sync: move into `tokio` crate (#1705)

A step towards collapsing Tokio sub crates into a single `tokio`
crate (#1318).

The sync implementation is now provided by the main `tokio` crate.
Functionality can be opted out of by using the various net related
feature flags.

1 files changed, 58 insertions, 0 deletions

diff --git a/tokio/src/sync/mod.rs b/tokio/src/sync/mod.rs
new file mode 100644
index 00000000..84f6bd98
--- /dev/null
+++ b/tokio/src/sync/mod.rs
@@ -0,0 +1,58 @@
+//! Future-aware synchronization
+//!
+//! This module is enabled with the **`sync`** feature flag.
+//!
+//! Tasks sometimes need to communicate with each other. This module contains
+//! two basic abstractions for doing so:
+//!
+//! - [oneshot](oneshot/index.html), a way of sending a single value
+//!   from one task to another.
+//! - [mpsc](mpsc/index.html), a multi-producer, single-consumer channel for
+//!   sending values between tasks.
+//! - [`Mutex`](struct.Mutex.html), an asynchronous `Mutex`-like type.
+//! - [watch](watch/index.html), a single-producer, multi-consumer channel that
+//!   only stores the **most recently** sent value.
+
+macro_rules! debug {
+    ($($t:tt)*) => {
+        if false {
+            println!($($t)*);
+        }
+    }
+}
+
+macro_rules! if_loom {
+    ($($t:tt)*) => {{
+        #[cfg(loom)]
+        const LOOM: bool = true;
+        #[cfg(not(loom))]
+        const LOOM: bool = false;
+
+        if LOOM {
+            $($t)*
+        }
+    }}
+}
+
+mod barrier;
+pub use barrier::{Barrier, BarrierWaitResult};
+
+mod loom;
+
+pub mod mpsc;
+
+mod mutex;
+pub use mutex::{Mutex, MutexGuard};
+
+pub mod oneshot;
+
+pub mod semaphore;
+
+mod task;
+pub use task::AtomicWaker;
+
+pub mod watch;
+
+/// Unit tests
+#[cfg(test)]
+mod tests;