LibCore: Add CEventLoop and make LibGUI/GEventLoop inherit from it.

This is shaping up to be quite nice.

LibCore/CEventLoop.cpp

@@ -0,0 +1,261 @@
+#include <LibCore/CObject.h>
+#include <LibCore/CEventLoop.h>
+#include <LibCore/CEvent.h>
+#include <LibGUI/GNotifier.h>
+#include <LibC/unistd.h>
+#include <LibC/stdio.h>
+#include <LibC/fcntl.h>
+#include <LibC/string.h>
+#include <LibC/time.h>
+#include <LibC/sys/select.h>
+#include <LibC/sys/socket.h>
+#include <LibC/sys/time.h>
+#include <LibC/errno.h>
+#include <LibC/string.h>
+#include <LibC/stdlib.h>
+
+//#define CEVENTLOOP_DEBUG
+
+static CEventLoop* s_main_event_loop;
+static Vector<CEventLoop*>* s_event_loop_stack;
+HashMap<int, OwnPtr<CEventLoop::EventLoopTimer>>* CEventLoop::s_timers;
+HashTable<GNotifier*>* CEventLoop::s_notifiers;
+int CEventLoop::s_next_timer_id = 1;
+
+CEventLoop::CEventLoop()
+{
+    if (!s_event_loop_stack) {
+        s_event_loop_stack = new Vector<CEventLoop*>;
+        s_timers = new HashMap<int, OwnPtr<CEventLoop::EventLoopTimer>>;
+        s_notifiers = new HashTable<GNotifier*>;
+    }
+
+    if (!s_main_event_loop) {
+        s_main_event_loop = this;
+        s_event_loop_stack->append(this);
+    }
+
+#ifdef CEVENTLOOP_DEBUG
+    dbgprintf("(%u) CEventLoop constructed :)\n", getpid());
+#endif
+}
+
+CEventLoop::~CEventLoop()
+{
+}
+
+CEventLoop& CEventLoop::main()
+{
+    ASSERT(s_main_event_loop);
+    return *s_main_event_loop;
+}
+
+CEventLoop& CEventLoop::current()
+{
+    return *s_event_loop_stack->last();
+}
+
+void CEventLoop::quit(int code)
+{
+    m_exit_requested = true;
+    m_exit_code = code;
+}
+
+struct CEventLoopPusher {
+public:
+    CEventLoopPusher(CEventLoop& event_loop) : m_event_loop(event_loop)
+    {
+        if (&m_event_loop != s_main_event_loop) {
+            m_event_loop.take_pending_events_from(CEventLoop::current());
+            s_event_loop_stack->append(&event_loop);
+        }
+    }
+    ~CEventLoopPusher()
+    {
+        if (&m_event_loop != s_main_event_loop) {
+            s_event_loop_stack->take_last();
+            CEventLoop::current().take_pending_events_from(m_event_loop);
+        }
+    }
+private:
+    CEventLoop& m_event_loop;
+};
+
+int CEventLoop::exec()
+{
+    CEventLoopPusher pusher(*this);
+
+    m_running = true;
+    for (;;) {
+        if (m_exit_requested)
+            return m_exit_code;
+        do_processing();
+        if (m_queued_events.is_empty()) {
+            wait_for_event();
+            do_processing();
+        }
+        Vector<QueuedEvent> events = move(m_queued_events);
+        for (auto& queued_event : events) {
+            auto* receiver = queued_event.receiver.ptr();
+            auto& event = *queued_event.event;
+#ifdef CEVENTLOOP_DEBUG
+            dbgprintf("CEventLoop: %s{%p} event %u\n", receiver->class_name(), receiver, (unsigned)event.type());
+#endif
+            if (!receiver) {
+                switch (event.type()) {
+                case CEvent::Quit:
+                    ASSERT_NOT_REACHED();
+                    return 0;
+                default:
+                    dbgprintf("Event type %u with no receiver :(\n", event.type());
+                }
+            } else if (event.type() == CEvent::Type::DeferredInvoke) {
+                printf("DeferredInvoke: receiver=%s{%p}\n", receiver->class_name(), receiver);
+                static_cast<CDeferredInvocationEvent&>(event).m_invokee(*receiver);
+            } else {
+                receiver->event(event);
+            }
+
+            if (m_exit_requested) {
+                auto rejigged_event_queue = move(events);
+                rejigged_event_queue.append(move(m_queued_events));
+                m_queued_events = move(rejigged_event_queue);
+                return m_exit_code;
+            }
+        }
+    }
+    ASSERT_NOT_REACHED();
+}
+
+void CEventLoop::post_event(CObject& receiver, OwnPtr<CEvent>&& event)
+{
+#ifdef CEVENTLOOP_DEBUG
+    dbgprintf("CEventLoop::post_event: {%u} << receiver=%p, event=%p\n", m_queued_events.size(), &receiver, event.ptr());
