feat(example): add a kv example based on fjall kv store

.github/workflows/ci.yaml

@@ -373,6 +373,7 @@ jobs:
           - 'raft-kv-memstore-network-v2'
           - 'raft-kv-memstore-opendal-snapshot-data'
           - 'raft-kv-memstore-single-threaded'
+          - 'raft-kv-fjall'
           - 'raft-kv-rocksdb'
           - 'multi-raft-kv'
 

Cargo.toml

@@ -90,6 +90,7 @@ exclude = [
     "examples/raft-kv-memstore-opendal-snapshot-data",
     "examples/raft-kv-rocksdb",
     "examples/multi-raft-kv",
+    "examples/raft-kv-fjall",
 
     "rt-monoio",
     "rt-compio",

Makefile

@@ -45,6 +45,7 @@ test-examples:
 	cargo test --manifest-path examples/raft-kv-memstore-network-v2/Cargo.toml
 	cargo test --manifest-path examples/raft-kv-memstore-opendal-snapshot-data/Cargo.toml
 	cargo test --manifest-path examples/raft-kv-memstore-single-threaded/Cargo.toml
+	cargo test --manifest-path examples/raft-kv-fjall/Cargo.toml
 	cargo test --manifest-path examples/raft-kv-rocksdb/Cargo.toml
 	cargo test --manifest-path examples/rocksstore/Cargo.toml
 	cargo test --manifest-path examples/multi-raft-kv/Cargo.toml
@@ -103,6 +104,7 @@ lint:
 	cargo fmt --manifest-path examples/raft-kv-memstore-opendal-snapshot-data/Cargo.toml
 	cargo fmt --manifest-path examples/raft-kv-memstore-single-threaded/Cargo.toml
 	cargo fmt --manifest-path examples/raft-kv-memstore/Cargo.toml
+	cargo fmt --manifest-path examples/raft-kv-fjall/Cargo.toml
 	cargo fmt --manifest-path examples/raft-kv-rocksdb/Cargo.toml
 	cargo fmt --manifest-path examples/multi-raft-kv/Cargo.toml
 	cargo clippy --no-deps --all-targets -- -D warnings
@@ -118,6 +120,7 @@ lint:
 	cargo clippy --no-deps --manifest-path examples/raft-kv-memstore-opendal-snapshot-data/Cargo.toml --all-targets -- -D warnings
 	cargo clippy --no-deps --manifest-path examples/raft-kv-memstore-single-threaded/Cargo.toml       --all-targets -- -D warnings
 	cargo clippy --no-deps --manifest-path examples/raft-kv-memstore/Cargo.toml                       --all-targets -- -D warnings
+	cargo clippy --no-deps --manifest-path examples/raft-kv-fjall/Cargo.toml                          --all-targets -- -D warnings
 	cargo clippy --no-deps --manifest-path examples/raft-kv-rocksdb/Cargo.toml                        --all-targets -- -D warnings
 	cargo clippy --no-deps --manifest-path examples/multi-raft-kv/Cargo.toml                          --all-targets -- -D warnings
 	# Bug: clippy --all-targets reports false warning about unused dep in
@@ -166,6 +169,7 @@ check:
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/raft-kv-memstore-opendal-snapshot-data/Cargo.toml
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/raft-kv-memstore-single-threaded/Cargo.toml
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/raft-kv-memstore/Cargo.toml
+	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/raft-kv-fjall/Cargo.toml
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/raft-kv-rocksdb/Cargo.toml
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/rocksstore/Cargo.toml
 	RUSTFLAGS="-D warnings" cargo check --manifest-path examples/multi-raft-kv/Cargo.toml
@@ -188,6 +192,7 @@ clean:
 	cargo clean --manifest-path examples/raft-kv-memstore-opendal-snapshot-data/Cargo.toml
 	cargo clean --manifest-path examples/raft-kv-memstore-single-threaded/Cargo.toml
 	cargo clean --manifest-path examples/raft-kv-memstore/Cargo.toml
+	cargo clean --manifest-path examples/raft-kv-fjall/Cargo.toml
 	cargo clean --manifest-path examples/raft-kv-rocksdb/Cargo.toml
 	cargo clean --manifest-path examples/rocksstore/Cargo.toml
 	cargo clean --manifest-path examples/multi-raft-kv/Cargo.toml

