core: Event loop rework (#5466)

* Event loop rework

* revert missed

4 files changed, 268 insertions, 0 deletions

diff --git a/src/managers/eventLoop/EventLoopManager.cpp b/src/managers/eventLoop/EventLoopManager.cpp
new file mode 100644
index 00000000..0dabdcfb
--- /dev/null
+++ b/src/managers/eventLoop/EventLoopManager.cpp
@@ -0,0 +1,140 @@
+#include "EventLoopManager.hpp"
+#include "../../debug/Log.hpp"
+
+#include <algorithm>
+
+#include <sys/poll.h>
+
+void CEventLoopManager::enterLoop(wl_display* display, wl_event_loop* wlEventLoop) {
+    m_sWayland.loop    = wlEventLoop;
+    m_sWayland.display = display;
+
+    pollfd pollfds[] = {
+        {
+            .fd     = wl_event_loop_get_fd(wlEventLoop),
+            .events = POLLIN,
+        },
+    };
+
+    std::thread pollThr([this, &pollfds]() {
+        while (!m_bTerminate) {
+            int ret = poll(pollfds, 1, 5000 /* 5 seconds, reasonable. Just in case we need to terminate and the signal fails */);
+
+            if (ret < 0) {
+                if (errno == EINTR)
+                    continue;
+
+                Debug::log(CRIT, "Polling fds failed with {}", errno);
+                m_bTerminate = true;
+                return;
+            }
+
+            for (size_t i = 0; i < 1; ++i) {
+                if (pollfds[i].revents & POLLHUP) {
+                    Debug::log(CRIT, "Disconnected from pollfd id {}", i);
+                    m_bTerminate = true;
+                    return;
+                }
+            }
+
+            if (ret != 0) {
+                {
+                    std::lock_guard<std::mutex> lg2(m_sLoopState.eventRequestMutex);
+                    std::lock_guard<std::mutex> lg(m_sLoopState.loopMutex);
+                    m_sLoopState.event = true;
+                }
+                m_sLoopState.cv.notify_all();
+            }
+        }
+    });
+
+    std::thread timersThr([this]() {
+        while (!m_bTerminate) {
+            // calc nearest thing
+
+            m_sTimers.timersMutex.lock();
+            float least = 1000 * 1000 * 10; // 10s in µs
+            for (auto& t : m_sTimers.timers) {
+                const auto TIME = std::clamp(t->leftUs(), 0.f, INFINITY);
+                if (TIME < least)
+                    least = TIME;
+            }
+            m_sTimers.timersMutex.unlock();
+
+            if (least > 0) {
+                std::unique_lock lk(m_sTimers.timersRqMutex);
+                m_sTimers.cv.wait_for(lk, std::chrono::microseconds((int)least + 1), [this] { return m_sTimers.event; });
+                m_sTimers.event = false;
+            }
+
+            // notify main
+            {
+                std::lock_guard<std::mutex> lg2(m_sLoopState.eventRequestMutex);
+                std::lock_guard<std::mutex> lg(m_sLoopState.loopMutex);
+                m_sLoopState.event = true;
+            }
+
+            m_sLoopState.cv.notify_all();
+        }
+    });
+
+    m_sLoopState.event = true; // let it process once
+
+    while (1) {
+        std::unique_lock lk(m_sLoopState.eventRequestMutex);
+        m_sLoopState.cv.wait_for(lk, std::chrono::milliseconds(5000), [this] { return m_sLoopState.event; });
+
+        if (m_bTerminate)
+            break;
+
+        std::lock_guard<std::mutex> lg(m_sLoopState.loopMutex);
+
+        m_sLoopState.event = false;
+
+        if (pollfds[0].revents & POLLIN /* wl event loop */) {
+            wl_display_flush_clients(m_sWayland.display);
+            if (wl_event_loop_dispatch(m_sWayland.loop, -1) < 0) {
+                m_bTerminate = true;
+                break;
+            }
+        }
+
+        // TODO: don't check timers without the timer thread requesting it
+        // I tried but it didnt work :/
+
+        m_sTimers.timersMutex.lock();
+        auto timerscpy = m_sTimers.timers;
+        m_sTimers.timersMutex.unlock();
+
+        for (auto& t : timerscpy) {
+            if (t->passed() && !t->cancelled())
+                t->call(t);
+        }
+
+        if (m_bTerminate)
+            break;
+    }
+
+    Debug::log(LOG, "Kicked off the event loop! :(");
+
+    m_sTimers.event = true;
+    m_sTimers.cv.notify_all();
+}
+
+void CEventLoopManager::addTimer(std::shared_ptr<CEventLoopTimer> timer) {
+    m_sTimers.timersMutex.lock();
+    m_sTimers.timers.push_back(timer);
+    m_sTimers.timersMutex.unlock();
+    nudgeTimers();
+}
+
+void CEventLoopManager::removeTimer(std::shared_ptr<CEventLoopTimer> timer) {
+    m_sTimers.timersMutex.lock();
+    std::erase_if(m_sTimers.timers, [timer](const auto& t) { return timer == t; });
+    m_sTimers.timersMutex.unlock();
+}
+
+void CEventLoopManager::nudgeTimers() {
