49 lines
1.2 KiB
C
49 lines
1.2 KiB
C
|
#ifndef INTRUSIVE_PTR_H
|
||
|
|
#define INTRUSIVE_PTR_H
|
||
|
|
|
||
|
|
#include "atomic.h"
|
||
|
|
#include "opthelpers.h"
|
||
|
|
|
||
|
|
|
||
|
|
namespace al {
|
||
|
|
|
||
|
|
template<typename T>
|
||
|
|
class intrusive_ref {
|
||
|
|
RefCount mRef{1u};
|
||
|
|
|
||
|
|
public:
|
||
|
|
unsigned int add_ref() noexcept { return IncrementRef(mRef); }
|
||
|
|
unsigned int release() noexcept
|
||
|
|
{
|
||
|
|
auto ref = DecrementRef(mRef);
|
||
|
|
if(UNLIKELY(ref == 0))
|
||
|
|
delete static_cast<T*>(this);
|
||
|
|
return ref;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Release only if doing so would not bring the object to 0 references and
|
||
|
|
* delete it. Returns false if the object could not be released.
|
||
|
|
*
|
||
|
|
* NOTE: The caller is responsible for handling a failed release, as it
|
||
|
|
* means the object has no other references and needs to be be deleted
|
||
|
|
* somehow.
|
||
|
|
*/
|
||
|
|
bool releaseIfNoDelete() noexcept
|
||
|
|
{
|
||
|
|
auto val = mRef.load(std::memory_order_acquire);
|
||
|
|
while(val > 1 && !mRef.compare_exchange_strong(val, val-1, std::memory_order_acq_rel))
|
||
|
|
{
|
||
|
|
/* val was updated with the current value on failure, so just try
|
||
|
|
* again.
|
||
|
|
*/
|
||
|
|
}
|
||
|
|
|
||
|
|
return val >= 2;
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace al
|
||
|
|
|
||
|
|
#endif /* INTRUSIVE_PTR_H */
|