refactor database engine/options; add column descriptors

Signed-off-by: Jason Volk <jason@zemos.net>

src/database/engine/backup.rs

@@ -0,0 +1,73 @@
+use std::fmt::Write;
+
+use conduwuit::{error, implement, info, utils::time::rfc2822_from_seconds, warn, Result};
+use rocksdb::backup::{BackupEngine, BackupEngineOptions};
+
+use super::Engine;
+use crate::{or_else, util::map_err};
+
+#[implement(Engine)]
+#[tracing::instrument(skip(self))]
+pub fn backup(&self) -> Result {
+	let server = &self.ctx.server;
+	let config = &server.config;
+	let path = config.database_backup_path.as_ref();
+	if path.is_none() || path.is_some_and(|path| path.as_os_str().is_empty()) {
+		return Ok(());
+	}
+
+	let options =
+		BackupEngineOptions::new(path.expect("valid database backup path")).map_err(map_err)?;
+	let mut engine = BackupEngine::open(&options, &*self.ctx.env.lock()?).map_err(map_err)?;
+	if config.database_backups_to_keep > 0 {
+		let flush = !self.is_read_only();
+		engine
+			.create_new_backup_flush(&self.db, flush)
+			.map_err(map_err)?;
+
+		let engine_info = engine.get_backup_info();
+		let info = &engine_info.last().expect("backup engine info is not empty");
+		info!(
+			"Created database backup #{} using {} bytes in {} files",
+			info.backup_id, info.size, info.num_files,
+		);
+	}
+
+	if config.database_backups_to_keep >= 0 {
+		let keep = u32::try_from(config.database_backups_to_keep)?;
+		if let Err(e) = engine.purge_old_backups(keep.try_into()?) {
+			error!("Failed to purge old backup: {e:?}");
+		}
+	}
+
+	Ok(())
+}
+
+#[implement(Engine)]
+pub fn backup_list(&self) -> Result<String> {
+	let server = &self.ctx.server;
+	let config = &server.config;
+	let path = config.database_backup_path.as_ref();
+	if path.is_none() || path.is_some_and(|path| path.as_os_str().is_empty()) {
+		return Ok("Configure database_backup_path to enable backups, or the path specified is \
+		           not valid"
+			.to_owned());
+	}
+
+	let mut res = String::new();
+	let options =
+		BackupEngineOptions::new(path.expect("valid database backup path")).or_else(or_else)?;
+	let engine = BackupEngine::open(&options, &*self.ctx.env.lock()?).or_else(or_else)?;
+	for info in engine.get_backup_info() {
+		writeln!(
+			res,
+			"#{} {}: {} bytes, {} files",
+			info.backup_id,
+			rfc2822_from_seconds(info.timestamp),
+			info.size,
+			info.num_files,
+		)?;
+	}
+
+	Ok(res)
+}