Exception thrown using boost thread library

Question

I have the following code to run a timed thread:

// Method to invoke a request with a timeout.
bool devices::server::CDeviceServer::invokeWithTimeout(CDeviceClientRequest&  request,
                                                       CDeviceServerResponse& response)
{
   // Retrieve the timeout from the device.
   int timeout = getTimeout();
   timeout += 500; // Add 500ms to cover invocation time.

   // Invoke the request within a timed thread.
   boost::promise<void>        boostPromise;
   boost::unique_future<void>  boostFuture = boostPromise.get_future();
   boost::thread               boostThread([&]()
                               {
                                  invoke(request, response); 
                                  boostPromise.set_value();
                               });

   // The thread has timed out, if the future is not ready.
   return (boostFuture.wait_for(boost::chrono::milliseconds(timeout)) 
           == 
           boost::future_status::ready);
}

This appears to work without a problem, the function returns false when it times out.

However, then the code being invoked (by invoke(request, response);) throws an exception which kills the application. How do I successfully terminate the thread if it has not completed, and consume any exceptions.

I have tried the following:

// The thread has timed out, if the future is not ready.
bool completed = (boostFuture.wait_for(boost::chrono::milliseconds(timeout)) 
                  == 
                  boost::future_status::ready);
if (!completed)
{
   boostThread.interrupt();
}
return completed;

But this also throws an exception and crashes the application. I need a completely safe mechanism where the timed thread can be safely killed off, if the timeout has been reached.

score 1 · Accepted Answer · answered Aug 12 '13 at 17:58

1

Boost documentation states:

If the function or callable object passed to the boost::thread constructor propagates an exception when invoked that is not of type boost::thread_interrupted, std::terminate() is called.

You must catch the exception and exit the thread cleanly (or throw boost::thread_interrupted)

http://www.boost.org/doc/libs/1_54_0/doc/html/thread/thread_management.html#thread.thread_management.tutorial.exceptions

answered Aug 12 '13 at 17:58

TimDave

652
3
6

In the above 2 examples, catch the thread where? Inside the code being run by boostThread, around the return, or around the interrupt()? Where exactly is the exception thrown, and where do I need to catch it? – Marcus MacWilliam Aug 13 '13 at 11:25
Also looking at the documentation, can simply detach() the thread? – Marcus MacWilliam Aug 13 '13 at 11:27

score 0 · Answer 2 · answered Aug 13 '13 at 12:42

OK, the code I came up with as a solution is:

// Functor to help invoke the device method, inside a timed thread.
struct invoke_fn
{
   void operator()(devices::server::CDeviceServer& server,
                   boost::promise<void>&           boostPromise,
                   CDeviceClientRequest&           request,
                   CDeviceServerResponse&          response)
   {
      try
      {
         server.invoke(request, response);
         boostPromise.set_value();
      }
      catch (devices::util::CDeviceException &e)
      {
         // Add any error to the response.
         std::string message = devices::util::retrieveDeviceExceptionMessage(e);
         response.set_errormessage(message);
      }
      catch (std::exception &e)
      {
         // Add any exception message to the response.
         std::string message(e.what());
         response.set_errormessage(message);
      }
   }
};

// Method to invoke a request with a timeout.
bool devices::server::CDeviceServer::invokeWithTimeout(CDeviceClientRequest&  request,
                                                       CDeviceServerResponse& response)
{
   // Retrieve the timeout from the device.
   int timeout = getTimeout();
   timeout += 500; // Add 500ms to cover invocation time.

   // Invoke the request within a timed thread.
   boost::promise<void>        boostPromise;
   boost::unique_future<void>  boostFuture = boostPromise.get_future();
   boost::thread               boostThread([&]()
                               {
                                  invoke_fn functor;
                                  functor(*this,
                                          boostPromise,
                                          request,
                                          response);
                               });

   // The thread has timed out, if the future is not ready.
   return (boostFuture.wait_for(boost::chrono::milliseconds(timeout)) 
           == 
           boost::future_status::ready);
}

Exception thrown using boost thread library

2 Answers2