[Qemu-devel] Re: [PATCH 07/18] Introduce fault tolerant VM transaction QEMUFile and ft_mode.

[Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>]

Juan Quintela wrote:
> Yoshiaki Tamura<tamura.yoshiaki@lab.ntt.co.jp>  wrote:
>> This code implements VM transaction protocol.  Like buffered_file, it
>> sits between savevm and migration layer.  With this architecture, VM
>> transaction protocol is implemented mostly independent from other
>> existing code.
>
> Could you explain what is the difference with buffered_file.c?
> I am fixing problems on buffered_file, and having something that copies
> lot of code from there makes me nervous.

The objective is different:

buffered_file buffers data for transmission control.
ft_trans_file adds headers to the stream, and controls the transaction between 
sender and receiver.

Although ft_trans_file sometimes buffers date, but it's not the main objective.
If you're fixing the problems on buffered_file, I'll keep eyes on them.

>> +typedef ssize_t (FtTransPutBufferFunc)(void *opaque, const void *data, size_t size);
>
> Can we get some sharing here?
> typedef ssize_t (BufferedPutFunc)(void *opaque, const void *data, size_t size);
>
> There are not so much types for a write function that the 1st element is
> one opaque :p

You're right, but I want to keep ft_trans_file independent of buffered_file at 
this point.  Once Kemari gets merged, I'm happy to work with you to fix the 
problems on buffered_file and ft_trans_file, and refactoring them.

Thanks,

Yoshi

>
> Later, Juan.
>