Line data    Source code

       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_FILE_LOCK_HPP
      12             : #define BOOST_INTERPROCESS_FILE_LOCK_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/exceptions.hpp>
      25             : #include <boost/interprocess/detail/os_file_functions.hpp>
      26             : #include <boost/interprocess/detail/os_thread_functions.hpp>
      27             : #include <boost/interprocess/detail/posix_time_types_wrk.hpp>
      28             : #include <boost/interprocess/sync/detail/common_algorithms.hpp>
      29             : #include <boost/interprocess/sync/detail/locks.hpp>
      30             : #include <boost/move/utility_core.hpp>
      31             : 
      32             : //!\file
      33             : //!Describes a class that wraps file locking capabilities.
      34             : 
      35             : namespace boost {
      36             : namespace interprocess {
      37             : 
      38             : 
      39             : //!A file lock, is a mutual exclusion utility similar to a mutex using a
      40             : //!file. A file lock has sharable and exclusive locking capabilities and
      41             : //!can be used with scoped_lock and sharable_lock classes.
      42             : //!A file lock can't guarantee synchronization between threads of the same
      43             : //!process so just use file locks to synchronize threads from different processes.
      44             : class file_lock
      45             : {
      46             :    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
      47             :    //Non-copyable
      48             :    BOOST_MOVABLE_BUT_NOT_COPYABLE(file_lock)
      49             :    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
      50             : 
      51             :    public:
      52             :    //!Constructs an empty file mapping.
      53             :    //!Does not throw
      54             :    file_lock()
      55             :       :  m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
      56             :    {}
      57             : 
      58             :    //!Opens a file lock. Throws interprocess_exception if the file does not
      59             :    //!exist or there are no operating system resources.
      60             :    file_lock(const char *name);
      61             : 
      62             :    //!Moves the ownership of "moved"'s file mapping object to *this.
      63             :    //!After the call, "moved" does not represent any file mapping object.
      64             :    //!Does not throw
      65             :    file_lock(BOOST_RV_REF(file_lock) moved)
      66             :       :  m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
      67             :    {  this->swap(moved);   }
      68             : 
      69             :    //!Moves the ownership of "moved"'s file mapping to *this.
      70             :    //!After the call, "moved" does not represent any file mapping.
      71             :    //!Does not throw
      72             :    file_lock &operator=(BOOST_RV_REF(file_lock) moved)
      73             :    {
      74             :       file_lock tmp(boost::move(moved));
      75             :       this->swap(tmp);
      76             :       return *this;
      77             :    }
      78             : 
      79             :    //!Closes a file lock. Does not throw.
      80             :    ~file_lock();
      81             : 
      82             :    //!Swaps two file_locks.
      83             :    //!Does not throw.
      84             :    void swap(file_lock &other)
      85             :    {
      86             :       file_handle_t tmp = m_file_hnd;
      87             :       m_file_hnd = other.m_file_hnd;
      88             :       other.m_file_hnd = tmp;
      89             :    }
      90             : 
      91             :    //Exclusive locking
      92             : 
      93             :    //!Effects: The calling thread tries to obtain exclusive ownership of the mutex,
      94             :    //!   and if another thread has exclusive, or sharable ownership of
      95             :    //!   the mutex, it waits until it can obtain the ownership.
      96             :    //!Throws: interprocess_exception on error.
      97             :    void lock();
      98             : 
      99             :    //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
     100             :    //!   without waiting. If no other thread has exclusive, or sharable
     101             :    //!   ownership of the mutex this succeeds.
     102             :    //!Returns: If it can acquire exclusive ownership immediately returns true.
     103             :    //!   If it has to wait, returns false.
     104             :    //!Throws: interprocess_exception on error.
     105             :    bool try_lock();
     106             : 
     107             :    //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
     108             :    //!   waiting if necessary until no other thread has exclusive, or sharable
     109             :    //!   ownership of the mutex or abs_time is reached.
     110             :    //!Returns: If acquires exclusive ownership, returns true. Otherwise returns false.
     111             :    //!Throws: interprocess_exception on error.
     112             :    bool timed_lock(const boost::posix_time::ptime &abs_time);
     113             : 
     114             :    //!Precondition: The thread must have exclusive ownership of the mutex.
     115             :    //!Effects: The calling thread releases the exclusive ownership of the mutex.
     116             :    //!Throws: An exception derived from interprocess_exception on error.
     117             :    void unlock();
     118             : 
     119             :    //Sharable locking
     120             : 
     121             :    //!Effects: The calling thread tries to obtain sharable ownership of the mutex,
     122             :    //!   and if another thread has exclusive ownership of the mutex, waits until
     123             :    //!   it can obtain the ownership.
     124             :    //!Throws: interprocess_exception on error.
