Update of /cvsroot/boost/boost/libs/asio/example/invocation
In directory sc8-pr-cvs3.sourceforge.net:/tmp/cvs-serv26299/invocation

Added Files:
        Jamfile Jamfile.v2 prioritised_handlers.cpp 
Log Message:
Add example illustrating a custom handler invocation hook.


--- NEW FILE: Jamfile ---
#
# Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
#
# Distributed under the Boost Software License, Version 1.0. (See accompanying
# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#

subproject libs/asio/example/invocation ;

project boost : $(BOOST_ROOT) ;

if $(UNIX)
{
  switch $(JAMUNAME)
  {
  case SunOS* :
    {
      SOCKET_LIBS = <find-library>socket <find-library>nsl ;
    }
  }
}

exe prioritised_handlers
  : <lib>@boost/libs/system/build/boost_system
    prioritised_handlers.cpp
  : <include>$(BOOST_ROOT)
    <include>../../../..
    <define>BOOST_ALL_NO_LIB=1
    <threading>multi
    <mingw><*><find-library>ws2_32
    <mingw><*><find-library>mswsock
    $(SOCKET_LIBS)
  ;

--- NEW FILE: Jamfile.v2 ---
#
# Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
#
# Distributed under the Boost Software License, Version 1.0. (See accompanying
# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#

import os ;

if [ os.name ] = SOLARIS
{
  lib socket ;
  lib nsl ;
}
else if [ os.name ] = NT
{
  lib ws2_32 ;
  lib mswsock ;
}

exe prioritised_handlers
  : prioritised_handlers.cpp
    /boost/system//boost_system
  : <define>BOOST_ALL_NO_LIB=1
    <threading>multi
    <os>SOLARIS:<library>socket
    <os>SOLARIS:<library>nsl
    <os>NT,<toolset>gcc:<library>ws2_32
    <os>NT,<toolset>gcc:<library>mswsock
  ;

--- NEW FILE: prioritised_handlers.cpp ---
//
// prioritised_handlers.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <boost/asio.hpp>
#include <boost/function.hpp>
#include <iostream>
#include <queue>

class handler_priority_queue
{
public:
  void add(int priority, boost::function<void()> function)
  {
    handlers_.push(queued_handler(priority, function));
  }

  void execute_all()
  {
    while (!handlers_.empty())
    {
      queued_handler handler = handlers_.top();
      handler.execute();
      handlers_.pop();
    }
  }

  // A generic wrapper class for handlers to allow the invocation to be hooked.
  template <typename Handler>
  class wrapped_handler
  {
  public:
    wrapped_handler(handler_priority_queue& q, int p, Handler h)
      : queue_(q), priority_(p), handler_(h)
    {
    }

    void operator()()
    {
      handler_();
    }

    template <typename Arg1>
    void operator()(Arg1 arg1)
    {
      handler_(arg1);
    }

    template <typename Arg1, typename Arg2>
    void operator()(Arg1 arg1, Arg2 arg2)
    {
      handler_(arg1, arg2);
    }

  //private:
    handler_priority_queue& queue_;
    int priority_;
    Handler handler_;
  };

  template <typename Handler>
  wrapped_handler<Handler> wrap(int priority, Handler handler)
  {
    return wrapped_handler<Handler>(*this, priority, handler);
  }

private:
  class queued_handler
  {
  public:
    queued_handler(int p, boost::function<void()> f)
      : priority_(p), function_(f)
    {
    }

    void execute()
    {
      function_();
    }

    friend bool operator<(const queued_handler& a,
        const queued_handler& b)
    {
      return a.priority_ < b.priority_;
    }

  private:
    int priority_;
    boost::function<void()> function_;
  };

  std::priority_queue<queued_handler> handlers_;
};

// Custom invocation hook for wrapped handlers.
template <typename Function, typename Handler>
void asio_handler_invoke(Function f,
    handler_priority_queue::wrapped_handler<Handler>* h)
{
  h->queue_.add(h->priority_, f);
}

//----------------------------------------------------------------------

void high_priority_handler()
{
  std::cout << "High priority handler\n";
}

void middle_priority_handler()
{
  std::cout << "Middle priority handler\n";
}

void low_priority_handler()
{
  std::cout << "Low priority handler\n";
}

int main()
{
  boost::asio::io_service io_service;

  handler_priority_queue pri_queue;

  io_service.post(pri_queue.wrap(0, low_priority_handler));
  io_service.post(pri_queue.wrap(100, high_priority_handler));
  io_service.post(pri_queue.wrap(42, middle_priority_handler));

  while (io_service.run_one())
  {
    // The custom invocation hook adds the handlers to the priority queue
    // rather than executing them from within the poll_one() call.
    while (io_service.poll_one())
      ;

    pri_queue.execute_all();
  }

  return 0;
}


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