oxifaster

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oxifaster is a Rust port of Microsoft's FASTER project, providing a high-performance concurrent key-value store and log engine.

Features

• High Performance: Efficient read/write operations for large-scale data exceeding memory capacity
• Concurrency Safe: Lock-free concurrent control based on Epoch protection mechanism
• Persistence: Complete Checkpoint and Recovery support with CPR protocol
• Hybrid Log: HybridLog architecture with hot data in memory + cold data on disk
• Async I/O: Async operation support based on Tokio runtime
• Read Cache: Hot data memory cache for accelerated reads, transparently integrated into the read path
• Log Compaction: Log compaction and space reclamation with automatic background compaction support
• Index Growth: Dynamic hash table expansion with rehash callback for correctness
• F2 Architecture: Two-tier storage with hot-cold data separation, including complete Checkpoint/Recovery
• Statistics: Comprehensive statistics collection integrated into all CRUD operations
• Prometheus Metrics: Render statistics snapshots as Prometheus text exposition for external scraping (feature = prometheus)

Quick Start

Installation

Add the dependency to your Cargo.toml:

[dependencies]
oxifaster = { path = "oxifaster" }

Enable the Linux io_uring backend (feature-gated):

[dependencies]
oxifaster = { path = "oxifaster", features = ["io_uring"] }

Note: the real io_uring backend is only available on Linux. On non-Linux platforms (or when the feature is disabled), IoUringDevice falls back to a portable file-backed implementation.

Enable Prometheus text exposition (for statistics snapshots):

[dependencies]
oxifaster = { path = "oxifaster", features = ["prometheus"] }

With prometheus enabled, you can also run a minimal HTTP /metrics server (Tokio required):

use std::net::SocketAddr;
use std::sync::Arc;

use oxifaster::device::NullDisk;
use oxifaster::stats::prometheus::{MetricsHttpServer, PrometheusRenderer};
use oxifaster::store::{FasterKv, FasterKvConfig};

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let store = Arc::new(FasterKv::<u64, u64, _>::new(
        FasterKvConfig::default(),
        NullDisk::new(),
    ));

    let store_for_server = store.clone();
    let render = Arc::new(move || {
        PrometheusRenderer::new().render_snapshot(&store_for_server.stats_snapshot())
    });

    let addr: SocketAddr = "127.0.0.1:9898".parse().unwrap();
    let server = MetricsHttpServer::bind(addr, render).await?;
    println!("metrics: http://{}/metrics", server.local_addr());

    tokio::signal::ctrl_c().await.ok();
    server.shutdown().await?;
    Ok(())
}

Basic Usage

use std::sync::Arc;
use oxifaster::device::FileSystemDisk;
use oxifaster::store::{FasterKv, FasterKvConfig};

fn main() -> std::io::Result<()> {
    // Create configuration
    let config = FasterKvConfig::default();
    
    // Create storage device (FileSystemDisk is the default persistent device)
    let device = FileSystemDisk::single_file("oxifaster.db")?;
    
    // Create store
    let store = Arc::new(FasterKv::new(config, device));
    
    // Start session
    let mut session = store.start_session().expect("failed to start session");
    
    // Insert data
    session.upsert(42u64, 100u64);
    
    // Read data
    if let Ok(Some(value)) = session.read(&42u64) {
        println!("Value: {}", value);
    }
    
    // Delete data
    session.delete(&42u64);

    Ok(())
}

Configuration (TOML + Environment)

Use oxifaster::config::OxifasterConfig to load a TOML file and apply environment overrides.

Example oxifaster.toml:

[store]
table_size = 1048576
log_memory_size = 536870912
page_size_bits = 22
mutable_fraction = 0.9

[compaction]
target_utilization = 0.5
min_compact_bytes = 1048576
max_compact_bytes = 1073741824
num_threads = 1
compact_tombstones = true

[cache]
enabled = true
mem_size = 268435456
mutable_fraction = 0.9
pre_allocate = false
copy_to_tail = true

[device]
kind = "single_file"
path = "oxifaster.db"

Load from OXIFASTER_CONFIG and apply overrides such as OXIFASTER__store__table_size=2097152:

use oxifaster::config::OxifasterConfig;

let config = OxifasterConfig::load_from_env()?;
let store_config = config.to_faster_kv_config();
let compaction_config = config.to_compaction_config();
let cache_config = config.to_read_cache_config();
let device = config.open_device()?;

Development Roadmap

Please refer to DEV.md for the detailed development roadmap, implementation status, and technical debt analysis.

