pgcat/src/admin.rs

use crate::pool::BanReason;
use crate::stats::pool::PoolStats;
use bytes::{Buf, BufMut, BytesMut};
use log::{error, info, trace};
use nix::sys::signal::{self, Signal};
use nix::unistd::Pid;
use std::collections::HashMap;
/// Admin database.
use std::sync::atomic::Ordering;
use std::time::{SystemTime, UNIX_EPOCH};
use tokio::time::Instant;

use crate::config::{get_config, reload_config, VERSION};
use crate::errors::Error;
use crate::messages::*;
use crate::pool::ClientServerMap;
use crate::pool::{get_all_pools, get_pool};
use crate::stats::{get_client_stats, get_server_stats, ClientState, ServerState};

pub fn generate_server_info_for_admin() -> BytesMut {
    let mut server_info = BytesMut::new();

    server_info.put(server_parameter_message("application_name", ""));
    server_info.put(server_parameter_message("client_encoding", "UTF8"));
    server_info.put(server_parameter_message("server_encoding", "UTF8"));
    server_info.put(server_parameter_message("server_version", VERSION));
    server_info.put(server_parameter_message("DateStyle", "ISO, MDY"));

    server_info
}

/// Handle admin client.
pub async fn handle_admin<T>(
    stream: &mut T,
    mut query: BytesMut,
    client_server_map: ClientServerMap,
) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let code = query.get_u8() as char;

    if code != 'Q' {
        return Err(Error::ProtocolSyncError(format!(
            "Invalid code, expected 'Q' but got '{}'",
            code
        )));
    }

    let len = query.get_i32() as usize;
    let query = String::from_utf8_lossy(&query[..len - 5]).to_string();

    trace!("Admin query: {}", query);

    let query_parts: Vec<&str> = query.trim_end_matches(';').split_whitespace().collect();

    match query_parts[0].to_ascii_uppercase().as_str() {
        "BAN" => {
            trace!("BAN");
            ban(stream, query_parts).await
        }
        "UNBAN" => {
            trace!("UNBAN");
            unban(stream, query_parts).await
        }
        "RELOAD" => {
            trace!("RELOAD");
            reload(stream, client_server_map).await
        }
        "SET" => {
            trace!("SET");
            ignore_set(stream).await
        }
        "PAUSE" => {
            trace!("PAUSE");
            pause(stream, query_parts[1]).await
        }
        "RESUME" => {
            trace!("RESUME");
            resume(stream, query_parts[1]).await
        }
        "SHUTDOWN" => {
            trace!("SHUTDOWN");
            shutdown(stream).await
        }
        "SHOW" => match query_parts[1].to_ascii_uppercase().as_str() {
            "HELP" => {
                trace!("SHOW HELP");
                show_help(stream).await
            }
            "BANS" => {
                trace!("SHOW BANS");
                show_bans(stream).await
            }
            "CONFIG" => {
                trace!("SHOW CONFIG");
                show_config(stream).await
            }
            "DATABASES" => {
                trace!("SHOW DATABASES");
                show_databases(stream).await
            }
            "LISTS" => {
                trace!("SHOW LISTS");
                show_lists(stream).await
            }
            "POOLS" => {
                trace!("SHOW POOLS");
                show_pools(stream).await
            }
            "CLIENTS" => {
                trace!("SHOW CLIENTS");
                show_clients(stream).await
            }
            "SERVERS" => {
                trace!("SHOW SERVERS");
                show_servers(stream).await
            }
            "STATS" => {
                trace!("SHOW STATS");
                show_stats(stream).await
            }
            "VERSION" => {
                trace!("SHOW VERSION");
                show_version(stream).await
            }
            "USERS" => {
                trace!("SHOW USERS");
                show_users(stream).await
            }
            _ => error_response(stream, "Unsupported SHOW query against the admin database").await,
        },
        _ => error_response(stream, "Unsupported query against the admin database").await,
    }
}

