thread/thread.cc

A glibmm thread example.

 
#include <condition_variable>
#include <iostream>
#include <memory>
#include <mutex>
#include <queue>
#include <thread>
#if defined(_MSC_VER) && (_MSC_VER < 1900)
/* For using noexcept on Visual Studio 2013 */
#include <glibmmconfig.h>
#endif
#include <glibmm/init.h>
#include <glibmm/random.h>
#include <glibmm/timer.h>
 
namespace
{
 
class MessageQueue
{
public:
  MessageQueue();
  ~MessageQueue();
 
  void producer();
  void consumer();
 
private:
  std::mutex mutex_;
  std::condition_variable cond_push_;
  std::condition_variable cond_pop_;
  std::queue<int> queue_;
};
 
MessageQueue::MessageQueue()
{
}
 
MessageQueue::~MessageQueue()
{
}
 
void
MessageQueue::producer()
{
  Glib::Rand rand(1234);
 
  for (auto i = 0; i < 200; ++i)
  {
    {
      std::unique_lock<std::mutex> lock(mutex_);
 
      cond_pop_.wait(lock, [this]() -> bool { return queue_.size() < 64; });
 
      queue_.push(i);
      std::cout << '*';
      std::cout.flush();
 
      // We unlock before notifying, because that is what the documentation suggests:
      // http://en.cppreference.com/w/cpp/thread/condition_variable
      lock.unlock();
      cond_push_.notify_one();
    }
 
    if (rand.get_bool())
      continue;
 
    Glib::usleep(rand.get_int_range(0, 100000));
  }
}
 
void
MessageQueue::consumer()
{
  Glib::Rand rand(4567);
 
  for (;;)
  {
    {
      std::unique_lock<std::mutex> lock(mutex_);
 
      cond_push_.wait(lock, [this]() -> bool { return !queue_.empty(); });
 
      const int i = queue_.front();
      queue_.pop();
      std::cout << "\x08 \x08";
      std::cout.flush();
 
      // We unlock before notifying, because that is what the documentation suggests:
      // http://en.cppreference.com/w/cpp/thread/condition_variable
      lock.unlock();
      cond_pop_.notify_one();
 
      if (i >= 199)
        break;
    }
 
    if (rand.get_bool())
      continue;
 
    Glib::usleep(rand.get_int_range(10000, 200000));
  }
}
}
 
int
main(int, char**)
{
  Glib::init();
 
  MessageQueue queue;
 
  // TODO: Use std::make_unique() when we use C++14:
  const auto producer =
    std::unique_ptr<std::thread>(new std::thread(&MessageQueue::producer, &queue));
 
  const auto consumer =
    std::unique_ptr<std::thread>(new std::thread(&MessageQueue::consumer, &queue));
 
  producer->join();
  consumer->join();
 
  std::cout << std::endl;
 
  return 0;
}