Re: I am confused by Mirage_kv.S.batch

[Mindy <mindy@xxxxxxxxxxxxxxxxxxx>]

On 1/3/22 08:41, Thomas Gazagnaire wrote:

> Hi Mindy :-)
>
> The semantics intend to match the “commit” operation of Irmin, e.g. a commit will ever 
> read what is in the current checkout (and/or what have been written in that commit since the 
> beginning of the transaction). The important bits is that it won’t be able to read writes 
> done by concurrent writers.
Good news - this implementation trivially fulfills this requirement by 
not supporting concurrent writes ;)
> It’s obviously not super easy to implement if you do not have access to a transactional file-system. In 
> that case, I won’t worry too much about it; the only important thing is durability, e.g. the data should be 
> written (and flushed) to disk once the operation has completed. We could probably edit that docstring to remove 
> the sentence about “reading inside a batch”: I don’t think any user of Mirage_kv is relying 
> on this behaviour at the moment.
Thanks for the reply!  I got a few suggestions for how I might implement 
this, but to be honest they don't seem worth the increased complexity to 
me.  I think any users who want to use this functionality should 
definitely be using `irmin` on top of the storage solution of their 
choice, rather than my Mirage_kv.RW implementation.
If the docstring is changed as you describe, I'll implement `batch` by 
just executing the given function; if not, I'll have all batch 
operations error out immediately, so nobody gets the wrong idea.
Thanks!

-Mindy