ceph/src/boost/libs/asio/include/boost/asio/detail/scoped_lock.hpp

   1 //
   2 // detail/scoped_lock.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2016 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.
  36   scoped_lock(Mutex& m, adopt_lock_t)
  37     : mutex_(m),
  38       locked_(true)
  39   {
  40   }
  41
  42   // Constructor acquires the lock.
  43   explicit scoped_lock(Mutex& m)
  44     : mutex_(m)
  45   {
  46     mutex_.lock();
  47     locked_ = true;
  48   }
  49
  50   // Destructor releases the lock.
  51   ~scoped_lock()
  52   {
  53     if (locked_)
  54       mutex_.unlock();
  55   }
  56
  57   // Explicitly acquire the lock.
  58   void lock()
  59   {
  60     if (!locked_)
  61     {
  62       mutex_.lock();
  63       locked_ = true;
  64     }
  65   }
  66
  67   // Explicitly release the lock.
  68   void unlock()
  69   {
  70     if (locked_)
  71     {
  72       mutex_.unlock();
  73       locked_ = false;
  74     }
  75   }
  76
  77   // Test whether the lock is held.
  78   bool locked() const
  79   {
  80     return locked_;
  81   }
  82
  83   // Get the underlying 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