/// Column-oriented statistics.
async fn show_lists<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let client_stats = get_client_stats();
    let server_stats = get_server_stats();

    let columns = vec![("list", DataType::Text), ("items", DataType::Int4)];

    let mut users = 1;
    let mut databases = 1;
    for (_, pool) in get_all_pools() {
        databases += pool.databases();
        users += 1; // One user per pool
    }
    let mut res = BytesMut::new();
    res.put(row_description(&columns));
    res.put(data_row(&vec![
        "databases".to_string(),
        databases.to_string(),
    ]));
    res.put(data_row(&vec!["users".to_string(), users.to_string()]));
    res.put(data_row(&vec!["pools".to_string(), databases.to_string()]));
    res.put(data_row(&vec![
        "free_clients".to_string(),
        client_stats
            .keys()
            .filter(|client_id| {
                client_stats
                    .get(client_id)
                    .unwrap()
                    .state
                    .load(Ordering::Relaxed)
                    == ClientState::Idle
            })
            .count()
            .to_string(),
    ]));
    res.put(data_row(&vec![
        "used_clients".to_string(),
        client_stats
            .keys()
            .filter(|client_id| {
                client_stats
                    .get(client_id)
                    .unwrap()
                    .state
                    .load(Ordering::Relaxed)
                    == ClientState::Active
            })
            .count()
            .to_string(),
    ]));
    res.put(data_row(&vec![
        "login_clients".to_string(),
        "0".to_string(),
    ]));
    res.put(data_row(&vec![
        "free_servers".to_string(),
        server_stats
            .keys()
            .filter(|server_id| {
                server_stats
                    .get(server_id)
                    .unwrap()
                    .state
                    .load(Ordering::Relaxed)
                    == ServerState::Idle
            })
            .count()
            .to_string(),
    ]));
    res.put(data_row(&vec![
        "used_servers".to_string(),
        server_stats
            .keys()
            .filter(|server_id| {
                server_stats
                    .get(server_id)
                    .unwrap()
                    .state
                    .load(Ordering::Relaxed)
                    == ServerState::Active
            })
            .count()
            .to_string(),
    ]));
    res.put(data_row(&vec!["dns_names".to_string(), "0".to_string()]));
    res.put(data_row(&vec!["dns_zones".to_string(), "0".to_string()]));
    res.put(data_row(&vec!["dns_queries".to_string(), "0".to_string()]));
    res.put(data_row(&vec!["dns_pending".to_string(), "0".to_string()]));

    res.put(command_complete("SHOW"));

    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show PgCat version.
async fn show_version<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let mut res = BytesMut::new();

    res.put(row_description(&vec![("version", DataType::Text)]));
    res.put(data_row(&vec![format!("PgCat {}", VERSION)]));
    res.put(command_complete("SHOW"));

    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show utilization of connection pools for each shard and replicas.
async fn show_pools<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let pool_lookup = PoolStats::construct_pool_lookup();
    let mut res = BytesMut::new();
    res.put(row_description(&PoolStats::generate_header()));
    pool_lookup.iter().for_each(|(_identifier, pool_stats)| {
        res.put(data_row(&pool_stats.generate_row()));
    });
    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show all available options.
async fn show_help<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let mut res = BytesMut::new();

    let detail_msg = vec![
        "",
        "SHOW HELP|CONFIG|DATABASES|POOLS|CLIENTS|SERVERS|USERS|VERSION",
        // "SHOW PEERS|PEER_POOLS", // missing PEERS|PEER_POOLS
        // "SHOW FDS|SOCKETS|ACTIVE_SOCKETS|LISTS|MEM|STATE", // missing FDS|SOCKETS|ACTIVE_SOCKETS|MEM|STATE
        "SHOW LISTS",
        // "SHOW DNS_HOSTS|DNS_ZONES", // missing DNS_HOSTS|DNS_ZONES
        "SHOW STATS", // missing STATS_TOTALS|STATS_AVERAGES|TOTALS
        "SET key = arg",
        "RELOAD",
        "PAUSE [<db>, <user>]",
        "RESUME [<db>, <user>]",
        // "DISABLE <db>", // missing
        // "ENABLE <db>", // missing
        // "RECONNECT [<db>]", missing
        // "KILL <db>",
        // "SUSPEND",
        "SHUTDOWN",
        // "WAIT_CLOSE [<db>]", // missing
    ];

    res.put(notify("Console usage", detail_msg.join("\n\t")));
    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show shards and replicas.
async fn show_databases<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    // Columns
    let columns = vec![
        ("name", DataType::Text),
        ("host", DataType::Text),
        ("port", DataType::Text),
        ("database", DataType::Text),
        ("force_user", DataType::Text),
        ("pool_size", DataType::Int4),
        ("min_pool_size", DataType::Int4),
        ("reserve_pool", DataType::Int4),
        ("pool_mode", DataType::Text),
        ("max_connections", DataType::Int4),
        ("current_connections", DataType::Int4),
        ("paused", DataType::Int4),
        ("disabled", DataType::Int4),
    ];

