ceph/src/boost/libs/pool/include/boost/pool/detail/guard.hpp

   1 // Copyright (C) 2000 Stephen Cleary
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org for updates, documentation, and revision history.
   8
   9 #ifndef BOOST_POOL_GUARD_HPP
  10 #define BOOST_POOL_GUARD_HPP
  11
  12 /*!
  13   \file
  14   \brief Extremely Light-Weight guard class.
  15   \details Auto-lock/unlock-er
  16   detail/guard.hpp provides a type guard<Mutex>
  17   that allows scoped access to the Mutex's locking and unlocking operations.
  18   It is used to ensure that a Mutex is unlocked, even if an exception is thrown.
  19 */
  20
  21 namespace boost {
  22
  23 namespace details {
  24 namespace pool {
  25
  26 template <typename Mutex> //!< \tparam Mutex (platform-specific) mutex class.
  27 class guard
  28 { //! Locks the mutex, binding guard<Mutex> to Mutex.
  29         /*! Example:
  30         Given a (platform-specific) mutex class, we can wrap code as follows:
  31
  32         extern mutex global_lock;
  33
  34         static void f()
  35         {
  36                 boost::details::pool::guard<mutex> g(global_lock);
  37                 // g's constructor locks "global_lock"
  38
  39                 ... // do anything:
  40                                 //   throw exceptions
  41                                 //   return
  42                                 //   or just fall through
  43         } // g's destructor unlocks "global_lock"
  44         */
  45   private:
  46     Mutex & mtx;
  47
  48     guard(const guard &); //!< Guards the mutex, ensuring unlocked on destruction, even if exception is thrown.
  49     void operator=(const guard &);
  50
  51   public:
  52     explicit guard(Mutex & nmtx)
  53     :mtx(nmtx)
  54     { //! Locks the mutex of the guard class.
  55                         mtx.lock();
  56                 }
  57
  58     ~guard()
  59     { //! destructor unlocks the mutex of the guard class.
  60                         mtx.unlock();
  61                 }
  62 }; // class guard
  63
  64 } // namespace pool
  65 } // namespace details
  66
  67 } // namespace boost
  68
  69 #endif