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84 lines
2.5 KiB
C++
84 lines
2.5 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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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_ATOMICCOUNTER_H_INCLUDED
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#define BEAST_ATOMICCOUNTER_H_INCLUDED
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/*============================================================================*/
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/**
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A thread safe usage counter.
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This provides a simplified interface to an atomic integer suitable for
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measuring reference or usage counts. The counter is signaled when the
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count is non zero.
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@ingroup beast_core
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*/
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class BEAST_API AtomicCounter
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{
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public:
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/** Create a new counter.
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@param initialValue An optional starting usage count (default is 0).
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*/
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AtomicCounter (int initialValue = 0) noexcept
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:
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m_value (initialValue)
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{
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}
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/** Increment the usage count.
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@return `true` if the counter became signaled.
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*/
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inline bool addref () noexcept
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{
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return (++m_value) == 1;
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}
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/** Decrements the usage count.
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@return `true` if the counter became non-signaled.
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*/
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inline bool release () noexcept
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{
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// Unfortunately, AllocatorWithoutTLS breaks this assert
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//bassert (isSignaled ());
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return (--m_value) == 0;
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}
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/** Determine if the counter is signaled.
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Note that another thread can cause the counter to become reset after
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this function returns true.
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@return `true` if the counter was signaled.
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*/
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inline bool isSignaled () const noexcept
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{
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return m_value.get () > 0;
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}
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private:
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Atomic <int> m_value;
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};
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#endif
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