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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "allocchunk.h"
namespace vespamalloc {
void AFListBase::linkInList(AtomicHeadPtr & head, AFListBase * list) noexcept
{
AFListBase * tail;
for (tail = list; tail->_next != nullptr ;tail = tail->_next) { }
linkIn(head, list, tail);
}
void AFListBase::linkIn(AtomicHeadPtr & head, AFListBase * csl, AFListBase * tail) noexcept
{
HeadPtr oldHead = head.load(std::memory_order_relaxed);
HeadPtr newHead(csl, oldHead._tag + 1);
tail->_next = static_cast<AFListBase *>(oldHead._ptr);
while ( __builtin_expect(! head.compare_exchange_weak(oldHead, newHead, std::memory_order_release, std::memory_order_relaxed), false) ) {
newHead._tag = oldHead._tag + 1;
tail->_next = static_cast<AFListBase *>(oldHead._ptr);
}
}
AFListBase * AFListBase::linkOut(AtomicHeadPtr & head) noexcept
{
HeadPtr oldHead = head.load(std::memory_order_relaxed);
auto *csl = static_cast<AFListBase *>(oldHead._ptr);
if (csl == nullptr) {
return nullptr;
}
HeadPtr newHead(csl->_next, oldHead._tag + 1);
while ( __builtin_expect(! head.compare_exchange_weak(oldHead, newHead, std::memory_order_acquire, std::memory_order_relaxed), false) ) {
csl = static_cast<AFListBase *>(oldHead._ptr);
if (csl == nullptr) {
return nullptr;
}
newHead._ptr = csl->_next;
newHead._tag = oldHead._tag + 1;
}
csl->_next = nullptr;
return csl;
}
}
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