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+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga 2005-2011. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying file
+// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/interprocess for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifndef BOOST_INTERPROCESS_FILE_LOCK_HPP
+#define BOOST_INTERPROCESS_FILE_LOCK_HPP
+
+#if (defined _MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif
+
+#include <boost/interprocess/detail/config_begin.hpp>
+#include <boost/interprocess/detail/workaround.hpp>
+#include <boost/interprocess/exceptions.hpp>
+#include <boost/interprocess/detail/os_file_functions.hpp>
+#include <boost/interprocess/detail/os_thread_functions.hpp>
+#include <boost/interprocess/detail/posix_time_types_wrk.hpp>
+#include <boost/move/move.hpp>
+
+//!\file
+//!Describes a class that wraps file locking capabilities.
+
+namespace boost {
+namespace interprocess {
+
+
+//!A file lock, is a mutual exclusion utility similar to a mutex using a
+//!file. A file lock has sharable and exclusive locking capabilities and
+//!can be used with scoped_lock and sharable_lock classes.
+//!A file lock can't guarantee synchronization between threads of the same
+//!process so just use file locks to synchronize threads from different processes.
+class file_lock
+{
+ /// @cond
+ //Non-copyable
+ BOOST_MOVABLE_BUT_NOT_COPYABLE(file_lock)
+ /// @endcond
+
+ public:
+ //!Constructs an empty file mapping.
+ //!Does not throw
+ file_lock()
+ : m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
+ {}
+
+ //!Opens a file lock. Throws interprocess_exception if the file does not
+ //!exist or there are no operating system resources.
+ file_lock(const char *name);
+
+ //!Moves the ownership of "moved"'s file mapping object to *this.
+ //!After the call, "moved" does not represent any file mapping object.
+ //!Does not throw
+ file_lock(BOOST_RV_REF(file_lock) moved)
+ : m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
+ { this->swap(moved); }
+
+ //!Moves the ownership of "moved"'s file mapping to *this.
+ //!After the call, "moved" does not represent any file mapping.
+ //!Does not throw
+ file_lock &operator=(BOOST_RV_REF(file_lock) moved)
+ {
+ file_lock tmp(boost::move(moved));
+ this->swap(tmp);
+ return *this;
+ }
+
+ //!Closes a file lock. Does not throw.
+ ~file_lock();
+
+ //!Swaps two file_locks.
+ //!Does not throw.
+ void swap(file_lock &other)
+ {
+ file_handle_t tmp = m_file_hnd;
+ m_file_hnd = other.m_file_hnd;
+ other.m_file_hnd = tmp;
+ }
+
+ //Exclusive locking
+
+ //!Effects: The calling thread tries to obtain exclusive ownership of the mutex,
+ //! and if another thread has exclusive, or sharable ownership of
+ //! the mutex, it waits until it can obtain the ownership.
+ //!Throws: interprocess_exception on error.
+ void lock();
+
+ //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
+ //! without waiting. If no other thread has exclusive, or sharable
+ //! ownership of the mutex this succeeds.
+ //!Returns: If it can acquire exclusive ownership immediately returns true.
+ //! If it has to wait, returns false.
+ //!Throws: interprocess_exception on error.
+ bool try_lock();
+
+ //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
+ //! waiting if necessary until no other thread has exclusive, or sharable
+ //! ownership of the mutex or abs_time is reached.
+ //!Returns: If acquires exclusive ownership, returns true. Otherwise returns false.
+ //!Throws: interprocess_exception on error.
+ bool timed_lock(const boost::posix_time::ptime &abs_time);
+
+ //!Precondition: The thread must have exclusive ownership of the mutex.
+ //!Effects: The calling thread releases the exclusive ownership of the mutex.
+ //!Throws: An exception derived from interprocess_exception on error.
+ void unlock();
+
+ //Sharable locking
+
+ //!Effects: The calling thread tries to obtain sharable ownership of the mutex,
+ //! and if another thread has exclusive ownership of the mutex, waits until
+ //! it can obtain the ownership.
+ //!Throws: interprocess_exception on error.
+ void lock_sharable();
+
+ //!Effects: The calling thread tries to acquire sharable ownership of the mutex
+ //! without waiting. If no other thread has exclusive ownership of the
+ //! mutex this succeeds.
+ //!Returns: If it can acquire sharable ownership immediately returns true. If it
+ //! has to wait, returns false.
+ //!Throws: interprocess_exception on error.
+ bool try_lock_sharable();
+
+ //!Effects: The calling thread tries to acquire sharable ownership of the mutex
+ //! waiting if necessary until no other thread has exclusive ownership of
+ //! the mutex or abs_time is reached.
