From b67ead665abf4a3707d8ad0710778e950cee61c0 Mon Sep 17 00:00:00 2001
From: Jane Lusby <jane@zfnd.org>
Date: Wed, 17 Jun 2020 17:44:17 -0700
Subject: [PATCH] cleaning

---
 tower-batch/src/future.rs  | 20 +++++++++---------
 tower-batch/src/layer.rs   | 18 ++++++++--------
 tower-batch/src/service.rs | 32 ++++++++++++++--------------
 tower-batch/src/worker.rs  | 43 +++++++++++++++++++-------------------
 4 files changed, 57 insertions(+), 56 deletions(-)

diff --git a/tower-batch/src/future.rs b/tower-batch/src/future.rs
index 1a5bd30e..f41301fa 100644
--- a/tower-batch/src/future.rs
+++ b/tower-batch/src/future.rs
@@ -13,20 +13,20 @@ use tower::Service;
 
 /// Future that completes when the batch processing is complete.
 #[pin_project]
-pub struct ResponseFuture<S, E, Response>
+pub struct ResponseFuture<S, E2, Response>
 where
     S: Service<crate::BatchControl<Response>>,
 {
     #[pin]
-    state: ResponseState<S, E, Response>,
+    state: ResponseState<S, E2, Response>,
 }
 
-impl<S, E, Response> Debug for ResponseFuture<S, E, Response>
+impl<S, E2, Response> Debug for ResponseFuture<S, E2, Response>
 where
     S: Service<crate::BatchControl<Response>>,
     S::Future: Debug,
     S::Error: Debug,
-    E: Debug,
+    E2: Debug,
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("ResponseFuture")
@@ -36,21 +36,21 @@ where
 }
 
 #[pin_project(project = ResponseStateProj)]
-enum ResponseState<S, E, Response>
+enum ResponseState<S, E2, Response>
 where
     S: Service<crate::BatchControl<Response>>,
 {
-    Failed(Option<E>),
+    Failed(Option<E2>),
     Rx(#[pin] message::Rx<S::Future, S::Error>),
     Poll(#[pin] S::Future),
 }
 
-impl<S, E, Response> Debug for ResponseState<S, E, Response>
+impl<S, E2, Response> Debug for ResponseState<S, E2, Response>
 where
     S: Service<crate::BatchControl<Response>>,
     S::Future: Debug,
     S::Error: Debug,
-    E: Debug,
+    E2: Debug,
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -61,7 +61,7 @@ where
     }
 }
 
-impl<S, E, Response> ResponseFuture<S, E, Response>
+impl<S, E2, Response> ResponseFuture<S, E2, Response>
 where
     S: Service<crate::BatchControl<Response>>,
 {
@@ -71,7 +71,7 @@ where
         }
     }
 
-    pub(crate) fn failed(err: E) -> Self {
+    pub(crate) fn failed(err: E2) -> Self {
         ResponseFuture {
             state: ResponseState::Failed(Some(err)),
         }
diff --git a/tower-batch/src/layer.rs b/tower-batch/src/layer.rs
index 187b6f5c..b137d19f 100644
--- a/tower-batch/src/layer.rs
+++ b/tower-batch/src/layer.rs
@@ -9,14 +9,14 @@ use tower::Service;
 /// which means that this layer can only be used on the Tokio runtime.
 ///
 /// See the module documentation for more details.
-pub struct BatchLayer<Request, E> {
+pub struct BatchLayer<Request, E2> {
     max_items: usize,
     max_latency: std::time::Duration,
     _p: PhantomData<fn(Request)>,
-    _e: PhantomData<E>,
+    _e: PhantomData<E2>,
 }
 
-impl<Request, E> BatchLayer<Request, E> {
+impl<Request, E2> BatchLayer<Request, E2> {
     /// Creates a new `BatchLayer`.
     ///
     /// The wrapper is responsible for telling the inner service when to flush a
@@ -34,23 +34,23 @@ impl<Request, E> BatchLayer<Request, E> {
     }
 }
 
-impl<S, Request, E> Layer<S> for BatchLayer<Request, E>
+impl<S, Request, E2> Layer<S> for BatchLayer<Request, E2>
 where
     S: Service<BatchControl<Request>> + Send + 'static,
     S::Future: Send,
-    S::Error: Clone + Into<E> + Send + Sync,
+    S::Error: Clone + Into<E2> + Send + Sync,
     Request: Send + 'static,
-    E: Send + 'static,
-    crate::error::Closed: Into<E>,
+    E2: Send + 'static,
+    crate::error::Closed: Into<E2>,
 {
-    type Service = Batch<S, Request, E>;
+    type Service = Batch<S, Request, E2>;
 
     fn layer(&self, service: S) -> Self::Service {
         Batch::new(service, self.max_items, self.max_latency)
     }
 }
 
-impl<Request, E> fmt::Debug for BatchLayer<Request, E> {
+impl<Request, E2> fmt::Debug for BatchLayer<Request, E2> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("BufferLayer")
             .field("max_items", &self.max_items)
diff --git a/tower-batch/src/service.rs b/tower-batch/src/service.rs
index 1454fad6..44ed9cc8 100644
--- a/tower-batch/src/service.rs
+++ b/tower-batch/src/service.rs
@@ -17,21 +17,21 @@ use tower::Service;
 ///
 /// See the module documentation for more details.
 #[derive(Debug)]
-pub struct Batch<T, Request, E = crate::BoxError>
+pub struct Batch<T, Request, E2 = crate::BoxError>
 where
     T: Service<BatchControl<Request>>,
 {
     tx: mpsc::Sender<Message<Request, T::Future, T::Error>>,
-    handle: Handle<T::Error, E>,
-    _error_type: PhantomData<E>,
+    handle: Handle<T::Error, E2>,
+    _e: PhantomData<E2>,
 }
 
