internal: add a watchdog

a watchdog will abort processing a signal if a timeout specified via debug:watchdog_timeout is reached.

src/Compositor.cpp

@@ -34,6 +34,13 @@ void handleUnrecoverableSignal(int sig) {
     abort();
 }
 
+void handleUserSignal(int sig) {
+    if (sig == SIGUSR1) {
+        // means we have to unwind a timed out event
+        throw std::exception();
+    }
+}
+
 CCompositor::CCompositor() {
     m_iHyprlandPID = getpid();
 
@@ -70,6 +77,8 @@ CCompositor::CCompositor() {
     setRandomSplash();
 
     Debug::log(LOG, "\nCurrent splash: {}\n\n", m_szCurrentSplash);
+
+    g_pWatchdog = std::make_unique<CWatchdog>();
 }
 
 CCompositor::~CCompositor() {
@@ -92,6 +101,7 @@ CCompositor::~CCompositor() {
     g_pAnimationManager.reset();
     g_pKeybindManager.reset();
     g_pHookSystem.reset();
+    g_pWatchdog.reset();
 }
 
 void CCompositor::setRandomSplash() {
@@ -112,6 +122,7 @@ void CCompositor::initServer() {
     wl_event_loop_add_signal(m_sWLEventLoop, SIGTERM, handleCritSignal, nullptr);
     signal(SIGSEGV, handleUnrecoverableSignal);
     signal(SIGABRT, handleUnrecoverableSignal);
+    signal(SIGUSR1, handleUserSignal);
     //wl_event_loop_add_signal(m_sWLEventLoop, SIGINT, handleCritSignal, nullptr);
 
     initManagers(STAGE_PRIORITY);

src/Compositor.hpp

@@ -27,6 +27,7 @@
 #include "render/OpenGL.hpp"
 #include "hyprerror/HyprError.hpp"
 #include "plugins/PluginSystem.hpp"
+#include "helpers/Watchdog.hpp"
 
 enum eManagersInitStage
 {

src/config/ConfigManager.cpp

@@ -134,6 +134,7 @@ void CConfigManager::setDefaultVars() {
     configValues["debug:damage_tracking"].intValue    = DAMAGE_TRACKING_FULL;
     configValues["debug:manual_crash"].intValue       = 0;
     configValues["debug:suppress_errors"].intValue    = 0;
+    configValues["debug:watchdog_timeout"].intValue   = 5;
 
     configValues["decoration:rounding"].intValue               = 0;
     configValues["decoration:blur:enabled"].intValue           = 1;

src/helpers/WLListener.cpp

@@ -6,7 +6,13 @@
 void handleWrapped(wl_listener* listener, void* data) {
     CHyprWLListener::SWrapper* pWrap = wl_container_of(listener, pWrap, m_sListener);
 
+    g_pWatchdog->startWatching();
+
+    try {
         pWrap->m_pSelf->emit(data);
+    } catch (std::exception& e) { Debug::log(ERR, "Listener {} timed out and was killed by Watchdog!!!", (uintptr_t)listener); }
+
+    g_pWatchdog->endWatching();
 }
 
 CHyprWLListener::CHyprWLListener(wl_signal* pSignal, std::function<void(void*, void*)> callback, void* pOwner) {

src/helpers/Watchdog.cpp

@@ -0,0 +1,49 @@
+#include "Watchdog.hpp"
+#include <signal.h>
+#include "config/ConfigManager.hpp"
+
+CWatchdog::CWatchdog() {
+    m_iMainThreadPID = pthread_self();
+
+    m_pWatchdog = std::make_unique<std::thread>([this] {
+        static auto* const PTIMEOUT = &g_pConfigManager->getConfigValuePtr("debug:watchdog_timeout")->intValue;
+
+        while (1337) {
+            std::unique_lock lk(m_mWatchdogMutex);
+
+            if (!m_bWillWatch)
+                m_cvWatchdogCondition.wait(lk, [this] { return m_bNotified; });
+            else {
+                if (m_cvWatchdogCondition.wait_for(lk, std::chrono::milliseconds((int)(*PTIMEOUT * 1000.0)), [this] { return m_bNotified; }) == false)
+                    pthread_kill(m_iMainThreadPID, SIGUSR1);
+            }
+
+            m_bWatching = false;
+            m_bNotified = false;
+        }
+    });
+
+    m_pWatchdog->detach();
+}
+
+void CWatchdog::startWatching() {
+    static auto* const PTIMEOUT = &g_pConfigManager->getConfigValuePtr("debug:watchdog_timeout")->intValue;
+
+    if (*PTIMEOUT == 0)
+        return;
+
+    m_tTriggered = std::chrono::high_resolution_clock::now();
+    m_bWillWatch = true;
+    m_bWatching  = true;
+
+    m_bNotified = true;
+    m_cvWatchdogCondition.notify_all();
+}
+
+void CWatchdog::endWatching() {
+    m_bWatching  = false;
+    m_bWillWatch = false;
+
+    m_bNotified = true;
+    m_cvWatchdogCondition.notify_all();
+}

src/helpers/Watchdog.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <memory>
+#include <chrono>
+#include <thread>
+#include <condition_variable>
+
+class CWatchdog {
+  public:
+    // must be called from the main thread
+    CWatchdog();
+
+    void startWatching();
+    void endWatching();
+
+  private:
+    std::chrono::high_resolution_clock::time_point m_tTriggered;
+
+    pthread_t                                      m_iMainThreadPID = 0;
+
+    bool                                           m_bWatching  = false;
+    bool                                           m_bWillWatch = false;
+
+    std::unique_ptr<std::thread>                   m_pWatchdog;
+    std::mutex                                     m_mWatchdogMutex;
+    bool                                           m_bNotified = false;
+    std::condition_variable                        m_cvWatchdogCondition;
+};
+
+inline std::unique_ptr<CWatchdog> g_pWatchdog;