text: //
  // strand.cpp
  // ~~~~~~~~~~
  //
  // Copyright (c) 2003-2014 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)
  //
  
  // Disable autolinking for unit tests.
  #if !defined(BOOST_ALL_NO_LIB)
  #define BOOST_ALL_NO_LIB 1
  #endif // !defined(BOOST_ALL_NO_LIB)
  
  // Test that header file is self-contained.
  #include <boost/asio/strand.hpp>
  
  #include <sstream>
  #include <boost/asio/io_service.hpp>
  #include <boost/asio/detail/thread.hpp>
  #include "unit_test.hpp"
  
  #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
  # include <boost/asio/deadline_timer.hpp>
  #else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
  # include <boost/asio/steady_timer.hpp>
  #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
  
  #if defined(BOOST_ASIO_HAS_BOOST_BIND)
  # include <boost/bind.hpp>
  #else // defined(BOOST_ASIO_HAS_BOOST_BIND)
  # include <functional>
  #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
  
  using namespace boost::asio;
  typedef io_service::strand strand;
  
  #if defined(BOOST_ASIO_HAS_BOOST_BIND)
  namespace bindns = boost;
  #else // defined(BOOST_ASIO_HAS_BOOST_BIND)
  namespace bindns = std;
  #endif
  
  #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
  typedef deadline_timer timer;
  namespace chronons = boost::posix_time;
  #elif defined(BOOST_ASIO_HAS_STD_CHRONO)
  typedef steady_timer timer;
  namespace chronons = std::chrono;
  #elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
  typedef steady_timer timer;
  namespace chronons = boost::chrono;
  #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
  
  void increment(int* count)
  {
    ++(*count);
  }
  
  void increment_without_lock(strand* s, int* count)
  {
    BOOST_ASIO_CHECK(!s->running_in_this_thread());
  
    int original_count = *count;
  
    s->dispatch(bindns::bind(increment, count));
  
    // No other functions are currently executing through the locking dispatcher,
    // so the previous call to dispatch should have successfully nested.
    BOOST_ASIO_CHECK(*count == original_count + 1);
  }
  
  void increment_with_lock(strand* s, int* count)
  {
    BOOST_ASIO_CHECK(s->running_in_this_thread());
  
    int original_count = *count;
  
    s->dispatch(bindns::bind(increment, count));
  
    // The current function already holds the strand's lock, so the
    // previous call to dispatch should have successfully nested.
    BOOST_ASIO_CHECK(*count == original_count + 1);
  }
  
  void sleep_increment(io_service* ios, int* count)
  {
    timer t(*ios, chronons::seconds(2));
    t.wait();
  
    ++(*count);
  }
  
  void start_sleep_increments(io_service* ios, strand* s, int* count)
  {
    // Give all threads a chance to start.
    timer t(*ios, chronons::seconds(2));
    t.wait();
  
    // Start three increments.
    s->post(bindns::bind(sleep_increment, ios, count));
    s->post(bindns::bind(sleep_increment, ios, count));
    s->post(bindns::bind(sleep_increment, ios, count));
  }
  
  void throw_exception()
  {
    throw 1;
  }
  
  void io_service_run(io_service* ios)
  {
    ios->run();
  }
  
  void strand_test()
  {
    io_service ios;
    strand s(ios);
    int count = 0;
  
    ios.post(bindns::bind(increment_without_lock, &s, &count));
  
    // No handlers can be called until run() is called.
    BOOST_ASIO_CHECK(count == 0);
  
    ios.run();
  
    // The run() call will not return until all work has finished.
    BOOST_ASIO_CHECK(count == 1);
  
    count = 0;
    ios.reset();
    s.post(bindns::bind(increment_with_lock, &s, &count));
  
    // No handlers can be called until run() is called.
    BOOST_ASIO_CHECK(count == 0);
  
    ios.run();
  
    // The run() call will not return until all work has finished.
    BOOST_ASIO_CHECK(count == 1);
  
    count = 0;
    ios.reset();
    ios.post(bindns::bind(start_sleep_increments, &ios, &s, &count));
    boost::asio::detail::thread thread1(bindns::bind(io_service_run, &ios));
    boost::asio::detail::thread thread2(bindns::bind(io_service_run, &ios));
  
    // Check all events run one after another even though there are two threads.
    timer timer1(ios, chronons::seconds(3));
    timer1.wait();
    BOOST_ASIO_CHECK(count == 0);
    timer1.expires_at(timer1.expires_at() + chronons::seconds(2));
    timer1.wait();
    BOOST_ASIO_CHECK(count == 1);
    timer1.expires_at(timer1.expires_at() + chronons::seconds(2));
    timer1.wait();
    BOOST_ASIO_CHECK(count == 2);
  
    thread1.join();
    thread2.join();
  
    // The run() calls will not return until all work has finished.
    BOOST_ASIO_CHECK(count == 3);
  
    count = 0;
    int exception_count = 0;
    ios.reset();
    s.post(throw_exception);
    s.post(bindns::bind(increment, &count));
    s.post(bindns::bind(increment, &count));
    s.post(throw_exception);
    s.post(bindns::bind(increment, &count));
  
    // No handlers can be called until run() is called.
    BOOST_ASIO_CHECK(count == 0);
    BOOST_ASIO_CHECK(exception_count == 0);
  
    for (;;)
    {
      try
      {
        ios.run();
        break;
      }
      catch (int)
      {
        ++exception_count;
      }
    }
  
    // The run() calls will not return until all work has finished.
    BOOST_ASIO_CHECK(count == 3);
    BOOST_ASIO_CHECK(exception_count == 2);
  
    count = 0;
    ios.reset();
  
    // Check for clean shutdown when handlers posted through an orphaned strand
    // are abandoned.
    {
      strand s2(ios);
      s2.post(bindns::bind(increment, &count));
      s2.post(bindns::bind(increment, &count));
      s2.post(bindns::bind(increment, &count));
    }
  
    // No handlers can be called until run() is called.
    BOOST_ASIO_CHECK(count == 0);
  }
  
  BOOST_ASIO_TEST_SUITE
  (
    "strand",
    BOOST_ASIO_TEST_CASE(strand_test)
  )
  