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d4a5c0353d
* New maybe_const_t alias for maybe_const * New asio::enable_wait_for_async for safe cleanup * New asio::memory_buffer, a managed boost::asio compatible buffer * shared_handler improvements: - Can be 'empty' (no stored handler). - Default constructible as 'empty'. - Safe evaluation in bool contexts, false==empty * Fix is_call_possible metafunction: - Works on empty argument lists - Works with reference types * Replace SafeBool idiom with C++11 explicit operator bool * Move IPAddress function definitions to the header * Move cyclic_iterator to container/ * Remove unused BufferType * Remove obsolete classes: - NamedPipe - ReadWriteLock - ScopedReadLock - ScopedWriteLock - LockGuard
99 lines
3.4 KiB
C++
99 lines
3.4 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of Beast: https://github.com/vinniefalco/Beast
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Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
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Portions of this file are from JUCE.
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Copyright (c) 2013 - Raw Material Software Ltd.
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Please visit http://www.juce.com
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#ifndef BEAST_THREADS_SPINLOCK_H_INCLUDED
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#define BEAST_THREADS_SPINLOCK_H_INCLUDED
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#include "../Atomic.h"
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#include "UnlockGuard.h"
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#include <mutex>
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namespace beast {
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//==============================================================================
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/**
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A simple spin-lock class that can be used as a simple, low-overhead mutex for
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uncontended situations.
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Note that unlike a CriticalSection, this type of lock is not re-entrant, and may
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be less efficient when used it a highly contended situation, but it's very small and
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requires almost no initialisation.
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It's most appropriate for simple situations where you're only going to hold the
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lock for a very brief time.
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@see CriticalSection
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*/
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class BEAST_API SpinLock : public Uncopyable
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{
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public:
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/** Provides the type of scoped lock to use for locking a SpinLock. */
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typedef std::lock_guard <SpinLock> ScopedLockType;
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/** Provides the type of scoped unlocker to use with a SpinLock. */
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typedef UnlockGuard <SpinLock> ScopedUnlockType;
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inline SpinLock() noexcept {}
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inline ~SpinLock() noexcept {}
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/** Acquires the lock.
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This will block until the lock has been successfully acquired by this thread.
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Note that a SpinLock is NOT re-entrant, and is not smart enough to know whether the
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caller thread already has the lock - so if a thread tries to acquire a lock that it
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already holds, this method will never return!
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It's strongly recommended that you never call this method directly - instead use the
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ScopedLockType class to manage the locking using an RAII pattern instead.
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*/
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void enter() const noexcept;
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/** Attempts to acquire the lock, returning true if this was successful. */
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inline bool tryEnter() const noexcept
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{
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return m_lock.compareAndSetBool (1, 0);
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}
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/** Releases the lock. */
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inline void exit() const noexcept
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{
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bassert (m_lock.value == 1); // Agh! Releasing a lock that isn't currently held!
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m_lock = 0;
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}
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void lock () const
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{ enter(); }
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void unlock () const
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{ exit(); }
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bool try_lock () const
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{ return tryEnter(); }
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private:
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//==============================================================================
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mutable Atomic<int> m_lock;
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};
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}
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#endif
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