ceph/src/boost/boost/fiber/algo/work_stealing.hpp

   1
   2 //          Copyright Oliver Kowalke 2015.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7
   8 #ifndef BOOST_FIBERS_ALGO_WORK_STEALING_H
   9 #define BOOST_FIBERS_ALGO_WORK_STEALING_H
  10
  11 #include <atomic>
  12 #include <condition_variable>
  13 #include <chrono>
  14 #include <cstddef>
  15 #include <cstdint>
  16 #include <mutex>
  17 #include <vector>
  18
  19 #include <boost/config.hpp>
  20 #include <boost/intrusive_ptr.hpp>
  21
  22 #include <boost/fiber/algo/algorithm.hpp>
  23 #include <boost/fiber/context.hpp>
  24 #include <boost/fiber/detail/config.hpp>
  25 #include <boost/fiber/detail/context_spinlock_queue.hpp>
  26 #include <boost/fiber/detail/context_spmc_queue.hpp>
  27 #include <boost/fiber/scheduler.hpp>
  28
  29 #ifdef BOOST_HAS_ABI_HEADERS
  30 #  include BOOST_ABI_PREFIX
  31 #endif
  32
  33 namespace boost {
  34 namespace fibers {
  35 namespace algo {
  36
  37 class work_stealing : public algorithm {
  38 private:
  39     static std::atomic< std::uint32_t >                     counter_;
  40     static std::vector< intrusive_ptr< work_stealing > >    schedulers_;
  41
  42     std::uint32_t                                           id_;
  43     std::uint32_t                                           thread_count_;
  44 #ifdef BOOST_FIBERS_USE_SPMC_QUEUE
  45     detail::context_spmc_queue                              rqueue_{};
  46 #else
  47     detail::context_spinlock_queue                          rqueue_{};
  48 #endif
  49     std::mutex                                              mtx_{};
  50     std::condition_variable                                 cnd_{};
  51     bool                                                    flag_{ false };
  52     bool                                                    suspend_;
  53
  54     static void init_( std::uint32_t, std::vector< intrusive_ptr< work_stealing > > &);
  55
  56 public:
  57     work_stealing( std::uint32_t, bool = false);
  58
  59     work_stealing( work_stealing const&) = delete;
  60     work_stealing( work_stealing &&) = delete;
  61
  62     work_stealing & operator=( work_stealing const&) = delete;
  63     work_stealing & operator=( work_stealing &&) = delete;
  64
  65     virtual void awakened( context *) noexcept;
  66
  67     virtual context * pick_next() noexcept;
  68
  69     virtual context * steal() noexcept {
  70         return rqueue_.steal();
  71     }
  72
  73     virtual bool has_ready_fibers() const noexcept {
  74         return ! rqueue_.empty();
  75     }
  76
  77     virtual void suspend_until( std::chrono::steady_clock::time_point const&) noexcept;
  78
  79     virtual void notify() noexcept;
  80 };
  81
  82 }}}
  83
  84 #ifdef BOOST_HAS_ABI_HEADERS
  85 #  include BOOST_ABI_SUFFIX
  86 #endif
  87
  88 #endif // BOOST_FIBERS_ALGO_WORK_STEALING_H