resolve comments

Signed-off-by: glorv <glorvs@163.com>

Author: glorv

src/pool/builder.rs

@@ -290,7 +290,9 @@ impl Builder {
         self.build_with_queue_and_runner(QueueType::Multilevel(queue_builder), runner_builder)
     }
 
+    /// Spawn a priority future pool.
     ///
+    /// It setups the pool with priority queue. Caller must provide a `TaskPriorityProvider` implementation to generate the proper priority value for each spawned task.
     pub fn build_priority_future_pool(
         &self,
         priority_priovider: Arc<dyn priority::TaskPriorityProvider>,

src/queue/extras.rs

@@ -28,8 +28,9 @@ pub struct Extras {
     pub(crate) fixed_level: Option<u8>,
     /// Number of execute times
     pub(crate) exec_times: u32,
-    /// The task group name. Used in priority queue.
-    pub(crate) group_name: String,
+    /// Extra metadata of this task. User can use this field to store arbitary data. It is useful 
+    /// in some case to implement more complext `TaskPriorityProvider` in the priority task queue.
+    pub(crate) metadata: Vec<u8>,
 }
 
 impl Extras {
@@ -45,7 +46,7 @@ impl Extras {
             current_level: 0,
             fixed_level: None,
             exec_times: 0,
-            group_name: String::new(),
+            metadata: Vec::new(),
         }
     }
 
@@ -68,7 +69,7 @@ impl Extras {
             current_level: fixed_level.unwrap_or(0),
             fixed_level,
             exec_times: 0,
-            group_name: String::new(),
+            metadata: Vec::new(),
         }
     }
 
@@ -94,13 +95,18 @@ impl Extras {
         self.current_level
     }
 
-    /// Gets the group name of this task.
-    pub fn group_name(&self) -> &str {
-        &self.group_name
+    /// Gets the metadata of this task.
+    pub fn metadata(&self) -> &[u8] {
+        &self.metadata
+    }
+
+    /// Gets the mutable metadata of this task.
+    pub fn metadata_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.metadata
     }
 
     /// Set the group name of this task.
-    pub fn set_group_name(&mut self, name: String) {
-        self.group_name = name;
+    pub fn set_metadata(&mut self, metadata: Vec<u8>) {
+        self.metadata = metadata;
     }
 }

src/queue/priority.rs

@@ -1,7 +1,7 @@
 // Copyright 2022 TiKV Project Authors. Licensed under Apache-2.0.
 
 //! A priority task queue. Tasks are scheduled based on its priority, tasks with small priority
-//! value will be scheduler earlier than bigger onces.. User should implement The [`TaskPriorityProvider`]
+//! value will be scheduler earlier than bigger onces. User should implement The [`TaskPriorityProvider`]
 //! to provide the priority value for each task. The priority value is fetched from the
 //! [`TaskPriorityProvider`] at each time the task is scheduled.
 //!
@@ -86,11 +86,11 @@ where
 
 /// A trait used to generate priority value for each task.
 pub trait TaskPriorityProvider: Send + Sync + 'static {
-    /// Return a priority value of this task, all tasks in the priority queue is ordered by this value.
+    /// Return a priority value of this task, all tasks in the priority
+    /// queue is ordered by this value.
     fn get_priority(&self, extras: &Extras) -> u64;
 }
 
-///
 #[derive(Clone)]
 struct PriorityTaskManager {
     level_manager: Arc<TaskLevelManager>,
@@ -152,8 +152,8 @@ impl<T: TaskCell + Send + 'static> QueueCore<T> {
     }
 
     #[inline]
-    fn gen_key(&self, weight: u64) -> MapKey {
-        MapKey(weight, self.sequence.fetch_add(1, Ordering::Relaxed))
+    fn gen_key(&self, priority: u64) -> MapKey {
+        MapKey(priority, self.sequence.fetch_add(1, Ordering::Relaxed))
     }
 }
 
@@ -265,8 +265,7 @@ pub struct Config {
 }
 
 impl Config {
-    /// Sets the name of the multilevel task queue. Metrics of multilevel
-    /// task queues are available if name is provided.
+    /// Sets the name of the priority task queue. Metrics are available if name is provided.
     pub fn name(mut self, name: Option<impl Into<String>>) -> Self {
         self.name = name.map(Into::into);
         self
@@ -290,7 +289,7 @@ pub struct Builder {
 }
 
 impl Builder {
-    /// Creates a multilevel task queue builder with specified config and [`TaskPriorityProvider`].
+    /// Creates a priority task queue builder with specified config and [`TaskPriorityProvider`].
     pub fn new(config: Config, priority_manager: Arc<dyn TaskPriorityProvider>) -> Builder {
         let Config {
             name,