Remove unstable read-initializer feature

futures-io/Cargo.toml

@@ -18,7 +18,6 @@ std = []
 # These features are outside of the normal semver guarantees and require the
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = []
-read-initializer = []
 
 [dependencies]
 

futures-io/src/lib.rs

@@ -8,7 +8,6 @@
 //! All items of this library are only available when the `std` feature of this
 //! library is activated, and it is activated by default.
 
-#![cfg_attr(all(feature = "read-initializer", feature = "std"), feature(read_initializer))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(missing_debug_implementations, missing_docs, rust_2018_idioms, unreachable_pub)]
 // It cannot be included in the published code because this lints have false positives in the minimum required version.
@@ -22,9 +21,6 @@
 ))]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 
-#[cfg(all(feature = "read-initializer", not(feature = "unstable")))]
-compile_error!("The `read-initializer` feature requires the `unstable` feature as an explicit opt-in to unstable features");
-
 #[cfg(feature = "std")]
 mod if_std {
     use std::io;
@@ -34,11 +30,6 @@ mod if_std {
 
     // Re-export some types from `std::io` so that users don't have to deal
     // with conflicts when `use`ing `futures::io` and `std::io`.
-    #[cfg(feature = "read-initializer")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-    #[doc(no_inline)]
-    #[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
-    pub use io::Initializer;
     #[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
     #[doc(no_inline)]
     pub use io::{Error, ErrorKind, IoSlice, IoSliceMut, Result, SeekFrom};
@@ -51,27 +42,6 @@ mod if_std {
     /// for wakeup and return if data is not yet available, rather than blocking
     /// the calling thread.
     pub trait AsyncRead {
-        /// Determines if this `AsyncRead`er can work with buffers of
-        /// uninitialized memory.
-        ///
-        /// The default implementation returns an initializer which will zero
-        /// buffers.
-        ///
-        /// This method is only available when the `read-initializer` feature of this
-        /// library is activated.
-        ///
-        /// # Safety
-        ///
-        /// This method is `unsafe` because an `AsyncRead`er could otherwise
-        /// return a non-zeroing `Initializer` from another `AsyncRead` type
-        /// without an `unsafe` block.
-        #[cfg(feature = "read-initializer")]
-        #[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-        #[inline]
-        unsafe fn initializer(&self) -> Initializer {
-            Initializer::zeroing()
-        }
-
         /// Attempt to read from the `AsyncRead` into `buf`.
         ///
         /// On success, returns `Poll::Ready(Ok(num_bytes_read))`.
@@ -329,11 +299,6 @@ mod if_std {
 
     macro_rules! deref_async_read {
         () => {
-            #[cfg(feature = "read-initializer")]
-            unsafe fn initializer(&self) -> Initializer {
-                (**self).initializer()
-            }
-
             fn poll_read(
                 mut self: Pin<&mut Self>,
                 cx: &mut Context<'_>,
@@ -365,11 +330,6 @@ mod if_std {
         P: DerefMut + Unpin,
         P::Target: AsyncRead,
     {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            (**self).initializer()
-        }
-
         fn poll_read(
             self: Pin<&mut Self>,
             cx: &mut Context<'_>,
@@ -389,11 +349,6 @@ mod if_std {
 
     macro_rules! delegate_async_read_to_stdio {
         () => {
-            #[cfg(feature = "read-initializer")]
-            unsafe fn initializer(&self) -> Initializer {
-                io::Read::initializer(self)
-            }
-
             fn poll_read(
                 mut self: Pin<&mut Self>,
                 _: &mut Context<'_>,

futures-util/Cargo.toml

@@ -27,7 +27,6 @@ channel = ["std", "futures-channel"]
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = []
 bilock = []
-read-initializer = ["io", "futures-io/read-initializer", "futures-io/unstable"]
 write-all-vectored = ["io"]
 