    let mut res = BytesMut::new();

    res.put(row_description(&columns));

    for (_, pool) in get_all_pools() {
        let pool_config = pool.settings.clone();
        for shard in 0..pool.shards() {
            let database_name = &pool.address(shard, 0).database;
            for server in 0..pool.servers(shard) {
                let address = pool.address(shard, server);
                let pool_state = pool.pool_state(shard, server);
                let banned = pool.is_banned(address);
                let paused = pool.paused();

                res.put(data_row(&vec![
                    address.name(),                                          // name
                    address.host.to_string(),                                // host
                    address.port.to_string(),                                // port
                    database_name.to_string(),                               // database
                    pool_config.user.username.to_string(),                   // force_user
                    pool_config.user.pool_size.to_string(),                  // pool_size
                    pool_config.user.min_pool_size.unwrap_or(0).to_string(), // min_pool_size
                    "0".to_string(),                                         // reserve_pool
                    pool_config.pool_mode.to_string(),                       // pool_mode
                    pool_config.user.pool_size.to_string(),                  // max_connections
                    pool_state.connections.to_string(),                      // current_connections
                    match paused {
                        // paused
                        true => "1".to_string(),
                        false => "0".to_string(),
                    },
                    match banned {
                        // disabled
                        true => "1".to_string(),
                        false => "0".to_string(),
                    },
                ]));
            }
        }
    }
    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Ignore any SET commands the client sends.
/// This is common initialization done by ORMs.
async fn ignore_set<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    custom_protocol_response_ok(stream, "SET").await
}

/// Bans a host from being used
async fn ban<T>(stream: &mut T, tokens: Vec<&str>) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let host = match tokens.get(1) {
        Some(host) => host,
        None => return error_response(stream, "usage: BAN hostname duration_seconds").await,
    };

    let duration_seconds = match tokens.get(2) {
        Some(duration_seconds) => match duration_seconds.parse::<i64>() {
            Ok(duration_seconds) => duration_seconds,
            Err(_) => {
                return error_response(stream, "duration_seconds must be an integer").await;
            }
        },
        None => return error_response(stream, "usage: BAN hostname duration_seconds").await,
    };

    if duration_seconds <= 0 {
        return error_response(stream, "duration_seconds must be >= 0").await;
    }

    let columns = vec![
        ("db", DataType::Text),
        ("user", DataType::Text),
        ("role", DataType::Text),
        ("host", DataType::Text),
    ];
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    for (id, pool) in get_all_pools().iter() {
        for address in pool.get_addresses_from_host(host) {
            if !pool.is_banned(&address) {
                pool.ban(&address, BanReason::AdminBan(duration_seconds), None);
                res.put(data_row(&vec![
                    id.db.clone(),
                    id.user.clone(),
                    address.role.to_string(),
                    address.host,
                ]));
            }
        }
    }

    res.put(command_complete("BAN"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Clear a host for use
async fn unban<T>(stream: &mut T, tokens: Vec<&str>) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let host = match tokens.get(1) {
        Some(host) => host,
        None => return error_response(stream, "UNBAN command requires a hostname to unban").await,
    };

    let columns = vec![
        ("db", DataType::Text),
        ("user", DataType::Text),
        ("role", DataType::Text),
        ("host", DataType::Text),
    ];
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    for (id, pool) in get_all_pools().iter() {
        for address in pool.get_addresses_from_host(host) {
            if pool.is_banned(&address) {
                pool.unban(&address);
                res.put(data_row(&vec![
                    id.db.clone(),
                    id.user.clone(),
                    address.role.to_string(),
                    address.host,
                ]));
            }
        }
    }

    res.put(command_complete("UNBAN"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Shows all the bans
async fn show_bans<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let columns = vec![
        ("db", DataType::Text),
        ("user", DataType::Text),
        ("role", DataType::Text),
        ("host", DataType::Text),
        ("reason", DataType::Text),
        ("ban_time", DataType::Text),
        ("ban_duration_seconds", DataType::Text),
        ("ban_remaining_seconds", DataType::Text),
    ];
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    // The block should be pretty quick so we cache the time outside
    let now = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .expect("Time went backwards")
        .as_secs() as i64;

