We currently allow increasing the max pool with:

/// Increase the number of connections the each server's pool can hold.
/// By default tools are allowed 10 concurrent connections.
pub fn pool_max(mut self, pool_max: usize) -> Self {
    self.pool_max = pool_max;
    self
}

But that only applies to sub-pools created after this is set. Presumably it should be part of a builder, so that once the WikiPool is constructed, the options don't change.

legoktm opened https://gitlab.wikimedia.org/repos/mwbot-rs/toolforge/-/merge_requests/3

pool: Add a builder so connection options are immutable

legoktm merged https://gitlab.wikimedia.org/repos/mwbot-rs/toolforge/-/merge_requests/3

pool: Add a builder so connection options are immutable

Currently the sub-pools are stored in RwLock<HashMap<usize, Pool>>, which requires locking upon creation and access (and currently has a race condition). But! There are only 8 specific servers. We could just have one member variable per pool:

match slice {
    1 => self.pool_s1,
    2 => self.pool_s2,
    ...
}

The downside is that when s9 & s10 are added, we'll have to add more member variables, requiring new releases and recompilation.

/// Get the pool for the corresponding slice, creating it if necessary.
async fn pool(&self, slice: usize) -> &Pool {
    let cell = match slice {
        1 => &self.pool_s1,
        2 => &self.pool_s2,
        num => panic!("Unknown slice s{}, please report a bug in the toolforge crate", num)
    };
    cell.get_or_init(|| async {
        Pool::new(self.connection_string(slice).as_str())
    }).await

Ends up being much cleaner, with a big exception of the panic.

I asked @Ladsgroup, who said we're likely a couple of years away from adding a new sX slice. If we add in some headroom, like up to s14 or s15 that would be "good for at least one decade or more". That's an acceptable level of future-proofing for me.

legoktm opened https://gitlab.wikimedia.org/repos/mwbot-rs/toolforge/-/merge_requests/4

Store pools as member variables instead of a RwLock<HashMap>

legoktm merged https://gitlab.wikimedia.org/repos/mwbot-rs/toolforge/-/merge_requests/4

Store pools as member variables instead of a RwLock<HashMap>