diff options
author | Carl Lerche <me@carllerche.com> | 2019-11-15 22:11:13 -0800 |
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committer | GitHub <noreply@github.com> | 2019-11-15 22:11:13 -0800 |
commit | 8a7e57786a5dca139f5b4261685e22991ded0859 (patch) | |
tree | b69d1c48f8a760a58fc7ccfe0376d9812a88d303 /tokio/src/io/util/write.rs | |
parent | 930679587ae42e4df3113159ccf33fb5923dd73a (diff) |
Limit `futures` dependency to `Stream` via feature flag (#1774)
In an effort to reach API stability, the `tokio` crate is shedding its
_public_ dependencies on crates that are either a) do not provide a
stable (1.0+) release with longevity guarantees or b) match the `tokio`
release cadence. Of course, implementing `std` traits fits the
requirements.
The on exception, for now, is the `Stream` trait found in `futures_core`.
It is expected that this trait will not change much and be moved into `std.
Since Tokio is not yet going reaching 1.0, I feel that it is acceptable to maintain
a dependency on this trait given how foundational it is.
Since the `Stream` implementation is optional, types that are logically
streams provide `async fn next_*` functions to obtain the next value.
Avoiding the `next()` name prevents fn conflicts with `StreamExt::next()`.
Additionally, some misc cleanup is also done:
- `tokio::io::io` -> `tokio::io::util`.
- `delay` -> `delay_until`.
- `Timeout::new` -> `timeout(...)`.
- `signal::ctrl_c()` returns a future instead of a stream.
- `{tcp,unix}::Incoming` is removed (due to lack of `Stream` trait).
- `time::Throttle` is removed (due to lack of `Stream` trait).
- Fix: `mpsc::UnboundedSender::send(&self)` (no more conflict with `Sink` fns).
Diffstat (limited to 'tokio/src/io/util/write.rs')
-rw-r--r-- | tokio/src/io/util/write.rs | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/tokio/src/io/util/write.rs b/tokio/src/io/util/write.rs new file mode 100644 index 00000000..42e59848 --- /dev/null +++ b/tokio/src/io/util/write.rs @@ -0,0 +1,46 @@ +use crate::io::AsyncWrite; + +use std::future::Future; +use std::io; +use std::pin::Pin; +use std::task::{Context, Poll}; + +/// A future to write some of the buffer to an `AsyncWrite`. +#[derive(Debug)] +#[must_use = "futures do nothing unless you `.await` or poll them"] +pub struct Write<'a, W: ?Sized> { + writer: &'a mut W, + buf: &'a [u8], +} + +/// Tries to write some bytes from the given `buf` to the writer in an +/// asynchronous manner, returning a future. +pub(crate) fn write<'a, W>(writer: &'a mut W, buf: &'a [u8]) -> Write<'a, W> +where + W: AsyncWrite + Unpin + ?Sized, +{ + Write { writer, buf } +} + +impl<W> Future for Write<'_, W> +where + W: AsyncWrite + Unpin + ?Sized, +{ + type Output = io::Result<usize>; + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<usize>> { + let me = &mut *self; + Pin::new(&mut *me.writer).poll_write(cx, me.buf) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn assert_unpin() { + use std::marker::PhantomPinned; + crate::is_unpin::<Write<'_, PhantomPinned>>(); + } +} |