pgcat/src/pool.rs

use async_trait::async_trait;
use bb8::{ManageConnection, PooledConnection};

use crate::errors::Error;
use crate::server::Server;
use crate::ClientServerMap;

pub struct ServerPool {
    host: String,
    port: String,
    user: String,
    password: String,
    database: String,
    client_server_map: ClientServerMap,
}

impl ServerPool {
    pub fn new(
        host: &str,
        port: &str,
        user: &str,
        password: &str,
        database: &str,
        client_server_map: ClientServerMap,
    ) -> ServerPool {
        ServerPool {
            host: host.to_string(),
            port: port.to_string(),
            user: user.to_string(),
            password: password.to_string(),
            database: database.to_string(),
            client_server_map: client_server_map,
        }
    }
}

#[async_trait]
impl ManageConnection for ServerPool {
    type Connection = Server;
    type Error = Error;

    /// Attempts to create a new connection.
    async fn connect(&self) -> Result<Self::Connection, Self::Error> {
        println!(">> Getting connetion from pool");

        //
        // TODO: Pick a random connection from a replica pool here.
        //
        Ok(Server::startup(
            &self.host,
            &self.port,
            &self.user,
            &self.password,
            &self.database,
            self.client_server_map.clone(),
        )
        .await?)
    }

    /// Determines if the connection is still connected to the database.
    async fn is_valid(&self, conn: &mut PooledConnection<'_, Self>) -> Result<(), Self::Error> {
        let server = &mut *conn;

        // Client disconnected before cleaning up
        if server.in_transaction() {
            return Err(Error::DirtyServer);
        }

        // If this fails, the connection will be closed and another will be grabbed from the pool quietly :-).
        // Failover, step 1, complete.
        match tokio::time::timeout(
            tokio::time::Duration::from_millis(1000),
            server.query("SELECT 1"),
        )
        .await
        {
            Ok(_) => Ok(()),
            Err(_err) => Err(Error::ServerTimeout),
        }
    }

    /// Synchronously determine if the connection is no longer usable, if possible.
    fn has_broken(&self, conn: &mut Self::Connection) -> bool {
        conn.is_bad()
    }
}