1 files changed, 56 insertions, 0 deletions
diff --git a/gc/mmtk/src/active_plan.rs b/gc/mmtk/src/active_plan.rs
new file mode 100644
index 0000000000..80372a7576
--- /dev/null
+++ b/gc/mmtk/src/active_plan.rs
@@ -0,0 +1,56 @@
+use std::collections::VecDeque;
+use std::marker::PhantomData;
+
+use crate::mmtk;
+use crate::upcalls;
+use crate::Ruby;
+use mmtk::util::opaque_pointer::*;
+use mmtk::vm::ActivePlan;
+use mmtk::Mutator;
+
+pub struct VMActivePlan {}
+
+impl ActivePlan<Ruby> for VMActivePlan {
+    fn number_of_mutators() -> usize {
+        (upcalls().number_of_mutators)()
+    }
+
+    fn is_mutator(_tls: VMThread) -> bool {
+        (upcalls().is_mutator)()
+    }
+
+    fn mutator(_tls: VMMutatorThread) -> &'static mut Mutator<Ruby> {
+        unimplemented!()
+    }
+
+    fn mutators<'a>() -> Box<dyn Iterator<Item = &'a mut Mutator<Ruby>> + 'a> {
+        let mut mutators = VecDeque::new();
+        (upcalls().get_mutators)(
+            add_mutator_to_vec,
+            &mut mutators as *mut VecDeque<&mut Mutator<Ruby>> as _,
+        );
+
+        Box::new(RubyMutatorIterator {
+            mutators,
+            phantom_data: PhantomData,
+        })
+    }
+}
+
+extern "C" fn add_mutator_to_vec(mutator: *mut Mutator<Ruby>, mutators: *mut libc::c_void) {
+    let mutators = unsafe { &mut *(mutators as *mut VecDeque<*mut Mutator<Ruby>>) };
+    mutators.push_back(unsafe { &mut *mutator });
+}
+
+struct RubyMutatorIterator<'a> {
+    mutators: VecDeque<&'a mut Mutator<Ruby>>,
+    phantom_data: PhantomData<&'a ()>,
+}
+
+impl<'a> Iterator for RubyMutatorIterator<'a> {
+    type Item = &'a mut Mutator<Ruby>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.mutators.pop_front()
+    }
+}