github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/fflib/include/ff/functionflow/utilities/hazard_pointer.h (about)

     1  /***********************************************
     2    The MIT License (MIT)
     3  
     4    Copyright (c) 2012 Athrun Arthur <athrunarthur@gmail.com>
     5  
     6    Permission is hereby granted, free of charge, to any person obtaining a copy
     7    of this software and associated documentation files (the "Software"), to deal
     8    in the Software without restriction, including without limitation the rights
     9    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    10    copies of the Software, and to permit persons to whom the Software is
    11    furnished to do so, subject to the following conditions:
    12  
    13    The above copyright notice and this permission notice shall be included in
    14    all copies or substantial portions of the Software.
    15  
    16    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    17    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    18    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    19    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    20    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    21    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    22    THE SOFTWARE.
    23   *************************************************/
    24  #ifndef FF_RUNTIME_HAZARD_POINTER_H_
    25  #define FF_RUNTIME_HAZARD_POINTER_H_
    26  #include "ff/functionflow/runtime/rtcmn.h"
    27  #include <atomic>
    28  #include <mutex>
    29  #ifdef FUNCTION_FLOW_DEBUG
    30  #include <sstream>
    31  #endif
    32  
    33  //! This hazard pointer is specifical for FF!!
    34  namespace ff {
    35  namespace rt {
    36  template <class T>
    37  class hp_owner {
    38   public:
    39    hp_owner() : m_oflag() {
    40  #ifdef CLANG_LLVM
    41      m_pPointers = new std::atomic<T *>[ff::rt::concurrency()];
    42  #else
    43      std::call_once(m_oflag, [this]() {
    44        m_pPointers = new std::atomic<T *>[ff::rt::concurrency()];
    45      });
    46  #endif
    47    }
    48  
    49    ~hp_owner() { delete[] m_pPointers; }
    50  
    51    std::atomic<T *> &get_hazard_pointer() {
    52      return m_pPointers[ff::rt::get_thrd_id()];
    53    }
    54  
    55    //! return true if other thread had it.
    56    bool outstanding_hazard_pointer_for(T *p) {
    57      thread_local static thrd_id_t id = ff::rt::get_thrd_id();
    58      if (!p) return false;
    59      for (int i = 0; i < ff::rt::concurrency(); i++) {
    60        if (i == id) continue;
    61        if (m_pPointers[i].load(std::memory_order_acquire) == p) return true;
    62      }
    63      return false;
    64    }
    65  #ifdef FUNCTION_FLOW_DEBUG
    66    std::string str() {
    67      std::stringstream ss;
    68      for (int i = 0; i < ff::rt::concurrency(); ++i) {
    69        ss << i << ":" << m_pPointers[i].load() << ";";
    70      }
    71      return ss.str();
    72    }
    73  #endif
    74   protected:
    75    std::once_flag m_oflag;
    76    std::atomic<T *> *m_pPointers;
    77  };  // end class hp_owner
    78  
    79  }  // end namespace rt
    80  }  // end namespace ff
    81  
    82  #endif