1 // 2 // detail/scoped_lock.hpp 3 // ~~~~~~~~~~~~~~~~~~~~~~ 4 // 5 // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com) 6 // 7 // Distributed under the Boost Software License, Version 1.0. (See accompanying 8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 9 // 10 11 #ifndef BOOST_ASIO_DETAIL_SCOPED_LOCK_HPP 12 #define BOOST_ASIO_DETAIL_SCOPED_LOCK_HPP 13 14 #if defined(_MSC_VER) && (_MSC_VER >= 1200) 15 # pragma once 16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) 17 18 #include <boost/asio/detail/noncopyable.hpp> 19 20 #include <boost/asio/detail/push_options.hpp> 21 22 namespace boost { 23 namespace asio { 24 namespace detail { 25 26 // Helper class to lock and unlock a mutex automatically. 27 template <typename Mutex> 28 class scoped_lock 29 : private noncopyable 30 { 31 public: 32 // Tag type used to distinguish constructors. 33 enum adopt_lock_t { adopt_lock }; 34 35 // Constructor adopts a lock that is already held. scoped_lock(Mutex & m,adopt_lock_t)36 scoped_lock(Mutex& m, adopt_lock_t) 37 : mutex_(m), 38 locked_(true) 39 { 40 } 41 42 // Constructor acquires the lock. scoped_lock(Mutex & m)43 explicit scoped_lock(Mutex& m) 44 : mutex_(m) 45 { 46 mutex_.lock(); 47 locked_ = true; 48 } 49 50 // Destructor releases the lock. ~scoped_lock()51 ~scoped_lock() 52 { 53 if (locked_) 54 mutex_.unlock(); 55 } 56 57 // Explicitly acquire the lock. lock()58 void lock() 59 { 60 if (!locked_) 61 { 62 mutex_.lock(); 63 locked_ = true; 64 } 65 } 66 67 // Explicitly release the lock. unlock()68 void unlock() 69 { 70 if (locked_) 71 { 72 mutex_.unlock(); 73 locked_ = false; 74 } 75 } 76 77 // Test whether the lock is held. locked() const78 bool locked() const 79 { 80 return locked_; 81 } 82 83 // Get the underlying mutex. mutex()84 Mutex& mutex() 85 { 86 return mutex_; 87 } 88 89 private: 90 // The underlying mutex. 91 Mutex& mutex_; 92 93 // Whether the mutex is currently locked or unlocked. 94 bool locked_; 95 }; 96 97 } // namespace detail 98 } // namespace asio 99 } // namespace boost 100 101 #include <boost/asio/detail/pop_options.hpp> 102 103 #endif // BOOST_ASIO_DETAIL_SCOPED_LOCK_HPP 104