+    m_sTimers.event = true;
+    m_sTimers.cv.notify_all();
+}
\ No newline at end of file
diff --git a/src/managers/eventLoop/EventLoopManager.hpp b/src/managers/eventLoop/EventLoopManager.hpp
new file mode 100644
index 00000000..d55b54a9
--- /dev/null
+++ b/src/managers/eventLoop/EventLoopManager.hpp
@@ -0,0 +1,46 @@
+#pragma once
+
+#include <condition_variable>
+#include <mutex>
+#include <memory>
+#include <thread>
+#include <wayland-server.h>
+
+#include "EventLoopTimer.hpp"
+
+class CEventLoopManager {
+  public:
+    void enterLoop(wl_display* display, wl_event_loop* wlEventLoop);
+    void addTimer(std::shared_ptr<CEventLoopTimer> timer);
+    void removeTimer(std::shared_ptr<CEventLoopTimer> timer);
+
+    // recalculates timers
+    void nudgeTimers();
+
+  private:
+    struct {
+        wl_event_loop* loop    = nullptr;
+        wl_display*    display = nullptr;
+        std::thread    pollThread;
+    } m_sWayland;
+
+    struct {
+        std::mutex                                    timersMutex;
+        std::mutex                                    timersRqMutex;
+        std::vector<std::shared_ptr<CEventLoopTimer>> timers;
+        std::thread                                   timerThread;
+        bool                                          event = false;
+        std::condition_variable                       cv;
+    } m_sTimers;
+
+    struct {
+        std::mutex              loopMutex;
+        std::mutex              eventRequestMutex;
+        bool                    event = false;
+        std::condition_variable cv;
+    } m_sLoopState;
+
+    bool m_bTerminate = false;
+};
+
+inline std::unique_ptr<CEventLoopManager> g_pEventLoopManager;
\ No newline at end of file
diff --git a/src/managers/eventLoop/EventLoopTimer.cpp b/src/managers/eventLoop/EventLoopTimer.cpp
new file mode 100644
index 00000000..ebfb696c
--- /dev/null
+++ b/src/managers/eventLoop/EventLoopTimer.cpp
@@ -0,0 +1,53 @@
+#include "EventLoopTimer.hpp"
+#include <numeric>
+#include "EventLoopManager.hpp"
+
+CEventLoopTimer::CEventLoopTimer(std::optional<std::chrono::system_clock::duration> timeout, std::function<void(std::shared_ptr<CEventLoopTimer> self, void* data)> cb_,
+                                 void* data_) :
+    cb(cb_),
+    data(data_) {
+
+    if (!timeout.has_value())
+        expires.reset();
+    else
+        expires = std::chrono::system_clock::now() + *timeout;
+}
+
+void CEventLoopTimer::updateTimeout(std::optional<std::chrono::system_clock::duration> timeout) {
+    if (!timeout.has_value()) {
+        expires.reset();
+        g_pEventLoopManager->nudgeTimers();
+        return;
+    }
+
+    expires = std::chrono::system_clock::now() + *timeout;
+
+    g_pEventLoopManager->nudgeTimers();
+}
+
+bool CEventLoopTimer::passed() {
+    if (!expires.has_value())
+        return false;
+    return std::chrono::system_clock::now() > *expires;
+}
+
+void CEventLoopTimer::cancel() {
+    wasCancelled = true;
+    expires.reset();
+}
+
+bool CEventLoopTimer::cancelled() {
+    return wasCancelled;
+}
+
+void CEventLoopTimer::call(std::shared_ptr<CEventLoopTimer> self) {
+    expires.reset();
+    cb(self, data);
+}
+
+float CEventLoopTimer::leftUs() {
+    if (!expires.has_value())
+        return std::numeric_limits<float>::max();
+
+    return std::chrono::duration_cast<std::chrono::microseconds>(*expires - std::chrono::system_clock::now()).count();
+}
diff --git a/src/managers/eventLoop/EventLoopTimer.hpp b/src/managers/eventLoop/EventLoopTimer.hpp
new file mode 100644
index 00000000..8865d29f
--- /dev/null
+++ b/src/managers/eventLoop/EventLoopTimer.hpp
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <chrono>
+#include <functional>
+#include <optional>
+
+class CEventLoopTimer {
+  public:
+    CEventLoopTimer(std::optional<std::chrono::system_clock::duration> timeout, std::function<void(std::shared_ptr<CEventLoopTimer> self, void* data)> cb_, void* data_);
+
+    // if not specified, disarms.
+    // if specified, arms.
+    void  updateTimeout(std::optional<std::chrono::system_clock::duration> timeout);
+
+    void  cancel();
+    bool  passed();
+
+    float leftUs();
+
+    bool  cancelled();
+    // resets expires
+    void call(std::shared_ptr<CEventLoopTimer> self);
+
+  private:
+    std::function<void(std::shared_ptr<CEventLoopTimer> self, void* data)> cb;
+    void*                                                                  data = nullptr;
+    std::optional<std::chrono::system_clock::time_point>                   expires;
+    bool                                                                   wasCancelled = false;
+};