fix: actually working incremental backup

.cargo/config.toml

@@ -1,3 +1,3 @@
 [alias]
-runs = "run -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds --jar data/paper.jar"
-runrs = "run --release -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds --jar data/paper.jar"
+runs = "run -- run paper 1.19.4-550 --config data/config --backup data/backups --world data/worlds --jar paper-1.19.4-550.jar"
+runrs = "run --release -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds --jar data/paper-1.19.4-525.jar"

.gitignore

@@ -19,4 +19,4 @@ target/
 
 # testing files
 *.jar
-data/
+data*/

CHANGELOG.md

@@ -7,6 +7,28 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://git.rustybever.be/Chewing_Bever/alex/src/branch/dev)
 
+### Changed
+
+* Running the server now uses the `run` CLI subcommand
+
+## [0.2.2](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.2.2)
+
+### Fixed
+
+* Use correct env var for backup directory
+
+## [0.2.1](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.2.1)
+
+### Added
+
+* `--dry` flag to inspect command that will be run
+
+### Changed
+
+* JVM flags now narrowely follow Aikar's specifications
+
+## [0.2.0](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.2.0)
+
 ### Added
 
 * Rudimentary signal handling for gently stopping server

Cargo.lock

@@ -10,7 +10,7 @@ checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
 [[package]]
 name = "alex"
-version = "0.1.0"
+version = "0.2.2"
 dependencies = [
  "chrono",
  "clap",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "alex"
-version = "0.1.0"
+version = "0.2.2"
 description = "Wrapper around Minecraft server processes, designed to complement Docker image installations."
 authors = ["Jef Roosens"]
 edition = "2021"

Dockerfile

@@ -18,11 +18,11 @@ RUN cargo build && \
 
 # We use ${:-} instead of a default value because the argument is always passed
 # to the build, it'll just be blank most likely
-FROM eclipse-temurin:17-jre-alpine
+FROM eclipse-temurin:18-jre-alpine
 
 # Build arguments
 ARG MC_VERSION=1.19.4
-ARG PAPERMC_VERSION=545
+ARG PAPERMC_VERSION=525
 
 RUN addgroup -Sg 1000 paper && \
     adduser -SHG paper -u 1000 paper
@@ -61,4 +61,5 @@ EXPOSE 25565
 # Switch to non-root user
 USER paper:paper
 
-ENTRYPOINT ["/bin/alex", "paper"]
+ENTRYPOINT ["/bin/dumb-init", "--"]
+CMD ["/bin/alex", "paper"]

README.md

@@ -1,3 +1,26 @@
-# mc-wrapper
+# Alex
 
-A wrapper around a standard Minecraft server, written in Rust.
+Alex is a wrapper around a typical Minecraft server process. It acts as the
+parent process, and sits in between the user's input and the server's stdin.
+This allows Alex to support additional commands that execute Rust code.
+
+## Why
+
+The primary usecase for this is backups. A common problem I've had with
+Minecraft backups is that they fail, because the server is writing to one of
+the region files as the backup is being created. Alex solves this be sending
+`save-off` and `save-all` to the server, before creating the tarball.
+Afterwards, saving is enabled again with `save-on`.
+
+## Features
+
+* Create safe backups as gzip-compressed tarballs using the `backup` command
+* Automatically create backups periodically
+* Properly configures the process (working directory, optimisation flags)
+* Configure everything as CLI arguments or environment variables
+
+## Installation
+
+Alex is distributed as statically compiled binaries for Linux amd64 and arm64.
+These can be found
+[here](https://git.rustybever.be/Chewing_Bever/alex/packages).

src/cli.rs

@@ -0,0 +1,91 @@
+use crate::server::ServerType;
+use clap::{Args, Parser, Subcommand};
+use std::path::PathBuf;
+
+#[derive(Parser)]
+#[command(author, version, about, long_about = None)]
+pub struct Cli {
+    #[command(subcommand)]
+    pub command: Commands,
+    /// Directory where configs are stored, and where the server will run
+    #[arg(
+        long,
+        value_name = "CONFIG_DIR",
+        default_value = ".",
+        env = "ALEX_CONFIG_DIR",
+        global = true
+    )]
+    pub config: PathBuf,
+    /// Directory where world files will be saved
+    #[arg(
+        long,
+        value_name = "WORLD_DIR",
+        default_value = "../worlds",
+        env = "ALEX_WORLD_DIR",
+        global = true
+    )]
+    pub world: PathBuf,
+    /// Directory where backups will be stored
+    #[arg(
+        long,
+        value_name = "BACKUP_DIR",
+        default_value = "../backups",
+        env = "ALEX_BACKUP_DIR",
+        global = true
+    )]
+    pub backup: PathBuf,
+
+    /// How many backups to keep
+    #[arg(
+        short = 'n',
+        long,
+        default_value_t = 7,
+        env = "ALEX_MAX_BACKUPS",
+        global = true
+    )]
+    pub max_backups: u64,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Run the server
+    Run(RunArgs),
+}
+
+#[derive(Args)]
+pub struct RunArgs {
+    /// Type of server
+    pub type_: ServerType,
+    /// Version string for the server, e.g. 1.19.4-545
+    #[arg(env = "ALEX_SERVER_VERSION")]
+    pub server_version: String,
+
+    /// Server jar to execute
+    #[arg(
+        long,
+        value_name = "JAR_PATH",
+        default_value = "server.jar",
+        env = "ALEX_JAR"
+    )]
+    pub jar: PathBuf,
+
+    /// Java command to run the server jar with
+    #[arg(long, value_name = "JAVA_CMD", default_value_t = String::from("java"), env = "ALEX_JAVA")]
+    pub java: String,
+
+    /// XMS value in megabytes for the server instance
+    #[arg(long, default_value_t = 1024, env = "ALEX_XMS")]
+    pub xms: u64,
+    /// XMX value in megabytes for the server instance
+    #[arg(long, default_value_t = 2048, env = "ALEX_XMX")]
+    pub xmx: u64,
+
+    /// How frequently to perform a backup, in minutes; 0 to disable.
+    #[arg(short = 't', long, default_value_t = 0, env = "ALEX_FREQUENCY")]
+    pub frequency: u64,
+
+    /// Don't actually run the server, but simply output the server configuration that would have
+    /// been ran
+    #[arg(short, long, default_value_t = false)]
+    pub dry: bool,
+}

src/main.rs

@@ -1,73 +1,13 @@
+mod cli;
 mod server;
 mod signals;
 mod stdin;
 
 use clap::Parser;
-use server::ServerType;
+use cli::{Cli, Commands, RunArgs};
 use std::io;
-use std::path::PathBuf;
 use std::sync::{Arc, Mutex};
 
-#[derive(Parser)]
-#[command(author, version, about, long_about = None)]
-struct Cli {
-    /// Type of server
-    type_: ServerType,
-    /// Version string for the server, e.g. 1.19.4-545
-    #[arg(env = "ALEX_SERVER_VERSION")]
-    server_version: String,
-
-    /// Server jar to execute
-    #[arg(
-        long,
-        value_name = "JAR_PATH",
-        default_value = "server.jar",
-        env = "ALEX_JAR"
-    )]
-    jar: PathBuf,
-    /// Directory where configs are stored, and where the server will run
-    #[arg(
-        long,
-        value_name = "CONFIG_DIR",
-        default_value = ".",
-        env = "ALEX_CONFIG_DIR"
-    )]
-    config: PathBuf,
-    /// Directory where world files will be saved
-    #[arg(
-        long,
-        value_name = "WORLD_DIR",
-        default_value = "../worlds",
-        env = "ALEX_WORLD_DIR"
-    )]
-    world: PathBuf,
-    /// Directory where backups will be stored
-    #[arg(
-        long,
-        value_name = "BACKUP_DIR",
-        default_value = "../backups",
-        env = "ALEX_WORLD_DIR"
-    )]
-    backup: PathBuf,
-    /// Java command to run the server jar with
-    #[arg(long, value_name = "JAVA_CMD", default_value_t = String::from("java"), env = "ALEX_JAVA")]
-    java: String,
-
-    /// XMS value in megabytes for the server instance
-    #[arg(long, default_value_t = 1024, env = "ALEX_XMS")]
-    xms: u64,
-    /// XMX value in megabytes for the server instance
-    #[arg(long, default_value_t = 2048, env = "ALEX_XMX")]
-    xmx: u64,
-
-    /// How many backups to keep
-    #[arg(short = 'n', long, default_value_t = 7, env = "ALEX_MAX_BACKUPS")]
-    max_backups: u64,
-    /// How frequently to perform a backup, in minutes; 0 to disable.
-    #[arg(short = 't', long, default_value_t = 0, env = "ALEX_FREQUENCY")]
-    frequency: u64,
-}
-
 fn backups_thread(counter: Arc<Mutex<server::ServerProcess>>, frequency: u64) {
     loop {
         std::thread::sleep(std::time::Duration::from_secs(frequency * 60));
@@ -81,24 +21,32 @@ fn backups_thread(counter: Arc<Mutex<server::ServerProcess>>, frequency: u64) {
     }
 }
 
-fn main() -> io::Result<()> {
+fn command_run(cli: &Cli, args: &RunArgs) -> io::Result<()> {
     let (_, mut signals) = signals::install_signal_handlers()?;
-    let cli = Cli::parse();
 
-    let cmd = server::ServerCommand::new(cli.type_, &cli.server_version)
-        .java(&cli.java)
-        .jar(cli.jar)
-        .config(cli.config)
-        .world(cli.world)
-        .backup(cli.backup)
-        .xms(cli.xms)
-        .xmx(cli.xmx)
+    let mut cmd = server::ServerCommand::new(args.type_, &args.server_version)
+        .java(&args.java)
+        .jar(args.jar.clone())
+        .config(cli.config.clone())
+        .world(cli.world.clone())
+        .backup(cli.backup.clone())
+        .xms(args.xms)
+        .xmx(args.xmx)
         .max_backups(cli.max_backups);
+    cmd.canonicalize()?;
+
+    if args.dry {
+        print!("{}", cmd);
+
+        return Ok(());
+    }
+
     let counter = Arc::new(Mutex::new(cmd.spawn()?));
 
-    if cli.frequency > 0 {
+    if args.frequency > 0 {
         let clone = Arc::clone(&counter);
-        std::thread::spawn(move || backups_thread(clone, cli.frequency));
+        let frequency = args.frequency;
+        std::thread::spawn(move || backups_thread(clone, frequency));
     }
 
     // Spawn thread that handles the main stdin loop
@@ -108,3 +56,11 @@ fn main() -> io::Result<()> {
     // Signal handler loop exits the process when necessary
     signals::handle_signals(&mut signals, counter)
 }
+
+fn main() -> io::Result<()> {
+    let cli = Cli::parse();
+
+    match &cli.command {
+        Commands::Run(args) => command_run(&cli, args),
+    }
+}

src/server/backups.rs

@@ -0,0 +1,340 @@
+use chrono::{Local, Utc};
+use flate2::write::GzEncoder;
+use flate2::Compression;
+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" {
+    fn geteuid() -> u32;
+    fn getegid() -> u32;
+}
+
+const FILENAME_FORMAT: &str = "%Y-%m-%d_%H-%M-%S.tar.gz";
+
+fn files(src_dir: PathBuf) -> io::Result<HashSet<PathBuf>> {
+    let mut dirs = vec![src_dir.clone()];
+    let mut files: HashSet<PathBuf> = HashSet::new();
+
+    while let Some(dir) = dirs.pop() {
+        for res in dir.read_dir()? {
+            let entry = res?;
+
+            if entry.file_name() == "cache" {
+                continue;
+            }
+
+            if entry.file_type()?.is_dir() {
+                dirs.push(entry.path());
+            } else {
+                files.insert(entry.path().strip_prefix(&src_dir).unwrap().to_path_buf());
+            }
+        }
+    }
+
+    Ok(files)
+}
+
+/// Check whether a file has been modified since the given timestamp.
+///
+/// Note that this function will *only* return true if it can determine with certainty that the
+/// file has not been modified. If any errors occur while obtaining the required metadata (e.g. if
+/// the file system does not support this metadata), this function will return false.
+fn not_modified_since<T: AsRef<Path>>(time: chrono::DateTime<Utc>, path: T) -> bool {
+    let path = path.as_ref();
+
+    if let Ok(metadata) = path.metadata() {
+        let last_modified = metadata.modified();
+
+        if let Ok(last_modified) = last_modified {
+            let t: chrono::DateTime<Utc> = last_modified.into();
+            let t = t.with_timezone(&Local);
+
+            return t < time;
+        }
+    }
+
+    false
+}
+
+#[derive(Debug, PartialEq)]
+pub enum BackupType {
+    Full,
+    Incremental,
+}
+
+#[derive(Debug)]
+pub enum BackupError {
+    NoFullAncestor,
+}
+
+type BackupResult<T> = Result<T, BackupError>;
+
+/// Represents the changes relative to the previous backup
+#[derive(Debug)]
+pub struct BackupDelta {
+    /// What files were added/modified in each part of the tarball.
+    pub added: HashMap<PathBuf, HashSet<PathBuf>>,
+    /// What files were removed in this backup, in comparison to the previous backup. For full
+    /// backups, this will always be empty, as they do not consider previous backups.
+    /// The map stores a separate list for each top-level directory, as the contents of these
+    /// directories can come for different source directories.
+    pub removed: HashMap<PathBuf, HashSet<PathBuf>>,
+}
+
+impl BackupDelta {
+    pub fn new() -> Self {
+        BackupDelta {
+            added: HashMap::new(),
+            removed: HashMap::new(),
+        }
+    }
+
+    /// Update the current state so that its result becomes the merge of itself and the other
+    /// state.
+    pub fn merge(&mut self, delta: &BackupDelta) {
+        for (dir, added) in delta.added.iter() {
+            // Files that were removed in the current state, but added in the new state, are no
+            // longer removed
+            if let Some(orig_removed) = self.removed.get_mut(dir) {
+                orig_removed.retain(|k| !added.contains(k));
+            }
+
+            // Newly added files are added to the state as well
+            if let Some(orig_added) = self.added.get_mut(dir) {
+                orig_added.extend(added.iter().cloned());
+            } else {
+                self.added.insert(dir.clone(), added.clone());
+            }
+        }
+
+        for (dir, removed) in delta.removed.iter() {
+            // Files that were originally added, but now deleted are removed from the added list
+            if let Some(orig_added) = self.added.get_mut(dir) {
+                orig_added.retain(|k| !removed.contains(k));
+            }
+
+            // Newly removed files are added to the state as well
+            if let Some(orig_removed) = self.removed.get_mut(dir) {
+                orig_removed.extend(removed.iter().cloned());
+            } else {
+                self.removed.insert(dir.clone(), removed.clone());
+            }
+        }
+    }
+
+    /// Modify the given state by applying this delta's changes to it
+    pub fn apply(&self, state: &mut HashMap<PathBuf, HashSet<PathBuf>>) {
+        // First we add new files, then we remove the old ones
+        for (dir, added) in self.added.iter() {
+            if let Some(current) = state.get_mut(dir) {
+                current.extend(added.iter().cloned());
+            } else {
+                state.insert(dir.clone(), added.clone());
+            }
+        }
+
+        for (dir, removed) in self.removed.iter() {
+            if let Some(current) = state.get_mut(dir) {
+                current.retain(|k| !removed.contains(k));
+            }
+        }
+    }
+}
+
+/// Represents a successful backup
+#[derive(Debug)]
+pub struct Backup {
+    previous: Option<Arc<Backup>>,
+    /// When the backup was started (also corresponds to the name)
+    start_time: chrono::DateTime<Utc>,
+    /// Type of the backup
+    type_: BackupType,
+    delta: BackupDelta,
+}
+
+impl Backup {
+    /// Calculate the full state of the backup by applying all its ancestors delta's in order,
+    /// starting from the last full ancestor.
+    pub fn state(&self) -> BackupResult<HashMap<PathBuf, HashSet<PathBuf>>> {
+        if self.type_ == BackupType::Full {
+            let mut state = HashMap::new();
+            self.delta.apply(&mut state);
+
+            Ok(state)
+        } else if let Some(previous) = &self.previous {
+            let mut state = previous.state()?;
+            self.delta.apply(&mut state);
+
+            Ok(state)
+        } else {
+            return Err(BackupError::NoFullAncestor);
+        }
+    }
+    /// Create a new Full backup, populated with the given directories.
+    ///
+    /// # Arguments
+    ///
+    /// * `backup_dir` - Directory to store archive in
+    /// * `dirs` - list of tuples `(path_in_tar, src_dir)` with `path_in_tar` the directory name
+    ///     under which `src_dir`'s contents should be stored in the archive
+    ///
+    /// # Returns
+    ///
+    /// The `Backup` instance describing this new backup.
+    pub fn create<P: AsRef<Path>>(
+        backup_dir: P,
+        dirs: Vec<(PathBuf, PathBuf)>,
+    ) -> io::Result<Self> {
+        let backup_dir = backup_dir.as_ref();
+        let start_time = chrono::offset::Utc::now();
+
+        let filename = format!("{}", start_time.format(FILENAME_FORMAT));
+        let path = backup_dir.join(filename);
+        let tar_gz = File::create(path)?;
+        let enc = GzEncoder::new(tar_gz, Compression::default());
+        let mut ar = tar::Builder::new(enc);
+
+        let mut added: HashMap<PathBuf, HashSet<PathBuf>> = HashMap::new();
+
+        for (dir_in_tar, src_dir) in dirs {
+            let files = files(src_dir.clone())?;
+
+            for path in &files {
+                ar.append_path_with_name(src_dir.join(path), dir_in_tar.join(path))?;
+            }
+
+            added.insert(dir_in_tar, files);
+        }
+
+        Ok(Backup {
+            previous: None,
+            type_: BackupType::Full,
+            start_time,
+            delta: BackupDelta {
+                added,
+                removed: HashMap::new(),
+            },
+        })
+    }
+
+    /// Create a new incremental backup from a given previous backup
+    pub fn create_from<P: AsRef<Path>>(
+        previous: Arc<Backup>,
+        backup_dir: P,
+        dirs: Vec<(PathBuf, PathBuf)>,
+    ) -> io::Result<Self> {
+        let backup_dir = backup_dir.as_ref();
+        let start_time = chrono::offset::Utc::now();
+
+        let filename = format!("{}", start_time.format(FILENAME_FORMAT));
+        let path = backup_dir.join(filename);
+        let tar_gz = File::create(path)?;
+        let enc = GzEncoder::new(tar_gz, Compression::default());
+        let mut ar = tar::Builder::new(enc);
+
+        // TODO remove unwrap
+        let previous_state = previous.state().unwrap();
+        let mut delta = BackupDelta::new();
+
+        for (dir_in_tar, src_dir) in dirs {
+            let files = files(src_dir.clone())?;
+            let added_files = files
+                .iter()
+                // This explicit negation is because we wish to also include files for which we
+                // couldn't determine the last modified time
+                .filter(|p| !not_modified_since(previous.start_time, src_dir.join(p)))
+                .cloned()
+                .collect::<HashSet<PathBuf>>();
+
+            for path in added_files.iter() {
+                ar.append_path_with_name(src_dir.join(path), dir_in_tar.join(path))?;
+            }
+
+            delta.added.insert(dir_in_tar.clone(), added_files);
+
+            if let Some(previous_files) = previous_state.get(&dir_in_tar) {
+                delta.removed.insert(
+                    dir_in_tar,
+                    previous_files.difference(&files).cloned().collect(),
+                );
+            }
+        }
+
+        Ok(Backup {
+            previous: Some(previous),
+            type_: BackupType::Incremental,
+            start_time,
+            delta,
+        })
+    }
+}
+
+pub struct BackupManager {
+    backup_dir: PathBuf,
+    config_dir: PathBuf,
+    world_dir: PathBuf,
+    max_backups: u64,
+    last_backup: Option<Arc<Backup>>,
+}
+
+impl BackupManager {
+    pub fn open(
+        backup_dir: PathBuf,
+        config_dir: PathBuf,
+        world_dir: PathBuf,
+        max_backups: u64,
+    ) -> Self {
+        BackupManager {
+            backup_dir,
+            config_dir,
+            world_dir,
+            max_backups,
+            last_backup: None,
+        }
+    }
+
+    pub fn create_backup(&mut self) -> io::Result<()> {
+        let dirs = vec![
+            (PathBuf::from("config"), self.config_dir.clone()),
+            (PathBuf::from("worlds"), self.world_dir.clone()),
+        ];
+
+        let backup = if let Some(last_backup) = &self.last_backup {
+            Backup::create_from(Arc::clone(last_backup), &self.backup_dir, dirs)?
+        } else {
+            Backup::create(&self.backup_dir, dirs)?
+        };
+
+        self.last_backup = Some(Arc::new(backup));
+
+        Ok(())
+    }
+
+    /// Remove the oldest backups
+    pub fn remove_old_backups(&mut self) -> std::io::Result<()> {
+        // The naming format used allows us to sort the backups by name and still get a sorting by
+        // creation time
+        let mut backups = self
+            .backup_dir
+            .read_dir()?
+            .filter_map(|res| res.map(|e| e.path()).ok())
+            .collect::<Vec<PathBuf>>();
+        backups.sort();
+
+        let max_backups: usize = self.max_backups.try_into().unwrap();
+
+        if backups.len() > max_backups {
+            let excess_backups = backups.len() - max_backups;
+
+            for backup in &backups[0..excess_backups] {
+                std::fs::remove_file(backup)?;
+            }
+        }
+
+        Ok(())
+    }
+}

src/server/command.rs

@@ -105,14 +105,19 @@ impl ServerCommand {
         Ok(())
     }
 
-    pub fn spawn(self) -> std::io::Result<ServerProcess> {
+    /// Canonicalize all paths to absolute paths. Without this command, all paths will be
+    /// interpreted relatively from the config directory.
+    pub fn canonicalize(&mut self) -> std::io::Result<()> {
         // To avoid any issues, we use absolute paths for everything when spawning the process
-        let jar = self.jar.canonicalize()?;
-        let config_dir = self.config_dir.canonicalize()?;
-        let world_dir = self.world_dir.canonicalize()?;
-        let backup_dir = self.backup_dir.canonicalize()?;
+        self.jar = self.jar.canonicalize()?;
+        self.config_dir = self.config_dir.canonicalize()?;
+        self.world_dir = self.world_dir.canonicalize()?;
+        self.backup_dir = self.backup_dir.canonicalize()?;
 
-        self.accept_eula()?;
+        Ok(())
+    }
+
+    fn create_cmd(&self) -> std::process::Command {
         let mut cmd = Command::new(&self.java);
 
         // Apply JVM optimisation flags
@@ -126,15 +131,6 @@ impl ServerCommand {
                 "-XX:+UnlockExperimentalVMOptions",
                 "-XX:+DisableExplicitGC",
                 "-XX:+AlwaysPreTouch",
-                "-XX:G1HeapWastePercent=5",
-                "-XX:G1MixedGCCountTarget=4",
-                "-XX:G1MixedGCLiveThresholdPercent=90",
-                "-XX:G1RSetUpdatingPauseTimePercent=5",
-                "-XX:SurvivorRatio=32",
-                "-XX:+PerfDisableSharedMem",
-                "-XX:MaxTenuringThreshold=1",
-                "-Dusing.aikars.flags=https://mcflags.emc.gs",
-                "-Daikars.new.flags=true",
             ]);
 
         if self.xms > 12 * 1024 {
@@ -143,36 +139,84 @@ impl ServerCommand {
                 "-XX:G1MaxNewSizePercent=50",
                 "-XX:G1HeapRegionSize=16M",
                 "-XX:G1ReservePercent=15",
-                "-XX:InitiatingHeapOccupancyPercent=20",
             ]);
         } else {
             cmd.args([
                 "-XX:G1NewSizePercent=30",
                 "-XX:G1MaxNewSizePercent=40",
                 "-XX:G1HeapRegionSize=8M",
-                "-XX:G1ReservePercent=15",
-                "-XX:InitiatingHeapOccupancyPercent=15",
+                "-XX:G1ReservePercent=20",
             ]);
         }
 