    for (id, pool) in get_all_pools().iter() {
        for (address, (ban_reason, ban_time)) in pool.get_bans().iter() {
            let ban_duration = match ban_reason {
                BanReason::AdminBan(duration) => *duration,
                _ => pool.settings.ban_time,
            };
            let remaining = ban_duration - (now - ban_time.timestamp());
            if remaining <= 0 {
                continue;
            }
            res.put(data_row(&vec![
                id.db.clone(),
                id.user.clone(),
                address.role.to_string(),
                address.host.clone(),
                format!("{:?}", ban_reason),
                ban_time.to_string(),
                ban_duration.to_string(),
                remaining.to_string(),
            ]));
        }
    }

    res.put(command_complete("SHOW BANS"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Reload the configuration file without restarting the process.
async fn reload<T>(stream: &mut T, client_server_map: ClientServerMap) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    info!("Reloading config");

    reload_config(client_server_map).await?;

    get_config().show();

    let mut res = BytesMut::new();

    res.put(command_complete("RELOAD"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Shows current configuration.
async fn show_config<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let config = &get_config();
    let config: HashMap<String, String> = config.into();

    // Configs that cannot be changed without restarting.
    let immutables = ["host", "port", "connect_timeout"];

    // Columns
    let columns = vec![
        ("key", DataType::Text),
        ("value", DataType::Text),
        ("default", DataType::Text),
        ("changeable", DataType::Text),
    ];

    // Response data
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    // DataRow rows
    for (key, value) in config {
        let changeable = if immutables.iter().filter(|col| *col == &key).count() == 1 {
            "no".to_string()
        } else {
            "yes".to_string()
        };

        let row = vec![key, value, "-".to_string(), changeable];

        res.put(data_row(&row));
    }

    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show shard and replicas statistics.
async fn show_stats<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let columns = vec![
        ("instance", DataType::Text),
        ("database", DataType::Text),
        ("user", DataType::Text),
        ("total_xact_count", DataType::Numeric),
        ("total_query_count", DataType::Numeric),
        ("total_received", DataType::Numeric),
        ("total_sent", DataType::Numeric),
        ("total_xact_time", DataType::Numeric),
        ("total_query_time", DataType::Numeric),
        ("total_wait_time", DataType::Numeric),
        ("total_errors", DataType::Numeric),
        ("avg_xact_count", DataType::Numeric),
        ("avg_query_count", DataType::Numeric),
        ("avg_recv", DataType::Numeric),
        ("avg_sent", DataType::Numeric),
        ("avg_errors", DataType::Numeric),
        ("avg_xact_time", DataType::Numeric),
        ("avg_query_time", DataType::Numeric),
        ("avg_wait_time", DataType::Numeric),
    ];

    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    for (user_pool, pool) in get_all_pools() {
        for shard in 0..pool.shards() {
            for server in 0..pool.servers(shard) {
                let address = pool.address(shard, server);

                let mut row = vec![address.name(), user_pool.db.clone(), user_pool.user.clone()];
                let stats = address.stats.clone();
                stats.populate_row(&mut row);

                res.put(data_row(&row));
            }
        }
    }

    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show currently connected clients
async fn show_clients<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let columns = vec![
        ("client_id", DataType::Text),
        ("database", DataType::Text),
        ("user", DataType::Text),
        ("application_name", DataType::Text),
        ("state", DataType::Text),
        ("transaction_count", DataType::Numeric),
        ("query_count", DataType::Numeric),
        ("error_count", DataType::Numeric),
        ("age_seconds", DataType::Numeric),
    ];

    let new_map = get_client_stats();
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    for (_, client) in new_map {
        let row = vec![
            format!("{:#010X}", client.client_id()),
            client.pool_name(),
            client.username(),
            client.application_name(),
            client.state.load(Ordering::Relaxed).to_string(),
            client.transaction_count.load(Ordering::Relaxed).to_string(),
            client.query_count.load(Ordering::Relaxed).to_string(),
            client.error_count.load(Ordering::Relaxed).to_string(),
            Instant::now()
                .duration_since(client.connect_time())
                .as_secs()
                .to_string(),
        ];

        res.put(data_row(&row));
    }

    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show currently connected servers
async fn show_servers<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let columns = vec![
        ("server_id", DataType::Text),
        ("database_name", DataType::Text),
        ("user", DataType::Text),
        ("address_id", DataType::Text),
        ("application_name", DataType::Text),
        ("state", DataType::Text),
        ("transaction_count", DataType::Numeric),
        ("query_count", DataType::Numeric),
        ("bytes_sent", DataType::Numeric),
        ("bytes_received", DataType::Numeric),
        ("age_seconds", DataType::Numeric),
        ("prepare_cache_hit", DataType::Numeric),
        ("prepare_cache_miss", DataType::Numeric),
        ("prepare_cache_size", DataType::Numeric),
    ];

