Improve typing and errors, clean up

src/server.rs

@@ -5,7 +5,7 @@ use axum::response::{IntoResponse, Response};
 use std::sync::Arc;
 
 use crate::db;
-use crate::error::AppError;
+use crate::error::{AppError, VolumeError};
 
 #[derive(Clone)]
 pub struct AppState {
@@ -32,11 +32,10 @@ pub async fn put_key(
 ) -> Result<Response, AppError> {
     let target_volumes = crate::hasher::volumes_for_key(&key, &state.volumes, state.replicas);
     if target_volumes.len() < state.replicas {
-        return Err(AppError::VolumeError(format!(
-            "need {} volumes but only {} available",
-            state.replicas,
-            target_volumes.len()
-        )));
+        return Err(AppError::InsufficientVolumes {
+            need: state.replicas,
+            have: target_volumes.len(),
+        });
     }
 
     // Fan out PUTs to all target volumes concurrently
@@ -47,9 +46,11 @@ pub async fn put_key(
             let client = state.http.clone();
             let data = body.clone();
             async move {
-                let resp = client.put(&url).body(data).send().await.map_err(|e| format!("PUT {url}: {e}"))?;
+                let resp = client.put(&url).body(data).send().await.map_err(|e| {
+                    VolumeError::Request { url: url.clone(), source: e }
+                })?;
                 if !resp.status().is_success() {
-                    return Err(format!("PUT {url}: status {}", resp.status()));
+                    return Err(VolumeError::BadStatus { url, status: resp.status() });
                 }
                 Ok(())
             }
@@ -57,20 +58,20 @@ pub async fn put_key(
         handles.push(handle);
     }
 
-    let mut all_ok = true;
+    let mut failed = false;
     for handle in handles {
         if let Err(e) = handle.await.unwrap() {
-            tracing::error!("PUT to volume failed: {e}");
-            all_ok = false;
+            tracing::error!("{e}");
+            failed = true;
         }
     }
 
-    if !all_ok {
+    if failed {
         // Rollback: best-effort delete from volumes
         for vol in &target_volumes {
             let _ = state.http.delete(format!("{vol}/{key}")).send().await;
         }
-        return Err(AppError::VolumeError("not all volume writes succeeded".into()));
+        return Err(AppError::PartialWrite);
     }
 
     let size = Some(body.len() as i64);