WindowServer: Add a simple CPU usage graph to the global menu bar.

This is pretty cute and helps me spot when something's chewing up CPU.

AK/CircularQueue.h

@@ -5,25 +5,25 @@
 
 namespace AK {
 
-template<typename T, size_t Capacity>
+template<typename T, int Capacity>
 class CircularQueue {
 public:
     CircularQueue()
     {
-        for (size_t i = 0; i < Capacity; ++i)
+        for (int i = 0; i < Capacity; ++i)
             m_elements[i] = T();
     }
 
     bool is_empty() const { return !m_size; }
-    size_t size() const { return m_size; }
+    int size() const { return m_size; }
 
-    size_t capacity() const { return Capacity; }
+    int capacity() const { return Capacity; }
 
     void dump() const
     {
         kprintf("CircularQueue<%zu>:\n", Capacity);
         kprintf(" size: %zu\n", m_size);
-        for (size_t i = 0; i < Capacity; ++i) {
+        for (int i = 0; i < Capacity; ++i) {
             kprintf(" [%zu] %d %c\n", i, m_elements[i], i == m_head ? '*' : ' ');
         }
     }
@@ -60,9 +60,9 @@ public:
         const T& operator*() const { return m_queue.m_elements[m_index]; }
     private:
         friend class CircularQueue;
-        ConstIterator(const CircularQueue& queue, const size_t index) : m_queue(queue), m_index(index) { }
+        ConstIterator(const CircularQueue& queue, const int index) : m_queue(queue), m_index(index) { }
         const CircularQueue& m_queue;
-        size_t m_index { 0 };
+        int m_index { 0 };
     };
 
     ConstIterator begin() const { return ConstIterator(*this, m_head); }
@@ -71,8 +71,8 @@ public:
 private:
     friend class ConstIterator;
     T m_elements[Capacity];
-    size_t m_size { 0 };
+    int m_size { 0 };
-    size_t m_head { 0 };
+    int m_head { 0 };
 };
 
 }

WindowServer/WSWindowManager.cpp

@@ -232,7 +232,7 @@ WSWindowManager::WSWindowManager()
         static time_t last_update_time;
         time_t now = time(nullptr);
         if (now != last_update_time) {
-            invalidate(menubar_rect());
+            tick_clock();
             last_update_time = now;
         }
     });
@@ -245,6 +245,55 @@ WSWindowManager::~WSWindowManager()
 {
 }
 
+static void get_cpu_usage(unsigned& busy, unsigned& idle)
+{
+    busy = 0;
+    idle = 0;
+
+    FILE* fp = fopen("/proc/all", "r");
+    if (!fp) {
+        perror("failed to open /proc/all");
+        exit(1);
+    }
+    for (;;) {
+        char buf[BUFSIZ];
+        char* ptr = fgets(buf, sizeof(buf), fp);
+        if (!ptr)
+            break;
+        auto parts = String(buf, Chomp).split(',');
+        if (parts.size() < 17)
+            break;
+        bool ok;
+        pid_t pid = parts[0].to_uint(ok);
+        ASSERT(ok);
+        unsigned nsched = parts[1].to_uint(ok);
+        ASSERT(ok);
+
+        if (pid == 0)
+            idle += nsched;
+        else
+            busy += nsched;
+    }
+    int rc = fclose(fp);
+    ASSERT(rc == 0);
+}
+
+void WSWindowManager::tick_clock()
+{
+    static unsigned last_busy;
+    static unsigned last_idle;
+    unsigned busy;
+    unsigned idle;
+    get_cpu_usage(busy, idle);
+    unsigned busy_diff = busy - last_busy;
+    unsigned idle_diff = idle - last_idle;
+    last_busy = busy;
+    last_idle = idle;
+    float cpu = (float)busy_diff / (float)(busy_diff + idle_diff);
+    m_cpu_history.enqueue(cpu);
+    invalidate(menubar_rect());
+}
+
 void WSWindowManager::set_resolution(int width, int height)
 {
     if (m_screen_rect.width() == width && m_screen_rect.height() == height)
@@ -866,6 +915,18 @@ void WSWindowManager::draw_menubar()
         tm->tm_sec);
     auto time_rect = menubar_rect().translated(-(menubar_menu_margin() / 2), 0);
     m_back_painter->draw_text(time_rect, time_text, TextAlignment::CenterRight, Color::Black);
+
+    Rect cpu_rect { time_rect.right() - font().glyph_width() * time_text.length() - (int)m_cpu_history.capacity() - 10, time_rect.y() + 1, (int)m_cpu_history.capacity(), time_rect.height() - 2 };
+    m_back_painter->fill_rect(cpu_rect, Color::Black);
+    int i = m_cpu_history.capacity() - m_cpu_history.size();
+    for (auto cpu_usage : m_cpu_history) {
+        m_back_painter->draw_line(
+            { cpu_rect.x() + i, cpu_rect.bottom() },
+            { cpu_rect.x() + i, (int)(cpu_rect.y() + (cpu_rect.height() - (cpu_usage * (float)cpu_rect.height()))) },
+            Color(0, 200, 0)
+        );
+        ++i;
+    }
 }
 
 void WSWindowManager::draw_cursor()

WindowServer/WSWindowManager.h

@@ -11,6 +11,7 @@
 #include "WSMessageReceiver.h"
 #include "WSMenuBar.h"
 #include <WindowServer/WSWindowType.h>
+#include <AK/CircularQueue.h>
 
 class WSAPIClientRequest;
 class WSScreen;
@@ -79,7 +80,6 @@ private:
     void handle_close_button_mouse_event(WSWindow&, WSMouseEvent&);
     void start_window_resize(WSWindow&, WSMouseEvent&);
     void handle_client_request(WSAPIClientRequest&);
-
     void set_active_window(WSWindow*);
     void set_hovered_window(WSWindow*);
     template<typename Callback> IterationDecision for_each_visible_window_of_type_from_back_to_front(WSWindowType, Callback);
@@ -88,12 +88,11 @@ private:
     template<typename Callback> IterationDecision for_each_visible_window_from_back_to_front(Callback);
     template<typename Callback> void for_each_active_menubar_menu(Callback);
     void close_current_menu();
-    
     virtual void on_message(WSMessage&) override;
-
     void compose();
     void paint_window_frame(WSWindow&);
     void flip_buffers();
+    void tick_clock();
 
     WSScreen& m_screen;
     Rect m_screen_rect;
@@ -155,4 +154,6 @@ private:
     Color m_menu_selection_color;
     WeakPtr<WSMenuBar> m_current_menubar;
     WeakPtr<WSMenu> m_current_menu;
+
+    CircularQueue<float, 30> m_cpu_history;
 };