metrics: stabilize RuntimeMetrics::worker_count

This PR stabilizes a single metric API to start the process of stabilizing metrics.
Future work will continue to stabilize more metrics.

Refs: #6546

tokio/src/lib.rs

@@ -471,6 +471,7 @@ compile_error!("The `tokio_taskdump` feature requires `--cfg tokio_unstable`.");
 
 #[cfg(all(
  tokio_taskdump,
+ not(doc),
  not(all(
  target_os = "linux",
  any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")

tokio/src/macros/cfg.rs

@@ -215,22 +215,40 @@ macro_rules! cfg_macros {
  }
 }
 
+// need to disable metrics on loom
 macro_rules! cfg_metrics {
  ($($item:item)*) => {
  $(
- // For now, metrics is only disabled in loom tests.
- // When stabilized, it might have a dedicated feature flag.
+ #[cfg(not(loom))]
+ $item
+ )*
+ }
+}
+
+macro_rules! cfg_unstable_metrics {
+ ($($item:item)*) => {
+ $(
  #[cfg(all(tokio_unstable, not(loom)))]
  #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
  $item
  )*
  }
 }
 
+macro_rules! cfg_not_unstable_metrics {
+ ($($item:item)*) => {
+ $(
+ #[cfg(any(not(tokio_unstable), loom))]
+ $item
+ )*
+ }
+
+}
+
 macro_rules! cfg_not_metrics {
  ($($item:item)*) => {
  $(
- #[cfg(not(all(tokio_unstable, not(loom))))]
+ #[cfg(loom)]
  $item
  )*
  }

tokio/src/runtime/blocking/pool.rs

@@ -40,7 +40,7 @@ impl SpawnerMetrics {
  self.num_idle_threads.load(Ordering::Relaxed)
  }
 
- cfg_metrics! {
+ cfg_unstable_metrics! {
  fn queue_depth(&self) -> usize {
  self.queue_depth.load(Ordering::Relaxed)
  }
@@ -474,7 +474,7 @@ impl Spawner {
  }
 }
 
-cfg_metrics! {
+cfg_unstable_metrics! {
  impl Spawner {
  pub(crate) fn num_threads(&self) -> usize {
  self.inner.metrics.num_threads()

tokio/src/runtime/builder.rs

@@ -956,7 +956,7 @@ impl Builder {
  }
  }
 
- cfg_metrics! {
+ cfg_unstable_metrics! {
  /// Enables tracking the distribution of task poll times.
  ///
  /// Task poll times are not instrumented by default as doing so requires

tokio/src/runtime/coop.rs

@@ -197,7 +197,7 @@ cfg_coop! {
  }
 
  cfg_rt! {
- cfg_metrics! {
+ cfg_unstable_metrics! {
  #[inline(always)]
  fn inc_budget_forced_yield_count() {
  let _ = context::with_current(|handle| {
@@ -206,7 +206,7 @@ cfg_coop! {
  }
  }
 
- cfg_not_metrics! {
+ cfg_not_unstable_metrics! {
  #[inline(always)]
  fn inc_budget_forced_yield_count() {}
  }

tokio/src/runtime/io/metrics.rs

@@ -17,7 +17,7 @@ cfg_not_rt_and_metrics_and_net! {
 
 cfg_net! {
  cfg_rt! {
- cfg_metrics! {
+ cfg_unstable_metrics! {
  pub(crate) use crate::runtime::IoDriverMetrics;
  }
  }

tokio/src/runtime/metrics/mod.rs

@@ -9,27 +9,34 @@
 #![allow(clippy::module_inception)]
 
 cfg_metrics! {
- mod batch;
- pub(crate) use batch::MetricsBatch;
-
- mod histogram;
- pub(crate) use histogram::{Histogram, HistogramBatch, HistogramBuilder};
- #[allow(unreachable_pub)] // rust-lang/rust#57411
- pub use histogram::HistogramScale;
-
  mod runtime;
- #[allow(unreachable_pub)] // rust-lang/rust#57411
  pub use runtime::RuntimeMetrics;
 
- mod scheduler;
- pub(crate) use scheduler::SchedulerMetrics;
+ cfg_unstable_metrics! {
+ mod batch;
+ pub(crate) use batch::MetricsBatch;
+
+ mod histogram;
+ pub(crate) use histogram::{HistogramBatch, HistogramBuilder, Histogram};
+
+ mod scheduler;
+ pub(crate) use scheduler::SchedulerMetrics;
+
+ mod worker;
+ pub(crate) use worker::WorkerMetrics;
+
+ cfg_net! {
+ mod io;
+ pub(crate) use io::IoDriverMetrics;
+ }
+ #[allow(unreachable_pub)] // rust-lang/rust#57411
+ pub use histogram::HistogramScale;
+ }
 
- mod worker;
- pub(crate) use worker::WorkerMetrics;
+ cfg_not_unstable_metrics! {
+  mod mock;
 
- cfg_net! {
- mod io;
- pub(crate) use io::IoDriverMetrics;
+ pub(crate) use mock::{SchedulerMetrics, WorkerMetrics, MetricsBatch, HistogramBuilder};
  }
 }