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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "ref_counted.h"
#include <cassert>
namespace vespalib {
void
enable_ref_counted::internal_addref(uint32_t cnt) const noexcept
{
// relaxed because:
// the thread obtaining the new reference already has a reference
auto prev = _refs.fetch_add(cnt, std::memory_order_relaxed);
assert(prev > 0);
assert(_guard == MAGIC);
}
void
enable_ref_counted::internal_subref(uint32_t cnt, [[maybe_unused]] uint32_t reserve) const noexcept
{
assert(_guard == MAGIC);
// release because:
// our changes to the object must be visible to the deleter
//
// acquire because:
// we need to see all object changes before deleting it
auto prev = _refs.fetch_sub(cnt, std::memory_order_acq_rel);
assert(prev >= (reserve + cnt));
if (prev == cnt) {
// not using conditional atomic thread fence since thread
// sanitizer does not support it.
delete this;
}
}
uint32_t
enable_ref_counted::count_refs() const noexcept {
auto result = _refs.load(std::memory_order_relaxed);
assert(result > 0);
assert(_guard == MAGIC);
return result;
}
enable_ref_counted::~enable_ref_counted() noexcept
{
// protect against early/double delete and memory overwrites
assert(_refs.load(std::memory_order_relaxed) == 0);
assert(_guard == MAGIC);
_guard = 0;
}
}
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