boost:asio thread pool implementation for occasionally synchronized tasks

Question

I have a \"main\" function that performs many small, independent tasks each once per time step. However, after each time step, I must wait for all of the tasks to complete befor

Answer 1

You may use futures for data processing and synchronize with them using boost::wait_for_all(). This will allow you to operate in terms of parts of work done, not threads.

int process_data() {...}

// Pending futures
std::vector> pending_data;

for(int i = 0; i < numSmallTasks; ++i)
{
   // Create task and corresponding future
   // Using shared ptr and binding operator() trick because
   // packaged_task is non-copyable, but asio::io_service::post requires argument to be copyable

   // Boost 1.51 syntax
   // For Boost 1.53+ or C++11 std::packaged_task shall be boost::packaged_task
   typedef boost::packaged_task task_t;

   boost::shared_ptr task = boost::make_shared(
      boost::bind(&process_data, i, theTime));

   boost::unique_future fut = task->get_future();

   pending_data.push_back(std::move(fut));
   io_service.post(boost::bind(&task_t::operator(), task));    
}

// After loop - wait until all futures are evaluated
boost::wait_for_all(pending_data.begin(), pending_data.end());