    let new_map = get_server_stats();
    let mut res = BytesMut::new();
    res.put(row_description(&columns));

    for (_, server) in new_map {
        let application_name = server.application_name.read();
        let row = vec![
            format!("{:#010X}", server.server_id()),
            server.pool_name(),
            server.username(),
            server.address_name(),
            application_name.clone(),
            server.state.load(Ordering::Relaxed).to_string(),
            server.transaction_count.load(Ordering::Relaxed).to_string(),
            server.query_count.load(Ordering::Relaxed).to_string(),
            server.bytes_sent.load(Ordering::Relaxed).to_string(),
            server.bytes_received.load(Ordering::Relaxed).to_string(),
            Instant::now()
                .duration_since(server.connect_time())
                .as_secs()
                .to_string(),
            server
                .prepared_hit_count
                .load(Ordering::Relaxed)
                .to_string(),
            server
                .prepared_miss_count
                .load(Ordering::Relaxed)
                .to_string(),
            server
                .prepared_cache_size
                .load(Ordering::Relaxed)
                .to_string(),
        ];

        res.put(data_row(&row));
    }

    res.put(command_complete("SHOW"));

    // ReadyForQuery
    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Pause a pool. It won't pass any more queries to the backends.
async fn pause<T>(stream: &mut T, query: &str) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let parts: Vec<&str> = query.split(",").map(|part| part.trim()).collect();

    if parts.len() != 2 {
        error_response(
            stream,
            "PAUSE requires a database and a user, e.g. PAUSE my_db,my_user",
        )
        .await
    } else {
        let database = parts[0];
        let user = parts[1];

        match get_pool(database, user) {
            Some(pool) => {
                pool.pause();

                let mut res = BytesMut::new();

                res.put(command_complete(&format!("PAUSE {},{}", database, user)));

                // ReadyForQuery
                res.put_u8(b'Z');
                res.put_i32(5);
                res.put_u8(b'I');

                write_all_half(stream, &res).await
            }

            None => {
                error_response(
                    stream,
                    &format!(
                        "No pool configured for database: {}, user: {}",
                        database, user
                    ),
                )
                .await
            }
        }
    }
}

/// Resume a pool. Queries are allowed again.
async fn resume<T>(stream: &mut T, query: &str) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let parts: Vec<&str> = query.split(",").map(|part| part.trim()).collect();

    if parts.len() != 2 {
        error_response(
            stream,
            "RESUME requires a database and a user, e.g. RESUME my_db,my_user",
        )
        .await
    } else {
        let database = parts[0];
        let user = parts[1];

        match get_pool(database, user) {
            Some(pool) => {
                pool.resume();

                let mut res = BytesMut::new();

                res.put(command_complete(&format!("RESUME {},{}", database, user)));

                // ReadyForQuery
                res.put_u8(b'Z');
                res.put_i32(5);
                res.put_u8(b'I');

                write_all_half(stream, &res).await
            }

            None => {
                error_response(
                    stream,
                    &format!(
                        "No pool configured for database: {}, user: {}",
                        database, user
                    ),
                )
                .await
            }
        }
    }
}

/// Send response packets for shutdown.
async fn shutdown<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let mut res = BytesMut::new();

    res.put(row_description(&vec![("success", DataType::Text)]));

    let mut shutdown_success = "t";

    let pid = std::process::id();
    if signal::kill(Pid::from_raw(pid.try_into().unwrap()), Signal::SIGINT).is_err() {
        error!("Unable to send SIGINT to PID: {}", pid);
        shutdown_success = "f";
    }

    res.put(data_row(&vec![shutdown_success.to_string()]));

    res.put(command_complete("SHUTDOWN"));

    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}

/// Show Users.
async fn show_users<T>(stream: &mut T) -> Result<(), Error>
where
    T: tokio::io::AsyncWrite + std::marker::Unpin,
{
    let mut res = BytesMut::new();

    res.put(row_description(&vec![
        ("name", DataType::Text),
        ("pool_mode", DataType::Text),
    ]));

    for (user_pool, pool) in get_all_pools() {
        let pool_config = &pool.settings;
        res.put(data_row(&vec![
            user_pool.user.clone(),
            pool_config.pool_mode.to_string(),
        ]));
    }

    res.put(command_complete("SHOW"));

    res.put_u8(b'Z');
    res.put_i32(5);
    res.put_u8(b'I');

    write_all_half(stream, &res).await
}