Imported existing code

libraries/include/boost/asio/detail/task_io_service.hpp

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+//
+// task_io_service.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2008 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)
+//
+
+#ifndef BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
+#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#if defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+#include <boost/asio/detail/task_io_service_2lock.hpp>
+#else // defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+
+#include <boost/asio/detail/push_options.hpp>
+
+#include <boost/asio/io_service.hpp>
+#include <boost/asio/detail/call_stack.hpp>
+#include <boost/asio/detail/event.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/handler_queue.hpp>
+#include <boost/asio/detail/mutex.hpp>
+#include <boost/asio/detail/service_base.hpp>
+#include <boost/asio/detail/task_io_service_fwd.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Task>
+class task_io_service
+  : public boost::asio::detail::service_base<task_io_service<Task> >
+{
+public:
+  // Constructor.
+  task_io_service(boost::asio::io_service& io_service)
+    : boost::asio::detail::service_base<task_io_service<Task> >(io_service),
+      mutex_(),
+      task_(0),
+      task_interrupted_(true),
+      outstanding_work_(0),
+      stopped_(false),
+      shutdown_(false),
+      first_idle_thread_(0)
+  {
+  }
+
+  void init(size_t /*concurrency_hint*/)
+  {
+  }
+
+  // Destroy all user-defined handler objects owned by the service.
+  void shutdown_service()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    shutdown_ = true;
+    lock.unlock();
+
+    // Destroy handler objects.
+    while (!handler_queue_.empty())
+    {
+      handler_queue::handler* h = handler_queue_.front();
+      handler_queue_.pop();
+      if (h != &task_handler_)
+        h->destroy();
+    }
+
+    // Reset to initial state.
+    task_ = 0;
+  }
+
+  // Initialise the task, if required.
+  void init_task()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    if (!shutdown_ && !task_)
+    {
+      task_ = &use_service<Task>(this->get_io_service());
+      handler_queue_.push(&task_handler_);
+      interrupt_one_idle_thread(lock);
+    }
+  }
+
+  // Run the event loop until interrupted or no more work.
+  size_t run(boost::system::error_code& ec)
+  {
+    typename call_stack<task_io_service>::context ctx(this);
+
+    idle_thread_info this_idle_thread;
+    this_idle_thread.next = 0;
+
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+    size_t n = 0;
+    while (do_one(lock, &this_idle_thread, ec))
+      if (n != (std::numeric_limits<size_t>::max)())
+        ++n;
+    return n;
+  }
+
+  // Run until interrupted or one operation is performed.
+  size_t run_one(boost::system::error_code& ec)
+  {
+    typename call_stack<task_io_service>::context ctx(this);
+
+    idle_thread_info this_idle_thread;
+    this_idle_thread.next = 0;
+
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+    return do_one(lock, &this_idle_thread, ec);
+  }
+
+  // Poll for operations without blocking.
+  size_t poll(boost::system::error_code& ec)
+  {
+    typename call_stack<task_io_service>::context ctx(this);
+
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+    size_t n = 0;
+    while (do_one(lock, 0, ec))
+      if (n != (std::numeric_limits<size_t>::max)())
+        ++n;
+    return n;
+  }
+
+  // Poll for one operation without blocking.
+  size_t poll_one(boost::system::error_code& ec)
+  {
+    typename call_stack<task_io_service>::context ctx(this);
+
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+    return do_one(lock, 0, ec);
+  }
+
+  // Interrupt the event processing loop.
+  void stop()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    stop_all_threads(lock);
+  }
+
+  // Reset in preparation for a subsequent run invocation.
+  void reset()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    stopped_ = false;
+  }
+
+  // Notify that some work has started.
+  void work_started()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    ++outstanding_work_;
+  }
+
+  // Notify that some work has finished.
+  void work_finished()
+  {
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+    if (--outstanding_work_ == 0)
+      stop_all_threads(lock);
+  }
+
+  // Request invocation of the given handler.
+  template <typename Handler>
+  void dispatch(Handler handler)
+  {
+    if (call_stack<task_io_service>::contains(this))
+      boost_asio_handler_invoke_helpers::invoke(handler, &handler);
+    else
+      post(handler);
+  }
+
+  // Request invocation of the given handler and return immediately.
+  template <typename Handler>
+  void post(Handler handler)
+  {
+    // Allocate and construct an operation to wrap the handler.
+    handler_queue::scoped_ptr ptr(handler_queue::wrap(handler));
+
+    boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+    // If the service has been shut down we silently discard the handler.
+    if (shutdown_)
+      return;
+
+    // Add the handler to the end of the queue.
+    handler_queue_.push(ptr.get());
+    ptr.release();
+
+    // An undelivered handler is treated as unfinished work.
+    ++outstanding_work_;
+
+    // Wake up a thread to execute the handler.
+    if (!interrupt_one_idle_thread(lock))
+    {
+      if (!task_interrupted_ && task_)
+      {
+        task_interrupted_ = true;
+        task_->interrupt();
+      }
+    }
+  }
+
+private:
+  struct idle_thread_info;
+
+  size_t do_one(boost::asio::detail::mutex::scoped_lock& lock,
+      idle_thread_info* this_idle_thread, boost::system::error_code& ec)
+  {
+    if (outstanding_work_ == 0 && !stopped_)
+    {
+      stop_all_threads(lock);
+      ec = boost::system::error_code();
+      return 0;
+    }
+
+    bool polling = !this_idle_thread;
+    bool task_has_run = false;
+    while (!stopped_)
+    {
+      if (!handler_queue_.empty())
+      {
+        // Prepare to execute first handler from queue.