examples/README.md

@@ -17,6 +17,7 @@ This directory contains example applications demonstrating different implementat
 | Example | Log | State Machine | RaftNetwork Impl | RaftNetwork | Client | Server | Special Features |
 |---------|-----|---------------|------------------|-------------|--------|--------|------------------|
 | [raft-kv-memstore] | [log-mem] | [sm-mem] | HTTP/reqwest | RaftNetwork | reqwest | actix-web | Basic example |
+| [raft-kv-fjall] | [fjall] | [fjall] | HTTP/reqwest([network-v1]) | RaftNetwork | reqwest | actix-web | Persistent storage |
 | [raft-kv-rocksdb] | [rocksstore] | [rocksstore] | HTTP/reqwest([network-v1]) | RaftNetwork | reqwest | actix-web | Persistent storage |
 | [raft-kv-memstore-network-v2] | [log-mem] | [sm-mem] | HTTP/reqwest | RaftNetworkV2 | reqwest | actix-web | Network V2 interface |
 | [multi-raft-kv] | [log-mem] | [sm-mem] | HTTP/channel | GroupRouter | channel | in-memory | Multi-Raft groups |
@@ -48,6 +49,7 @@ The following symbolic links are provided for backward compatibility:
 
 <!-- Reference Links -->
 [raft-kv-memstore]: raft-kv-memstore/
+[raft-kv-fjall]: raft-kv-fjall/
 [raft-kv-rocksdb]: raft-kv-rocksdb/
 [raft-kv-memstore-network-v2]: raft-kv-memstore-network-v2/
 [raft-kv-memstore-grpc]: raft-kv-memstore-grpc/

examples/raft-kv-fjall/Cargo.toml

@@ -0,0 +1,46 @@
+[package]
+name = "raft-kv-fjall"
+version = "0.1.0"
+readme = "README.md"
+
+edition = "2024"
+authors = [
+    "ariesdevil <ariesdevil77@gmail.com>",
+]
+categories = ["algorithms", "asynchronous", "data-structures"]
+description = "An example distributed key-value store built upon `openraft`."
+homepage = "https://github.com/databendlabs/openraft"
+keywords = ["raft", "consensus"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/databendlabs/openraft"
+
+[[bin]]
+name = "raft-key-value-fjall"
+path = "src/bin/main.rs"
+
+[dependencies]
+client-http         = { path = "../client-http" }
+network-v1-http     = { path = "../network-v1-http" }
+openraft            = { path = "../../openraft", features = ["serde", "type-alias"] }
+openraft-legacy = { path = "../../legacy" }
+types-kv            = { path = "../types-kv" }
+
+actix-web          = { version = "4.0.0-rc.2" }
+clap               = { version = "4.1.11", features = ["derive", "env"] }
+fjall = {version = "3.0.1"}
+futures            = { version = "0.3" }
+serde              = { version = "1.0.114", features = ["derive"] }
+serde_json         = { version = "1.0.57" }
+tracing            = { version = "0.1.40" }
+tracing-subscriber = { version = "0.3.0", features = ["env-filter"] }
+byteorder = "1.5.0"
+
+[dev-dependencies]
+maplit = { version = "1.0.2" }
+tempfile = { version = "3.4.0" }
+
+
+[features]
+
+[package.metadata.docs.rs]
+all-features = true

examples/raft-kv-fjall/README.md

@@ -0,0 +1,47 @@
+# openraft-fjall-kv-example
+
+A fjall-backed persistent storage implementation for Openraft, demonstrating production-ready log storage and state machine patterns.
+
+## Key Features Demonstrated
+
+- **Persistent storage**: [`RaftLogStorage`] and [`RaftStateMachine`] with fjall
+- **Column families**: Separate storage for logs, state machine, and metadata
+- **Durability**: On-disk persistence for cluster recovery
+- **Performance**: Efficient batch operations and compaction
+
+## Overview
+
+This example implements:
+- **[`RaftLogStorage`](https://docs.rs/openraft/latest/openraft/storage/trait.RaftLogStorage.html)** - Persistent Raft log storage
+- **[`RaftStateMachine`](https://docs.rs/openraft/latest/openraft/storage/trait.RaftStateMachine.html)** - Persistent application state machine
+
+Built with [fjall v3](https://fjall-rs.github.io/) for production-grade durability and performance. 
+
+## Architecture
+
+**Storage structure**:
+- Logs stored in dedicated fjall key space
+- State machine data in separate key space
+- Vote and metadata persisted independently
+
+**Asynchronous I/O operations**:
+- WAL flush operations run in spawned tasks to avoid blocking the async runtime
+- `save_vote()` and `append_to_log()` spawn async tasks for disk persistence
+- Callbacks receive actual flush results for proper error propagation
+- Log truncation (`purge()`) doesn't require immediate persistence
+
+**Key Code Locations**:
+- Storage implementation: `src/store.rs`
+- Log storage with async WAL flush: `src/log_store.rs`
+- Type definitions: See parent example for network and client implementations
+
+## Comparison
+
+| Feature | kv-fjall     | memstore |
+|---------|--------------|----------|
+| Storage | fjall (disk) | Memory |
+| Persistence | Yes          | No |
+| Recovery | Full         | None |
+| Complexity | Higher       | Lower |
+
+Built for testing and demonstration purposes.

