1 /*
2 * Copyright Andrey Semashev 2007 - 2015.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * http://www.boost.org/LICENSE_1_0.txt)
6 */
7 /*!
8 * \file locking_ptr.hpp
9 * \author Andrey Semashev
10 * \date 15.07.2009
11 *
12 * This header is the Boost.Log library implementation, see the library documentation
13 * at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
14 */
15
16 #ifndef BOOST_LOG_DETAIL_LOCKING_PTR_HPP_INCLUDED_
17 #define BOOST_LOG_DETAIL_LOCKING_PTR_HPP_INCLUDED_
18
19 #include <cstddef>
20 #include <boost/move/core.hpp>
21 #include <boost/smart_ptr/shared_ptr.hpp>
22 #include <boost/thread/lock_options.hpp>
23 #include <boost/log/detail/config.hpp>
24 #include <boost/utility/explicit_operator_bool.hpp>
25 #include <boost/log/detail/header.hpp>
26
27 #ifdef BOOST_HAS_PRAGMA_ONCE
28 #pragma once
29 #endif
30
31 namespace boost {
32
33 BOOST_LOG_OPEN_NAMESPACE
34
35 namespace aux {
36
37 //! A pointer type that locks the backend until it's destroyed
38 template< typename T, typename LockableT >
39 class locking_ptr
40 {
41 typedef locking_ptr this_type;
42 BOOST_COPYABLE_AND_MOVABLE_ALT(this_type)
43
44 public:
45 //! Pointed type
46 typedef T element_type;
47
48 private:
49 //! Lockable type
50 typedef LockableT lockable_type;
51
52 private:
53 //! The pointer to the backend
54 shared_ptr< element_type > m_pElement;
55 //! Reference to the shared lock control object
56 lockable_type* m_pLock;
57
58 public:
59 //! Default constructor
locking_ptr()60 locking_ptr() BOOST_NOEXCEPT : m_pLock(NULL)
61 {
62 }
63 //! Constructor
locking_ptr(shared_ptr<element_type> const & p,lockable_type & l)64 locking_ptr(shared_ptr< element_type > const& p, lockable_type& l) : m_pElement(p), m_pLock(&l)
65 {
66 m_pLock->lock();
67 }
68 //! Constructor
locking_ptr(shared_ptr<element_type> const & p,lockable_type & l,try_to_lock_t const &)69 locking_ptr(shared_ptr< element_type > const& p, lockable_type& l, try_to_lock_t const&) : m_pElement(p), m_pLock(&l)
70 {
71 if (!m_pLock->try_lock())
72 {
73 m_pElement.reset();
74 m_pLock = NULL;
75 }
76 }
77 //! Copy constructor
locking_ptr(locking_ptr const & that)78 locking_ptr(locking_ptr const& that) : m_pElement(that.m_pElement), m_pLock(that.m_pLock)
79 {
80 if (m_pLock)
81 m_pLock->lock();
82 }
83 //! Move constructor
locking_ptr(BOOST_RV_REF (this_type)that)84 locking_ptr(BOOST_RV_REF(this_type) that) BOOST_NOEXCEPT : m_pLock(that.m_pLock)
85 {
86 m_pElement.swap(that.m_pElement);
87 that.m_pLock = NULL;
88 }
89
90 //! Destructor
~locking_ptr()91 ~locking_ptr()
92 {
93 if (m_pLock)
94 m_pLock->unlock();
95 }
96
97 //! Assignment
operator =(locking_ptr that)98 locking_ptr& operator= (locking_ptr that) BOOST_NOEXCEPT
99 {
100 this->swap(that);
101 return *this;
102 }
103
104 //! Indirection
operator ->() const105 element_type* operator-> () const BOOST_NOEXCEPT { return m_pElement.get(); }
106 //! Dereferencing
operator *() const107 element_type& operator* () const BOOST_NOEXCEPT { return *m_pElement; }
108
109 //! Accessor to the raw pointer
get() const110 element_type* get() const BOOST_NOEXCEPT { return m_pElement.get(); }
111
112 //! Checks for null pointer
113 BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()
114 //! Checks for null pointer
115 bool operator! () const BOOST_NOEXCEPT { return !m_pElement; }
116
117 //! Swaps two pointers
swap(locking_ptr & that)118 void swap(locking_ptr& that) BOOST_NOEXCEPT
119 {
120 m_pElement.swap(that.m_pElement);
121 lockable_type* p = m_pLock;
122 m_pLock = that.m_pLock;
123 that.m_pLock = p;
124 }
125 };
126
127 //! Free raw pointer getter to assist generic programming
128 template< typename T, typename LockableT >
get_pointer(locking_ptr<T,LockableT> const & p)129 inline T* get_pointer(locking_ptr< T, LockableT > const& p) BOOST_NOEXCEPT
130 {
131 return p.get();
132 }
133 //! Free swap operation
134 template< typename T, typename LockableT >
swap(locking_ptr<T,LockableT> & left,locking_ptr<T,LockableT> & right)135 inline void swap(locking_ptr< T, LockableT >& left, locking_ptr< T, LockableT >& right) BOOST_NOEXCEPT
136 {
137 left.swap(right);
138 }
139
140 } // namespace aux
141
142 BOOST_LOG_CLOSE_NAMESPACE // namespace log
143
144 } // namespace boost
145
146 #include <boost/log/detail/footer.hpp>
147
148 #endif // BOOST_LOG_DETAIL_LOCKING_PTR_HPP_INCLUDED_
149