-impl<T, Request, E> Batch<T, Request, E>
+impl<T, Request, E2> Batch<T, Request, E2>
 where
     T: Service<BatchControl<Request>>,
-    T::Error: Into<E> + Clone,
-    E: Send + 'static,
-    crate::error::Closed: Into<E>,
+    T::Error: Into<E2> + Clone,
+    E2: Send + 'static,
+    crate::error::Closed: Into<E2>,
     // crate::error::Closed: Into<<Self as Service<Request>>::Error> + Send + Sync + 'static,
     // crate::error::ServiceError: Into<<Self as Service<Request>>::Error> + Send + Sync + 'static,
 {
@@ -59,25 +59,25 @@ where
         Batch {
             tx,
             handle,
-            _error_type: PhantomData,
+            _e: PhantomData,
         }
     }
 
-    fn get_worker_error(&self) -> E {
+    fn get_worker_error(&self) -> E2 {
         self.handle.get_error_on_closed()
     }
 }
 
-impl<T, Request, E> Service<Request> for Batch<T, Request, E>
+impl<T, Request, E2> Service<Request> for Batch<T, Request, E2>
 where
     T: Service<BatchControl<Request>>,
-    crate::error::Closed: Into<E>,
-    T::Error: Into<E> + Clone,
-    E: Send + 'static,
+    crate::error::Closed: Into<E2>,
+    T::Error: Into<E2> + Clone,
+    E2: Send + 'static,
 {
     type Response = T::Response;
-    type Error = E;
-    type Future = ResponseFuture<T, E, Request>;
+    type Error = E2;
+    type Future = ResponseFuture<T, E2, Request>;
 
     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
         // If the inner service has errored, then we error here.
@@ -127,7 +127,7 @@ where
         Self {
             tx: self.tx.clone(),
             handle: self.handle.clone(),
-            _error_type: PhantomData,
+            _e: PhantomData,
         }
     }
 }
diff --git a/tower-batch/src/worker.rs b/tower-batch/src/worker.rs
index 6fdcf4f4..3d4121a1 100644
--- a/tower-batch/src/worker.rs
+++ b/tower-batch/src/worker.rs
@@ -26,18 +26,18 @@ use tracing_futures::Instrument;
 /// implement (only call).
 #[pin_project]
 #[derive(Debug)]
-pub struct Worker<T, Request, E>
+pub struct Worker<S, Request, E2>
 where
-    T: Service<BatchControl<Request>>,
-    T::Error: Into<E>,
+    S: Service<BatchControl<Request>>,
+    S::Error: Into<E2>,
 {
-    rx: mpsc::Receiver<Message<Request, T::Future, T::Error>>,
-    service: T,
-    failed: Option<T::Error>,
-    handle: Handle<T::Error, E>,
+    rx: mpsc::Receiver<Message<Request, S::Future, S::Error>>,
+    service: S,
+    failed: Option<S::Error>,
+    handle: Handle<S::Error, E2>,
     max_items: usize,
     max_latency: std::time::Duration,
-    _error_type: PhantomData<E>,
+    _e: PhantomData<E2>,
 }
 
 /// Get the error out
@@ -47,17 +47,17 @@ pub(crate) struct Handle<E, E2> {
     _e: PhantomData<E2>,
 }
 
-impl<T, Request, E> Worker<T, Request, E>
+impl<S, Request, E2> Worker<S, Request, E2>
 where
-    T: Service<BatchControl<Request>>,
-    T::Error: Into<E> + Clone,
+    S: Service<BatchControl<Request>>,
+    S::Error: Into<E2> + Clone,
 {
     pub(crate) fn new(
-        service: T,
-        rx: mpsc::Receiver<Message<Request, T::Future, T::Error>>,
+        service: S,
+        rx: mpsc::Receiver<Message<Request, S::Future, S::Error>>,
         max_items: usize,
         max_latency: std::time::Duration,
-    ) -> (Handle<T::Error, E>, Worker<T, Request, E>) {
+    ) -> (Handle<S::Error, E2>, Worker<S, Request, E2>) {
         let handle = Handle {
             inner: Arc::new(Mutex::new(None)),
             _e: PhantomData,
@@ -70,13 +70,13 @@ where
             failed: None,
             max_items,
             max_latency,
-            _error_type: PhantomData,
+            _e: PhantomData,
         };
 
         (handle, worker)
     }
 
-    async fn process_req(&mut self, req: Request, tx: message::Tx<T::Future, T::Error>) {
+    async fn process_req(&mut self, req: Request, tx: message::Tx<S::Future, S::Error>) {
         if let Some(failed) = self.failed.clone() {
             tracing::trace!("notifying caller about worker failure");
             let _ = tx.send(Err(failed));
@@ -171,11 +171,12 @@ where
         }
     }
 
-    fn failed(&mut self, error: T::Error) {
-        // The underlying service failed when we called `poll_ready` on it with the given `error`. We
-        // need to communicate this to all the `Buffer` handles. To do so, we wrap up the error in
-        // an `Arc`, send that `Arc<E>` to all pending requests, and store it so that subsequent
-        // requests will also fail with the same error.
+    fn failed(&mut self, error: S::Error) {
+        // The underlying service failed when we called `poll_ready` on it with
+        // the given `error`. We need to communicate this to all the `Buffer`
+        // handles. To do so, we require that `S::Error` implements `Clone`,
+        // clone the error to send to all pending requests, and store it so that
+        // subsequent requests will also fail with the same error.
 
         // Note that we need to handle the case where some handle is concurrently trying to send us
         // a request. We need to make sure that *either* the send of the request fails *or* it