Re: [Libguestfs] [RFC nbdkit PATCH] multi-conn: New filter

Implement a TODO item of emulating multi-connection consistency via multiple plugin flush calls to allow a client to assume that a flush on a single connection is good enough. This also gives us some fine-tuning over whether to advertise the bit, including some setups that are unsafe but may be useful in timing tests. Testing is interesting: I used the sh plugin to implement a server that intentionally keeps a per-connection cache. Note that this filter assumes that multiple connections will still share the same data (other than caching effects); effects are not guaranteed when trying to mix it with more exotic plugins like info that violate that premise. --- I'm still working on the test; the sh plugin is good enough that it does what I want when playing with it manually, but I still need to write up various scenarios in test-multi-conn.sh to match what I've played with manually. I'm open to feedback on the set of options I've exposed during .config (too many, not enough, better names?) Right now, it is: multi-conn-mode=auto|plugin|disable|emulate|unsafe multi-conn-track-dirty=fast|connection|off