Add multi-producer, multi-consumer channel (mpmc)

Author: obeis

library/std/src/lib.rs

@@ -153,7 +153,7 @@
 //! the [`io`], [`fs`], and [`net`] modules.
 //!
 //! The [`thread`] module contains Rust's threading abstractions. [`sync`]
-//! contains further primitive shared memory types, including [`atomic`] and
+//! contains further primitive shared memory types, including [`atomic`], [`mpmc`] and
 //! [`mpsc`], which contains the channel types for message passing.
 //!
 //! # Use before and after `main()`
@@ -177,6 +177,7 @@
 //! - after-main use of thread-locals, which also affects additional features:
 //!   - [`thread::current()`]
 //!   - [`thread::scope()`]
+//!   - [`sync::mpmc`]
 //!   - [`sync::mpsc`]
 //! - before-main stdio file descriptors are not guaranteed to be open on unix platforms
 //!
@@ -202,6 +203,7 @@
 //! [`atomic`]: sync::atomic
 //! [`for`]: ../book/ch03-05-control-flow.html#looping-through-a-collection-with-for
 //! [`str`]: prim@str
+//! [`mpmc`]: sync::mpmc
 //! [`mpsc`]: sync::mpsc
 //! [`std::cmp`]: cmp
 //! [`std::slice`]: mod@slice

library/std/src/sync/mod.rs

@@ -133,6 +133,11 @@
 //!   inter-thread synchronisation mechanism, at the cost of some
 //!   extra memory.
 //!
+//! - [`mpmc`]: Multi-producer, multi-consumer queues, used for
+//!   message-based communication. Can provide a lightweight
+//!   inter-thread synchronisation mechanism, at the cost of some
+//!   extra memory.
+//!
 //! - [`Mutex`]: Mutual Exclusion mechanism, which ensures that at
 //!   most one thread at a time is able to access some data.
 //!
@@ -153,6 +158,7 @@
 //! [`Arc`]: crate::sync::Arc
 //! [`Barrier`]: crate::sync::Barrier
 //! [`Condvar`]: crate::sync::Condvar
+//! [`mpmc`]: crate::sync::mpmc
 //! [`mpsc`]: crate::sync::mpsc
 //! [`Mutex`]: crate::sync::Mutex
 //! [`Once`]: crate::sync::Once
@@ -184,7 +190,7 @@ pub use self::mutex::{Mutex, MutexGuard};
 pub use self::once::{ONCE_INIT, Once, OnceState};
 #[stable(feature = "once_cell", since = "1.70.0")]
 pub use self::once_lock::OnceLock;
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "once_cell", since = "1.70.0")]
 pub use self::poison::{LockResult, PoisonError, TryLockError, TryLockResult};
 #[unstable(feature = "reentrant_lock", issue = "121440")]
 pub use self::reentrant_lock::{ReentrantLock, ReentrantLockGuard};
@@ -193,12 +199,13 @@ pub use self::rwlock::{MappedRwLockReadGuard, MappedRwLockWriteGuard};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 
+#[unstable(feature = "mpmc_channel", issue = "126840")]
+pub mod mpmc;
 pub mod mpsc;
 
 mod barrier;
 mod condvar;
 mod lazy_lock;
-mod mpmc;
 mod mutex;
 pub(crate) mod once;
 mod once_lock;

library/std/src/sync/mpmc/error.rs

@@ -7,6 +7,7 @@ use crate::{error, fmt};
 ///
 /// [`send_timeout`]: super::Sender::send_timeout
 #[derive(PartialEq, Eq, Clone, Copy)]
+#[unstable(feature = "mpmc_channel", issue = "126840")]
 pub enum SendTimeoutError<T> {
     /// The message could not be sent because the channel is full and the operation timed out.
     ///
@@ -18,12 +19,14 @@ pub enum SendTimeoutError<T> {
     Disconnected(T),
 }
 
+#[unstable(feature = "mpmc_channel", issue = "126840")]
 impl<T> fmt::Debug for SendTimeoutError<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         "SendTimeoutError(..)".fmt(f)
     }
 }
 
+#[unstable(feature = "mpmc_channel", issue = "126840")]
 impl<T> fmt::Display for SendTimeoutError<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
@@ -33,8 +36,10 @@ impl<T> fmt::Display for SendTimeoutError<T> {
     }
 }
 
+#[unstable(feature = "mpmc_channel", issue = "126840")]
 impl<T> error::Error for SendTimeoutError<T> {}
 
+#[unstable(feature = "mpmc_channel", issue = "126840")]
 impl<T> From<SendError<T>> for SendTimeoutError<T> {
     fn from(err: SendError<T>) -> SendTimeoutError<T> {
         match err {

library/std/src/sync/mpmc/mod.rs

@@ -14,7 +14,7 @@ LL + use std::collections::btree_map::IntoIter;
    |
 LL + use std::collections::btree_set::IntoIter;
    |
-     and 8 other candidates
+     and 9 other candidates
 
 error: aborting due to 1 previous error
 

library/std/src/sync/mpmc/tests.rs

@@ -4,7 +4,7 @@ error[E0382]: use of moved value: `tx`
 LL |             let tx = tx;
    |                      ^^ value moved here, in previous iteration of loop
    |
-   = note: move occurs because `tx` has type `Sender<i32>`, which does not implement the `Copy` trait
+   = note: move occurs because `tx` has type `std::sync::mpsc::Sender<i32>`, which does not implement the `Copy` trait
 
 error: aborting due to 1 previous error
 

tests/ui/const-generics/issues/issue-82956.stderr

@@ -348,6 +348,29 @@ mod foo {
           "label": null,
           "suggested_replacement": "use std::slice::Iter;
 
+",
+          "suggestion_applicability": "MaybeIncorrect",
+          "expansion": null
+        },
+        {
+          "file_name": "$DIR/use_suggestion_json.rs",
+          "byte_start": 541,
+          "byte_end": 541,
+          "line_start": 11,
+          "line_end": 11,
+          "column_start": 1,
+          "column_end": 1,
+          "is_primary": true,
+          "text": [
+            {
+              "text": "fn main() {",
+              "highlight_start": 1,
+              "highlight_end": 1
+            }
+          ],
+          "label": null,
+          "suggested_replacement": "use std::sync::mpmc::Iter;
+
 ",
           "suggestion_applicability": "MaybeIncorrect",
           "expansion": null
@@ -396,7 +419,7 @@ mod foo {
 \u001b[0m   \u001b[0m\u001b[0m\u001b[1m\u001b[38;5;12m|\u001b[0m
 \u001b[0m\u001b[1m\u001b[38;5;12mLL\u001b[0m\u001b[0m \u001b[0m\u001b[0m\u001b[38;5;10m+ use std::collections::hash_map::Iter;\u001b[0m
 \u001b[0m   \u001b[0m\u001b[0m\u001b[1m\u001b[38;5;12m|\u001b[0m
-\u001b[0m     and 8 other candidates\u001b[0m
+\u001b[0m     and 9 other candidates\u001b[0m
 
 "
 }