+ //!Returns: If acquires sharable ownership, returns true. Otherwise returns false.
+ //!Throws: interprocess_exception on error.
+ bool timed_lock_sharable(const boost::posix_time::ptime &abs_time);
+
+ //!Precondition: The thread must have sharable ownership of the mutex.
+ //!Effects: The calling thread releases the sharable ownership of the mutex.
+ //!Throws: An exception derived from interprocess_exception on error.
+ void unlock_sharable();
+ /// @cond
+ private:
+ file_handle_t m_file_hnd;
+
+ bool timed_acquire_file_lock
+ (file_handle_t hnd, bool &acquired, const boost::posix_time::ptime &abs_time)
+ {
+ //Obtain current count and target time
+ boost::posix_time::ptime now = microsec_clock::universal_time();
+ using namespace boost::detail;
+
+ if(now >= abs_time) return false;
+
+ do{
+ if(!ipcdetail::try_acquire_file_lock(hnd, acquired))
+ return false;
+
+ if(acquired)
+ return true;
+ else{
+ now = microsec_clock::universal_time();
+
+ if(now >= abs_time){
+ acquired = false;
+ return true;
+ }
+ // relinquish current time slice
+ ipcdetail::thread_yield();
+ }
+ }while (true);
+ }
+
+ bool timed_acquire_file_lock_sharable
+ (file_handle_t hnd, bool &acquired, const boost::posix_time::ptime &abs_time)
+ {
+ //Obtain current count and target time
+ boost::posix_time::ptime now = microsec_clock::universal_time();
+ using namespace boost::detail;
+
+ if(now >= abs_time) return false;
+
+ do{
+ if(!ipcdetail::try_acquire_file_lock_sharable(hnd, acquired))
+ return false;
+
+ if(acquired)
+ return true;
+ else{
+ now = microsec_clock::universal_time();
+
+ if(now >= abs_time){
+ acquired = false;
+ return true;
+ }
+ // relinquish current time slice
+ ipcdetail::thread_yield();
+ }
+ }while (true);
+ }
+ /// @endcond
+};
+
+inline file_lock::file_lock(const char *name)
+{
+ m_file_hnd = ipcdetail::open_existing_file(name, read_write);
+
+ if(m_file_hnd == ipcdetail::invalid_file()){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+}
+
+inline file_lock::~file_lock()
+{
+ if(m_file_hnd != ipcdetail::invalid_file()){
+ ipcdetail::close_file(m_file_hnd);
+ m_file_hnd = ipcdetail::invalid_file();
+ }
+}
+
+inline void file_lock::lock()
+{
+ if(!ipcdetail::acquire_file_lock(m_file_hnd)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+}
+
+inline bool file_lock::try_lock()
+{
+ bool result;
+ if(!ipcdetail::try_acquire_file_lock(m_file_hnd, result)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+ return result;
+}
+
+inline bool file_lock::timed_lock(const boost::posix_time::ptime &abs_time)
+{
+ if(abs_time == boost::posix_time::pos_infin){
+ this->lock();
+ return true;
+ }
+ bool result;
+ if(!this->timed_acquire_file_lock(m_file_hnd, result, abs_time)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+ return result;
+}
+
+inline void file_lock::unlock()
+{
+ if(!ipcdetail::release_file_lock(m_file_hnd)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+}
+
+inline void file_lock::lock_sharable()
+{
+ if(!ipcdetail::acquire_file_lock_sharable(m_file_hnd)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+}
+
+inline bool file_lock::try_lock_sharable()
+{
+ bool result;
+ if(!ipcdetail::try_acquire_file_lock_sharable(m_file_hnd, result)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+ return result;
+}
+
+inline bool file_lock::timed_lock_sharable(const boost::posix_time::ptime &abs_time)
+{
+ if(abs_time == boost::posix_time::pos_infin){
+ this->lock_sharable();
+ return true;
+ }
+ bool result;
+ if(!this->timed_acquire_file_lock_sharable(m_file_hnd, result, abs_time)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+ return result;
+}
+
+inline void file_lock::unlock_sharable()
+{
+ if(!ipcdetail::release_file_lock_sharable(m_file_hnd)){
+ error_info err(system_error_code());
+ throw interprocess_exception(err);
+ }
+}
+
+} //namespace interprocess {
+} //namespace boost {
+
+#include <boost/interprocess/detail/config_end.hpp>
+
+#endif //BOOST_INTERPROCESS_FILE_LOCK_HPP
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