 [dependencies]

futures-util/src/compat/compat01as03.rs

@@ -351,8 +351,6 @@ unsafe impl UnsafeNotify01 for NotifyWaker {
 #[cfg_attr(docsrs, doc(cfg(feature = "io-compat")))]
 mod io {
     use super::*;
-    #[cfg(feature = "read-initializer")]
-    use futures_io::Initializer;
     use futures_io::{AsyncRead as AsyncRead03, AsyncWrite as AsyncWrite03};
     use std::io::Error;
     use tokio_io::{AsyncRead as AsyncRead01, AsyncWrite as AsyncWrite01};
@@ -416,16 +414,6 @@ mod io {
     impl<W: AsyncWrite01> AsyncWrite01CompatExt for W {}
 
     impl<R: AsyncRead01> AsyncRead03 for Compat01As03<R> {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            // check if `prepare_uninitialized_buffer` needs zeroing
-            if self.inner.get_ref().prepare_uninitialized_buffer(&mut [1]) {
-                Initializer::zeroing()
-            } else {
-                Initializer::nop()
-            }
-        }
-
         fn poll_read(
             mut self: Pin<&mut Self>,
             cx: &mut Context<'_>,

futures-util/src/compat/compat03as01.rs

@@ -236,17 +236,7 @@ mod io {
         }
     }
 
-    impl<R: AsyncRead03 + Unpin> AsyncRead01 for Compat<R> {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool {
-            let initializer = self.inner.initializer();
-            let does_init = initializer.should_initialize();
-            if does_init {
-                initializer.initialize(buf);
-            }
-            does_init
-        }
-    }
+    impl<R: AsyncRead03 + Unpin> AsyncRead01 for Compat<R> {}
 
     impl<W: AsyncWrite03 + Unpin> std::io::Write for Compat<W> {
         fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {

futures-util/src/future/either.rs

@@ -184,8 +184,6 @@ mod if_std {
 
     use core::pin::Pin;
     use core::task::{Context, Poll};
-    #[cfg(feature = "read-initializer")]
-    use futures_io::Initializer;
     use futures_io::{
         AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, Result, SeekFrom,
     };
@@ -195,14 +193,6 @@ mod if_std {
         A: AsyncRead,
         B: AsyncRead,
     {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            match self {
-                Either::Left(x) => x.initializer(),
-                Either::Right(x) => x.initializer(),
-            }
-        }
-
         fn poll_read(
             self: Pin<&mut Self>,
             cx: &mut Context<'_>,

futures-util/src/io/allow_std.rs

@@ -1,6 +1,4 @@
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, SeekFrom};
 use std::pin::Pin;
 use std::{fmt, io};
@@ -121,10 +119,6 @@ where
     fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
         self.0.read_vectored(bufs)
     }
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.0.initializer()
-    }
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         self.0.read_to_end(buf)
     }
@@ -155,11 +149,6 @@ where
     ) -> Poll<io::Result<usize>> {
         Poll::Ready(Ok(try_with_interrupt!(self.0.read_vectored(bufs))))
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.0.initializer()
-    }
 }
 
 impl<T> io::Seek for AllowStdIo<T>

futures-util/src/io/buf_reader.rs

@@ -2,8 +2,6 @@ use super::DEFAULT_BUF_SIZE;
 use futures_core::future::Future;
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSliceMut, SeekFrom};
 use pin_project_lite::pin_project;
 use std::io::{self, Read};
@@ -141,12 +139,6 @@ impl<R: AsyncRead> AsyncRead for BufReader<R> {
         self.consume(nread);
         Poll::Ready(Ok(nread))
     }
-
-    // we can't skip unconditionally because of the large buffer case in read.
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.inner.initializer()
-    }
 }
 
 impl<R: AsyncRead> AsyncBufRead for BufReader<R> {

futures-util/src/io/chain.rs

@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, IoSliceMut};
 use pin_project_lite::pin_project;
 use std::fmt;
@@ -111,16 +109,6 @@ where
         }
         this.second.poll_read_vectored(cx, bufs)
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        let initializer = self.first.initializer();
-        if initializer.should_initialize() {
-            initializer
-        } else {
-            self.second.initializer()
-        }
-    }
 }
 
 impl<T, U> AsyncBufRead for Chain<T, U>

futures-util/src/io/empty.rs

@@ -1,6 +1,4 @@
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead};
 use std::fmt;
 use std::io;
@@ -43,12 +41,6 @@ impl AsyncRead for Empty {
     ) -> Poll<io::Result<usize>> {
         Poll::Ready(Ok(0))
     }
-
-    #[cfg(feature = "read-initializer")]
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
 }
 
