Struct CheckpointManager 

pub struct CheckpointManager { /* private fields */ }

Checkpoint manager for WAL maintenance.

Manages periodic checkpoints and WAL trimming to keep the WAL file size bounded.

Implementations

impl CheckpointManager

pub fn new(wal: Arc<WriteAheadLog>, wal_path: &Path) -> Self

Creates a new checkpoint manager.

Arguments

• wal - Shared reference to the WAL
• wal_path - Path to the WAL file

Example

let wal = Arc::new(WriteAheadLog::open(Path::new("./wal.log"))?);
let checkpoint_mgr = CheckpointManager::new(wal, Path::new("./wal.log"));

pub fn with_interval(self, interval: Duration) -> Self

Sets the checkpoint interval.

Arguments

• interval - Duration between checkpoints

pub fn checkpoint<F>(&self, apply_fn: F) -> DbxResult<u64>

where F: Fn(&WalRecord) -> DbxResult<()>,

Performs a checkpoint.

Applies all WAL records to the database and writes a checkpoint marker. This method should be called by the Database engine.

Arguments

• apply_fn - Function to apply a WAL record to the database

Returns

The sequence number of the checkpoint

Example

let wal = Arc::new(WriteAheadLog::open(Path::new("./wal.log"))?);
let checkpoint_mgr = CheckpointManager::new(wal, Path::new("./wal.log"));

let apply_fn = |record: &WalRecord| -> dbx_core::DbxResult<()> {
    // Apply record to database
    Ok(())
};

let checkpoint_seq = checkpoint_mgr.checkpoint(apply_fn)?;

pub fn recover<F>(wal_path: &Path, apply_fn: F) -> DbxResult<usize>

where F: Fn(&WalRecord) -> DbxResult<()>,

Recovers the database by replaying WAL records.

This is called during database startup to restore the state after a crash.

Arguments

• wal_path - Path to the WAL file
• apply_fn - Function to apply a WAL record to the database

Returns

The number of records replayed

Example

let apply_fn = |record: &WalRecord| -> dbx_core::DbxResult<()> {
    // Apply record to database
    Ok(())
};

let count = CheckpointManager::recover(Path::new("./wal.log"), apply_fn)?;
println!("Replayed {} records", count);

pub fn trim_before(&self, sequence: u64) -> DbxResult<()>

Trims the WAL file by removing records before the specified sequence.

This is called after a successful checkpoint to keep the WAL file size bounded.

Arguments

• sequence - Sequence number to trim before

Example

let wal = Arc::new(WriteAheadLog::open(Path::new("./wal.log"))?);
let checkpoint_mgr = CheckpointManager::new(wal, Path::new("./wal.log"));

// Trim records before sequence 100
checkpoint_mgr.trim_before(100)?;

pub fn interval(&self) -> Duration

Returns the checkpoint interval.