多執行緒同步回撥
#include <cstdio>
#include <iostream>
#include <boost/asio.hpp> 
#include <boost/thread.hpp>
#include <boost/asio/strand.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
using namespace boost;
using namespace std;
class CPrinter
{
public:
    CPrinter(boost::asio::io_service 
 
&io)
        :m_strand(io)
        , m_timer1(io, boost::posix_time::seconds(5))
        , m_timer2(io, boost::posix_time::seconds(5))
        , m_count(0)
    {
        m_timer1.async_wait(m_strand.wrap(boost::bind(&CPrinter::Print1, this)));
        m_timer2.async_wait(m_strand.wrap(boost::bind(
 
&CPrinter::Print2, this)));
    }
    ~CPrinter()
    {
        cout << "m_count = " << m_count << endl;
    }
    void Print1()
    {
        if (m_count < 10)
        {
            cout << "Timer1 count = " << m_count << endl;
            cout << boost::this_thread::get_id() << endl;
            m_count
 
++;
            m_timer1.expires_at(m_timer1.expires_at() + boost::posix_time::seconds(1));
            m_timer1.async_wait(m_strand.wrap(boost::bind(&CPrinter::Print1, this)));
        }
    }
    void Print2()
    {
        if (m_count < 10)
        {
            cout << "Timer2 count = " << m_count << endl;
            cout << boost::this_thread::get_id() << endl;
            m_count++;
            m_timer2.expires_at(m_timer2.expires_at() + boost::posix_time::seconds(1));
            m_timer2.async_wait(m_strand.wrap(boost::bind(&CPrinter::Print2, this)));
        }
    }
private:
    //strand提供序列執行, 能夠保證執行緒安全, 同時被post或dispatch的方法, 不會被併發
    boost::asio::strand m_strand;
    boost::asio::deadline_timer m_timer1;
    boost::asio::deadline_timer m_timer2;
    int m_count;
};

int main()
{
    cout << boost::this_thread::get_id() << endl;
    boost::asio::io_service io;
    CPrinter cp(io);
    cout << "to run" << endl;
    boost::thread td(boost::bind(&boost::asio::io_service::run, &io));
    io.run();
    cout << "exit" << endl;

    return EXIT_SUCCESS;
}