
                     .json::<Vec<ListEntry>>()
                     .await?;
                 Ok(list.into_iter().map(|i| (i.name, i.size)).collect())
@@ -155,7 +173,7 @@ impl ReadBackend for RestBackend {
                     .get(self.url(tpe, id))
                     .send()
                     .await?
-                    .error_for_status()?
+                    .check_error()?
                     .bytes()
                     .await?
                     .into_iter()
@@ -185,7 +203,7 @@ impl ReadBackend for RestBackend {
                     .header("Range", header_value.clone())
                     .send()
                     .await?
-                    .error_for_status()?
+                    .check_error()?
                     .bytes()
                     .await?
                     .into_iter()
@@ -207,7 +225,7 @@ impl WriteBackend for RestBackend {
                     .post(self.url.join("?create=true").unwrap())
                     .send()
                     .await?
-                    .error_for_status()?;
+                    .check_error()?;
                 Ok(())
             },
             notify,
@@ -232,7 +250,7 @@ impl WriteBackend for RestBackend {
                     .unwrap()
                     .send()
                     .await?
-                    .error_for_status()?;
+                    .check_error()?;
                 Ok(())
             },
             notify,
@@ -249,7 +267,7 @@ impl WriteBackend for RestBackend {
                     .delete(self.url(tpe, id))
                     .send()
                     .await?
-                    .error_for_status()?;
+                    .check_error()?;
                 Ok(())
             },
             notify,