actix-utils: Remove unsound custom Cell as well (#161)

Author: JohnTitor

actix-utils/CHANGES.md

@@ -1,7 +1,9 @@
 # Changes
 
 ## Unreleased - 2020-xx-xx
+
 * Upgrade `tokio-util` to `0.3`.
+* Remove unsound custom Cell and use `std::cell::RefCell` instead, as well as `actix-service`.
 
 ## [1.0.6] - 2020-01-08
 

actix-utils/src/cell.rs

@@ -1,14 +1,15 @@
+use std::cell::RefCell;
 use std::future::Future;
 use std::pin::Pin;
+use std::rc::Rc;
 use std::task::{Context, Poll};
 
 use slab::Slab;
 
-use crate::cell::Cell;
 use crate::task::LocalWaker;
 
 /// Condition allows to notify multiple receivers at the same time
-pub struct Condition(Cell<Inner>);
+pub struct Condition(Rc<RefCell<Inner>>);
 
 struct Inner {
     data: Slab<Option<LocalWaker>>,
@@ -22,12 +23,12 @@ impl Default for Condition {
 
 impl Condition {
     pub fn new() -> Condition {
-        Condition(Cell::new(Inner { data: Slab::new() }))
+        Condition(Rc::new(RefCell::new(Inner { data: Slab::new() })))
     }
 
     /// Get condition waiter
     pub fn wait(&mut self) -> Waiter {
-        let token = self.0.get_mut().data.insert(None);
+        let token = self.0.borrow_mut().data.insert(None);
         Waiter {
             token,
             inner: self.0.clone(),
@@ -36,7 +37,7 @@ impl Condition {
 
     /// Notify all waiters
     pub fn notify(&self) {
-        let inner = self.0.get_ref();
+        let inner = self.0.borrow();
         for item in inner.data.iter() {
             if let Some(waker) = item.1 {
                 waker.wake();
@@ -54,12 +55,12 @@ impl Drop for Condition {
 #[must_use = "Waiter do nothing unless polled"]
 pub struct Waiter {
     token: usize,
-    inner: Cell<Inner>,
+    inner: Rc<RefCell<Inner>>,
 }
 
 impl Clone for Waiter {
     fn clone(&self) -> Self {
-        let token = unsafe { self.inner.get_mut_unsafe() }.data.insert(None);
+        let token = self.inner.borrow_mut().data.insert(None);
         Waiter {
             token,
             inner: self.inner.clone(),
@@ -73,7 +74,8 @@ impl Future for Waiter {
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.get_mut();
 
-        let inner = unsafe { this.inner.get_mut().data.get_unchecked_mut(this.token) };
+        let mut inner = this.inner.borrow_mut();
+        let inner = unsafe { inner.data.get_unchecked_mut(this.token) };
         if inner.is_none() {
             let waker = LocalWaker::default();
             waker.register(cx.waker());
@@ -89,7 +91,7 @@ impl Future for Waiter {
 
 impl Drop for Waiter {
     fn drop(&mut self) {
-        self.inner.get_mut().data.remove(self.token);
+        self.inner.borrow_mut().data.remove(self.token);
     }
 }
 

actix-utils/src/condition.rs

@@ -3,7 +3,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 
 use actix_service::{Service, ServiceFactory};
-use futures_util::{future, ready, future::Future};
+use futures_util::{future, future::Future, ready};
 
 /// Combine two different service types into a single type.
 ///

actix-utils/src/either.rs

@@ -2,7 +2,6 @@
 #![deny(rust_2018_idioms)]
 #![allow(clippy::type_complexity)]
 
-mod cell;
 pub mod condition;
 pub mod counter;
 pub mod either;

actix-utils/src/lib.rs

@@ -1,24 +1,25 @@
 //! A multi-producer, single-consumer, futures-aware, FIFO queue.
 use std::any::Any;
+use std::cell::RefCell;
 use std::collections::VecDeque;
 use std::error::Error;
 use std::fmt;
 use std::pin::Pin;
+use std::rc::Rc;
 use std::task::{Context, Poll};
 
 use futures_sink::Sink;
 use futures_util::stream::Stream;
 
-use crate::cell::Cell;
 use crate::task::LocalWaker;
 
 /// Creates a unbounded in-memory channel with buffered storage.
 pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
-    let shared = Cell::new(Shared {
+    let shared = Rc::new(RefCell::new(Shared {
         has_receiver: true,
         buffer: VecDeque::new(),
         blocked_recv: LocalWaker::new(),
-    });
+    }));
     let sender = Sender {
         shared: shared.clone(),
     };
@@ -38,15 +39,15 @@ struct Shared<T> {
 /// This is created by the `channel` function.
 #[derive(Debug)]
 pub struct Sender<T> {
-    shared: Cell<Shared<T>>,
+    shared: Rc<RefCell<Shared<T>>>,
 }
 
 impl<T> Unpin for Sender<T> {}
 
 impl<T> Sender<T> {
     /// Sends the provided message along this channel.
     pub fn send(&self, item: T) -> Result<(), SendError<T>> {
-        let shared = unsafe { self.shared.get_mut_unsafe() };
+        let mut shared = self.shared.borrow_mut();
         if !shared.has_receiver {
             return Err(SendError(item)); // receiver was dropped
         };
@@ -60,7 +61,7 @@ impl<T> Sender<T> {
     /// This prevents any further messages from being sent on the channel while
     /// still enabling the receiver to drain messages that are buffered.
     pub fn close(&mut self) {
-        self.shared.get_mut().has_receiver = false;
+        self.shared.borrow_mut().has_receiver = false;
     }
 }
 
@@ -94,8 +95,8 @@ impl<T> Sink<T> for Sender<T> {
 
 impl<T> Drop for Sender<T> {
     fn drop(&mut self) {
-        let count = self.shared.strong_count();
-        let shared = self.shared.get_mut();
+        let count = Rc::strong_count(&self.shared);
+        let shared = self.shared.borrow_mut();
 
         // check is last sender is about to drop
         if shared.has_receiver && count == 2 {
@@ -110,7 +111,7 @@ impl<T> Drop for Sender<T> {
 /// This is created by the `channel` function.
 #[derive(Debug)]
 pub struct Receiver<T> {
-    shared: Cell<Shared<T>>,
+    shared: Rc<RefCell<Shared<T>>>,
 }
 
 impl<T> Receiver<T> {
@@ -127,23 +128,24 @@ impl<T> Unpin for Receiver<T> {}
 impl<T> Stream for Receiver<T> {
     type Item = T;
 
-    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        if self.shared.strong_count() == 1 {
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let mut shared = self.shared.borrow_mut();
+        if Rc::strong_count(&self.shared) == 1 {
             // All senders have been dropped, so drain the buffer and end the
             // stream.
-            Poll::Ready(self.shared.get_mut().buffer.pop_front())
-        } else if let Some(msg) = self.shared.get_mut().buffer.pop_front() {
+            Poll::Ready(shared.buffer.pop_front())
+        } else if let Some(msg) = shared.buffer.pop_front() {
             Poll::Ready(Some(msg))
         } else {
-            self.shared.get_mut().blocked_recv.register(cx.waker());
+            shared.blocked_recv.register(cx.waker());
             Poll::Pending
         }
     }
 }
 
 impl<T> Drop for Receiver<T> {
     fn drop(&mut self) {
-        let shared = self.shared.get_mut();
+        let mut shared = self.shared.borrow_mut();
         shared.buffer.clear();
         shared.has_receiver = false;
     }