+#endif
+    m_queued_events.append({ receiver.make_weak_ptr(), move(event) });
+}
+
+void CEventLoop::wait_for_event()
+{
+    fd_set rfds;
+    fd_set wfds;
+    FD_ZERO(&rfds);
+    FD_ZERO(&wfds);
+
+    int max_fd = 0;
+    auto add_fd_to_set = [&max_fd] (int fd, fd_set& set){
+        FD_SET(fd, &set);
+        if (fd > max_fd)
+            max_fd = fd;
+    };
+
+    int max_fd_added = -1;
+    add_file_descriptors_for_select(rfds, max_fd_added);
+    max_fd = max(max_fd, max_fd_added);
+    for (auto& notifier : *s_notifiers) {
+        if (notifier->event_mask() & GNotifier::Read)
+            add_fd_to_set(notifier->fd(), rfds);
+        if (notifier->event_mask() & GNotifier::Write)
+            add_fd_to_set(notifier->fd(), wfds);
+        if (notifier->event_mask() & GNotifier::Exceptional)
+            ASSERT_NOT_REACHED();
+    }
+
+    struct timeval timeout = { 0, 0 };
+    if (!s_timers->is_empty() && m_queued_events.is_empty())
+        get_next_timer_expiration(timeout);
+
+    int rc = select(max_fd + 1, &rfds, &wfds, nullptr, (m_queued_events.is_empty() && s_timers->is_empty()) ? nullptr : &timeout);
+    if (rc < 0) {
+        ASSERT_NOT_REACHED();
+    }
+
+    for (auto& it : *s_timers) {
+        auto& timer = *it.value;
+        if (!timer.has_expired())
+            continue;
+#ifdef CEVENTLOOP_DEBUG
+        dbgprintf("CEventLoop: Timer %d has expired, sending CTimerEvent to %p\n", timer.timer_id, timer.owner);
+#endif
+        post_event(*timer.owner, make<CTimerEvent>(timer.timer_id));
+        if (timer.should_reload) {
+            timer.reload();
+        } else {
+            // FIXME: Support removing expired timers that don't want to reload.
+            ASSERT_NOT_REACHED();
+        }
+    }
+
+    for (auto& notifier : *s_notifiers) {
+        if (FD_ISSET(notifier->fd(), &rfds)) {
+            if (notifier->on_ready_to_read)
+                notifier->on_ready_to_read(*notifier);
+        }
+        if (FD_ISSET(notifier->fd(), &wfds)) {
+            if (notifier->on_ready_to_write)
+                notifier->on_ready_to_write(*notifier);
+        }
+    }
+
+    process_file_descriptors_after_select(rfds);
+}
+
+bool CEventLoop::EventLoopTimer::has_expired() const
+{
+    timeval now;
+    gettimeofday(&now, nullptr);
+    return now.tv_sec > fire_time.tv_sec || (now.tv_sec == fire_time.tv_sec && now.tv_usec >= fire_time.tv_usec);
+}
+
+void CEventLoop::EventLoopTimer::reload()
+{
+    gettimeofday(&fire_time, nullptr);
+    fire_time.tv_sec += interval / 1000;
+    fire_time.tv_usec += (interval % 1000) * 1000;
+}
+
+void CEventLoop::get_next_timer_expiration(timeval& soonest)
+{
+    ASSERT(!s_timers->is_empty());
+    bool has_checked_any = false;
+    for (auto& it : *s_timers) {
+        auto& fire_time = it.value->fire_time;
+        if (!has_checked_any || fire_time.tv_sec < soonest.tv_sec || (fire_time.tv_sec == soonest.tv_sec && fire_time.tv_usec < soonest.tv_usec))
+            soonest = fire_time;
+        has_checked_any = true;
+    }
+}
+
+int CEventLoop::register_timer(CObject& object, int milliseconds, bool should_reload)
+{
+    ASSERT(milliseconds >= 0);
+    auto timer = make<EventLoopTimer>();
+    timer->owner = object.make_weak_ptr();
+    timer->interval = milliseconds;
+    timer->reload();
+    timer->should_reload = should_reload;
+    int timer_id = ++s_next_timer_id;  // FIXME: This will eventually wrap around.
+    ASSERT(timer_id); // FIXME: Aforementioned wraparound.
+    timer->timer_id = timer_id;
+    s_timers->set(timer->timer_id, move(timer));
+    return timer_id;
+}
+
+bool CEventLoop::unregister_timer(int timer_id)
+{
+    auto it = s_timers->find(timer_id);
+    if (it == s_timers->end())
+        return false;
+    s_timers->remove(it);
+    return true;
+}
+
+void CEventLoop::register_notifier(Badge<GNotifier>, GNotifier& notifier)
+{
+    s_notifiers->set(&notifier);
+}
+
+void CEventLoop::unregister_notifier(Badge<GNotifier>, GNotifier& notifier)
+{
+    s_notifiers->remove(&notifier);
+}