Files
marathon/crates/app/src/setup.rs
2025-12-11 22:10:06 +00:00

280 lines
11 KiB
Rust

//! Gossip networking setup with dedicated tokio runtime
//!
//! This module manages iroh-gossip networking with a tokio runtime running as a sidecar to Bevy.
//! The tokio runtime runs in a dedicated background thread, separate from Bevy's ECS loop.
//!
//! # Architecture
//!
//! ```text
//! ┌─────────────────────────────────────┐
//! │ Bevy Main Thread │
//! │ ┌────────────────────────────────┐ │
//! │ │ setup_gossip_networking() │ │ Startup System
//! │ │ - Creates channel │ │
//! │ │ - Spawns background thread │ │
//! │ └────────────────────────────────┘ │
//! │ ┌────────────────────────────────┐ │
//! │ │ poll_gossip_bridge() │ │ Update System
//! │ │ - Receives GossipBridge │ │ (runs every frame)
//! │ │ - Inserts as resource │ │
//! │ └────────────────────────────────┘ │
//! └─────────────────────────────────────┘
//! ↕ (crossbeam channel)
//! ┌─────────────────────────────────────┐
//! │ Background Thread (macOS only) │
//! │ ┌────────────────────────────────┐ │
//! │ │ Tokio Runtime │ │
//! │ │ ┌────────────────────────────┐ │ │
//! │ │ │ init_gossip() │ │ │
//! │ │ │ - Creates iroh endpoint │ │ │
//! │ │ │ - Sets up mDNS discovery │ │ │
//! │ │ │ - Subscribes to topic │ │ │
//! │ │ │ - Creates GossipBridge │ │ │
//! │ │ └────────────────────────────┘ │ │
//! │ │ ┌────────────────────────────┐ │ │
//! │ │ │ spawn_bridge_tasks() │ │ │
//! │ │ │ - Task 1: Forward outgoing │ │ │
//! │ │ │ - Task 2: Forward incoming │ │ │
//! │ │ └────────────────────────────┘ │ │
//! │ └────────────────────────────────┘ │
//! └─────────────────────────────────────┘
//! ```
//!
//! # Communication Pattern
//!
//! 1. **Bevy → Tokio**: GossipBridge's internal queue (try_recv_outgoing)
//! 2. **Tokio → Bevy**: GossipBridge's internal queue (push_incoming)
//! 3. **Thread handoff**: crossbeam_channel (one-time GossipBridge transfer)
use anyhow::Result;
use bevy::prelude::*;
use lib::networking::GossipBridge;
use uuid::Uuid;
/// Channel for receiving the GossipBridge from the background thread
///
/// This resource exists temporarily during startup. Once the GossipBridge
/// is received and inserted, this channel resource is removed.
#[cfg(not(target_os = "ios"))]
#[derive(Resource)]
pub struct GossipBridgeChannel(crossbeam_channel::Receiver<GossipBridge>);
/// Set up gossip networking with iroh
///
/// This is a Bevy startup system that initializes the gossip networking stack.
/// On macOS, it spawns a dedicated thread with a tokio runtime. On iOS, it logs
/// a warning (iOS networking not yet implemented).
///
/// # Platform Support
///
/// - **macOS**: Full support with mDNS discovery
/// - **iOS**: Not yet implemented
pub fn setup_gossip_networking(mut commands: Commands) {
info!("Setting up gossip networking...");
// Spawn dedicated thread with Tokio runtime for gossip initialization
#[cfg(not(target_os = "ios"))]
{
let (sender, receiver) = crossbeam_channel::unbounded();
commands.insert_resource(GossipBridgeChannel(receiver));
std::thread::spawn(move || {
let rt = tokio::runtime::Runtime::new().unwrap();
rt.block_on(async move {
match init_gossip().await {
Ok(bridge) => {
info!("Gossip bridge initialized successfully");
if let Err(e) = sender.send(bridge) {
error!("Failed to send bridge to main thread: {}", e);
}
}
Err(e) => {
error!("Failed to initialize gossip: {}", e);
}
}
});
});
}
#[cfg(target_os = "ios")]
{
warn!("iOS networking not yet implemented - gossip networking disabled");
}
}
/// Poll the channel for the GossipBridge and insert it when ready
///
/// This is a Bevy update system that runs every frame. It checks the channel
/// for the GossipBridge created in the background thread. Once received, it
/// inserts the bridge as a resource and removes the channel.
///
/// # Platform Support
///
/// - **macOS**: Polls the channel and inserts GossipBridge
/// - **iOS**: No-op (networking not implemented)
pub fn poll_gossip_bridge(
mut commands: Commands,
#[cfg(not(target_os = "ios"))]
channel: Option<Res<GossipBridgeChannel>>,
) {
#[cfg(not(target_os = "ios"))]
if let Some(channel) = channel {
if let Ok(bridge) = channel.0.try_recv() {
info!("Inserting GossipBridge resource into Bevy world");
commands.insert_resource(bridge);
commands.remove_resource::<GossipBridgeChannel>();
}
}
}
/// Initialize iroh-gossip networking stack
///
/// This async function runs in the background tokio runtime and:
/// 1. Creates an iroh endpoint with mDNS discovery
/// 2. Spawns the gossip protocol
/// 3. Sets up the router to accept gossip connections
/// 4. Subscribes to a shared topic (ID: [42; 32])
/// 5. Waits for join with a 2-second timeout
/// 6. Creates and configures the GossipBridge
/// 7. Spawns forwarding tasks to bridge messages
///
/// # Returns
///
/// - `Ok(GossipBridge)`: Successfully initialized networking
/// - `Err(anyhow::Error)`: Initialization failed
///
/// # Platform Support
///
/// This function is only compiled on non-iOS platforms.
