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use std::fs;
use std::path::PathBuf;
use std::sync::Arc;
use std::sync::Mutex;
use std::time::{Duration, Instant};
use async_trait::async_trait;
use rand::prelude::*;
use tokio::sync::watch;
use garage_util::background::*;
use garage_util::error::*;
use crate::garage::Garage;
// The two most recent snapshots are kept
const KEEP_SNAPSHOTS: usize = 2;
static SNAPSHOT_MUTEX: Mutex<()> = Mutex::new(());
// ================ snapshotting logic =====================
/// Run snashot_metadata in a blocking thread and async await on it
pub async fn async_snapshot_metadata(garage: &Arc<Garage>) -> Result<(), Error> {
let garage = garage.clone();
let worker = tokio::task::spawn_blocking(move || snapshot_metadata(&garage));
worker.await.unwrap()?;
Ok(())
}
/// Take a snapshot of the metadata database, and erase older
/// snapshots if necessary.
/// This is not an async function, it should be spawned on a thread pool
pub fn snapshot_metadata(garage: &Garage) -> Result<(), Error> {
let lock = match SNAPSHOT_MUTEX.try_lock() {
Ok(lock) => lock,
Err(_) => {
return Err(Error::Message(
"Cannot acquire lock, another snapshot might be in progress".into(),
))
}
};
let mut snapshots_dir = garage.config.metadata_dir.clone();
snapshots_dir.push("snapshots");
fs::create_dir_all(&snapshots_dir)?;
let mut new_path = snapshots_dir.clone();
new_path.push(chrono::Utc::now().to_rfc3339_opts(chrono::SecondsFormat::Secs, true));
info!("Snapshotting metadata db to {}", new_path.display());
garage.db.snapshot(&new_path)?;
info!("Metadata db snapshot finished");
if let Err(e) = cleanup_snapshots(&snapshots_dir) {
error!("Failed to do cleanup in snapshots directory: {}", e);
}
drop(lock);
Ok(())
}
fn cleanup_snapshots(snapshots_dir: &PathBuf) -> Result<(), Error> {
let mut snapshots =
fs::read_dir(&snapshots_dir)?.collect::<Result<Vec<fs::DirEntry>, std::io::Error>>()?;
snapshots.retain(|x| x.file_name().len() > 8);
snapshots.sort_by_key(|x| x.file_name());
for to_delete in snapshots.iter().rev().skip(KEEP_SNAPSHOTS) {
let path = snapshots_dir.join(to_delete.path());
if to_delete.metadata()?.file_type().is_dir() {
for file in fs::read_dir(&path)? {
let file = file?;
if file.metadata()?.is_file() {
fs::remove_file(path.join(file.path()))?;
}
}
std::fs::remove_dir(&path)?;
} else {
std::fs::remove_file(&path)?;
}
}
Ok(())
}
// ================ auto snapshot worker =====================
pub struct AutoSnapshotWorker {
garage: Arc<Garage>,
next_snapshot: Instant,
snapshot_interval: Duration,
}
impl AutoSnapshotWorker {
pub(crate) fn new(garage: Arc<Garage>, snapshot_interval: Duration) -> Self {
Self {
garage,
snapshot_interval,
next_snapshot: Instant::now() + (snapshot_interval / 2),
}
}
}
#[async_trait]
impl Worker for AutoSnapshotWorker {
fn name(&self) -> String {
"Metadata snapshot worker".into()
}
fn status(&self) -> WorkerStatus {
WorkerStatus {
freeform: vec![format!(
"Next snapshot: {}",
(chrono::Utc::now() + (self.next_snapshot - Instant::now())).to_rfc3339()
)],
..Default::default()
}
}
async fn work(&mut self, _must_exit: &mut watch::Receiver<bool>) -> Result<WorkerState, Error> {
if Instant::now() < self.next_snapshot {
return Ok(WorkerState::Idle);
}
async_snapshot_metadata(&self.garage).await?;
let rand_factor = 1f32 + thread_rng().gen::<f32>() / 5f32;
self.next_snapshot = Instant::now() + self.snapshot_interval.mul_f32(rand_factor);
Ok(WorkerState::Idle)
}
async fn wait_for_work(&mut self) -> WorkerState {
tokio::time::sleep_until(self.next_snapshot.into()).await;
WorkerState::Busy
}
}
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