Event / Task Queue Multithreading C++

Question

I would like to create a class whose methods can be called from multiple threads. but instead of executing the method in the thread from which it was called, it should perform t

Answer 1

Here's a class I wrote for a similar purpose (I use it for event handling but you could of course rename it to ActionQueue -- and rename its methods).

You use it like this:

With function you want to call: void foo (const int x, const int y) { /*...*/ }

And: EventQueue q;

q.AddEvent (boost::bind (foo, 10, 20));

In the worker thread

q.PlayOutEvents ();

Note: It should be fairly easy to add code to block on condition to avoid using up CPU cycles.

The code (Visual Studio 2003 with boost 1.34.1):

#pragma once

#include 
#include 
#include 
#include 
#include 
#include 
using std::string;


// Records & plays out actions (closures) in a safe-thread manner.

class EventQueue
{
    typedef boost::function  Event;

public:

    const bool PlayOutEvents ()
    {
        // The copy is there to ensure there are no deadlocks.
        const std::vector eventsCopy = PopEvents ();

        BOOST_FOREACH (const Event& e, eventsCopy)
        {
            e ();
            Sleep (0);
        }

        return eventsCopy.size () > 0;
    }

    void AddEvent (const Event& event)
    {
        Mutex::scoped_lock lock (myMutex);

        myEvents.push_back (event);
    }

protected:

    const std::vector PopEvents ()
    {
        Mutex::scoped_lock lock (myMutex);

        const std::vector eventsCopy = myEvents;
        myEvents.clear ();

        return eventsCopy;
    }

private:

    typedef boost::recursive_mutex Mutex;
    Mutex myMutex;

    std::vector  myEvents;

};

I hope this helps. :)

Martin Bilski