Add a global lock

mmtk/src/active_plan.rs

@@ -10,18 +10,22 @@ use JikesRVM;
 use JTOC_BASE;
 use SINGLETON;
 
-use std::marker::PhantomData;
+use std::sync::{Mutex, MutexGuard};
+
+lazy_static! {
+ static ref MUTATOR_LOCK: Mutex<()> = Mutex::new(());
+}
 
 struct JikesRVMMutatorIterator<'a> {
+ _guard: MutexGuard<'a, ()>,
  counter: usize,
- _p: PhantomData<&'a ()>,
 }
 
 impl<'a> JikesRVMMutatorIterator<'a> {
- fn new() -> Self {
+ fn new(guard: MutexGuard<'a, ()>) -> Self {
  Self {
+ _guard: guard,
  counter: 0,
- _p: PhantomData,
  }
  }
 }
@@ -33,8 +37,8 @@ impl<'a> Iterator for JikesRVMMutatorIterator<'a> {
  // We don't need this in the loop for STW-GC
  let num_threads = unsafe { (JTOC_BASE + NUM_THREADS_FIELD_OFFSET).load::<usize>() };
  loop {
- self.counter += 1;
  let idx = self.counter;
+ self.counter += 1;
  if idx >= num_threads {
  return None;
  } else {
@@ -79,6 +83,7 @@ impl ActivePlan<JikesRVM> for VMActivePlan {
  }
 
  fn mutators<'a>() -> Box<dyn Iterator<Item = &'a mut Mutator<JikesRVM>> + 'a> {
- Box::new(JikesRVMMutatorIterator::new())
+ let guard = MUTATOR_LOCK.lock().unwrap();
+ Box::new(JikesRVMMutatorIterator::new(guard))
  }
 }