sig_handler.cc

#include "sig_handler.h"
#include "logging/logging.h"
 
std::atomic<bool> SigHandler::signal_marker_;
std::mutex SigHandler::exit_m_;
std::condition_variable SigHandler::exit_cv_;
bool SigHandler::exit_flag_;
 
SigHandler& SigHandler::get() {
  static SigHandler handler;
  return handler;
}
 
SigHandler::~SigHandler() {
  try {
    {
      std::lock_guard<std::mutex> g(exit_m_);
      exit_flag_ = true;
    }
    exit_cv_.notify_all();
 
    if (polling_thread_.joinable()) {
      polling_thread_.join();
    }
  } catch (...) {
  }
}
 
void SigHandler::start(const std::function<void()>& on_signal) {
  if (polling_thread_.get_id() != boost::thread::id()) {
    throw std::runtime_error("SigHandler can only be started once");
  }
 
  polling_thread_ = boost::thread([on_signal]() {
    std::unique_lock<std::mutex> l(exit_m_);
    while (true) {
      bool got_signal = signal_marker_.exchange(false);
 
      if (got_signal) {
        on_signal();
        return;
      }
 
      if (exit_cv_.wait_for(l, std::chrono::seconds(1), [] { return exit_flag_; })) {
        break;
      }
    }
  });
}
 
void SigHandler::signal(int sig) { ::signal(sig, signal_handler); }
 
void SigHandler::signal_handler(int sig) {
  (void)sig;
  bool v = false;
  // put true if currently set to false
  SigHandler::signal_marker_.compare_exchange_strong(v, true);
}