MeiliSearch/meilisearch-lib/src/index_controller/snapshot.rs

use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::time::Duration;

use anyhow::bail;
use log::{error, info, trace};
use tokio::fs;
use tokio::task::spawn_blocking;
use tokio::time::sleep;

use crate::index_controller::updates::UpdateMsg;

use super::index_resolver::HardStateIndexResolver;
use super::updates::UpdateSender;

pub struct SnapshotService {
    index_resolver: Arc<HardStateIndexResolver>,
    update_sender: UpdateSender,
    snapshot_period: Duration,
    snapshot_path: PathBuf,
    db_name: String,
}

impl SnapshotService {
    pub fn new(
        index_resolver: Arc<HardStateIndexResolver>,
        update_sender: UpdateSender,
        snapshot_period: Duration,
        snapshot_path: PathBuf,
        db_name: String,
    ) -> Self {
        Self {
            index_resolver,
            update_sender,
            snapshot_period,
            snapshot_path,
            db_name,
        }
    }

    pub async fn run(self) {
        info!(
            "Snapshot scheduled every {}s.",
            self.snapshot_period.as_secs()
        );
        loop {
            if let Err(e) = self.perform_snapshot().await {
                error!("Error while performing snapshot: {}", e);
            }
            sleep(self.snapshot_period).await;
        }
    }

    async fn perform_snapshot(&self) -> anyhow::Result<()> {
        trace!("Performing snapshot.");

        let snapshot_dir = self.snapshot_path.clone();
        fs::create_dir_all(&snapshot_dir).await?;
        let temp_snapshot_dir = spawn_blocking(tempfile::tempdir).await??;
        let temp_snapshot_path = temp_snapshot_dir.path().to_owned();

        let indexes = self
            .index_resolver
            .snapshot(temp_snapshot_path.clone())
            .await?;

        if indexes.is_empty() {
            return Ok(());
        }

        UpdateMsg::snapshot(&self.update_sender, temp_snapshot_path.clone(), indexes).await?;

        let snapshot_path = self
            .snapshot_path
            .join(format!("{}.snapshot", self.db_name));
        let snapshot_path = spawn_blocking(move || -> anyhow::Result<PathBuf> {
            let temp_snapshot_file = tempfile::NamedTempFile::new()?;
            let temp_snapshot_file_path = temp_snapshot_file.path().to_owned();
            crate::compression::to_tar_gz(temp_snapshot_path, temp_snapshot_file_path)?;
            temp_snapshot_file.persist(&snapshot_path)?;
            Ok(snapshot_path)
        })
        .await??;

        trace!("Created snapshot in {:?}.", snapshot_path);

        Ok(())
    }
}

pub fn load_snapshot(
    db_path: impl AsRef<Path>,
    snapshot_path: impl AsRef<Path>,
    ignore_snapshot_if_db_exists: bool,
    ignore_missing_snapshot: bool,
) -> anyhow::Result<()> {
    if !db_path.as_ref().exists() && snapshot_path.as_ref().exists() {
        match crate::from_tar_gz(snapshot_path, &db_path) {
            Ok(()) => Ok(()),
            Err(e) => {
                //clean created db folder
                std::fs::remove_dir_all(&db_path)?;
                Err(e)
            }
        }
    } else if db_path.as_ref().exists() && !ignore_snapshot_if_db_exists {
        bail!(
            "database already exists at {:?}, try to delete it or rename it",
            db_path
                .as_ref()
                .canonicalize()
                .unwrap_or_else(|_| db_path.as_ref().to_owned())
        )
    } else if !snapshot_path.as_ref().exists() && !ignore_missing_snapshot {
        bail!(
            "snapshot doesn't exist at {:?}",
            snapshot_path
                .as_ref()
                .canonicalize()
                .unwrap_or_else(|_| snapshot_path.as_ref().to_owned())
        )
    } else {
        Ok(())
    }
}

//#[cfg(test)]
//mod test {
//use std::iter::FromIterator;
//use std::{collections::HashSet, sync::Arc};

//use futures::future::{err, ok};
//use rand::Rng;
//use tokio::time::timeout;
//use uuid::Uuid;

//use super::*;

