add application event loop "wake-up"

src/Application.cpp

@@ -1,14 +1,37 @@
 #include "Application.hpp"
 #include <poll.h>
+#include <unistd.h>
 
 namespace Raven {
 
+bool Application::wake() {
+    if (!m_wakeup_pipe_available) {
+        return false;
+    }
+
+    uint32_t buf = 0;
+    write(m_wakeup_pipe_write_end, &buf, 1);
+    return true;
+}
+
 void Application::add_window(std::shared_ptr<Window> window) {
     m_windows.push_back(window);
     update_fds();
 }
 
 void Application::update_fds() {
+    if (m_should_create_wakeup_pipe) {
+        m_should_create_wakeup_pipe = false;
+        int pipe_fds[2];
+        if (pipe(pipe_fds) != 0) {
+            // TODO: handle this?
+            return;
+        }
+
+        m_wakeup_pipe_read_end = pipe_fds[0];
+        m_wakeup_pipe_write_end = pipe_fds[1];
+        m_wakeup_pipe_available = true;
+    }
     for (int i = 0; i < RAVEN_APPLICATION_MAX_WINDOWS; i++) {
         m_fds[i].fd = -1;
         m_fds[i].events = 0;
@@ -18,6 +41,12 @@ void Application::update_fds() {
         m_fds[i].fd = m_windows[i]->file_descriptor();
         m_fds[i].events = POLL_IN;
     }
+    if (m_wakeup_pipe_available) {
+        int wakeup_pipe_index = m_windows.size();
+        m_fds[wakeup_pipe_index].fd = m_wakeup_pipe_read_end;
+        m_fds[wakeup_pipe_index].events = POLL_IN;
+        m_fds[wakeup_pipe_index].revents = 0;
+    }
 }
 
 int Application::turn() {
@@ -25,11 +54,14 @@ int Application::turn() {
         update_fds();
         m_fds_need_update = false;
     }
-    if (poll(m_fds, m_windows.size(), -1) > 0) {
+    if (poll(m_fds, m_windows.size() + 1, -1) > 0) {
         for (size_t i = 0; i < m_windows.size(); i++) {
-            if (m_fds[i].revents & POLLIN) {
-                m_windows[i]->run(false);
-            }
+            m_windows[i]->run(false);
+        }
+        while (!m_microtasks.empty()) {
+            auto callback = m_microtasks.front();
+            callback();
+            m_microtasks.pop();
         }
     } else {
         return 1;

src/Application.hpp

@@ -12,8 +12,12 @@ namespace Raven {
 class Application {
 public:
     Application() {}
+    Application(bool should_create_wakeup_pipe)
+        : m_should_create_wakeup_pipe(should_create_wakeup_pipe) {}
 
     void add_window(std::shared_ptr<Window>);
+    bool wake();
+    void queue_microtask(std::function<void()> callback) { m_microtasks.push(callback); }
     int turn();
     int run();
 
@@ -29,6 +33,11 @@ private:
     std::vector<std::shared_ptr<Window>> m_windows;
     struct pollfd m_fds[RAVEN_APPLICATION_MAX_WINDOWS];
     bool m_fds_need_update { true };
+    bool m_should_create_wakeup_pipe { false };
+    bool m_wakeup_pipe_available { false };
+    int m_wakeup_pipe_read_end { -1 };
+    int m_wakeup_pipe_write_end { -1 };
+    std::queue<std::function<void()>> m_microtasks;
 };
 
 }