| // |
| // detail/conditionally_enabled_mutex.hpp |
| // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2016 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 ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP |
| #define ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| # pragma once |
| #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
| |
| #include "asio/detail/config.hpp" |
| #include "asio/detail/mutex.hpp" |
| #include "asio/detail/noncopyable.hpp" |
| #include "asio/detail/scoped_lock.hpp" |
| |
| #include "asio/detail/push_options.hpp" |
| |
| namespace asio { |
| namespace detail { |
| |
| // Mutex adapter used to conditionally enable or disable locking. |
| class conditionally_enabled_mutex |
| : private noncopyable |
| { |
| public: |
| // Helper class to lock and unlock a mutex automatically. |
| class scoped_lock |
| : private noncopyable |
| { |
| public: |
| // Tag type used to distinguish constructors. |
| enum adopt_lock_t { adopt_lock }; |
| |
| // Constructor adopts a lock that is already held. |
| scoped_lock(conditionally_enabled_mutex& m, adopt_lock_t) |
| : mutex_(m), |
| locked_(m.enabled_) |
| { |
| } |
| |
| // Constructor acquires the lock. |
| explicit scoped_lock(conditionally_enabled_mutex& m) |
| : mutex_(m) |
| { |
| if (m.enabled_) |
| { |
| mutex_.mutex_.lock(); |
| locked_ = true; |
| } |
| else |
| locked_ = false; |
| } |
| |
| // Destructor releases the lock. |
| ~scoped_lock() |
| { |
| if (locked_) |
| mutex_.mutex_.unlock(); |
| } |
| |
| // Explicitly acquire the lock. |
| void lock() |
| { |
| if (mutex_.enabled_ && !locked_) |
| { |
| mutex_.mutex_.lock(); |
| locked_ = true; |
| } |
| } |
| |
| // Explicitly release the lock. |
| void unlock() |
| { |
| if (locked_) |
| { |
| mutex_.unlock(); |
| locked_ = false; |
| } |
| } |
| |
| // Test whether the lock is held. |
| bool locked() const |
| { |
| return locked_; |
| } |
| |
| // Get the underlying mutex. |
| asio::detail::mutex& mutex() |
| { |
| return mutex_.mutex_; |
| } |
| |
| private: |
| friend class conditionally_enabled_event; |
| conditionally_enabled_mutex& mutex_; |
| bool locked_; |
| }; |
| |
| // Constructor. |
| explicit conditionally_enabled_mutex(bool enabled) |
| : enabled_(enabled) |
| { |
| } |
| |
| // Destructor. |
| ~conditionally_enabled_mutex() |
| { |
| } |
| |
| // Determine whether locking is enabled. |
| bool enabled() const |
| { |
| return enabled_; |
| } |
| |
| // Lock the mutex. |
| void lock() |
| { |
| if (enabled_) |
| mutex_.lock(); |
| } |
| |
| // Unlock the mutex. |
| void unlock() |
| { |
| if (enabled_) |
| mutex_.unlock(); |
| } |
| |
| private: |
| friend class scoped_lock; |
| friend class conditionally_enabled_event; |
| asio::detail::mutex mutex_; |
| const bool enabled_; |
| }; |
| |
| } // namespace detail |
| } // namespace asio |
| |
| #include "asio/detail/pop_options.hpp" |
| |
| #endif // ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP |