Do not append to file when size of m_dic is only one and new key is the same with that one in m_dic

[kaitian521]

In some circumstances, I store only one key in MMKV.

For example, I put user's latest edit content to MMKV, giving me a chance to restore them for next startup of My App

mmkv.encode("latest_edit_content", "long content");

At present, key-value will be appended to the file, then a rewrite will be called when being full

I think maybe there is a very small improvement for this:

if (m_dic.size() == 1 && m_dic.find(key) != m_dic.end()) {
     // no appending, just reset m_actualSize, write key-value, then recalculate crc for metaFile
}

Thank you !

[lingol]

This could work, but only in SINGLE_PROCESS_MODE. In multi-process mode, MMKV relys on the fact that m_actualSize will increase whenever there's update made by others. Checkout MMKV::checkLoadData() & MMKV::partialLoadFromFile().

[kaitian521]

Thanks for your reminds. So it would work only if m_isInterProcess is false.
But honest to say, maybe MMKV_SINGLE_PROCESS is used even more compared with MMKV_MULTI_PROCESS.

I can give a pr if possible（Actually my team use MMKV heavily, feel sorry to annoy you many times 😭）

[lingol]

You are welcome to make improvements. There's absolutely no reason to feel sorry for making it better.