darling-WTF/wtf/ParallelVectorIterator.h
2020-08-28 15:00:43 -04:00

79 lines
2.6 KiB
C++

/*
* Copyright (C) 2015 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/FastMalloc.h>
#include <wtf/Lock.h>
#include <wtf/Noncopyable.h>
namespace WTF {
template<typename VectorType>
class ParallelVectorIterator {
WTF_MAKE_NONCOPYABLE(ParallelVectorIterator);
WTF_MAKE_FAST_ALLOCATED;
public:
ParallelVectorIterator(VectorType& vector, size_t shardSize)
: m_vector(vector)
, m_shardSize(shardSize)
{
}
template<typename Functor>
ALWAYS_INLINE void iterate(const Functor& functor)
{
for (;;) {
size_t begin;
size_t end;
{
LockHolder locker(m_lock);
begin = m_next;
if (begin == m_vector.size())
return;
if (m_vector.size() - begin < m_shardSize)
end = m_vector.size();
else
end = begin + m_shardSize;
RELEASE_ASSERT(end <= m_vector.size());
RELEASE_ASSERT(begin < end);
m_next = end;
}
for (size_t i = begin; i < end; ++i)
functor(m_vector[i]);
}
}
private:
VectorType& m_vector;
Lock m_lock;
size_t m_shardSize;
size_t m_next { 0 };
};
} // namespace WTF
using WTF::ParallelVectorIterator;