sync: move CancellationToken to tokio-util (#2721)

* sync: move CancellationToken to tokio-util

The `CancellationToken` utility is only available with the
`tokio_unstable` flag. This was done as the API is not final, but it
adds friction for users.

This patch moves `CancellationToken` to tokio-util where it is generally
available. The tokio-util crate does not have any constraints on
breaking change releases.

* fix clippy

* clippy again

2 files changed, 0 insertions, 157 deletions

diff --git a/tokio/src/sync/tests/loom_cancellation_token.rs b/tokio/src/sync/tests/loom_cancellation_token.rs
deleted file mode 100644
index e9c9f3dd..00000000
--- a/tokio/src/sync/tests/loom_cancellation_token.rs
+++ /dev/null
@@ -1,155 +0,0 @@
-use crate::sync::CancellationToken;
-
-use loom::{future::block_on, thread};
-use tokio_test::assert_ok;
-
-#[test]
-fn cancel_token() {
-    loom::model(|| {
-        let token = CancellationToken::new();
-        let token1 = token.clone();
-
-        let th1 = thread::spawn(move || {
-            block_on(async {
-                token1.cancelled().await;
-            });
-        });
-
-        let th2 = thread::spawn(move || {
-            token.cancel();
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-    });
-}
-
-#[test]
-fn cancel_with_child() {
-    loom::model(|| {
-        let token = CancellationToken::new();
-        let token1 = token.clone();
-        let token2 = token.clone();
-        let child_token = token.child_token();
-
-        let th1 = thread::spawn(move || {
-            block_on(async {
-                token1.cancelled().await;
-            });
-        });
-
-        let th2 = thread::spawn(move || {
-            token2.cancel();
-        });
-
-        let th3 = thread::spawn(move || {
-            block_on(async {
-                child_token.cancelled().await;
-            });
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-        assert_ok!(th3.join());
-    });
-}
-
-#[test]
-fn drop_token_no_child() {
-    loom::model(|| {
-        let token = CancellationToken::new();
-        let token1 = token.clone();
-        let token2 = token.clone();
-
-        let th1 = thread::spawn(move || {
-            drop(token1);
-        });
-
-        let th2 = thread::spawn(move || {
-            drop(token2);
-        });
-
-        let th3 = thread::spawn(move || {
-            drop(token);
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-        assert_ok!(th3.join());
-    });
-}
-
-#[test]
-fn drop_token_with_childs() {
-    loom::model(|| {
-        let token1 = CancellationToken::new();
-        let child_token1 = token1.child_token();
-        let child_token2 = token1.child_token();
-
-        let th1 = thread::spawn(move || {
-            drop(token1);
-        });
-
-        let th2 = thread::spawn(move || {
-            drop(child_token1);
-        });
-
-        let th3 = thread::spawn(move || {
-            drop(child_token2);
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-        assert_ok!(th3.join());
-    });
-}
-
-#[test]
-fn drop_and_cancel_token() {
-    loom::model(|| {
-        let token1 = CancellationToken::new();
-        let token2 = token1.clone();
-        let child_token = token1.child_token();
-
-        let th1 = thread::spawn(move || {
-            drop(token1);
-        });
-
-        let th2 = thread::spawn(move || {
-            token2.cancel();
-        });
-
-        let th3 = thread::spawn(move || {
-            drop(child_token);
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-        assert_ok!(th3.join());
-    });
-}
-
-#[test]
-fn cancel_parent_and_child() {
-    loom::model(|| {
-        let token1 = CancellationToken::new();
-        let token2 = token1.clone();
-        let child_token = token1.child_token();
-
-        let th1 = thread::spawn(move || {
-            drop(token1);
-        });
-
-        let th2 = thread::spawn(move || {
-            token2.cancel();
-        });
-
-        let th3 = thread::spawn(move || {
-            child_token.cancel();
-        });
-
-        assert_ok!(th1.join());
-        assert_ok!(th2.join());
-        assert_ok!(th3.join());
-    });
-}
diff --git a/tokio/src/sync/tests/mod.rs b/tokio/src/sync/tests/mod.rs
index 6ba8c1f9..d571754c 100644
--- a/tokio/src/sync/tests/mod.rs
+++ b/tokio/src/sync/tests/mod.rs
@@ -7,8 +7,6 @@ cfg_not_loom! {
 cfg_loom! {
     mod loom_atomic_waker;
     mod loom_broadcast;
-    #[cfg(tokio_unstable)]
-    mod loom_cancellation_token;
     mod loom_list;
     mod loom_mpsc;
     mod loom_notify;