Rollblock

A super-fast, block-oriented and rollbackable key-value store.

⚡ Super Fast — The entire dataset lives in RAM. Under the hood, hashbrown's RawTable delivers O(1) reads and writes with minimal overhead. On an Apple M4, Rollblock sustains ~1.4M ops/sec—35× faster than LMDB.

📦 Block-Oriented — Every mutation belongs to a block identified by a BlockId. When you commit, all operations succeed together or fail together. No partial state, no corruption—like SQL transactions, but designed for sequential workflows.

⏪ Rollbackable — An undo journal on disk lets you rewind to any previous state with a single call. Whether you roll back one block or a thousand, the store returns to that exact point in time: store.rollback(height)?

Built for blockchain nodes, event sourcing, game state, and any system that needs atomic commits with time-travel capabilities.

Documentation

• Architecture — Internal design, data flow, and component overview
• Configuration — All settings, durability modes, and tuning options
• Examples — Annotated code samples for common use cases
• Observability — Metrics, health checks, and monitoring integration
• Benchmark — Performance methodology and results

Install

Add rollblock to your Cargo.toml:

[dependencies]
rollblock = "0.3"

To use a specific key size, enable a feature:

[dependencies]
rollblock = { version = "0.3", features = ["key-32"] }

Available features: key-8 through key-64 (one per byte).

For custom sizes, set ROLLBLOCK_KEY_BYTES=64 cargo build (any value from 8 to 64).

Quick Examples

Server: Read & Write Operations

use rollblock::{MhinStoreFacade, StoreConfig, StoreFacade};
use rollblock::types::{Operation, StoreKey as Key, Value};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a new store
    let config = StoreConfig::new(
        "./data/mystore",  // Data directory
        4,                 // Number of shards
        10_000,            // Initial capacity per shard
        1,                 // Thread count (1 = sequential)
        false,             // Journal compression
    )?;
    let store = MhinStoreFacade::new(config)?;

    // Write a block with multiple operations
    let key_alice: Key = [0x01, 0, 0, 0, 0, 0, 0, 0].into();
    let key_bob: Key   = [0x02, 0, 0, 0, 0, 0, 0, 0].into();

    store.set(1, vec![
        Operation { key: key_alice, value: Value::from_slice(b"balance:1000") },
        Operation { key: key_bob,   value: Value::from_slice(b"balance:500") },
    ])?;

    // Read values back
    let alice_balance = store.get(key_alice)?;
    println!("Alice: {}", String::from_utf8_lossy(alice_balance.as_slice()));

    // Update in a new block
    store.set(2, vec![
        Operation { key: key_alice, value: Value::from_slice(b"balance:900") },
        Operation { key: key_bob,   value: Value::from_slice(b"balance:600") },
    ])?;

    // Remove Bob and capture the previous balance in one call
    let removed = store.pop(3, key_bob)?;
    println!("Removed Bob: {}", String::from_utf8_lossy(removed.as_slice()));

    // Oops! Roll back to block 1
    store.rollback(1)?;

    // Alice's balance is restored
    let restored = store.get(key_alice)?;
    assert_eq!(restored.as_slice(), b"balance:1000");

    store.close()?;
    Ok(())
}

Client: Remote Reads via Socket

Rollblock includes an embedded TCP server for read-only remote access. The client is zero-allocation and speaks a compact binary protocol.

use std::time::Duration;
use rollblock::client::{ClientConfig, RemoteStoreClient};
use rollblock::net::BasicAuthConfig;
use rollblock::types::StoreKey as Key;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Connect to a running Rollblock server
    let auth = BasicAuthConfig::new("reader", "secret-token");
    let config = ClientConfig::without_tls(auth)
        .with_timeout(Duration::from_secs(2));

    let mut client = RemoteStoreClient::connect("127.0.0.1:9443", config)?;

    // Fetch a single key
    let key: Key = Key::from_prefix([0x01, 0, 0, 0, 0, 0, 0, 0]);
    let value = client.get_one(key)?;

    if value.is_empty() {
        println!("Key not found");
    } else {
        println!("Value: {} bytes", value.len());
    }

    // Batch fetch multiple keys
    let keys: Vec<Key> = vec![
        Key::from_prefix([0x01; 8]),
        Key::from_prefix([0x02; 8]),
        Key::from_prefix([0x03; 8]),
    ];
    let values = client.get(&keys)?;

    for (i, v) in values.iter().enumerate() {
        println!("Key {}: {} bytes", i, v.len());
    }

    client.close()?;
    Ok(())
}

To enable the server on the writer side:

use rollblock::RemoteServerSettings;

let settings = RemoteServerSettings::default()
    .with_bind_address("0.0.0.0:9443".parse()?)
    .with_basic_auth("reader", "secret-token");

let config = StoreConfig::new("./data", 4, 10_000, 1, false)?
    .with_remote_server(settings);

Configuration

Durability Modes

use rollblock::orchestrator::DurabilityMode;

// Async (default): fast, acknowledges before fsync
let config = config.with_durability_mode(DurabilityMode::Async {
    max_pending_blocks: 1024
});

// Synchronous: fsync after every block (slower but safer)
let config = config.with_durability_mode(DurabilityMode::Synchronous);

Key Size Configuration

The key size is fixed at compile time. Two methods are available:

Method 1: Cargo feature (recommended for libraries)

# In your Cargo.toml
[dependencies]
rollblock = { version = "0.3", features = ["key-32"] }

Available features: key-8 through key-64 (one per byte).

Method 2: Environment variable (for custom sizes)

ROLLBLOCK_KEY_BYTES=64 cargo build

Any value between 8 and 64 is accepted.

Priority: Feature > Environment variable > Default (8 bytes).

⚠️ Only one key-XX feature can be active at a time. Server and client must use the same key size.

Data Model

Keys are sharded using xxh3 over the key bytes: shard = xxh3_64(key) % shard_count. Design your key space accordingly for even distribution.

Choosing the key width: Use a Cargo feature (key-8 through key-64) or set ROLLBLOCK_KEY_BYTES at build time. Both server and client builds must use the same width and data directories must be recreated after changing it. See Key Size Configuration below.

Limitations

Rollblock makes deliberate trade-offs. Know them before you commit:

Running the Examples

# Basic CRUD operations
cargo run --example basic_usage

# Chain reorganization simulation
cargo run --example blockchain_reorg

# Parallel processing (release mode recommended)
cargo run --example parallel_processing --release

# Remote client/server demo
cargo run --example network_client

# Metrics and health monitoring
cargo run --example observability

Examples store data in ./data/. Clean up with:

rm -rf data/

License

Licensed under either of MIT or Apache-2.0 at your option.