ceph/src/boost/boost/asio/detail/concurrency_hint.hpp

   1 //
   2 // detail/concurrency_hint.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP
  12 #define BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/config.hpp>
  19 #include <boost/asio/detail/noncopyable.hpp>
  20
  21 // The concurrency hint ID and mask are used to identify when a "well-known"
  22 // concurrency hint value has been passed to the io_context.
  23 #define BOOST_ASIO_CONCURRENCY_HINT_ID 0xA5100000u
  24 #define BOOST_ASIO_CONCURRENCY_HINT_ID_MASK 0xFFFF0000u
  25
  26 // If set, this bit indicates that the scheduler should perform locking.
  27 #define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER 0x1u
  28
  29 // If set, this bit indicates that the reactor should perform locking when
  30 // managing descriptor registrations.
  31 #define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION 0x2u
  32
  33 // If set, this bit indicates that the reactor should perform locking for I/O.
  34 #define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO 0x4u
  35
  36 // Helper macro to determine if we have a special concurrency hint.
  37 #define BOOST_ASIO_CONCURRENCY_HINT_IS_SPECIAL(hint) \
  38   ((static_cast<unsigned>(hint) \
  39     & BOOST_ASIO_CONCURRENCY_HINT_ID_MASK) \
  40       == BOOST_ASIO_CONCURRENCY_HINT_ID)
  41
  42 // Helper macro to determine if locking is enabled for a given facility.
  43 #define BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(facility, hint) \
  44   (((static_cast<unsigned>(hint) \
  45     & (BOOST_ASIO_CONCURRENCY_HINT_ID_MASK \
  46       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_ ## facility)) \
  47         ^ BOOST_ASIO_CONCURRENCY_HINT_ID) != 0)
  48
  49 // This special concurrency hint disables locking in both the scheduler and
  50 // reactor I/O. This hint has the following restrictions:
  51 //
  52 // - Care must be taken to ensure that all operations on the io_context and any
  53 //   of its associated I/O objects (such as sockets and timers) occur in only
  54 //   one thread at a time.
  55 //
  56 // - Asynchronous resolve operations fail with operation_not_supported.
  57 //
  58 // - If a signal_set is used with the io_context, signal_set objects cannot be
  59 //   used with any other io_context in the program.
  60 #define BOOST_ASIO_CONCURRENCY_HINT_UNSAFE \
  61   static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID)
  62
  63 // This special concurrency hint disables locking in the reactor I/O. This hint
  64 // has the following restrictions:
  65 //
  66 // - Care must be taken to ensure that run functions on the io_context, and all
  67 //   operations on the io_context's associated I/O objects (such as sockets and
  68 //   timers), occur in only one thread at a time.
  69 #define BOOST_ASIO_CONCURRENCY_HINT_UNSAFE_IO \
  70   static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID \
  71       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
  72       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION)
  73
  74 // The special concurrency hint provides full thread safety.
  75 #define BOOST_ASIO_CONCURRENCY_HINT_SAFE \
  76   static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID \
  77       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
  78       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION \
  79       | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO)
  80
  81 // This #define may be overridden at compile time to specify a program-wide
  82 // default concurrency hint, used by the zero-argument io_context constructor.
  83 #if !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
  84 # define BOOST_ASIO_CONCURRENCY_HINT_DEFAULT -1
  85 #endif // !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
  86
  87 // This #define may be overridden at compile time to specify a program-wide
  88 // concurrency hint, used by the one-argument io_context constructor when
  89 // passed a value of 1.
  90 #if !defined(BOOST_ASIO_CONCURRENCY_HINT_1)
  91 # define BOOST_ASIO_CONCURRENCY_HINT_1 1
  92 #endif // !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
  93
  94 #endif // BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP