Fix clippy

Author: wenyuzhao

src/scheduler/scheduler.rs

@@ -1,6 +1,6 @@
 use super::stat::SchedulerStat;
 use super::work_bucket::*;
-use super::worker::{GCWorker, WorkerGroup};
+use super::worker::{GCWorker, StealerWithOrdinal, WorkerGroup};
 use super::*;
 use crate::mmtk::MMTK;
 use crate::util::opaque_pointer::*;
@@ -119,13 +119,7 @@ impl<VM: VMBinding> GCWorkScheduler<VM> {
         {
             // Unconstrained is always open. Prepare will be opened at the beginning of a GC.
             // This vec will grow for each stage we call with open_next()
-            let first_stw_stage = self
-                .work_buckets
-                .iter()
-                .skip(1)
-                .next()
-                .map(|(id, _)| id)
-                .unwrap();
+            let first_stw_stage = self.work_buckets.iter().nth(1).map(|(id, _)| id).unwrap();
             let mut open_stages: Vec<WorkBucketStage> = vec![first_stw_stage];
             // The rest will open after the previous stage is done.
             let mut open_next = |s: WorkBucketStage| {
@@ -320,13 +314,7 @@ impl<VM: VMBinding> GCWorkScheduler<VM> {
     }
 
     pub fn reset_state(&self) {
-        let first_stw_stage = self
-            .work_buckets
-            .iter()
-            .skip(1)
-            .next()
-            .map(|(id, _)| id)
-            .unwrap();
+        let first_stw_stage = self.work_buckets.iter().nth(1).map(|(id, _)| id).unwrap();
         self.work_buckets.iter().for_each(|(id, bkt)| {
             if id != WorkBucketStage::Unconstrained && id != first_stw_stage {
                 bkt.deactivate();
@@ -366,7 +354,7 @@ impl<VM: VMBinding> GCWorkScheduler<VM> {
                 _ => {}
             }
         }
-        for (id, stealer) in &self.worker_group().stealers {
+        for StealerWithOrdinal { id, stealer } in &self.worker_group().stealers {
             if *id == worker.ordinal {
                 continue;
             }
@@ -463,7 +451,7 @@ impl<VM: VMBinding> GCWorkScheduler<VM> {
 
     pub fn notify_mutators_paused(&self, mmtk: &'static MMTK<VM>) {
         mmtk.plan.base().control_collector_context.clear_request();
-        let first_stw_bucket = self.work_buckets.values().skip(1).next().unwrap();
+        let first_stw_bucket = self.work_buckets.values().nth(1).unwrap();
         debug_assert!(!first_stw_bucket.is_activated());
         first_stw_bucket.activate();
         let _guard = self.worker_monitor.0.lock().unwrap();

src/scheduler/worker.rs

@@ -155,9 +155,14 @@ impl<VM: VMBinding> GCWorker<VM> {
     }
 }
 
+pub struct StealerWithOrdinal<VM: VMBinding> {
+    pub id: usize,
+    pub stealer: Stealer<Box<dyn GCWork<VM>>>,
+}
+
 pub struct WorkerGroup<VM: VMBinding> {
     pub workers: Vec<GCWorker<VM>>,
-    pub stealers: Vec<(usize, Stealer<Box<dyn GCWork<VM>>>)>,
+    pub stealers: Vec<StealerWithOrdinal<VM>>,
     parked_workers: AtomicUsize,
 }
 
@@ -172,7 +177,10 @@ impl<VM: VMBinding> WorkerGroup<VM> {
             .collect::<Vec<_>>();
         let stealers = workers
             .iter()
-            .map(|w| (w.ordinal, w.local_work_buffer.stealer()))
+            .map(|w| StealerWithOrdinal {
+                id: w.ordinal,
+                stealer: w.local_work_buffer.stealer(),
+            })
             .collect();
         Arc::new(Self {
             workers,