     125             :    void lock_sharable();
     126             : 
     127             :    //!Effects: The calling thread tries to acquire sharable ownership of the mutex
     128             :    //!   without waiting. If no other thread has exclusive ownership of the
     129             :    //!   mutex this succeeds.
     130             :    //!Returns: If it can acquire sharable ownership immediately returns true. If it
     131             :    //!   has to wait, returns false.
     132             :    //!Throws: interprocess_exception on error.
     133             :    bool try_lock_sharable();
     134             : 
     135             :    //!Effects: The calling thread tries to acquire sharable ownership of the mutex
     136             :    //!   waiting if necessary until no other thread has exclusive ownership of
     137             :    //!   the mutex or abs_time is reached.
     138             :    //!Returns: If acquires sharable ownership, returns true. Otherwise returns false.
     139             :    //!Throws: interprocess_exception on error.
     140             :    bool timed_lock_sharable(const boost::posix_time::ptime &abs_time);
     141             : 
     142             :    //!Precondition: The thread must have sharable ownership of the mutex.
     143             :    //!Effects: The calling thread releases the sharable ownership of the mutex.
     144             :    //!Throws: An exception derived from interprocess_exception on error.
     145             :    void unlock_sharable();
     146             :    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
     147             :    private:
     148             :    file_handle_t m_file_hnd;
     149             : 
     150             :    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
     151             : };
     152             : 
     153           0 : inline file_lock::file_lock(const char *name)
     154             : {
     155           0 :    m_file_hnd = ipcdetail::open_existing_file(name, read_write);
     156             : 
     157           0 :    if(m_file_hnd == ipcdetail::invalid_file()){
     158           0 :       error_info err(system_error_code());
     159           0 :       throw interprocess_exception(err);
     160             :    }
     161           0 : }
     162             : 
     163           0 : inline file_lock::~file_lock()
     164             : {
     165           0 :    if(m_file_hnd != ipcdetail::invalid_file()){
     166           0 :       ipcdetail::close_file(m_file_hnd);
     167           0 :       m_file_hnd = ipcdetail::invalid_file();
     168             :    }
     169             : }
     170             : 
     171           0 : inline void file_lock::lock()
     172             : {
     173           0 :    if(!ipcdetail::acquire_file_lock(m_file_hnd)){
     174           0 :       error_info err(system_error_code());
     175           0 :       throw interprocess_exception(err);
     176             :    }
     177           0 : }
     178             : 
     179             : inline bool file_lock::try_lock()
     180             : {
     181             :    bool result;
     182             :    if(!ipcdetail::try_acquire_file_lock(m_file_hnd, result)){
     183             :       error_info err(system_error_code());
     184             :       throw interprocess_exception(err);
     185             :    }
     186             :    return result;
     187             : }
     188             : 
     189             : inline bool file_lock::timed_lock(const boost::posix_time::ptime &abs_time)
     190             : {  return ipcdetail::try_based_timed_lock(*this, abs_time);   }
     191             : 
     192           0 : inline void file_lock::unlock()
     193             : {
     194           0 :    if(!ipcdetail::release_file_lock(m_file_hnd)){
     195           0 :       error_info err(system_error_code());
     196           0 :       throw interprocess_exception(err);
     197             :    }
     198           0 : }
     199             : 
     200             : inline void file_lock::lock_sharable()
     201             : {
     202             :    if(!ipcdetail::acquire_file_lock_sharable(m_file_hnd)){
     203             :       error_info err(system_error_code());
     204             :       throw interprocess_exception(err);
     205             :    }
     206             : }
     207             : 
     208             : inline bool file_lock::try_lock_sharable()
     209             : {
     210             :    bool result;
     211             :    if(!ipcdetail::try_acquire_file_lock_sharable(m_file_hnd, result)){
     212             :       error_info err(system_error_code());
     213             :       throw interprocess_exception(err);
     214             :    }
     215             :    return result;
     216             : }
     217             : 
     218             : inline bool file_lock::timed_lock_sharable(const boost::posix_time::ptime &abs_time)
     219             : {
     220             :    ipcdetail::lock_to_sharable<file_lock> lsh(*this);
     221             :    return ipcdetail::try_based_timed_lock(lsh, abs_time);
     222             : }
     223             : 
     224             : inline void file_lock::unlock_sharable()
     225             : {
     226             :    if(!ipcdetail::release_file_lock_sharable(m_file_hnd)){
     227             :       error_info err(system_error_code());
     228             :       throw interprocess_exception(err);
     229             :    }
     230             : }
     231             : 
     232             : }  //namespace interprocess {
     233             : }  //namespace boost {
     234             : 
     235             : #include <boost/interprocess/detail/config_end.hpp>
     236             : 
     237             : #endif   //BOOST_INTERPROCESS_FILE_LOCK_HPP