ceph/src/boost/boost/interprocess/sync/detail/common_algorithms.hpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2012-2013. 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_SYNC_DETAIL_COMMON_ALGORITHMS_HPP
  12 #define BOOST_INTERPROCESS_SYNC_DETAIL_COMMON_ALGORITHMS_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
  25 #include <boost/interprocess/sync/spin/wait.hpp>
  26
  27 namespace boost {
  28 namespace interprocess {
  29 namespace ipcdetail {
  30
  31 template<class MutexType>
  32 bool try_based_timed_lock(MutexType &m, const boost::posix_time::ptime &abs_time)
  33 {
  34    //Same as lock()
  35    if(abs_time == boost::posix_time::pos_infin){
  36       m.lock();
  37       return true;
  38    }
  39    //Always try to lock to achieve POSIX guarantees:
  40    // "Under no circumstance shall the function fail with a timeout if the mutex
  41    //  can be locked immediately. The validity of the abs_timeout parameter need not
  42    //  be checked if the mutex can be locked immediately."
  43    else if(m.try_lock()){
  44       return true;
  45    }
  46    else{
  47       spin_wait swait;
  48       while(microsec_clock::universal_time() < abs_time){
  49          if(m.try_lock()){
  50             return true;
  51          }
  52          swait.yield();
  53       }
  54       return false;
  55    }
  56 }
  57
  58 template<class MutexType>
  59 void try_based_lock(MutexType &m)
  60 {
  61    if(!m.try_lock()){
  62       spin_wait swait;
  63       do{
  64          if(m.try_lock()){
  65             break;
  66          }
  67          else{
  68             swait.yield();
  69          }
  70       }
  71       while(1);
  72    }
  73 }
  74
  75 }  //namespace ipcdetail
  76 }  //namespace interprocess
  77 }  //namespace boost
  78
  79 #include <boost/interprocess/detail/config_end.hpp>
  80
  81 #endif   //BOOST_INTERPROCESS_SYNC_DETAIL_COMMON_ALGORITHMS_HPP