feat: configurable parameters for incremental backups

CHANGELOG.md

@@ -9,12 +9,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-* Added `backup` CLI command
+* `backup` CLI command
+* Incremental backups
+    * Chain length descibres how many incremental backups to create from the
+      same full backup
+    * "backups to keep" has been replaced by "chains to keep"
 
 ### Changed
 
 * Running the server now uses the `run` CLI subcommand
 
+### Removed
+
+* `max_backups` setting
+
 ## [0.2.2](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.2.2)
 
 ### Fixed

src/cli.rs

@@ -35,15 +35,24 @@ pub struct Cli {
     )]
     pub backup: PathBuf,
 
-    /// How many backups to keep
+    /// Length of a backup chain
+    #[arg(
+        short = 'l',
+        long,
+        default_value_t = 4,
+        env = "ALEX_CHAIN_LEN",
+        global = true
+    )]
+    pub chain_len: u64,
+    /// How many backup chains to keep
     #[arg(
         short = 'n',
         long,
         default_value_t = 7,
-        env = "ALEX_MAX_BACKUPS",
+        env = "ALEX_CHAINS",
         global = true
     )]
-    pub max_backups: u64,
+    pub chains: u64,
 }
 
 #[derive(Subcommand)]

src/main.rs

@@ -32,7 +32,8 @@ fn command_run(cli: &Cli, args: &RunArgs) -> io::Result<()> {
         .backup(cli.backup.clone())
         .xms(args.xms)
         .xmx(args.xmx)
-        .max_backups(cli.max_backups);
+        .chain_len(cli.chain_len)
+        .chains_to_keep(cli.chains);
     cmd.canonicalize()?;
 
     if args.dry {
@@ -58,12 +59,13 @@ fn command_run(cli: &Cli, args: &RunArgs) -> io::Result<()> {
 }
 
 fn commands_backup(cli: &Cli, _args: &BackupArgs) -> io::Result<()> {
-    let mut manager = server::BackupManager::open(
+    let mut manager = server::BackupManager::new(
         cli.backup.clone(),
         cli.config.clone(),
         cli.world.clone(),
-        cli.max_backups,
-    )?;
+        cli.chain_len,
+        cli.chains,
+    );
 
     manager.create_backup()?;
     manager.remove_old_backups()

src/server/backups.rs

@@ -1,5 +1,5 @@
 use crate::server::path::PathExt;
-use chrono::{Local, Utc};
+use chrono::Utc;
 use flate2::write::GzEncoder;
 use flate2::Compression;
 use serde::{Deserialize, Serialize};
@@ -7,7 +7,6 @@ use std::collections::{HashMap, HashSet};
 use std::fs::File;
 use std::io;
 use std::path::{Path, PathBuf};
-use std::sync::Arc;
 
 #[link(name = "c")]
 extern "C" {
@@ -21,13 +20,6 @@ pub enum BackupType {
     Incremental,
 }
 
-#[derive(Debug)]
-pub enum BackupError {
-    NoFullAncestor,
-}
-
-type BackupResult<T> = Result<T, BackupError>;
-
 /// Represents the changes relative to the previous backup
 #[derive(Debug, Serialize, Deserialize)]
 pub struct BackupDelta {
@@ -113,6 +105,8 @@ pub struct Backup {
 impl Backup {
     const FILENAME_FORMAT: &str = "%Y-%m-%d_%H-%M-%S.tar.gz";
 
+    /// Resolve the state of the list of backups by applying their deltas in-order to an initially
+    /// empty state.
     pub fn state(backups: &Vec<Backup>) -> HashMap<PathBuf, HashSet<PathBuf>> {
         let mut state: HashMap<PathBuf, HashSet<PathBuf>> = HashMap::new();
 
@@ -232,29 +226,27 @@ pub struct BackupManager {
     world_dir: PathBuf,
     chain_len: u64,
     chains_to_keep: u64,
-    max_backups: u64,
-    last_backup: Option<Arc<Backup>>,
     chains: Vec<Vec<Backup>>,
 }
 
 impl BackupManager {
     const METADATA_FILE: &str = "alex.json";
 
+    /// Initialize a new instance of a `BackupManager`.
     pub fn new(
         backup_dir: PathBuf,
         config_dir: PathBuf,
         world_dir: PathBuf,
-        max_backups: u64,
+        chain_len: u64,
+        chains_to_keep: u64,
     ) -> Self {
         BackupManager {
             backup_dir,
             config_dir,
             world_dir,
-            max_backups,
-            chain_len: 2,
-            chains_to_keep: 1,
+            chain_len,
+            chains_to_keep,
             chains: Vec::new(),
-            last_backup: None,
         }
     }
 
@@ -262,9 +254,10 @@ impl BackupManager {
         backup_dir: PathBuf,
         config_dir: PathBuf,
         world_dir: PathBuf,
-        max_backups: u64,
+        chain_len: u64,
+        chains_to_keep: u64,
     ) -> std::io::Result<Self> {
-        let mut manager = Self::new(backup_dir, config_dir, world_dir, max_backups);
+        let mut manager = Self::new(backup_dir, config_dir, world_dir, chain_len, chains_to_keep);
         manager.load_json()?;
 
         Ok(manager)

src/server/command.rs

@@ -35,7 +35,8 @@ pub struct ServerCommand {
     backup_dir: PathBuf,
     xms: u64,
     xmx: u64,
-    max_backups: u64,
+    chain_len: u64,
+    chains_to_keep: u64,
 }
 
 impl ServerCommand {
@@ -50,7 +51,8 @@ impl ServerCommand {
             backup_dir: PathBuf::from("backups"),
             xms: 1024,
             xmx: 2048,
-            max_backups: 7,
+            chain_len: 4,
+            chains_to_keep: 7,
         }
     }
 
@@ -91,8 +93,13 @@ impl ServerCommand {
         self
     }
 
-    pub fn max_backups(mut self, v: u64) -> Self {
-        self.max_backups = v;
+    pub fn chain_len(mut self, v: u64) -> Self {
+        self.chain_len = v;
+        self
+    }
+
+    pub fn chains_to_keep(mut self, v: u64) -> Self {
+        self.chains_to_keep = v;
         self
     }
 
@@ -183,7 +190,8 @@ impl ServerCommand {
             self.backup_dir.clone(),
             self.config_dir.clone(),
             self.world_dir.clone(),
-            self.max_backups,
+            self.chain_len,
+            self.chains_to_keep,
         )?;
         let mut cmd = self.create_cmd();
         self.accept_eula()?;