Remove coordinator thread

MMTk PR: mmtk/mmtk-core#1067

Author: k-sareen

art/mmtk.h

@@ -15,7 +15,7 @@ typedef void* MmtkMutator;
 // An opaque pointer to a VMThread
 typedef void* VMThread;
 // Type of GC worker
-enum GcThreadKind { MmtkGcController, MmtkGcWorker };
+enum GcThreadKind { MmtkGcWorker };
 // Allocation semantics
 enum AllocationSemantics {
   AllocatorDefault   = 0,
@@ -213,14 +213,6 @@ bool mmtk_is_object_forwarded(void* object);
  */
 void* mmtk_get_forwarded_object(void* object);
 
-/**
- * Start the GC Controller thread
- *
- * @param tls the thread that will be used as the GC Controller
- * @param context the context for the GC Controller
- */
-void mmtk_start_gc_controller_thread(void* tls, void* context);
-
 /**
  * Start a GC Worker thread
  *

mmtk/src/api.rs

@@ -11,10 +11,7 @@ use mmtk::{
     AllocationSemantics,
     Mutator,
     MutatorContext,
-    scheduler::{
-        GCController,
-        GCWorker,
-    },
+    scheduler::GCWorker,
     util::{
         alloc::{
             AllocatorSelector,
@@ -57,18 +54,6 @@ pub extern "C" fn mmtk_set_heap_size(min: usize, max: usize) -> bool {
     builder.options.gc_trigger.set(policy)
 }
 
-/// Start the GC Controller thread. We trust the `gc_controller` pointer is valid
-#[no_mangle]
-#[allow(clippy::not_unsafe_ptr_arg_deref)]
-pub extern "C" fn mmtk_start_gc_controller_thread(
-    tls: VMWorkerThread,
-    gc_controller: *mut GCController<Art>,
-) {
-    // SAFETY: Assumes gc_controller is valid
-    let mut gc_controller = unsafe { Box::from_raw(gc_controller) };
-    mmtk::memory_manager::start_control_collector(&SINGLETON, tls, &mut gc_controller);
-}
-
 /// Start a GC Worker thread. We trust the `worker` pointer is valid
 #[no_mangle]
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -77,8 +62,8 @@ pub extern "C" fn mmtk_start_gc_worker_thread(
     worker: *mut GCWorker<Art>
 ) {
     // SAFETY: Assumes worker is valid
-    let mut worker = unsafe { Box::from_raw(worker) };
-    mmtk::memory_manager::start_worker::<Art>(&SINGLETON, tls, &mut worker)
+    let worker = unsafe { Box::from_raw(worker) };
+    mmtk::memory_manager::start_worker::<Art>(&SINGLETON, tls, worker)
 }
 
 /// Release a RustBuffer by dropping it

mmtk/src/collection.rs

@@ -13,10 +13,8 @@ use mmtk::{
 /// Type of GC worker
 #[repr(C)]
 pub enum GcThreadKind {
-    /// GC Controller Context thread
-    Controller = 0,
     /// Simple GC Worker thread
-    Worker     = 1,
+    Worker = 0,
 }
 
 /// Implements collection trait
@@ -53,10 +51,6 @@ impl Collection<Art> for ArtCollection {
 
     fn spawn_gc_thread(tls: VMThread, ctx: GCThreadContext<Art>) {
         let (ctx_ptr, kind) = match ctx {
-            GCThreadContext::Controller(c) => (
-                Box::into_raw(c) as *mut libc::c_void,
-                GcThreadKind::Controller,
-            ),
             GCThreadContext::Worker(w) => (
                 Box::into_raw(w) as *mut libc::c_void,
                 GcThreadKind::Worker,