From a99096b0ff8dbaf5f3dc01a91f566e08bfea4548 Mon Sep 17 00:00:00 2001
From: Drew Galbraith <dgalbraith33@gmail.com>
Date: Wed, 21 Jun 2023 16:28:42 -0700
Subject: [PATCH] [zion] Move the scheduler to the IntrusiveList for runnable
 threads

---
 zion/object/thread.h         | 3 ++-
 zion/scheduler/scheduler.cpp | 5 ++---
 zion/scheduler/scheduler.h   | 3 ++-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/zion/object/thread.h b/zion/object/thread.h
index a47147f..bd8c9c4 100644
--- a/zion/object/thread.h
+++ b/zion/object/thread.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <glacier/container/intrusive_list.h>
 #include <glacier/memory/ref_ptr.h>
 #include <stdint.h>
 
@@ -14,7 +15,7 @@ struct KernelObjectTag<Thread> {
   static const uint64_t type = KernelObject::THREAD;
 };
 
-class Thread : public KernelObject {
+class Thread : public KernelObject, public glcr::IntrusiveListNode<Thread> {
  public:
   uint64_t TypeTag() override { return KernelObject::THREAD; }
   enum State {
diff --git a/zion/scheduler/scheduler.cpp b/zion/scheduler/scheduler.cpp
index 214b00f..431dc04 100644
--- a/zion/scheduler/scheduler.cpp
+++ b/zion/scheduler/scheduler.cpp
@@ -61,7 +61,8 @@ void Scheduler::Preempt() {
 
   glcr::RefPtr<Thread> prev = current_thread_;
   prev->SetState(Thread::RUNNABLE);
-  current_thread_ = runnable_threads_.CycleFront(prev);
+  runnable_threads_.PushBack(prev);
+  current_thread_ = runnable_threads_.PopFront();
 
   SwapToCurrent(*prev);
 }
@@ -79,7 +80,6 @@ void Scheduler::Yield() {
       panic("Sleep thread yielded without next.");
       return;
     } else {
-      // FIXME: Memory operation.
       current_thread_ = runnable_threads_.PopFront();
       prev->SetState(Thread::RUNNABLE);
     }
@@ -89,7 +89,6 @@ void Scheduler::Yield() {
       dbgln("Sleeping");
       gProcMan->DumpProcessStates();
     } else {
-      // FIXME: Memory operation.
       current_thread_ = runnable_threads_.PopFront();
     }
   }
diff --git a/zion/scheduler/scheduler.h b/zion/scheduler/scheduler.h
index fc29f4c..ed2f0ca 100644
--- a/zion/scheduler/scheduler.h
+++ b/zion/scheduler/scheduler.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <glacier/container/intrusive_list.h>
 #include <glacier/memory/ref_ptr.h>
 
 #include "object/process.h"
@@ -28,7 +29,7 @@ class Scheduler {
   bool enabled_ = false;
 
   glcr::RefPtr<Thread> current_thread_;
-  LinkedList<glcr::RefPtr<Thread>> runnable_threads_;
+  glcr::IntrusiveList<Thread> runnable_threads_;
 
   glcr::RefPtr<Thread> sleep_thread_;