-        cmd.current_dir(&config_dir)
+        cmd.args(["-XX:G1HeapWastePercent=5", "-XX:G1MixedGCCountTarget=4"]);
+
+        if self.xms > 12 * 1024 {
+            cmd.args(["-XX:InitiatingHeapOccupancyPercent=20"]);
+        } else {
+            cmd.args(["-XX:InitiatingHeapOccupancyPercent=15"]);
+        }
+
+        cmd.args([
+            "-XX:G1MixedGCLiveThresholdPercent=90",
+            "-XX:G1RSetUpdatingPauseTimePercent=5",
+            "-XX:SurvivorRatio=32",
+            "-XX:+PerfDisableSharedMem",
+            "-XX:MaxTenuringThreshold=1",
+            "-Dusing.aikars.flags=https://mcflags.emc.gs",
+            "-Daikars.new.flags=true",
+        ]);
+
+        cmd.current_dir(&self.config_dir)
             .arg("-jar")
-            .arg(&jar)
+            .arg(&self.jar)
             .arg("--universe")
-            .arg(&world_dir)
+            .arg(&self.world_dir)
             .arg("--nogui")
             .stdin(Stdio::piped());
 
+        cmd
+    }
+
+    pub fn spawn(&mut self) -> std::io::Result<ServerProcess> {
+        let mut cmd = self.create_cmd();
+        self.accept_eula()?;
         let child = cmd.spawn()?;
 
         Ok(ServerProcess::new(
             self.type_,
-            self.version,
-            config_dir,
-            world_dir,
-            backup_dir,
+            self.version.clone(),
+            self.config_dir.clone(),
+            self.world_dir.clone(),
+            self.backup_dir.clone(),
             self.max_backups,
             child,
         ))
     }
 }
+
+impl fmt::Display for ServerCommand {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let cmd = self.create_cmd();
+
+        writeln!(f, "Command: {}", self.java)?;
+        writeln!(f, "Working dir: {}", self.config_dir.as_path().display())?;
+
+        // Print command env vars
+        writeln!(f, "Environment:")?;
+
+        for (key, val) in cmd.get_envs().filter(|(_, v)| v.is_some()) {
+            let val = val.unwrap();
+            writeln!(f, "  {}={}", key.to_string_lossy(), val.to_string_lossy())?;
+        }
+
+        // Print command arguments
+        writeln!(f, "Arguments:")?;
+
+        for arg in cmd.get_args() {
+            writeln!(f, "  {}", arg.to_string_lossy())?;
+        }
+
+        Ok(())
+    }
+}

src/server/mod.rs

@@ -1,5 +1,8 @@
+mod backups;
 mod command;
+mod path;
 mod process;
 
+pub use backups::BackupManager;
 pub use command::{ServerCommand, ServerType};
 pub use process::ServerProcess;

src/server/path.rs

@@ -0,0 +1,19 @@
+use chrono::Utc;
+use std::collections::HashSet;
+use std::path::PathBuf;
+use std::{fs, io};
+
+struct ReadDirRecursive {
+    ignored_dirs: HashSet<PathBuf>,
+    read_dir: Option<fs::ReadDir>,
+    stack: Vec<fs::ReadDir>,
+}
+
+impl ReadDirRecursive {
+    // pub fn new()
+}
+
+trait PathExt {
+    fn modified_since(timestamp: chrono::DateTime<Utc>) -> bool;
+    fn read_dir_recusive() -> ReadDirRecursive;
+}

src/server/process.rs

@@ -1,3 +1,4 @@
+use crate::server::BackupManager;
 use crate::server::ServerType;
 use flate2::write::GzEncoder;
 use flate2::Compression;
@@ -5,12 +6,6 @@ use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::Child;
 
