quiverdb-server 0.29.0

// SPDX-License-Identifier: MIT OR Apache-2.0
//! In-memory Raft log store (`RaftLogStorage`), vendored from openraft.
//!
//! Source: `examples/memstore/src/log_store.rs` in
//! <https://github.com/databendlabs/openraft> at tag `v0.9.24`
//! (license: MIT OR Apache-2.0 — retained for this file).
//!
//! Why vendored rather than depended-upon: the published `openraft-memstore`
//! crate implements the deprecated v1 combined `RaftStorage`, which openraft's
//! `storage-v2` feature (the split log/state-machine API we use, ADR-0067)
//! removes — so it does not compile against our configuration. This file is the
//! generic, reusable v2 `LogStore<C>`: a deliberately trivial in-memory log
//! container with **no consensus logic** (the audited protocol stays in
//! `openraft` core). Increment 4a runs a single-member group on this volatile
//! store; increment 4c replaces it with a durable, ADR-0050-snapshot-backed
//! store for log compaction. Edits from upstream: the `LogStore` import path in
//! the inner module, and reformatting to this project's rustfmt style — the
//! logic is unchanged.
#![allow(missing_docs)]

use std::collections::BTreeMap;
use std::fmt::Debug;
use std::ops::RangeBounds;
use std::sync::Arc;

use openraft::LogId;
use openraft::LogState;
use openraft::RaftLogId;
use openraft::RaftTypeConfig;
use openraft::StorageError;
use openraft::Vote;
use openraft::storage::LogFlushed;
use tokio::sync::Mutex;

/// RaftLogStore implementation with a in-memory storage
#[derive(Clone, Debug, Default)]
pub struct LogStore<C: RaftTypeConfig> {
    inner: Arc<Mutex<LogStoreInner<C>>>,
}

#[derive(Debug)]
pub struct LogStoreInner<C: RaftTypeConfig> {
    /// The last purged log id.
    last_purged_log_id: Option<LogId<C::NodeId>>,

    /// The Raft log.
    log: BTreeMap<u64, C::Entry>,

    /// The commit log id.
    committed: Option<LogId<C::NodeId>>,

    /// The current granted vote.
    vote: Option<Vote<C::NodeId>>,
}

impl<C: RaftTypeConfig> Default for LogStoreInner<C> {
    fn default() -> Self {
        Self {
            last_purged_log_id: None,
            log: BTreeMap::new(),
            committed: None,
            vote: None,
        }
    }
}

impl<C: RaftTypeConfig> LogStoreInner<C> {
    async fn try_get_log_entries<RB: RangeBounds<u64> + Clone + Debug>(
        &mut self,
        range: RB,
    ) -> Result<Vec<C::Entry>, StorageError<C::NodeId>>
    where
        C::Entry: Clone,
    {
        let response = self
            .log
            .range(range.clone())
            .map(|(_, val)| val.clone())
            .collect::<Vec<_>>();
        Ok(response)
    }

    async fn get_log_state(&mut self) -> Result<LogState<C>, StorageError<C::NodeId>> {
        let last = self
            .log
            .iter()
            .next_back()
            .map(|(_, ent)| ent.get_log_id().clone());

        let last_purged = self.last_purged_log_id.clone();

        let last = match last {
            None => last_purged.clone(),
            Some(x) => Some(x),
        };

        Ok(LogState {
            last_purged_log_id: last_purged,
            last_log_id: last,
        })
    }

    async fn save_committed(
        &mut self,
        committed: Option<LogId<C::NodeId>>,
    ) -> Result<(), StorageError<C::NodeId>> {
        self.committed = committed;
        Ok(())
    }

    async fn read_committed(
        &mut self,
    ) -> Result<Option<LogId<C::NodeId>>, StorageError<C::NodeId>> {
        Ok(self.committed.clone())
    }

    async fn save_vote(&mut self, vote: &Vote<C::NodeId>) -> Result<(), StorageError<C::NodeId>> {
        self.vote = Some(vote.clone());
        Ok(())
    }

