add basic metrics of multilevel task queue

Cargo.toml

@@ -14,6 +14,8 @@ parking_lot_core = "0.7"
 crossbeam-deque = "0.7"
 dashmap = "1.2.0"
 rand = "0.7"
+prometheus = "0.7"
+lazy_static = "1"
 
 [dev-dependencies]
 criterion = "0.3"

src/lib.rs

@@ -4,6 +4,7 @@
 
 //! Yatp is a thread pool that tries to be adaptive, responsive and generic.
 
+pub mod metrics;
 pub mod pool;
 pub mod queue;
 pub mod task;

src/metrics.rs

@@ -0,0 +1,28 @@
+// Copyright 2020 TiKV Project Authors. Licensed under Apache-2.0.
+
+//! Metrics of the thread pool.
+
+use lazy_static::lazy_static;
+use prometheus::*;
+
+lazy_static! {
+    /// Elapsed time of each level in the multilevel task queue.
+    pub static ref MULTILEVEL_LEVEL_ELAPSED: IntCounterVec = IntCounterVec::new(
+        Opts::new(
+            "multilevel_level_elapsed",
+            "elapsed time of each level in the multilevel task queue"
+        ),
+        &["name", "level"]
+    )
+    .unwrap();
+
+    /// The chance that a level 0 task is scheduled to run.
+    pub static ref MULTILEVEL_LEVEL0_CHANCE: GaugeVec = GaugeVec::new(
+        Opts::new(
+            "multilevel_level0_chance",
+            "the chance that a level 0 task is scheduled to run"
+        ),
+        &["name"]
+    )
+    .unwrap();
+}