 impl AsyncBufRead for Empty {

futures-util/src/io/mod.rs

@@ -26,10 +26,6 @@ use std::{pin::Pin, ptr};
 // Re-export some types from `std::io` so that users don't have to deal
 // with conflicts when `use`ing `futures::io` and `std::io`.
 #[doc(no_inline)]
-#[cfg(feature = "read-initializer")]
-#[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-pub use std::io::Initializer;
-#[doc(no_inline)]
 pub use std::io::{Error, ErrorKind, IoSlice, IoSliceMut, Result, SeekFrom};
 
 pub use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite};
@@ -40,15 +36,9 @@ const DEFAULT_BUF_SIZE: usize = 8 * 1024;
 
 /// Initializes a buffer if necessary.
 ///
-/// A buffer is always initialized if `read-initializer` feature is disabled.
+/// A buffer is currently always initialized.
 #[inline]
 unsafe fn initialize<R: AsyncRead>(_reader: &R, buf: &mut [u8]) {
-    #[cfg(feature = "read-initializer")]
-    {
-        if !_reader.initializer().should_initialize() {
-            return;
-        }
-    }
     ptr::write_bytes(buf.as_mut_ptr(), 0, buf.len())
 }
 

futures-util/src/io/repeat.rs

@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncRead, IoSliceMut};
 use std::fmt;
 use std::io;
@@ -59,12 +57,6 @@ impl AsyncRead for Repeat {
         }
         Poll::Ready(Ok(nwritten))
     }
-
-    #[cfg(feature = "read-initializer")]
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
 }
 
 impl fmt::Debug for Repeat {

futures-util/src/io/take.rs

@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead};
 use pin_project_lite::pin_project;
 use std::pin::Pin;
@@ -100,11 +98,6 @@ impl<R: AsyncRead> AsyncRead for Take<R> {
         *this.limit -= n as u64;
         Poll::Ready(Ok(n))
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.inner.initializer()
-    }
 }
 
 impl<R: AsyncBufRead> AsyncBufRead for Take<R> {

futures-util/src/lib.rs

@@ -1,7 +1,6 @@
 //! Combinators and utilities for working with `Future`s, `Stream`s, `Sink`s,
 //! and the `AsyncRead` and `AsyncWrite` traits.
 
-#![cfg_attr(feature = "read-initializer", feature(read_initializer))]
 #![cfg_attr(feature = "write-all-vectored", feature(io_slice_advance))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(
@@ -24,9 +23,6 @@
 #[cfg(all(feature = "bilock", not(feature = "unstable")))]
 compile_error!("The `bilock` feature requires the `unstable` feature as an explicit opt-in to unstable features");
 
-#[cfg(all(feature = "read-initializer", not(feature = "unstable")))]
-compile_error!("The `read-initializer` feature requires the `unstable` feature as an explicit opt-in to unstable features");
-
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
@@ -149,11 +145,6 @@ macro_rules! delegate_async_write {
 #[cfg(feature = "std")]
 macro_rules! delegate_async_read {
     ($field:ident) => {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> $crate::io::Initializer {
-            self.$field.initializer()
-        }
-
         fn poll_read(
             self: core::pin::Pin<&mut Self>,
             cx: &mut core::task::Context<'_>,

futures-util/src/stream/select_with_strategy.rs

@@ -16,6 +16,7 @@ pub enum PollNext {
 
 impl PollNext {
     /// Toggle the value and return the old one.
+    #[must_use]
     pub fn toggle(&mut self) -> Self {
         let old = *self;
 

futures/Cargo.toml

@@ -47,7 +47,6 @@ thread-pool = ["executor", "futures-executor/thread-pool"]
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = ["futures-io/unstable", "futures-util/unstable"]
 bilock = ["futures-util/bilock"]
-read-initializer = ["futures-io/read-initializer", "futures-util/read-initializer"]
 write-all-vectored = ["futures-util/write-all-vectored"]
 
 [package.metadata.docs.rs]