    async fn read_vote(&mut self) -> Result<Option<Vote<C::NodeId>>, StorageError<C::NodeId>> {
        Ok(self.vote.clone())
    }

    async fn append<I>(
        &mut self,
        entries: I,
        callback: LogFlushed<C>,
    ) -> Result<(), StorageError<C::NodeId>>
    where
        I: IntoIterator<Item = C::Entry>,
    {
        // Simple implementation that calls the flush-before-return `append_to_log`.
        for entry in entries {
            self.log.insert(entry.get_log_id().index, entry);
        }
        callback.log_io_completed(Ok(()));

        Ok(())
    }

    async fn truncate(&mut self, log_id: LogId<C::NodeId>) -> Result<(), StorageError<C::NodeId>> {
        let keys = self
            .log
            .range(log_id.index..)
            .map(|(k, _v)| *k)
            .collect::<Vec<_>>();
        for key in keys {
            self.log.remove(&key);
        }

        Ok(())
    }

    async fn purge(&mut self, log_id: LogId<C::NodeId>) -> Result<(), StorageError<C::NodeId>> {
        {
            let ld = &mut self.last_purged_log_id;
            assert!(ld.as_ref() <= Some(&log_id));
            *ld = Some(log_id.clone());
        }

        {
            let keys = self
                .log
                .range(..=log_id.index)
                .map(|(k, _v)| *k)
                .collect::<Vec<_>>();
            for key in keys {
                self.log.remove(&key);
            }
        }

        Ok(())
    }
}

mod impl_log_store {
    use std::fmt::Debug;
    use std::ops::RangeBounds;

    use openraft::LogId;
    use openraft::LogState;
    use openraft::RaftLogReader;
    use openraft::RaftTypeConfig;
    use openraft::StorageError;
    use openraft::Vote;
    use openraft::storage::LogFlushed;
    use openraft::storage::RaftLogStorage;

    use super::LogStore;

    impl<C: RaftTypeConfig> RaftLogReader<C> for LogStore<C>
    where
        C::Entry: Clone,
    {
        async fn try_get_log_entries<RB: RangeBounds<u64> + Clone + Debug>(
            &mut self,
            range: RB,
        ) -> Result<Vec<C::Entry>, StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.try_get_log_entries(range).await
        }
    }

    impl<C: RaftTypeConfig> RaftLogStorage<C> for LogStore<C>
    where
        C::Entry: Clone,
    {
        type LogReader = Self;

        async fn get_log_state(&mut self) -> Result<LogState<C>, StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.get_log_state().await
        }

        async fn save_committed(
            &mut self,
            committed: Option<LogId<C::NodeId>>,
        ) -> Result<(), StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.save_committed(committed).await
        }

        async fn read_committed(
            &mut self,
        ) -> Result<Option<LogId<C::NodeId>>, StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.read_committed().await
        }

        async fn save_vote(
            &mut self,
            vote: &Vote<C::NodeId>,
        ) -> Result<(), StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.save_vote(vote).await
        }

        async fn read_vote(&mut self) -> Result<Option<Vote<C::NodeId>>, StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.read_vote().await
        }

        async fn append<I>(
            &mut self,
            entries: I,
            callback: LogFlushed<C>,
        ) -> Result<(), StorageError<C::NodeId>>
        where
            I: IntoIterator<Item = C::Entry>,
        {
            let mut inner = self.inner.lock().await;
            inner.append(entries, callback).await
        }

        async fn truncate(
            &mut self,
            log_id: LogId<C::NodeId>,
        ) -> Result<(), StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.truncate(log_id).await
        }

        async fn purge(&mut self, log_id: LogId<C::NodeId>) -> Result<(), StorageError<C::NodeId>> {
            let mut inner = self.inner.lock().await;
            inner.purge(log_id).await
        }

        async fn get_log_reader(&mut self) -> Self::LogReader {
            self.clone()
        }
    }
}