//#[actix_rt::test]
//async fn test_normal() {
//let mut rng = rand::thread_rng();
//let uuids_num: usize = rng.gen_range(5..10);
//let uuids = (0..uuids_num)
//.map(|_| Uuid::new_v4())
//.collect::<HashSet<_>>();

//let mut uuid_resolver = MockUuidResolverHandle::new();
//let uuids_clone = uuids.clone();
//uuid_resolver
//.expect_snapshot()
//.times(1)
//.returning(move |_| Box::pin(ok(uuids_clone.clone())));

//let uuids_clone = uuids.clone();
//let mut index_handle = MockIndexActorHandle::new();
//index_handle
//.expect_snapshot()
//.withf(move |uuid, _path| uuids_clone.contains(uuid))
//.times(uuids_num)
//.returning(move |_, _| Box::pin(ok(())));

//let dir = tempfile::tempdir_in(".").unwrap();
//let handle = Arc::new(index_handle);
//let update_handle =
//UpdateActorHandleImpl::<Vec<u8>>::new(handle.clone(), dir.path(), 4096 * 100).unwrap();

//let snapshot_path = tempfile::tempdir_in(".").unwrap();
//let snapshot_service = SnapshotService::new(
//uuid_resolver,
//update_handle,
//Duration::from_millis(100),
//snapshot_path.path().to_owned(),
//"data.ms".to_string(),
//);

//snapshot_service.perform_snapshot().await.unwrap();
//}

//#[actix_rt::test]
//async fn error_performing_uuid_snapshot() {
//let mut uuid_resolver = MockUuidResolverHandle::new();
//uuid_resolver
//.expect_snapshot()
//.times(1)
////abitrary error
//.returning(|_| Box::pin(err(UuidResolverError::NameAlreadyExist)));

//let update_handle = MockUpdateActorHandle::new();

//let snapshot_path = tempfile::tempdir_in(".").unwrap();
//let snapshot_service = SnapshotService::new(
//uuid_resolver,
//update_handle,
//Duration::from_millis(100),
//snapshot_path.path().to_owned(),
//"data.ms".to_string(),
//);

//assert!(snapshot_service.perform_snapshot().await.is_err());
////Nothing was written to the file
//assert!(!snapshot_path.path().join("data.ms.snapshot").exists());
//}

//#[actix_rt::test]
//async fn error_performing_index_snapshot() {
//let uuid = Uuid::new_v4();
//let mut uuid_resolver = MockUuidResolverHandle::new();
//uuid_resolver
//.expect_snapshot()
//.times(1)
//.returning(move |_| Box::pin(ok(HashSet::from_iter(Some(uuid)))));

//let mut update_handle = MockUpdateActorHandle::new();
//update_handle
//.expect_snapshot()
////abitrary error
//.returning(|_, _| Box::pin(err(UpdateActorError::UnexistingUpdate(0))));

//let snapshot_path = tempfile::tempdir_in(".").unwrap();
//let snapshot_service = SnapshotService::new(
//uuid_resolver,
//update_handle,
//Duration::from_millis(100),
//snapshot_path.path().to_owned(),
//"data.ms".to_string(),
//);

//assert!(snapshot_service.perform_snapshot().await.is_err());
////Nothing was written to the file
//assert!(!snapshot_path.path().join("data.ms.snapshot").exists());
//}

//#[actix_rt::test]
//async fn test_loop() {
//let mut uuid_resolver = MockUuidResolverHandle::new();
//uuid_resolver
//.expect_snapshot()
////we expect the funtion to be called between 2 and 3 time in the given interval.
//.times(2..4)
////abitrary error, to short-circuit the function
//.returning(move |_| Box::pin(err(UuidResolverError::NameAlreadyExist)));

//let update_handle = MockUpdateActorHandle::new();

//let snapshot_path = tempfile::tempdir_in(".").unwrap();
//let snapshot_service = SnapshotService::new(
//uuid_resolver,
//update_handle,
//Duration::from_millis(100),
//snapshot_path.path().to_owned(),
//"data.ms".to_string(),
//);

//let _ = timeout(Duration::from_millis(300), snapshot_service.run()).await;
//}
//}