Chris@16: // (C) Copyright 2012 Vicente J. Botet Escriba
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: 
Chris@16: #ifndef BOOST_THREAD_TESTABLE_LOCKABLE_HPP
Chris@16: #define BOOST_THREAD_TESTABLE_LOCKABLE_HPP
Chris@16: 
Chris@16: #include <boost/thread/detail/config.hpp>
Chris@16: 
Chris@16: #include <boost/thread/thread_only.hpp>
Chris@16: 
Chris@16: #include <boost/atomic.hpp>
Chris@16: #include <boost/assert.hpp>
Chris@16: 
Chris@16: #include <boost/config/abi_prefix.hpp>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:   /**
Chris@16:    * Based on Associate Mutexes with Data to Prevent Races, By Herb Sutter, May 13, 2010
Chris@16:    * http://www.drdobbs.com/windows/associate-mutexes-with-data-to-prevent-r/224701827?pgno=3
Chris@16:    *
Chris@16:    * Make our mutex testable if it isn't already.
Chris@16:    *
Chris@16:    * Many mutex services (including boost::mutex) don't provide a way to ask,
Chris@16:    * "Do I already hold a lock on this mutex?"
Chris@16:    * Sometimes it is needed to know if a method like is_locked to be available.
Chris@16:    * This wrapper associates an arbitrary lockable type with a thread id that stores the ID of the thread that
Chris@16:    * currently holds the lockable. The thread id initially holds an invalid value that means no threads own the mutex.
Chris@16:    * When we acquire a lock, we set the thread id; and when we release a lock, we reset it back to its default no id state.
Chris@16:    *
Chris@16:    */
Chris@16:   template <typename Lockable>
Chris@16:   class testable_mutex
Chris@16:   {
Chris@16:     Lockable mtx_;
Chris@16:     atomic<thread::id> id_;
Chris@16:   public:
Chris@16:     /// the type of the wrapped lockable
Chris@16:     typedef Lockable lockable_type;
Chris@16: 
Chris@16:     /// Non copyable
Chris@16:     BOOST_THREAD_NO_COPYABLE(testable_mutex)
Chris@16: 
Chris@16:     testable_mutex() : id_(thread::id()) {}
Chris@16: 
Chris@16:     void lock()
Chris@16:     {
Chris@16:       BOOST_ASSERT(! is_locked_by_this_thread());
Chris@16:       mtx_.lock();
Chris@16:       id_ = this_thread::get_id();
Chris@16:     }
Chris@16: 
Chris@16:     void unlock()
Chris@16:     {
Chris@16:       BOOST_ASSERT(is_locked_by_this_thread());
Chris@16:       id_ = thread::id();
Chris@16:       mtx_.unlock();
Chris@16:     }
Chris@16: 
Chris@16:     bool try_lock()
Chris@16:     {
Chris@16:       BOOST_ASSERT(! is_locked_by_this_thread());
Chris@16:       if (mtx_.try_lock())
Chris@16:       {
Chris@16:         id_ = this_thread::get_id();
Chris@16:         return true;
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         return false;
Chris@16:       }
Chris@16:     }
Chris@16: #ifdef BOOST_THREAD_USES_CHRONO
Chris@16:     template <class Rep, class Period>
Chris@16:     bool try_lock_for(const chrono::duration<Rep, Period>& rel_time)
Chris@16:     {
Chris@16:       BOOST_ASSERT(! is_locked_by_this_thread());
Chris@16:       if (mtx_.try_lock_for(rel_time))
Chris@16:       {
Chris@16:         id_ = this_thread::get_id();
Chris@16:         return true;
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         return false;
Chris@16:       }
Chris@16:     }
Chris@16:     template <class Clock, class Duration>
Chris@16:     bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time)
Chris@16:     {
Chris@16:       BOOST_ASSERT(! is_locked_by_this_thread());
Chris@16:       if (mtx_.try_lock_until(abs_time))
Chris@16:       {
Chris@16:         id_ = this_thread::get_id();
Chris@16:         return true;
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         return false;
Chris@16:       }
Chris@16:     }
Chris@16: #endif
Chris@16: 
Chris@16:     bool is_locked_by_this_thread() const
Chris@16:     {
Chris@16:       return this_thread::get_id() == id_;
Chris@16:     }
Chris@16:     bool is_locked() const
Chris@16:     {
Chris@16:       return ! (thread::id() == id_);
Chris@16:     }
Chris@16: 
Chris@16:     thread::id get_id() const
Chris@16:     {
Chris@16:       return id_;
Chris@16:     }
Chris@16: 
Chris@16:     // todo add the shared and upgrade mutex functions
Chris@16:   };
Chris@16: 
Chris@16:   template <typename Lockable>
Chris@16:   struct is_testable_lockable : false_type
Chris@16:   {};
Chris@16: 
Chris@16:   template <typename Lockable>
Chris@16:   struct is_testable_lockable<testable_mutex<Lockable> > : true_type
Chris@16:   {};
Chris@16: 
Chris@16: //  /**
Chris@16: //   * Overloaded function used to check if the mutex is locked when it is testable and do nothing otherwise.
Chris@16: //   *
Chris@16: //   * This function is used usually to assert the pre-condition when the function can only be called when the mutex
Chris@16: //   * must be locked by the current thread.
Chris@16: //   */
Chris@16: //  template <typename Lockable>
Chris@16: //  bool is_locked_by_this_thread(testable_mutex<Lockable> const& mtx)
Chris@16: //  {
Chris@16: //    return mtx.is_locked();
Chris@16: //  }
Chris@16: //  template <typename Lockable>
Chris@16: //  bool is_locked_by_this_thread(Lockable const&)
Chris@16: //  {
Chris@16: //    return true;
Chris@16: //  }
Chris@16: }
Chris@16: 
Chris@16: #include <boost/config/abi_suffix.hpp>
Chris@16: 
Chris@16: #endif // header