feat(modules): pause background threads when display is asleep

Currently, modules polling hardware nodes continuously wake up kernel drivers even when the monitor is asleep (e.g., DPMS off), flooding dmesg.

- Adds 'disable-on-sleep' config flag
- Hooks GTK window map/unmap signals to track DPMS state
- Propagates suspend/resume calls to AModule worker threads

include/AModule.hpp

@@ -25,6 +25,10 @@ class AModule : public IModule {
 
   bool expandEnabled() const;
 
+  virtual void suspend() {};
+  virtual void resume() {};
+  bool shouldSuspend() const { return disable_on_sleep_; }
+
  protected:
   // Don't need to make an object directly
   // Derived classes are able to use it
@@ -48,6 +52,8 @@ class AModule : public IModule {
   virtual bool handleMouseLeave(GdkEventCrossing* const& ev);
   virtual bool handleScroll(GdkEventScroll*);
   virtual bool handleRelease(GdkEventButton* const& ev);
+
+  bool disable_on_sleep_{false};
   GObject* menu_ = nullptr;
 
  private:

include/bar.hpp

@@ -75,6 +75,8 @@ class Bar : public sigc::trackable {
   util::KillSignalAction getOnSigusr1Action();
   util::KillSignalAction getOnSigusr2Action();
 
+  void toggleSuspend(bool suspend);
+
   struct waybar_output* output;
   Json::Value config;
   struct wl_surface* surface;

include/modules/temperature.hpp

@@ -14,6 +14,8 @@ class Temperature : public ALabel {
   Temperature(const std::string&, const Json::Value&);
   virtual ~Temperature() = default;
   auto update() -> void override;
+  void suspend() override;
+  void resume() override;
 
  private:
   float getTemperature();

include/util/sleeper_thread.hpp

@@ -79,6 +79,12 @@ class SleeperThread {
   auto sleep_for(std::chrono::system_clock::duration dur) {
     std::unique_lock lk(mutex_);
     CancellationGuard cancel_lock;
+
+    condvar_.wait(lk, [this] {
+      return !is_paused_ || signal_.load(std::memory_order_relaxed) ||
+             !do_run_.load(std::memory_order_relaxed);
+    });
+
     constexpr auto max_time_point = std::chrono::steady_clock::time_point::max();
     auto wait_end = max_time_point;
     auto now = std::chrono::steady_clock::now();
@@ -95,6 +101,12 @@ class SleeperThread {
           time_point) {
     std::unique_lock lk(mutex_);
     CancellationGuard cancel_lock;
+
+    condvar_.wait(lk, [this] {
+      return !is_paused_ || signal_.load(std::memory_order_relaxed) ||
+             !do_run_.load(std::memory_order_relaxed);
+    });
+
     return condvar_.wait_until(lk, time_point, [this] {
       return signal_.load(std::memory_order_relaxed) || !do_run_.load(std::memory_order_relaxed);
     });
@@ -122,6 +134,17 @@ class SleeperThread {
     }
   }
 
+  void pause() {
+    std::lock_guard<std::mutex> lock(mutex_);
+    is_paused_ = true;
+  }
+
+  void resume() {
+    std::lock_guard<std::mutex> lock(mutex_);
+    is_paused_ = false;
+    condvar_.notify_all();
+  }
+
   ~SleeperThread() {
     connection_.disconnect();
     stop();
@@ -137,6 +160,7 @@ class SleeperThread {
   std::atomic<bool> do_run_ = true;
   std::atomic<bool> signal_ = false;
   sigc::connection connection_;
+  bool is_paused_{false};
 };
 
 }  // namespace waybar::util

src/AModule.cpp

@@ -21,6 +21,9 @@ AModule::AModule(const Json::Value& config, const std::string& name, const std::
   // Configure module action Map
   const Json::Value actions{config_["actions"]};
 
+  disable_on_sleep_ =
+      config_["disable-on-sleep"].isBool() ? config_["disable-on-sleep"].asBool() : false;
+
   for (Json::Value::const_iterator it = actions.begin(); it != actions.end(); ++it) {
     if (it.key().isString() && it->isString())
       if (!eventActionMap_.contains(it.key().asString())) {

src/bar.cpp

@@ -263,6 +263,16 @@ waybar::Bar::Bar(struct waybar_output* w_output, const Json::Value& w_config)
 
   window.signal_map_event().connect_notify(sigc::mem_fun(*this, &Bar::onMap));
 
+  window.signal_unmap().connect([this]() {
+    spdlog::debug("Output {} unmapped (DPMS off), suspending modules", output->name);
+    toggleSuspend(true);
+  });
+
+  window.signal_map().connect([this]() {
+    spdlog::debug("Output {} mapped (DPMS on), resuming modules", output->name);
+    toggleSuspend(false);
+  });
+
 #if HAVE_SWAY
   if (auto ipc = config["ipc"]; ipc.isBool() && ipc.asBool()) {
     bar_id = Client::inst()->bar_id;
@@ -545,8 +555,8 @@ void waybar::Bar::getModules(const Factory& factory, const std::string& pos,
           if (group_config["modules"].isNull()) {
             spdlog::warn("Group definition '{}' has not been found, group will be hidden", ref);
           }
-          auto group_module = std::make_unique<waybar::Group>(
-          id_name, class_name, group_config, vertical);
+          auto group_module =
+              std::make_unique<waybar::Group>(id_name, class_name, group_config, vertical);
 
           getModules(factory, ref, group_module.get());
           module = group_module.release();
@@ -696,3 +706,22 @@ void waybar::Bar::configureGlobalOffset(int width, int height) {
 void waybar::Bar::onOutputGeometryChanged() {
   configureGlobalOffset(window.get_width(), window.get_height());
 }
+
+void waybar::Bar::toggleSuspend(bool suspend) {
+  auto process_modules = [suspend](Gtk::Box& module_box) {
+    for (auto* widget : module_box.get_children()) {
+      auto* module = dynamic_cast<waybar::AModule*>(widget);
+      if (module && module->shouldSuspend()) {
+        if (suspend) {
+          module->suspend();
+        } else {
+          module->resume();
+        }
+      }
+    }
+  };
+
+  process_modules(left_);
+  process_modules(center_);
+  process_modules(right_);
+}

src/modules/temperature.cpp

@@ -155,3 +155,7 @@ bool waybar::modules::Temperature::isCritical(uint16_t temperature_c) {
   return config_["critical-threshold"].isInt() &&
          temperature_c >= config_["critical-threshold"].asInt();
 }
+
+void waybar::modules::Temperature::suspend() { thread_.pause(); }
+
+void waybar::modules::Temperature::resume() { thread_.resume(); }