+        handler_queue::handler* h = handler_queue_.front();
+        handler_queue_.pop();
+
+        if (h == &task_handler_)
+        {
+          bool more_handlers = (!handler_queue_.empty());
+          task_interrupted_ = more_handlers || polling;
+
+          // If the task has already run and we're polling then we're done.
+          if (task_has_run && polling)
+          {
+            task_interrupted_ = true;
+            handler_queue_.push(&task_handler_);
+            ec = boost::system::error_code();
+            return 0;
+          }
+          task_has_run = true;
+
+          lock.unlock();
+          task_cleanup c(lock, *this);
+
+          // Run the task. May throw an exception. Only block if the handler
+          // queue is empty and we have an idle_thread_info object, otherwise
+          // we want to return as soon as possible.
+          task_->run(!more_handlers && !polling);
+        }
+        else
+        {
+          lock.unlock();
+          handler_cleanup c(lock, *this);
+
+          // Invoke the handler. May throw an exception.
+          h->invoke(); // invoke() deletes the handler object
+
+          ec = boost::system::error_code();
+          return 1;
+        }
+      }
+      else if (this_idle_thread)
+      {
+        // Nothing to run right now, so just wait for work to do.
+        this_idle_thread->next = first_idle_thread_;
+        first_idle_thread_ = this_idle_thread;
+        this_idle_thread->wakeup_event.clear(lock);
+        this_idle_thread->wakeup_event.wait(lock);
+      }
+      else
+      {
+        ec = boost::system::error_code();
+        return 0;
+      }
+    }
+
+    ec = boost::system::error_code();
+    return 0;
+  }
+
+  // Stop the task and all idle threads.
+  void stop_all_threads(
+      boost::asio::detail::mutex::scoped_lock& lock)
+  {
+    stopped_ = true;
+    interrupt_all_idle_threads(lock);
+    if (!task_interrupted_ && task_)
+    {
+      task_interrupted_ = true;
+      task_->interrupt();
+    }
+  }
+
+  // Interrupt a single idle thread. Returns true if a thread was interrupted,
+  // false if no running thread could be found to interrupt.
+  bool interrupt_one_idle_thread(
+      boost::asio::detail::mutex::scoped_lock& lock)
+  {
+    if (first_idle_thread_)
+    {
+      idle_thread_info* idle_thread = first_idle_thread_;
+      first_idle_thread_ = idle_thread->next;
+      idle_thread->next = 0;
+      idle_thread->wakeup_event.signal(lock);
+      return true;
+    }
+    return false;
+  }
+
+  // Interrupt all idle threads.
+  void interrupt_all_idle_threads(
+      boost::asio::detail::mutex::scoped_lock& lock)
+  {
+    while (first_idle_thread_)
+    {
+      idle_thread_info* idle_thread = first_idle_thread_;
+      first_idle_thread_ = idle_thread->next;
+      idle_thread->next = 0;
+      idle_thread->wakeup_event.signal(lock);
+    }
+  }
+
+  // Helper class to perform task-related operations on block exit.
+  class task_cleanup;
+  friend class task_cleanup;
+  class task_cleanup
+  {
+  public:
+    task_cleanup(boost::asio::detail::mutex::scoped_lock& lock,
+        task_io_service& task_io_svc)
+      : lock_(lock),
+        task_io_service_(task_io_svc)
+    {
+    }
+
+    ~task_cleanup()
+    {
+      // Reinsert the task at the end of the handler queue.
+      lock_.lock();
+      task_io_service_.task_interrupted_ = true;
+      task_io_service_.handler_queue_.push(&task_io_service_.task_handler_);
+    }
+
+  private:
+    boost::asio::detail::mutex::scoped_lock& lock_;
+    task_io_service& task_io_service_;
+  };
+
+  // Helper class to perform handler-related operations on block exit.
+  class handler_cleanup;
+  friend class handler_cleanup;
+  class handler_cleanup
+  {
+  public:
+    handler_cleanup(boost::asio::detail::mutex::scoped_lock& lock,
+        task_io_service& task_io_svc)
+      : lock_(lock),
+        task_io_service_(task_io_svc)
+    {
+    }
+
+    ~handler_cleanup()
+    {
+      lock_.lock();
+      if (--task_io_service_.outstanding_work_ == 0)
+        task_io_service_.stop_all_threads(lock_);
+    }
+
+  private:
+    boost::asio::detail::mutex::scoped_lock& lock_;
+    task_io_service& task_io_service_;
+  };
+
+  // Mutex to protect access to internal data.
+  boost::asio::detail::mutex mutex_;
+
+  // The task to be run by this service.
+  Task* task_;
+
+  // Handler object to represent the position of the task in the queue.
+  class task_handler
+    : public handler_queue::handler
+  {
+  public:
+    task_handler()
+      : handler_queue::handler(0, 0)
+    {
+    }
+  } task_handler_;
+
+  // Whether the task has been interrupted.
+  bool task_interrupted_;
+
+  // The count of unfinished work.
+  int outstanding_work_;
+
+  // The queue of handlers that are ready to be delivered.
+  handler_queue handler_queue_;
+
+  // Flag to indicate that the dispatcher has been stopped.
+  bool stopped_;
+
+  // Flag to indicate that the dispatcher has been shut down.
+  bool shutdown_;
+
+  // Structure containing information about an idle thread.
+  struct idle_thread_info
+  {
+    event wakeup_event;
+    idle_thread_info* next;
+  };
+
+  // The number of threads that are currently idle.
+  idle_thread_info* first_idle_thread_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/system/error_code.hpp>
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+
+#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP