metrics: Stabilize injection_queue_depth API

tokio/src/runtime/metrics/runtime.rs

@@ -70,6 +70,32 @@ impl RuntimeMetrics {
         self.handle.inner.num_alive_tasks()
     }
 
+    /// Returns the number of tasks currently scheduled in the runtime's
+    /// injection queue.
+    ///
+    /// Tasks that are spawned or notified from a non-runtime thread are
+    /// scheduled using the runtime's injection queue. This metric returns the
+    /// **current** number of tasks pending in the injection queue. As such, the
+    /// returned value may increase or decrease as new tasks are scheduled and
+    /// processed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.injection_queue_depth();
+    ///     println!("{} tasks currently pending in the runtime's injection queue", n);
+    /// }
+    /// ```
+    pub fn injection_queue_depth(&self) -> usize {
+        self.handle.inner.injection_queue_depth()
+    }
+
     cfg_unstable_metrics! {
 
         /// Returns the number of additional threads spawned by the runtime.
@@ -655,32 +681,6 @@ impl RuntimeMetrics {
             }
         }
 
-        /// Returns the number of tasks currently scheduled in the runtime's
-        /// injection queue.
-        ///
-        /// Tasks that are spawned or notified from a non-runtime thread are
-        /// scheduled using the runtime's injection queue. This metric returns the
-        /// **current** number of tasks pending in the injection queue. As such, the
-        /// returned value may increase or decrease as new tasks are scheduled and
-        /// processed.
-        ///
-        /// # Examples
-        ///
-        /// ```
-        /// use tokio::runtime::Handle;
-        ///
-        /// #[tokio::main]
-        /// async fn main() {
-        ///     let metrics = Handle::current().metrics();
-        ///
-        ///     let n = metrics.injection_queue_depth();
-        ///     println!("{} tasks currently pending in the runtime's injection queue", n);
-        /// }
-        /// ```
-        pub fn injection_queue_depth(&self) -> usize {
-            self.handle.inner.injection_queue_depth()
-        }
-
         /// Returns the number of tasks currently scheduled in the given worker's
         /// local queue.
         ///

tokio/src/runtime/scheduler/current_thread/mod.rs

@@ -528,6 +528,10 @@ impl Handle {
     pub(crate) fn num_alive_tasks(&self) -> usize {
         self.shared.owned.num_alive_tasks()
     }
+
+    pub(crate) fn injection_queue_depth(&self) -> usize {
+        self.shared.inject.len()
+    }
 }
 
 cfg_unstable_metrics! {
@@ -536,10 +540,6 @@ cfg_unstable_metrics! {
             &self.shared.scheduler_metrics
         }
 
-        pub(crate) fn injection_queue_depth(&self) -> usize {
-            self.shared.inject.len()
-        }
-
         pub(crate) fn worker_metrics(&self, worker: usize) -> &WorkerMetrics {
             assert_eq!(0, worker);
             &self.shared.worker_metrics

tokio/src/runtime/scheduler/inject.rs

@@ -16,9 +16,7 @@ cfg_rt_multi_thread! {
     mod rt_multi_thread;
 }
 
-cfg_unstable_metrics! {
-    mod metrics;
-}
+mod metrics;
 
 /// Growable, MPMC queue used to inject new tasks into the scheduler and as an
 /// overflow queue when the local, fixed-size, array queue overflows.

tokio/src/runtime/scheduler/mod.rs

@@ -189,6 +189,10 @@ cfg_rt! {
         pub(crate) fn num_alive_tasks(&self) -> usize {
             match_flavor!(self, Handle(handle) => handle.num_alive_tasks())
         }
+
+        pub(crate) fn injection_queue_depth(&self) -> usize {
+            match_flavor!(self, Handle(handle) => handle.injection_queue_depth())
+        }
     }
 
     cfg_unstable_metrics! {
@@ -217,10 +221,6 @@ cfg_rt! {
                 match_flavor!(self, Handle(handle) => handle.worker_metrics(worker))
             }
 
-            pub(crate) fn injection_queue_depth(&self) -> usize {
-                match_flavor!(self, Handle(handle) => handle.injection_queue_depth())
-            }
-
             pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
                 match_flavor!(self, Handle(handle) => handle.worker_local_queue_depth(worker))
             }

tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs

@@ -13,6 +13,10 @@ impl Handle {
         self.shared.owned.num_alive_tasks()
     }
 
+    pub(crate) fn injection_queue_depth(&self) -> usize {
+        self.shared.injection_queue_depth()
+    }
+
     cfg_unstable_metrics! {
         cfg_64bit_metrics! {
             pub(crate) fn spawned_tasks_count(&self) -> u64 {
@@ -39,10 +43,6 @@ impl Handle {
             &self.shared.worker_metrics[worker]
         }
 