examples/raft-kv-fjall/src/app.rs

@@ -0,0 +1,18 @@
+use std::collections::BTreeMap;
+use std::sync::Arc;
+
+use futures::lock::Mutex;
+use openraft::Config;
+
+use crate::NodeId;
+use crate::Raft;
+
+// Representation of an application state. This struct can be shared around to share
+// instances of raft, store and more.
+pub struct App {
+    pub id: NodeId,
+    pub addr: String,
+    pub raft: Raft,
+    pub key_values: Arc<Mutex<BTreeMap<String, String>>>,
+    pub config: Arc<Config>,
+}

examples/raft-kv-fjall/src/bin/main.rs

@@ -0,0 +1,30 @@
+use clap::Parser;
+use raft_kv_fjall::start_example_raft_node;
+use tracing_subscriber::EnvFilter;
+
+#[derive(Parser, Clone, Debug)]
+#[clap(author, version, about, long_about = None)]
+pub struct Opt {
+    #[clap(long)]
+    pub id: u64,
+
+    #[clap(long)]
+    pub addr: String,
+}
+
+#[actix_web::main]
+async fn main() -> std::io::Result<()> {
+    // Setup the logger
+    tracing_subscriber::fmt()
+        .with_target(true)
+        .with_thread_ids(true)
+        .with_level(true)
+        .with_ansi(false)
+        .with_env_filter(EnvFilter::from_default_env())
+        .init();
+
+    // Parse the parameters passed by arguments.
+    let options = Opt::parse();
+
+    start_example_raft_node(options.id, format!("{}.db", options.addr), options.addr).await
+}

examples/raft-kv-fjall/src/lib.rs

@@ -0,0 +1,92 @@
+use std::path::Path;
+use std::sync::Arc;
+
+use actix_web::HttpServer;
+use actix_web::middleware;
+use actix_web::middleware::Logger;
+use actix_web::web::Data;
+use openraft::Config;
+
+use crate::app::App;
+use crate::network::api;
+use crate::network::management;
+use crate::network::raft;
+use crate::store::new_storage;
+
+pub mod app;
+pub mod log_store;
+pub mod network;
+pub mod store;
+
+pub type NodeId = u64;
+
+openraft::declare_raft_types!(
+    pub TypeConfig:
+        D = types_kv::Request,
+        R = types_kv::Response,
+);
+
+pub type LogStore = log_store::FjallLogStore<TypeConfig>;
+pub type StateMachineStore = store::StateMachineStore;
+pub type Raft = openraft::Raft<TypeConfig>;
+
+#[path = "../../utils/declare_types.rs"]
+pub mod typ;
+
+pub async fn start_example_raft_node<P>(node_id: NodeId, dir: P, addr: String) -> std::io::Result<()>
+where P: AsRef<Path> {
+    // Create a configuration for the raft instance.
+    let config = Config {
+        heartbeat_interval: 250,
+        election_timeout_min: 299,
+        ..Default::default()
+    };
+
+    let config = Arc::new(config.validate().unwrap());
+
+    let (log_store, state_machine_store) = new_storage(&dir).await;
+
+    let kvs = state_machine_store.data.kvs.clone();
+
+    // Create the network layer using network-v1 crate
+    let network = network_v1_http::NetworkFactory {};
+
+    // Create a local raft instance.
+    let raft = openraft::Raft::new(node_id, config.clone(), network, log_store, state_machine_store).await.unwrap();
+
+    // Create an application that will store all the instances created above, this will
+    // later be used on the actix-web services.
+    let app_data = Data::new(App {
+        id: node_id,
+        addr: addr.clone(),
+        raft,
+        key_values: kvs,
+        config,
+    });
+
+    // Start the actix-web server.
+    let server = HttpServer::new(move || {
+        actix_web::App::new()
+            .wrap(Logger::default())
+            .wrap(Logger::new("%a %{User-Agent}i"))
+            .wrap(middleware::Compress::default())
+            .app_data(app_data.clone())
+            // raft internal RPC
+            .service(raft::append)
+            .service(raft::snapshot)
+            .service(raft::vote)
+            // admin API
+            .service(management::init)
+            .service(management::add_learner)
+            .service(management::change_membership)
+            .service(management::metrics)
+            // application API
+            .service(api::write)
+            .service(api::read)
+            .service(api::linearizable_read)
+    });
+
+    let x = server.bind(addr)?;
+
+    x.run().await
+}