Add unix::pipe (#1356)

Adds one new function: unix::pipe, which is a wrapper around the pipe(2)
system call, and two new types: Sender and Receiver, wrappers around the
file descriptors.

This is a port of https://github.com/Thomasdezeeuw/mio-pipe, commit
8c3025edf128e90733e95327d88493887b93fcdd.

Cargo.toml

@@ -29,6 +29,7 @@ include       = [
 default = []
 os-poll = []
 os-util = []
+pipe = ["os-poll"]
 tcp = []
 udp = []
 uds = []

ci/azure-test-stable.yml

@@ -29,7 +29,7 @@ jobs:
       - ${{ if eq(parameters.cmd, 'test') }}:
           - script: |
               cargo install cargo-hack
-              cargo hack check --feature-powerset --skip guide
+              cargo hack check --feature-powerset --skip guide,extra-docs
             displayName: Check feature powerset
 
       - script: cargo ${{ parameters.cmd }} --all-features

src/lib.rs

@@ -69,9 +69,11 @@ mod waker;
 
 pub mod event;
 
-cfg_net! {
+cfg_io_source! {
     mod io_source;
+}
 
+cfg_net! {
     pub mod net;
 }
 
@@ -82,11 +84,27 @@ pub use poll::{Poll, Registry};
 pub use token::Token;
 pub use waker::Waker;
 
-#[cfg(all(unix, feature = "os-util"))]
-#[cfg_attr(docsrs, doc(cfg(all(unix, feature = "os-util"))))]
+#[cfg(all(unix, any(feature = "os-util", feature = "pipe")))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(all(unix, any(feature = "os-util", feature = "pipe"))))
+)]
 pub mod unix {
     //! Unix only extensions.
+
+    #[cfg(feature = "os-util")]
+    #[cfg_attr(docsrs, doc(cfg(all(unix, feature = "os-util"))))]
     pub use crate::sys::SourceFd;
+
+    cfg_pipe! {
+        pub mod pipe {
+            //! Unix pipe.
+            //!
+            //! See the [`new`] function for documentation.
+
+            pub use crate::sys::pipe::{new, Receiver, Sender};
+        }
+    }
 }
 
 #[cfg(all(windows, feature = "os-util"))]
@@ -121,6 +139,12 @@ pub mod features {
     //! `os-util` enables additional OS specific facilities. Currently this
     //! means the `unix` module (with `SourceFd`) becomes available.
     //!
+    #![cfg_attr(feature = "pipe", doc = "## `pipe` (enabled)")]
+    #![cfg_attr(not(feature = "pipe"), doc = "## `pipe` (disabled)")]
+    //!
+    //! The `pipe` feature adds `unix::pipe`, and related types, a non-blocking
+    //! wrapper around the `pipe(2)` system call.
+    //!
     //! ## Network types
     //!
     //! Mio provide three features to enable network types:

src/macros/mod.rs

@@ -36,6 +36,18 @@ macro_rules! cfg_net {
     }
 }
 
+/// One of the features enabled that needs `IoSource`. That is `tcp`, or `udp`,
+/// or on Unix `uds` or `pipe`.
+macro_rules! cfg_io_source {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(feature = "tcp", feature = "udp", all(unix, any(feature = "uds",  feature = "pipe"))))]
+            #[cfg_attr(docsrs, doc(any(feature = "tcp", feature = "udp", all(unix, any(feature = "uds",  feature = "pipe")))))]
+            $item
+        )*
+    }
+}
+
 /// One of the `tcp`, `udp` features enabled.
 #[cfg(windows)]
 macro_rules! cfg_net {
@@ -82,13 +94,25 @@ macro_rules! cfg_uds {
     }
 }
 
+/// Feature `pipe` enabled.
+#[cfg(unix)]
+macro_rules! cfg_pipe {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "pipe")]
+            #[cfg_attr(docsrs, doc(cfg(feature = "pipe")))]
+            $item
+        )*
+    }
+}
+
 /// Feature `os-util` enabled, or one of the features that need `os-util`.
 #[cfg(unix)]
 macro_rules! cfg_any_os_util {
     ($($item:item)*) => {
         $(
-            #[cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "uds"))]
-            #[cfg_attr(docsrs, doc(cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "uds"))))]
+            #[cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "uds", feature = "pipe"))]
+            #[cfg_attr(docsrs, doc(cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "uds", feature = "pipe"))))]
             $item
         )*
     }
@@ -99,8 +123,8 @@ macro_rules! cfg_any_os_util {
 macro_rules! cfg_any_os_util {
     ($($item:item)*) => {
         $(
-            #[cfg(any(feature = "os-util", feature = "tcp", feature = "udp"))]
-            #[cfg_attr(docsrs, doc(cfg(any(feature = "os-util", feature = "tcp", feature = "udp"))))]
+            #[cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "pipe"))]
+            #[cfg_attr(docsrs, doc(cfg(any(feature = "os-util", feature = "tcp", feature = "udp", feature = "pipe"))))]
             $item
         )*
     }

src/sys/mod.rs

@@ -72,7 +72,11 @@ cfg_os_poll! {
         pub(crate) use self::unix::uds;
     }
 
-    cfg_net! {
+    cfg_pipe! {
+        pub(crate) use self::unix::pipe;
+    }
+
+    cfg_io_source! {
         pub(crate) use self::unix::IoSourceState;
     }
 }

src/sys/shell/mod.rs

@@ -23,7 +23,7 @@ cfg_uds! {
     pub(crate) mod uds;
 }
 
-cfg_net! {
+cfg_io_source! {
     use std::io;
     #[cfg(windows)]
     use std::os::windows::io::RawSocket;

src/sys/shell/selector.rs

@@ -44,7 +44,7 @@ cfg_any_os_util! {
     }
 }
 
-cfg_net! {
+cfg_io_source! {
     #[cfg(debug_assertions)]
     impl Selector {
         pub fn id(&self) -> usize {

src/sys/unix/mod.rs

@@ -38,7 +38,7 @@ cfg_os_poll! {
         pub use self::uds::SocketAddr;
     }
 
-    cfg_net! {
+    cfg_io_source! {
         use std::io;
 
         // Both `kqueue` and `epoll` don't need to hold any user space state.
@@ -59,6 +59,10 @@ cfg_os_poll! {
             }
         }
     }
+
+    cfg_pipe! {
+        pub(crate) mod pipe;
+    }
 }
 
 cfg_not_os_poll! {