libcruft-util/thread/spinlock.cpp

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/*
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* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2018-2019 Danny Robson <danny@nerdcruft.net>
*/
#include "spinlock.hpp"
#include "primitive.hpp"
#include "../debug/assert.hpp"
using cruft::thread::spinlock;
///////////////////////////////////////////////////////////////////////////////
spinlock::spinlock ():
held (false)
{ ; }
//-----------------------------------------------------------------------------
spinlock::spinlock (spinlock &&rhs) noexcept:
held (rhs.held.load ())
{ ; }
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//-----------------------------------------------------------------------------
spinlock& spinlock::operator= (spinlock &&rhs) noexcept
{
lock ();
rhs.lock ();
held = rhs.held.load ();
rhs.unlock ();
unlock ();
return *this;
}
///////////////////////////////////////////////////////////////////////////////
void
spinlock::lock (void)
{
do {
bool expected = false;
if (held.compare_exchange_weak (expected, true))
return;
while (held)
pause ();
} while (true);
}
//-----------------------------------------------------------------------------
void
spinlock::unlock (void)
{
CHECK (held);
held = false;
}