Module Structure

oxifaster/
├── src/
│   ├── lib.rs              # Library entry
│   ├── address.rs          # Address system (Address, AtomicAddress)
│   ├── record.rs           # Record structure (RecordInfo, Record, Key, Value)
│   ├── status.rs           # Status codes (Status, OperationStatus)
│   ├── utility.rs          # Utility functions
│   │
│   ├── epoch/              # Epoch protection mechanism
│   │   ├── mod.rs
│   │   └── light_epoch.rs
│   │
│   ├── index/              # Hash index
│   │   ├── mod.rs
│   │   ├── hash_bucket.rs
│   │   ├── hash_table.rs
│   │   ├── mem_index.rs
│   │   ├── grow.rs         # Index growth
│   │   └── cold_index.rs   # Disk cold index
│   │
│   ├── allocator/          # Memory allocator
│   │   ├── mod.rs
│   │   ├── page_allocator.rs
│   │   └── hybrid_log.rs
│   │
│   ├── device/             # Storage devices
│   │   ├── mod.rs
│   │   ├── traits.rs
│   │   ├── file_device.rs
│   │   ├── null_device.rs
│   │   ├── io_uring.rs        # io_uring entrypoint (Linux + mock)
│   │   ├── io_uring_common.rs # Shared types
│   │   ├── io_uring_linux.rs  # Linux backend (feature = "io_uring")
│   │   └── io_uring_mock.rs   # Non-Linux / feature off fallback
│   │
│   ├── store/              # FasterKV store
│   │   ├── mod.rs
│   │   ├── faster_kv.rs
│   │   ├── session.rs
│   │   ├── contexts.rs
│   │   └── state_transitions.rs
│   │
│   ├── checkpoint/         # Checkpoint and recovery
│   │   ├── mod.rs
│   │   ├── state.rs
│   │   ├── locks.rs        # CPR checkpoint locks
│   │   ├── recovery.rs
│   │   └── serialization.rs
│   │
│   ├── log/                # FASTER Log
│   │   ├── mod.rs
│   │   └── faster_log.rs
│   │
│   ├── cache/              # Read Cache
│   │   ├── mod.rs
│   │   ├── config.rs
│   │   ├── read_cache.rs
│   │   ├── record_info.rs
│   │   └── stats.rs
│   │
│   ├── compaction/         # Log compaction
│   │   ├── mod.rs
│   │   ├── compact.rs
│   │   ├── concurrent.rs    # Concurrent compaction
│   │   ├── auto_compact.rs  # Auto compaction background thread
│   │   └── contexts.rs
│   │
│   ├── f2/                 # F2 hot-cold architecture
│   │   ├── mod.rs
│   │   ├── config.rs
│   │   ├── store.rs
│   │   └── state.rs
│   │
│   ├── scan/               # Log scanning
│   │   ├── mod.rs
│   │   └── log_iterator.rs
│   │
│   └── stats/              # Statistics collection
│       ├── mod.rs
│       ├── collector.rs
│       ├── metrics.rs
│       └── reporter.rs
│
├── examples/               # Example code
│   ├── async_operations.rs
│   ├── basic_kv.rs
│   ├── cold_index.rs
│   ├── compaction.rs
│   ├── concurrent_access.rs
│   ├── custom_types.rs
│   ├── epoch_protection.rs
│   ├── f2_hot_cold.rs
│   ├── faster_log.rs
│   ├── index_growth.rs
│   ├── log_scan.rs
│   ├── read_cache.rs
│   ├── statistics.rs
│   └── variable_length.rs
│
├── benches/
│   └── ycsb.rs             # YCSB benchmark
│
└── tests/
    ├── async_session.rs    # Async session tests
    ├── basic_ops.rs        # Basic operations tests
    ├── checkpoint_locks.rs # Checkpoint locks tests
    ├── checkpoint.rs       # Checkpoint tests
    ├── cold_index.rs       # Cold index tests
    ├── compaction.rs       # Compaction tests
    ├── f2.rs               # F2 tests
    ├── incremental_checkpoint.rs # Incremental checkpoint tests
    ├── index_growth.rs     # Index growth tests
    ├── log_scan.rs         # Log scan tests
    ├── read_cache.rs       # Read cache tests
    ├── recovery.rs         # Recovery tests
    ├── statistics.rs       # Statistics tests
    └── varlen.rs           # Variable length tests

Core Concepts

Address

48-bit logical address used to identify record positions in the hybrid log:

• 25-bit page offset (32 MB per page)
• 23-bit page number (~8 million pages)

Epoch Protection

Lightweight epoch protection mechanism for:

• Safe memory reclamation
• Lock-free concurrent control
• Delayed operation execution

Hybrid Log

Hybrid log allocator managing memory and disk storage:

• Mutable Region: Latest pages supporting in-place updates
• Read-Only Region: Older pages in memory
• Disk Region: Cold data

Hash Index

High-performance in-memory hash index:

• Cache-line aligned hash buckets (64 bytes)
• 14-bit tags for fast comparison
• Overflow bucket support
• Dynamic expansion support

Read Cache

Hot data cache:

• In-memory storage for frequently read records
• LRU-like eviction policy
• Transparently integrated into read path

Log Compaction

Space reclamation mechanism:

• Scan old record regions
• Retain latest version records
• Release expired space

