veloren/server/src/persistence/mod.rs

pub mod character;

mod error;
mod models;
mod schema;

extern crate diesel;

use diesel::{connection::SimpleConnection, prelude::*};
use diesel_migrations::embed_migrations;
use std::{env, fs, path::PathBuf};
use tracing::warn;

// See: https://docs.rs/diesel_migrations/1.4.0/diesel_migrations/macro.embed_migrations.html
// This macro is called at build-time, and produces the necessary migration info
// for the `embedded_migrations` call below.
embed_migrations!();

pub fn run_migrations(db_dir: &str) -> Result<(), diesel_migrations::RunMigrationsError> {
    let db_dir = &apply_saves_dir_override(db_dir);
    let _ = fs::create_dir(format!("{}/", db_dir));
    embedded_migrations::run_with_output(&establish_connection(db_dir), &mut std::io::stdout())
}

fn establish_connection(db_dir: &str) -> SqliteConnection {
    let db_dir = &apply_saves_dir_override(db_dir);
    let database_url = format!("{}/db.sqlite", db_dir);

    let connection = SqliteConnection::establish(&database_url)
        .unwrap_or_else(|_| panic!("Error connecting to {}", database_url));

    // Use Write-Ahead-Logging for improved concurrency: https://sqlite.org/wal.html
    // Set a busy timeout (in ms): https://sqlite.org/c3ref/busy_timeout.html
    if let Err(e) = connection.batch_execute(
        "
        PRAGMA journal_mode = WAL;
        PRAGMA busy_timeout = 250; 
        ",
    ) {
        warn!(
            ?e,
            "Failed adding PRAGMA statements while establishing sqlite connection, this will \
             result in a higher likelihood of locking errors"
        );
    }

    connection
}

#[allow(clippy::single_match)] // TODO: Pending review in #587
fn apply_saves_dir_override(db_dir: &str) -> String {
    if let Some(saves_dir) = env::var_os("VELOREN_SAVES_DIR") {
        let path = PathBuf::from(saves_dir.clone());
        if path.exists() || path.parent().map(|x| x.exists()).unwrap_or(false) {
            // Only allow paths with valid unicode characters
            match path.to_str() {
                Some(path) => return path.to_owned(),
                None => {},
            }
        }
        warn!(?saves_dir, "VELOREN_SAVES_DIR points to an invalid path.");
    }
    db_dir.to_string()
}