1 //////////////////////////////////////////////////////////////////////////////
2 //
3 // (C) Copyright Ion Gaztanaga 2005-2012. Distributed under the Boost
4 // Software License, Version 1.0. (See accompanying file
5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // See http://www.boost.org/libs/interprocess for documentation.
8 //
9 //////////////////////////////////////////////////////////////////////////////
10
11 #ifndef BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP
12 #define BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP
13
14 #ifndef BOOST_CONFIG_HPP
15 # include <boost/config.hpp>
16 #endif
17 #
18 #if defined(BOOST_HAS_PRAGMA_ONCE)
19 # pragma once
20 #endif
21
22 #include <boost/interprocess/detail/config_begin.hpp>
23 #include <boost/interprocess/detail/workaround.hpp>
24 #include <boost/interprocess/creation_tags.hpp>
25 #include <boost/interprocess/exceptions.hpp>
26 #include <boost/interprocess/permissions.hpp>
27 #include <boost/interprocess/detail/interprocess_tester.hpp>
28 #include <boost/interprocess/detail/posix_time_types_wrk.hpp>
29
30 #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES)
31 #include <boost/interprocess/sync/posix/named_semaphore.hpp>
32 //Experimental...
33 #elif !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && defined (BOOST_INTERPROCESS_WINDOWS)
34 #include <boost/interprocess/sync/windows/named_semaphore.hpp>
35 #define BOOST_INTERPROCESS_USE_WINDOWS
36 #else
37 #include <boost/interprocess/sync/shm/named_semaphore.hpp>
38 #endif
39
40 //!\file
41 //!Describes a named semaphore class for inter-process synchronization
42
43 namespace boost {
44 namespace interprocess {
45
46 //!A semaphore with a global name, so it can be found from different
47 //!processes. Allows several resource sharing patterns and efficient
48 //!acknowledgment mechanisms.
49 class named_semaphore
50 {
51 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
52
53 //Non-copyable
54 named_semaphore();
55 named_semaphore(const named_semaphore &);
56 named_semaphore &operator=(const named_semaphore &);
57 #endif //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
58
59 public:
60 //!Creates a global semaphore with a name, and an initial count.
61 //!If the semaphore can't be created throws interprocess_exception
62 named_semaphore(create_only_t, const char *name, unsigned int initialCount, const permissions &perm = permissions());
63
64 //!Opens or creates a global semaphore with a name, and an initial count.
65 //!If the semaphore is created, this call is equivalent to
66 //!named_semaphore(create_only_t, ...)
67 //!If the semaphore is already created, this call is equivalent to
68 //!named_semaphore(open_only_t, ... )
69 //!and initialCount is ignored.
70 named_semaphore(open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm = permissions());
71
72 //!Opens a global semaphore with a name if that semaphore is previously.
73 //!created. If it is not previously created this function throws
74 //!interprocess_exception.
75 named_semaphore(open_only_t, const char *name);
76
77 //!Destroys *this and indicates that the calling process is finished using
78 //!the resource. The destructor function will deallocate
79 //!any system resources allocated by the system for use by this process for
80 //!this resource. The resource can still be opened again calling
81 //!the open constructor overload. To erase the resource from the system
82 //!use remove().
83 ~named_semaphore();
84
85 //!Increments the semaphore count. If there are processes/threads blocked waiting
86 //!for the semaphore, then one of these processes will return successfully from
87 //!its wait function. If there is an error an interprocess_exception exception is thrown.
88 void post();
89
90 //!Decrements the semaphore. If the semaphore value is not greater than zero,
91 //!then the calling process/thread blocks until it can decrement the counter.
92 //!If there is an error an interprocess_exception exception is thrown.
93 void wait();
94
95 //!Decrements the semaphore if the semaphore's value is greater than zero
96 //!and returns true. If the value is not greater than zero returns false.
97 //!If there is an error an interprocess_exception exception is thrown.
98 bool try_wait();
99
100 //!Decrements the semaphore if the semaphore's value is greater
101 //!than zero and returns true. Otherwise, waits for the semaphore
102 //!to the posted or the timeout expires. If the timeout expires, the
103 //!function returns false. If the semaphore is posted the function
104 //!returns true. If there is an error throws sem_exception
105 bool timed_wait(const boost::posix_time::ptime &abs_time);
106
107 //!Erases a named semaphore from the system.
108 //!Returns false on error. Never throws.
109 static bool remove(const char *name);
110
111 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
112 private:
113 friend class ipcdetail::interprocess_tester;
114 void dont_close_on_destruction();
115
116 #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES)
117 typedef ipcdetail::posix_named_semaphore impl_t;
118 #elif defined(BOOST_INTERPROCESS_USE_WINDOWS)
119 #undef BOOST_INTERPROCESS_USE_WINDOWS
120 typedef ipcdetail::windows_named_semaphore impl_t;
121 #else
122 typedef ipcdetail::shm_named_semaphore impl_t;
123 #endif
124 impl_t m_sem;
125 #endif //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
126 };
127
128 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
129
named_semaphore(create_only_t,const char * name,unsigned int initialCount,const permissions & perm)130 inline named_semaphore::named_semaphore
131 (create_only_t, const char *name, unsigned int initialCount, const permissions &perm)
132 : m_sem(create_only, name, initialCount, perm)
133 {}
134
named_semaphore(open_or_create_t,const char * name,unsigned int initialCount,const permissions & perm)135 inline named_semaphore::named_semaphore
136 (open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm)
137 : m_sem(open_or_create, name, initialCount, perm)
138 {}
139
named_semaphore(open_only_t,const char * name)140 inline named_semaphore::named_semaphore(open_only_t, const char *name)
141 : m_sem(open_only, name)
142 {}
143
~named_semaphore()144 inline named_semaphore::~named_semaphore()
145 {}
146
dont_close_on_destruction()147 inline void named_semaphore::dont_close_on_destruction()
148 { ipcdetail::interprocess_tester::dont_close_on_destruction(m_sem); }
149
wait()150 inline void named_semaphore::wait()
151 { m_sem.wait(); }
152
post()153 inline void named_semaphore::post()
154 { m_sem.post(); }
155
try_wait()156 inline bool named_semaphore::try_wait()
157 { return m_sem.try_wait(); }
158
timed_wait(const boost::posix_time::ptime & abs_time)159 inline bool named_semaphore::timed_wait(const boost::posix_time::ptime &abs_time)
160 { return m_sem.timed_wait(abs_time); }
161
remove(const char * name)162 inline bool named_semaphore::remove(const char *name)
163 { return impl_t::remove(name); }
164
165 #endif //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
166
167 } //namespace interprocess {
168 } //namespace boost {
169
170
171 #include <boost/interprocess/detail/config_end.hpp>
172
173 #endif //BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP
174