Disparity between Java and C++ versions of putRawTailOrdered()

[denizevrenci]

putRawTailOrdered() in Java is implemented with packTail() with the implementation below:

return ((long)termId << 32) | (termOffset & 0xFFFF_FFFFL);

This has the expected behaviour of 32 termId bits followed by 32 termOffset bits.

While in C++ the same code is implemented with:

((termId << 32) + termOffset)

Where termId is cast to an int64_t implicitly at the function call.

I suppose both termId and termOffset can take negative values. In that case the two implementations produce different results. Also it is possible to get numeric overflow. And, furthermore, left shift of negative integers is undefined in C and C++ even though most implementations pad zeroes.

Compatible C++ implementation is:

inline void putRawTailOrdered(const std::int32_t termId, const std::int32_t termOffset)
{
    aeron::concurrent::atomic::putInt64Ordered(m_tailAddr, termId * ((int64_t(1) << 32) | (int64_t(0xFFFFFFFF) & termOffset);
}