Module checkpoint 

Checkpoint and recovery for FASTER

This module provides checkpointing and recovery functionality for FasterKV stores.

Overview

FASTER uses the CPR (Concurrent Prefix Recovery) protocol for checkpointing, which allows checkpoints to be taken without stopping normal operations.

Checkpoint Types

• Full Checkpoint: Saves both index and hybrid log state
• Index-Only Checkpoint: Saves only the hash index
• HybridLog-Only Checkpoint: Saves only the log state
• Incremental Checkpoint: Saves only changes since last snapshot

CPR Protocol Phases

1. PrepIndexChkpt: Prepare index checkpoint, synchronize threads
2. IndexChkpt: Write index to disk
3. Prepare: Prepare HybridLog checkpoint
4. InProgress: Increment version, mark checkpoint in progress
5. WaitPending: Wait for pending operations
6. WaitFlush: Wait for log flush
7. PersistenceCallback: Invoke persistence callback
8. Rest: Return to rest state

File Structure

Each checkpoint creates a directory with the following files:

• index.meta: Index checkpoint metadata (JSON)
• index.dat: Hash index data (binary)
• log.meta: Log checkpoint metadata (JSON)
• log.snapshot: Log snapshot data (binary)

Usage

use std::path::Path;

// Create checkpoint
let token = store.checkpoint(Path::new("/checkpoints"))?;

// Recover from checkpoint
let recovered = FasterKv::recover(
    Path::new("/checkpoints"),
    token,
    config,
    device
)?;

Re-exports

pub use serialization::create_checkpoint_directory;

pub use serialization::delta_log_path;

pub use serialization::delta_metadata_path;

pub use serialization::incremental_info_path;

pub use serialization::index_data_path;

pub use serialization::index_metadata_path;

pub use serialization::log_metadata_path;

pub use serialization::log_snapshot_path;

pub use serialization::DeltaLogMetadata;

pub use serialization::IncrementalCheckpointChain;

pub use serialization::SerializableCheckpointInfo;

pub use serialization::SerializableIndexMetadata;

pub use serialization::SerializableLogMetadata;

Modules

binary_format

C-style binary format serialization for FASTER C++ compatibility

serialization

Serialization support for checkpoint metadata

Structs

AtomicCheckpointLock

Atomic checkpoint lock for thread-safe operations.

CheckpointInfo

Information about a checkpoint for recovery

CheckpointLock

A checkpoint lock that tracks old and new version lock counts.

CheckpointLockGuard

RAII guard for checkpoint locks.

CheckpointLocks

A table of checkpoint locks indexed by key hash.

CheckpointState

State of an active checkpoint operation

IndexMetadata

Index metadata for checkpoint

LogMetadata

Log metadata for checkpoint

RecoveryState

Recovery state and operations

SessionState

Session state for checkpoint persistence

Enums

CheckpointType

Checkpoint type

LockType

Type of lock held by a CheckpointLockGuard

PageRecoveryStatus

Fine-grained recovery status for individual pages. Based on C++ FASTER’s five-phase page recovery tracking.

RecoveryStatus

Status of a recovery operation

Functions

find_latest_checkpoint

Find the latest checkpoint in a directory

list_checkpoints

List all checkpoints in a directory

validate_checkpoint

Validate that a checkpoint directory contains all required files

Type Aliases

CheckpointToken

Token identifying a checkpoint

HybridLogPersistenceCallback

Callback for hybrid log persistence completion

IndexPersistenceCallback

Callback for index persistence completion