API Reference

FasterKv

Main KV store class:

use std::sync::Arc;
use oxifaster::device::FileSystemDisk;
use oxifaster::store::{FasterKv, FasterKvConfig};

// Create store
let config = FasterKvConfig::default();
let store_device = FileSystemDisk::single_file("oxifaster.db")?;
let store = Arc::new(FasterKv::new(config, store_device));

// Start session
let mut session = store.start_session().expect("failed to start session");

// Basic operations
session.upsert(key, value);                    // Insert/Update
let value = session.read(&key)?;               // Read
session.delete(&key);                          // Delete
session.rmw(key, |v| { *v += 1; true });       // Read-Modify-Write

// Checkpoint and Recovery (Phase 2 complete)
let token = store.checkpoint(checkpoint_dir)?; // Create checkpoint
let recovered = FasterKv::recover(            // Recover from checkpoint
    checkpoint_dir,
    token,
    config,
    FileSystemDisk::single_file("oxifaster.db")?
)?;

// Session persistence
let states = store.get_recovered_sessions();   // Get recovered session states
let session = store
    .continue_session(state)
    .expect("failed to continue session");     // Restore session from saved state

FasterKv with Read Cache

Enable read cache:

use oxifaster::cache::ReadCacheConfig;

let cache_config = ReadCacheConfig::default()
    .with_mem_size(256 * 1024 * 1024)  // 256 MB
    .with_mutable_fraction(0.5);

let store = FasterKv::with_read_cache(config, device, cache_config);

FasterKv with Compaction

Enable compaction:

use oxifaster::compaction::CompactionConfig;

let compaction_config = CompactionConfig::default()
    .with_target_utilization(0.5)
    .with_num_threads(2);

let store = FasterKv::with_compaction_config(config, device, compaction_config);

Automatic Background Compaction

Start a background compaction worker and manage its lifecycle via the returned handle:

use oxifaster::compaction::AutoCompactionConfig;

let handle = store.start_auto_compaction(AutoCompactionConfig::new());
drop(handle); // Stops and joins the worker thread

FasterLog

Standalone high-performance log:

use oxifaster::log::{FasterLog, FasterLogConfig};
use oxifaster::device::FileSystemDisk;

let config = FasterLogConfig::default();
let device = FileSystemDisk::single_file("oxifaster.log")?;
let log = FasterLog::open(config, device)?;

// Append data
let addr = log.append(b"data")?;

// Commit
log.commit()?;

// Read
let data = log.read_entry(addr);

// Scan all entries
for (addr, data) in log.scan_all() {
    println!("{}: {:?}", addr, data);
}

F2Kv (Hot-Cold Architecture)

Two-tier storage architecture:

use oxifaster::f2::{F2Kv, F2Config, HotStoreConfig, ColdStoreConfig};

let config = F2Config {
    hot: HotStoreConfig::default(),
    cold: ColdStoreConfig::default(),
    ..Default::default()
};

let f2_store = F2Kv::new(config, hot_device, cold_device);

Statistics

Collect performance statistics:

use oxifaster::stats::{StatsCollector, StatsConfig};

let stats = store.stats();
println!("Read hits: {}", stats.read_hits);
println!("Read misses: {}", stats.read_misses);
println!("Cache hit rate: {:.2}%", stats.cache_hit_rate() * 100.0);

Running Examples

Note: most examples will run twice to compare devices — first with NullDisk (in-memory), then with FileSystemDisk (temp file).

# Async operations
cargo run --example async_operations

# Basic KV operations
cargo run --example basic_kv

# io_uring (Linux, enable feature for real backend)
cargo run --example io_uring --features io_uring

# Cold index
cargo run --example cold_index

# Compaction
cargo run --example compaction

# Concurrent access
cargo run --example concurrent_access

# Custom types
cargo run --example custom_types

# Epoch protection
cargo run --example epoch_protection

# F2 hot-cold architecture
cargo run --example f2_hot_cold

# FasterLog
cargo run --example faster_log

# Index growth
cargo run --example index_growth

# Log scan
cargo run --example log_scan

# Read cache
cargo run --example read_cache

# Statistics
cargo run --example statistics

# Variable length
cargo run --example variable_length

Running Tests

cargo test

Running Benchmarks

cargo bench

Contributing

Contributions are welcome! Please check DEV.md for the development roadmap and technical debt analysis.

Development Workflow

1. Fork this repository
2. Create a feature branch: git checkout -b feature/your-feature
3. Commit changes: git commit -am 'Add new feature'
4. Push branch: git push origin feature/your-feature
5. Create Pull Request

Code Standards

• Use cargo fmt to format code
• Use cargo clippy for code quality checks
• Add unit tests for new features
• Update relevant documentation

References

• FASTER Official Documentation
• FASTER C++ Source
• FASTER C# Source
• FASTER Paper

License

MIT License

Acknowledgments

Thanks to the Microsoft FASTER team for their open-source contributions.