3 files changed, 193 insertions, 0 deletions
diff --git a/kernel/sched/roundrobin.cpp b/kernel/sched/roundrobin.cpp
new file mode 100644
index 0000000..c3d6cb6
--- /dev/null
+++ b/kernel/sched/roundrobin.cpp
@@ -0,0 +1,21 @@
+#include "../sched.hpp"
+
+/// Each task is run for a time quantum or the remainder of its cpu burst
+Task *
+RoundRobinQueue::next(int slice)
+{
+  if (head == nullptr) return nullptr;
+  if (head->node->burst <= 0) {
+    delete head->node;
+    remove(head->node);
+    return next(slice);
+  }
+
+  auto *it = head;
+  it->node->burst -= slice;
+  if (head->next) head = head->next;
+  it->next = nullptr;
+  tail->next = it;
+  tail = it;
+  return it->node;
+}
diff --git a/kernel/sched/test_roundrobin.cc b/kernel/sched/test_roundrobin.cc
new file mode 100644
index 0000000..89f60bf
--- /dev/null
+++ b/kernel/sched/test_roundrobin.cc
@@ -0,0 +1,50 @@
+#include <chrono>
+#include <gtest/gtest.h>
+#include <iomanip>
+#include <iostream>
+#include <valgrind/valgrind.h>
+
+#include "../sched/roundrobin.cpp"
+
+void
+run(Task *task, int slice)
+{
+  std::cout << "Running task " << task->name << " id=" << std::setw(2) << task->id << " prio=" << std::setw(2)
+            << task->priority << " burst=" << std::setw(2) << task->burst << " slice=" << slice << "    ";
+}
+
+struct DebugRoundRobinQueue : public RoundRobinQueue {
+public:
+  void
+  print() const
+  {
+    for (auto *it = head; it != nullptr; it = it->next) {
+      std::cout << it->node->name << '(' << std::setw(2) << it->node->burst << ") ";
+    }
+    std::cout << std::endl;
+  }
+};
+
+TEST(roundrobin, RoundRobinQueue)
+{
+  DebugRoundRobinQueue queue;
+  queue.insert(new Task{"P1", 1, 1, 50});
+  queue.insert(new Task{"P2", 2, 1, 40});
+  queue.insert(new Task{"P3", 3, 1, 50});
+  queue.insert(new Task{"P4", 4, 1, 40});
+
+  const auto begin = std::chrono::system_clock::now();
+  for (auto *t = queue.next(10); t != nullptr; t = queue.next(10)) {
+    run(t, 10);
+    queue.print();
+  }
+  const auto end = std::chrono::system_clock::now();
+  const auto duration = std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count();
+
+  std::cout << "Completed in (us): " << duration << std::endl;
+  // test should complete in 250us unless running on valgrind
+  if (!RUNNING_ON_VALGRIND) { EXPECT_LE(duration, 250); }
+
+  EXPECT_EQ(queue.head, nullptr);
+  EXPECT_EQ(queue.tail, nullptr);
+}
diff --git a/kernel/sched/test_taskqueue.cc b/kernel/sched/test_taskqueue.cc
new file mode 100644
index 0000000..217c44d
--- /dev/null
+++ b/kernel/sched/test_taskqueue.cc
@@ -0,0 +1,122 @@
+#include <gtest/gtest.h>
+
+#include "../sched.hpp"
+
+struct DebugQueue : public Queue<Task> {
+public:
+  void
+  expect_ordered() const
+  {
+    int id = 1;
+    for (auto *it = head; it != nullptr; it = it->next) {
+      // std::cout << it->node->name << std::endl;
+      EXPECT_EQ(it->node->id, id++);
+    }
+  }
+};
+
+TEST(taskqueue, insert)
+{
+  DebugQueue queue;
+  auto *p1 = new Task{"P1", 1, 1, 10};
+  queue.insert(p1);
+  queue.insert(new Task{"P2", 2, 1, 10});
+  queue.insert(new Task{"P3", 3, 1, 10});
+  auto *p4 = new Task{"P4", 4, 1, 10};
+  queue.insert(p4);
+  queue.expect_ordered();
+
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p4);
+}
+
+TEST(taskqueue, removeHead)
+{
+  DebugQueue queue;
+  auto *p0 = new Task{"P0", 0, 1, 10};
+  queue.insert(p0);
+  auto *p1 = new Task{"P1", 1, 1, 10};
+  queue.insert(p1);
+  queue.insert(new Task{"P2", 2, 1, 10});
+  queue.insert(new Task{"P3", 3, 1, 10});
+  auto *p4 = new Task{"P4", 4, 1, 10};
+  queue.insert(p4);
+  queue.remove(p0);
+  delete p0;
+
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p4);
+  queue.expect_ordered();
+}
+
+TEST(taskqueue, removeTail)
+{
+  DebugQueue queue;
+  auto *p1 = new Task{"P1", 1, 1, 10};
+  queue.insert(p1);
+  queue.insert(new Task{"P2", 2, 1, 10});
+  queue.insert(new Task{"P3", 3, 1, 10});
+  auto *p4 = new Task{"P4", 4, 1, 10};
+  queue.insert(p4);
+  auto *p5 = new Task{"P5", 5, 1, 10};
+  queue.insert(p5);
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p5);
+
+  queue.remove(p5);
+  delete p5;
+
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p4);
+  queue.expect_ordered();
+}
+
+TEST(taskqueue, removeLast)
+{
+  DebugQueue queue;
+
+  auto *p0 = new Task{"P0", 0, 1, 10};
+  queue.insert(p0);
+  EXPECT_EQ(queue.head->node, p0);
+  EXPECT_EQ(queue.tail->node, p0);
+
+  queue.remove(p0);
+  delete p0;
+
+  EXPECT_EQ(queue.head, nullptr);
+  EXPECT_EQ(queue.tail, nullptr);
+}
+
+TEST(taskqueue, removeNullptr)
+{
+  DebugQueue queue;
+  queue.insert(new Task{"P1", 1, 1, 10});
+  queue.insert(new Task{"P2", 2, 1, 10});
+  queue.insert(new Task{"P3", 3, 1, 10});
+  queue.insert(new Task{"P4", 4, 1, 10});
+  queue.remove(nullptr);
+  queue.expect_ordered();
+}
+
+TEST(taskqueue, remove)
+{
+  DebugQueue queue;
+  auto *p1 = new Task{"P1", 1, 1, 10};
+  queue.insert(p1);
+  queue.insert(new Task{"P2", 2, 1, 10});
+  auto *p0 = new Task{"P0", 0, 1, 10};
+  queue.insert(p0);
+  queue.insert(new Task{"P3", 3, 1, 10});
+  auto *p4 = new Task{"P4", 4, 1, 10};
+  queue.insert(p4);
+
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p4);
+
+  queue.remove(p0);
+  delete p0;
+
+  EXPECT_EQ(queue.head->node, p1);
+  EXPECT_EQ(queue.tail->node, p4);
+  queue.expect_ordered();
+}