-        pub(crate) fn injection_queue_depth(&self) -> usize {
-            self.shared.injection_queue_depth()
-        }
-
         pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
             self.shared.worker_local_queue_depth(worker)
         }

tokio/src/runtime/scheduler/multi_thread/worker.rs

@@ -75,9 +75,7 @@ use std::task::Waker;
 use std::thread;
 use std::time::Duration;
 
-cfg_unstable_metrics! {
-    mod metrics;
-}
+mod metrics;
 
 cfg_taskdump! {
     mod taskdump;

tokio/src/runtime/scheduler/multi_thread/worker/metrics.rs

@@ -4,8 +4,12 @@ impl Shared {
     pub(crate) fn injection_queue_depth(&self) -> usize {
         self.inject.len()
     }
+}
 
-    pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
-        self.remotes[worker].steal.len()
+cfg_unstable_metrics! {
+    impl Shared {
+        pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
+            self.remotes[worker].steal.len()
+        }
     }
 }

tokio/tests/rt_metrics.rs

@@ -2,6 +2,7 @@
 #![warn(rust_2018_idioms)]
 #![cfg(all(feature = "full", not(target_os = "wasi"), target_has_atomic = "64"))]
 
+use std::sync::{Arc, Barrier};
 use tokio::runtime::Runtime;
 
 #[test]
@@ -45,6 +46,51 @@ fn num_alive_tasks() {
     assert_eq!(0, rt.metrics().num_alive_tasks());
 }
 
+#[test]
+fn injection_queue_depth_current_thread() {
+    use std::thread;
+
+    let rt = current_thread();
+    let handle = rt.handle().clone();
+    let metrics = rt.metrics();
+
+    thread::spawn(move || {
+        handle.spawn(async {});
+    })
+    .join()
+    .unwrap();
+
+    assert_eq!(1, metrics.injection_queue_depth());
+}
+
+#[test]
+fn injection_queue_depth_multi_thread() {
+    let rt = threaded();
+    let metrics = rt.metrics();
+
+    let barrier1 = Arc::new(Barrier::new(3));
+    let barrier2 = Arc::new(Barrier::new(3));
+
+    // Spawn a task per runtime worker to block it.
+    for _ in 0..2 {
+        let barrier1 = barrier1.clone();
+        let barrier2 = barrier2.clone();
+        rt.spawn(async move {
+            barrier1.wait();
+            barrier2.wait();
+        });
+    }
+
+    barrier1.wait();
+
+    for i in 0..10 {
+        assert_eq!(i, metrics.injection_queue_depth());
+        rt.spawn(async {});
+    }
+
+    barrier2.wait();
+}
+
 fn current_thread() -> Runtime {
     tokio::runtime::Builder::new_current_thread()
         .enable_all()

tokio/tests/rt_unstable_metrics.rs

@@ -8,7 +8,7 @@
 ))]
 
 use std::future::Future;
-use std::sync::{Arc, Barrier, Mutex};
+use std::sync::{Arc, Mutex};
 use std::task::Poll;
 use std::thread;
 use tokio::macros::support::poll_fn;
@@ -622,51 +622,6 @@ fn worker_overflow_count() {
     assert_eq!(1, n);
 }
 
-#[test]
-fn injection_queue_depth_current_thread() {
-    use std::thread;
-
-    let rt = current_thread();
-    let handle = rt.handle().clone();
-    let metrics = rt.metrics();
-
-    thread::spawn(move || {
-        handle.spawn(async {});
-    })
-    .join()
-    .unwrap();
-
-    assert_eq!(1, metrics.injection_queue_depth());
-}
-
-#[test]
-fn injection_queue_depth_multi_thread() {
-    let rt = threaded();
-    let metrics = rt.metrics();
-
-    let barrier1 = Arc::new(Barrier::new(3));
-    let barrier2 = Arc::new(Barrier::new(3));
-
-    // Spawn a task per runtime worker to block it.
-    for _ in 0..2 {
-        let barrier1 = barrier1.clone();
-        let barrier2 = barrier2.clone();
-        rt.spawn(async move {
-            barrier1.wait();
-            barrier2.wait();
-        });
-    }
-
-    barrier1.wait();
-
-    for i in 0..10 {
-        assert_eq!(i, metrics.injection_queue_depth());
-        rt.spawn(async {});
-    }
-
-    barrier2.wait();
-}
-
 #[test]
 fn worker_local_queue_depth() {
     const N: usize = 100;