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#pragma once
#include <glibmm/dispatcher.h>
#include <sigc++/signal.h>
#include <functional>
#include <mutex>
#include <queue>
#include <thread>
#include <tuple>
#include <type_traits>
#include <utility>
#ifdef __OpenBSD__
#define SIGRTMIN SIGUSR1 - 1
#define SIGRTMAX SIGUSR1 + 1
#endif
namespace waybar {
/**
* Thread-safe signal wrapper.
* Uses Glib::Dispatcher to pass events to another thread and locked queue to pass the arguments.
*/
template <typename... Args>
struct SafeSignal : sigc::signal<void(std::decay_t<Args>...)> {
public:
SafeSignal() { dp_.connect(sigc::mem_fun(*this, &SafeSignal::handle_event)); }
template <typename... EmitArgs>
void emit(EmitArgs&&... args) {
if (main_tid_ == std::this_thread::get_id()) {
/*
* Bypass the queue if the method is called the main thread.
* Ensures that events emitted from the main thread are processed synchronously and saves a
* few CPU cycles on locking/queuing.
* As a downside, this makes main thread events prioritized over the other threads and
* disrupts chronological order.
*/
signal_t::emit(std::forward<EmitArgs>(args)...);
} else {
{
std::unique_lock lock(mutex_);
queue_.emplace(std::forward<EmitArgs>(args)...);
}
dp_.emit();
}
}
template <typename... EmitArgs>
inline void operator()(EmitArgs&&... args) {
emit(std::forward<EmitArgs>(args)...);
}
protected:
using signal_t = sigc::signal<void(std::decay_t<Args>...)>;
using slot_t = decltype(std::declval<signal_t>().make_slot());
using arg_tuple_t = std::tuple<std::decay_t<Args>...>;
// ensure that unwrapped methods are not accessible
using signal_t::emit_reverse;
using signal_t::make_slot;
void handle_event() {
for (std::unique_lock lock(mutex_); !queue_.empty(); lock.lock()) {
auto args = queue_.front();
queue_.pop();
lock.unlock();
std::apply(cached_fn_, args);
}
}
Glib::Dispatcher dp_;
std::mutex mutex_;
std::queue<arg_tuple_t> queue_;
const std::thread::id main_tid_ = std::this_thread::get_id();
// cache functor for signal emission to avoid recreating it on each event
const slot_t cached_fn_ = make_slot();
};
} // namespace waybar
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