95 lines
3.8 KiB
C++
95 lines
3.8 KiB
C++
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//
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// detail/concurrency_hint.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_DETAIL_CONCURRENCY_HINT_HPP
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#define ASIO_DETAIL_CONCURRENCY_HINT_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/config.hpp"
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#include "asio/detail/noncopyable.hpp"
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// The concurrency hint ID and mask are used to identify when a "well-known"
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// concurrency hint value has been passed to the io_context.
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#define ASIO_CONCURRENCY_HINT_ID 0xA5100000u
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#define ASIO_CONCURRENCY_HINT_ID_MASK 0xFFFF0000u
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// If set, this bit indicates that the scheduler should perform locking.
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#define ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER 0x1u
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// If set, this bit indicates that the reactor should perform locking when
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// managing descriptor registrations.
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#define ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION 0x2u
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// If set, this bit indicates that the reactor should perform locking for I/O.
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#define ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO 0x4u
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// Helper macro to determine if we have a special concurrency hint.
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#define ASIO_CONCURRENCY_HINT_IS_SPECIAL(hint) \
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((static_cast<unsigned>(hint) \
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& ASIO_CONCURRENCY_HINT_ID_MASK) \
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== ASIO_CONCURRENCY_HINT_ID)
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// Helper macro to determine if locking is enabled for a given facility.
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#define ASIO_CONCURRENCY_HINT_IS_LOCKING(facility, hint) \
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(((static_cast<unsigned>(hint) \
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& (ASIO_CONCURRENCY_HINT_ID_MASK \
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| ASIO_CONCURRENCY_HINT_LOCKING_ ## facility)) \
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^ ASIO_CONCURRENCY_HINT_ID) != 0)
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// This special concurrency hint disables locking in both the scheduler and
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// reactor I/O. This hint has the following restrictions:
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//
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// - Care must be taken to ensure that all operations on the io_context and any
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// of its associated I/O objects (such as sockets and timers) occur in only
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// one thread at a time.
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//
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// - Asynchronous resolve operations fail with operation_not_supported.
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//
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// - If a signal_set is used with the io_context, signal_set objects cannot be
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// used with any other io_context in the program.
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#define ASIO_CONCURRENCY_HINT_UNSAFE \
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static_cast<int>(ASIO_CONCURRENCY_HINT_ID)
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// This special concurrency hint disables locking in the reactor I/O. This hint
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// has the following restrictions:
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//
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// - Care must be taken to ensure that run functions on the io_context, and all
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// operations on the io_context's associated I/O objects (such as sockets and
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// timers), occur in only one thread at a time.
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#define ASIO_CONCURRENCY_HINT_UNSAFE_IO \
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static_cast<int>(ASIO_CONCURRENCY_HINT_ID \
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| ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
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| ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION)
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// The special concurrency hint provides full thread safety.
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#define ASIO_CONCURRENCY_HINT_SAFE \
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static_cast<int>(ASIO_CONCURRENCY_HINT_ID \
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| ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
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| ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION \
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| ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO)
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// This #define may be overridden at compile time to specify a program-wide
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// default concurrency hint, used by the zero-argument io_context constructor.
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#if !defined(ASIO_CONCURRENCY_HINT_DEFAULT)
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# define ASIO_CONCURRENCY_HINT_DEFAULT -1
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#endif // !defined(ASIO_CONCURRENCY_HINT_DEFAULT)
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// This #define may be overridden at compile time to specify a program-wide
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// concurrency hint, used by the one-argument io_context constructor when
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// passed a value of 1.
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#if !defined(ASIO_CONCURRENCY_HINT_1)
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# define ASIO_CONCURRENCY_HINT_1 1
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#endif // !defined(ASIO_CONCURRENCY_HINT_DEFAULT)
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#endif // ASIO_DETAIL_CONCURRENCY_HINT_HPP
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