Rework WindowServer to use select() in its main event loop.

The system can finally idle without burning CPU. :^)

There are some issues with scheduling making the mouse cursor sloppy
and unresponsive that need to be dealt with.

WindowServer/WSEventLoop.cpp

@@ -4,7 +4,9 @@
 #include "WSWindowManager.h"
 #include "WSScreen.h"
 #include "PS2MouseDevice.h"
-#include "Scheduler.h"
+#include <Kernel/Keyboard.h>
+#include <AK/Bitmap.h>
+#include "Process.h"
 
 //#define WSEVENTLOOP_DEBUG
 
@@ -34,10 +36,19 @@ WSEventLoop& WSEventLoop::the()
 int WSEventLoop::exec()
 {
     m_server_process = current;
+
+    m_keyboard_fd = m_server_process->sys$open("/dev/keyboard", O_RDONLY);
+    m_mouse_fd = m_server_process->sys$open("/dev/psaux", O_RDONLY);
+
+    ASSERT(m_keyboard_fd >= 0);
+    ASSERT(m_mouse_fd >= 0);
+
     m_running = true;
     for (;;) {
+
         if (m_queued_events.is_empty())
-            waitForEvent();
+            wait_for_event();
+
         Vector<QueuedEvent> events;
         {
             LOCKER(m_lock);
@@ -69,20 +80,48 @@ void WSEventLoop::post_event(WSEventReceiver* receiver, OwnPtr<WSEvent>&& event)
     dbgprintf("WSEventLoop::post_event: {%u} << receiver=%p, event=%p\n", m_queued_events.size(), receiver, event.ptr());
 #endif
     m_queued_events.append({ receiver, move(event) });
+
+    if (current != m_server_process)
+        m_server_process->request_wakeup();
 }
 
-void WSEventLoop::waitForEvent()
+void WSEventLoop::wait_for_event()
+{
+    fd_set rfds;
+    memset(&rfds, 0, sizeof(rfds));
+    auto bitmap = Bitmap::wrap((byte*)&rfds, FD_SETSIZE);
+    bitmap.set(m_keyboard_fd, true);
+    bitmap.set(m_mouse_fd, true);
+    Syscall::SC_select_params params;
+    params.nfds = max(m_keyboard_fd, m_mouse_fd) + 1;
+    params.readfds = &rfds;
+    params.writefds = nullptr;
+    params.exceptfds = nullptr;
+    params.timeout = nullptr;
+    int rc = m_server_process->sys$select(&params);
+    memory_barrier();
+    if (rc < 0) {
+        ASSERT_NOT_REACHED();
+    }
+
+    //if (bitmap.get(m_keyboard_fd))
+        drain_keyboard();
+    //if (bitmap.get(m_mouse_fd))
+        drain_mouse();
+}
+
+void WSEventLoop::drain_mouse()
 {
-    auto& mouse = PS2MouseDevice::the();
     auto& screen = WSScreen::the();
+    auto& mouse = PS2MouseDevice::the();
     bool prev_left_button = screen.left_mouse_button_pressed();
     bool prev_right_button = screen.right_mouse_button_pressed();
     int dx = 0;
     int dy = 0;
     while (mouse.can_read(*m_server_process)) {
         signed_byte data[3];
-        ssize_t nread = mouse.read(*m_server_process, (byte*)data, 3);
-        ASSERT(nread == 3);
+        ssize_t nread = mouse.read(*m_server_process, (byte*)data, sizeof(data));
+        ASSERT(nread == sizeof(data));
         bool left_button = data[0] & 1;
         bool right_button = data[0] & 2;
         dx += data[1];
@@ -96,3 +135,18 @@ void WSEventLoop::waitForEvent()
         }
     }
 }
+
+void WSEventLoop::drain_keyboard()
+{
+    auto& screen = WSScreen::the();
+    auto& keyboard = Keyboard::the();
+    while (keyboard.can_read(*m_server_process)) {
+        byte data[2];
+        ssize_t nread = keyboard.read(*m_server_process, (byte*)data, sizeof(data));
+        ASSERT(nread == sizeof(data));
+        Keyboard::Key key;
+        key.character = data[0];
+        key.modifiers = data[1];
+        screen.on_receive_keyboard_data(key);
+    }
+}

WindowServer/WSEventLoop.h

@@ -25,7 +25,9 @@ public:
     Process& server_process() { return *m_server_process; }
 
 private:
-    void waitForEvent();
+    void wait_for_event();
+    void drain_mouse();
+    void drain_keyboard();
 
     SpinLock m_lock;
 
@@ -37,4 +39,7 @@ private:
 
     Process* m_server_process { nullptr };
     bool m_running { false };
+
+    int m_keyboard_fd { -1 };
+    int m_mouse_fd { -1 };
 };

WindowServer/WSFrameBuffer.h

@@ -9,7 +9,7 @@ class WSFrameBuffer final : public WSScreen {
 public:
     WSFrameBuffer(unsigned width, unsigned height);
     WSFrameBuffer(RGBA32*, unsigned width, unsigned height);
-    virtual ~WSFrameBuffer() override;
+    ~WSFrameBuffer();
 
     void show();
 

WindowServer/WSScreen.cpp

@@ -25,8 +25,6 @@ WSScreen::WSScreen(unsigned width, unsigned height)
     s_the = this;
 
     m_cursor_location = rect().center();
-
-    Keyboard::the().set_client(this);
 }
 
 WSScreen::~WSScreen()
@@ -62,7 +60,7 @@ void WSScreen::on_receive_mouse_data(int dx, int dy, bool left_button, bool righ
         WSWindowManager::the().draw_cursor();
 }
 
-void WSScreen::on_key_pressed(Keyboard::Key key)
+void WSScreen::on_receive_keyboard_data(Keyboard::Key key)
 {
     auto event = make<KeyEvent>(WSEvent::KeyDown, 0);
     int key_code = 0;

WindowServer/WSScreen.h

@@ -4,9 +4,9 @@
 #include <Widgets/Size.h>
 #include <Kernel/Keyboard.h>
 
-class WSScreen : public KeyboardClient {
+class WSScreen {
 public:
-    virtual ~WSScreen();
+    ~WSScreen();
 
     int width() const { return m_width; }
     int height() const { return m_height; }
@@ -23,14 +23,12 @@ public:
     bool right_mouse_button_pressed() const { return m_right_mouse_button_pressed; }
 
     void on_receive_mouse_data(int dx, int dy, bool left_button, bool right_button);
+    void on_receive_keyboard_data(Keyboard::Key);
 
 protected:
     WSScreen(unsigned width, unsigned height);
 
 private:
-    // ^KeyboardClient
-    virtual void on_key_pressed(Keyboard::Key) final;
-
     int m_width { 0 };
     int m_height { 0 };