Files
neon/compute_tools/src/lib.rs
Alexey Kondratov 17d6c568bf Implement live reconfiguration in the compute_ctl
Accept spec in JSON format and request compute reconfiguration from
the configurator thread. If anything goes wrong after we set the
compute state to `ConfigurationPending` and / or sent spec to the
configurator thread, we basically leave compute in the potentially
wrong state. That said, it's control-plane's responsibility to
watch compute state after reconfiguration request and to clean
restart it in case of errors.

It still lacks ability of starting up without spec and some validations,
i.e. that live reconfiguration should be only available with
`--compute-id` and `--control-plane-uri` options.

Otherwise, it works fine and could be tested by running `compute_ctl`
locally, then sending it a new spec:
```shell
curl -d "$(cat ./compute-spec-new.json)" http://localhost:3080/spec
```

We have one configurator thread and async http server, so generally we
have single consumer - multiple producers pattern here. That's why we
use `mpsc` channel, not `tokio::sync::watch`. Actually, concurrency of
producers is limited to one due to code logic, but we still need an
ability to potentially pass `Sender` to several threads.

Next, we use async `hyper` + `tokio` http server, but all the other code
is completely synchronous. So we need to send data from async to sync,
that's why we use `mpsc::unbounded_channel` here, not `mpsc::channel`.
It doesn't make much sense to rewrite all code to async now, but we can
consider doing this in the future.

I think that a combination of `Mutex` and `CondVar` would work just fine
too, but as we already have `tokio`, I decided to try something from it.
2023-04-04 16:50:57 +02:00

16 lines
283 B
Rust

//!
//! Various tools and helpers to handle cluster / compute node (Postgres)
//! configuration.
//!
pub mod checker;
pub mod config;
pub mod configurator;
pub mod http;
#[macro_use]
pub mod logger;
pub mod compute;
pub mod monitor;
pub mod params;
pub mod pg_helpers;
pub mod spec;