Add sched/roundrobin tests

6 files changed, 286 insertions, 0 deletions

diff --git a/src/Makefile b/src/Makefile
index 8f7c47c..df59f24 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -5,6 +5,13 @@ kernel.OBJS := include conf.h
 
 include ../rules.mk
 
+.PHONY: test valgrind
+test: tst/test_taskqueue tst/test_roundrobin
+	$(foreach f,$^,./$f;)
+
+valgrind: tst/test_taskqueue tst/test_roundrobin
+	$(foreach f,$^,valgrind --leak-check=full ./$f;)
+
 conf.h: conf.h.in
 	@echo '  GEN  $@'
 	@cp conf.h.in conf.h
diff --git a/src/sched.hpp b/src/sched.hpp
new file mode 100644
index 0000000..cfa3ff0
--- /dev/null
+++ b/src/sched.hpp
@@ -0,0 +1,8 @@
+#pragma once
+
+#include "task.h"
+
+class RoundRobinQueue : public Queue<Task> {
+public:
+  [[nodiscard]] Task *next(int slice);
+};
diff --git a/src/sched/roundrobin.cpp b/src/sched/roundrobin.cpp
new file mode 100644
index 0000000..c3d6cb6
--- /dev/null
+++ b/src/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/src/task.h b/src/task.h
new file mode 100644
index 0000000..381f628
--- /dev/null
+++ b/src/task.h
@@ -0,0 +1,78 @@
+#pragma once
+
+/**
+ * Representation of a task in the system
+ */
+struct Task {
+  const char *name;
+  int id;
+  int priority;
+  int burst;
+};
+
+#ifdef __cplusplus
+template <typename T> struct Queue {
+  struct Item {
+    Item(T *node) : node(node) {}
+    T *node;
+    Item *next = nullptr;
+
+    [[nodiscard]] bool
+    operator==(const T *other) const
+    {
+      return node == other;
+    }
+  };
+
+  ~Queue() noexcept
+  {
+    for (auto *it = head; it != nullptr;) {
+      auto *current = it;
+      it = it->next;
+      delete current->node;
+      delete current;
+    }
+  }
+
+  /// Insert item at the end of the queue
+  void
+  insert(T *item)
+  {
+    if (head == nullptr) {
+      head = new Item(item);
+      tail = head;
+    }
+    else {
+      tail->next = new Item(item);
+      tail = tail->next;
+    }
+  }
+
+  void
+  remove(T *item)
+  {
+    if (head == nullptr) return;
+    if (item == head->node) {
+      auto *it = head;
+      head = head->next;
+      if (*tail == item) tail = nullptr;
+      delete it;
+      return;
+    }
+
+    Item *prev = nullptr;
+    for (auto *it = head; it != nullptr; it = it->next) {
+      if (it->node == item) {
+        if (prev) { prev->next = it->next; }
+        if (tail == it) { tail = prev; }
+        delete it;
+        return;
+      }
+      prev = it;
+    }
+  }
+
+  Item *head = nullptr;
+  Item *tail = nullptr;
+};
+#endif
diff --git a/src/tst/roundrobin.cc b/src/tst/roundrobin.cc
new file mode 100644
index 0000000..1431788
--- /dev/null
+++ b/src/tst/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/src/tst/taskqueue.cc b/src/tst/taskqueue.cc
new file mode 100644
index 0000000..217c44d
--- /dev/null
+++ b/src/tst/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();
+}