-#[link(name = "c")]
-extern "C" {
-    fn geteuid() -> u32;
-    fn getegid() -> u32;
-}
-
 pub struct ServerProcess {
     type_: ServerType,
     version: String,
@@ -19,6 +14,7 @@ pub struct ServerProcess {
     backup_dir: PathBuf,
     max_backups: u64,
     child: Child,
+    backups: BackupManager,
 }
 
 impl ServerProcess {
@@ -31,6 +27,13 @@ impl ServerProcess {
         max_backups: u64,
         child: Child,
     ) -> ServerProcess {
+        let backup_manager = BackupManager::open(
+            backup_dir.clone(),
+            config_dir.clone(),
+            world_dir.clone(),
+            max_backups,
+        );
+
         ServerProcess {
             type_,
             version,
@@ -39,6 +42,7 @@ impl ServerProcess {
             backup_dir,
             max_backups,
             child,
+            backups: backup_manager,
         }
     }
 
@@ -84,94 +88,32 @@ impl ServerProcess {
         // We wait some time to (hopefully) ensure the save-all call has completed
         std::thread::sleep(std::time::Duration::from_secs(10));
 
-        let res = self.create_backup_archive();
+        let start_time = chrono::offset::Utc::now();
+        let res = self.backups.create_backup();
 
         if res.is_ok() {
-            self.remove_old_backups()?;
+            self.backups.remove_old_backups()?;
         }
 
         // The server's save feature needs to be enabled again even if the archive failed to create
         self.custom("save-on")?;
 
+        let duration = chrono::offset::Utc::now() - start_time;
+        let duration_str = format!(
+            "{}m{}s",
+            duration.num_seconds() / 60,
+            duration.num_seconds() % 60
+        );
+
         if res.is_ok() {
-            self.custom("say server backed up successfully")?;
+            self.custom(&format!("say server backed up in {}", duration_str))?;
         } else {
-            self.custom("an error occured while backing up the server")?;
+            self.custom(&format!(
+                "an error occured after {} while backing up the server",
+                duration_str
+            ))?;
         }
 
         res
     }
-
-    /// Create a new compressed backup archive of the server's data.
-    fn create_backup_archive(&mut self) -> std::io::Result<()> {
-        // Create a gzip-compressed tarball of the worlds folder
-        let filename = format!(
-            "{}",
-            chrono::offset::Local::now().format("%Y-%m-%d_%H-%M-%S.tar.gz")
-        );
-        let path = self.backup_dir.join(filename);
-        let tar_gz = std::fs::File::create(path)?;
-        let enc = GzEncoder::new(tar_gz, Compression::default());
-        let mut tar = tar::Builder::new(enc);
-
-        tar.append_dir_all("worlds", &self.world_dir)?;
-
-        // Add all files from the config directory that aren't the cache
-        for entry in self
-            .config_dir
-            .read_dir()?
-            .filter_map(|e| e.ok())
-            .filter(|e| e.file_name() != "cache")
-        {
-            let tar_path = Path::new("config").join(entry.file_name());
-
-            if entry.file_type()?.is_dir() {
-                tar.append_dir_all(tar_path, entry.path())?;
-            } else {
-                tar.append_path_with_name(entry.path(), tar_path)?;
-            }
-        }
-
-        // We add a file to the backup describing for what version it was made
-        let info = format!("{} {}", self.type_, self.version);
-        let info_bytes = info.as_bytes();
-
-        let mut header = tar::Header::new_gnu();
-        header.set_size(info_bytes.len().try_into().unwrap());
-        header.set_mode(0o100644);
-        unsafe {
-            header.set_gid(getegid().into());
-            header.set_uid(geteuid().into());
-        }
-
-        tar.append_data(&mut header, "info.txt", info_bytes)?;
-
-        // Backup file gets finalized in the drop
-
-        Ok(())
-    }
-
-    /// Remove the oldest backups
-    fn remove_old_backups(&mut self) -> std::io::Result<()> {
-        // The naming format used allows us to sort the backups by name and still get a sorting by
-        // creation time
-        let mut backups = self
-            .backup_dir
-            .read_dir()?
-            .filter_map(|res| res.map(|e| e.path()).ok())
-            .collect::<Vec<PathBuf>>();
-        backups.sort();
-
-        let max_backups: usize = self.max_backups.try_into().unwrap();
-
-        if backups.len() > max_backups {
-            let excess_backups = backups.len() - max_backups;
-
-            for backup in &backups[0..excess_backups] {
-                std::fs::remove_file(backup)?;
-            }
-        }
-
-        Ok(())
-    }
 }