#[cfg(not(target_os = "ios"))]
async fn init_gossip() -> Result<GossipBridge> {
use iroh::discovery::mdns::MdnsDiscovery;
use iroh::protocol::Router;
use iroh::Endpoint;
use iroh_gossip::net::Gossip;
use iroh_gossip::proto::TopicId;
info!("Creating endpoint with mDNS discovery...");
let endpoint = Endpoint::builder()
.discovery(MdnsDiscovery::builder())
.bind()
.await?;
let endpoint_id = endpoint.addr().id;
info!("Endpoint created: {}", endpoint_id);
// Convert endpoint ID to UUID
let id_bytes = endpoint_id.as_bytes();
let mut uuid_bytes = [0u8; 16];
uuid_bytes.copy_from_slice(&id_bytes[..16]);
let node_id = Uuid::from_bytes(uuid_bytes);
info!("Spawning gossip protocol...");
let gossip = Gossip::builder().spawn(endpoint.clone());
info!("Setting up router...");
let router = Router::builder(endpoint.clone())
.accept(iroh_gossip::ALPN, gossip.clone())
.spawn();
// Subscribe to shared topic
let topic_id = TopicId::from_bytes([42; 32]);
info!("Subscribing to topic...");
let subscribe_handle = gossip.subscribe(topic_id, vec![]).await?;
let (sender, mut receiver) = subscribe_handle.split();
// Wait for join (with timeout since we might be the first node)
info!("Waiting for gossip join...");
match tokio::time::timeout(std::time::Duration::from_secs(2), receiver.joined()).await {
Ok(Ok(())) => info!("Joined gossip swarm"),
Ok(Err(e)) => warn!("Join error: {} (proceeding anyway)", e),
Err(_) => info!("Join timeout (first node in swarm)"),
}
// Create bridge
let bridge = GossipBridge::new(node_id);
info!("GossipBridge created with node ID: {}", node_id);
// Spawn forwarding tasks - pass endpoint, router, gossip to keep them alive
spawn_bridge_tasks(sender, receiver, bridge.clone(), endpoint, router, gossip);
Ok(bridge)
}
/// Spawn tokio tasks to forward messages between iroh-gossip and GossipBridge
///
/// This function spawns two concurrent tokio tasks that run for the lifetime of the application:
///
/// 1. **Outgoing Task**: Polls GossipBridge for outgoing messages and broadcasts them via gossip
/// 2. **Incoming Task**: Receives messages from gossip and pushes them into GossipBridge
///
/// # Lifetime Management
///
/// The iroh resources (endpoint, router, gossip) are moved into the first task to keep them
/// alive for the application lifetime. Without this, they would be dropped immediately and
/// the gossip connection would close.
///
/// # Platform Support
///
/// This function is only compiled on non-iOS platforms.
#[cfg(not(target_os = "ios"))]
fn spawn_bridge_tasks(
sender: iroh_gossip::api::GossipSender,
mut receiver: iroh_gossip::api::GossipReceiver,
bridge: GossipBridge,
_endpoint: iroh::Endpoint,
_router: iroh::protocol::Router,
_gossip: iroh_gossip::net::Gossip,
) {
use bytes::Bytes;
use futures_lite::StreamExt;
use lib::networking::VersionedMessage;
use std::time::Duration;
let node_id = bridge.node_id();
// Task 1: Forward outgoing messages from GossipBridge → iroh-gossip
// Keep endpoint, router, gossip alive by moving them into this task
let bridge_out = bridge.clone();
tokio::spawn(async move {
let _endpoint = _endpoint; // Keep alive for app lifetime
let _router = _router; // Keep alive for app lifetime
let _gossip = _gossip; // Keep alive for app lifetime
loop {
if let Some(msg) = bridge_out.try_recv_outgoing() {
if let Ok(bytes) = bincode::serialize(&msg) {
if let Err(e) = sender.broadcast(Bytes::from(bytes)).await {
error!("[Node {}] Broadcast failed: {}", node_id, e);
}
}
}
tokio::time::sleep(Duration::from_millis(10)).await;
}
});
// Task 2: Forward incoming messages from iroh-gossip → GossipBridge
let bridge_in = bridge.clone();
tokio::spawn(async move {
loop {
match tokio::time::timeout(Duration::from_millis(100), receiver.next()).await {
Ok(Some(Ok(event))) => {
if let iroh_gossip::api::Event::Received(msg) = event {
if let Ok(versioned_msg) =
bincode::deserialize::<VersionedMessage>(&msg.content)
{
if let Err(e) = bridge_in.push_incoming(versioned_msg) {
error!("[Node {}] Push incoming failed: {}", node_id, e);
}
}
}
}
Ok(Some(Err(e))) => error!("[Node {}] Receiver error: {}", node_id, e),
Ok(None) => break,
Err(_) => {} // Timeout
}
}
});
}