Struct Topic 

pub struct Topic { /* private fields */ }

Handle to a joined gossip topic with auto-discovery.

Manages bootstrap, publishing, bubble detection, and split-brain recovery. Can be split into sender and receiver for message exchange.

Implementations

impl Topic

pub async fn new( record_publisher: RecordPublisher, gossip: Gossip, async_bootstrap: bool, ) -> Result<Self>

Create and initialize a new topic with auto-discovery.

Arguments

• record_publisher - Record publisher for DHT operations
• gossip - Gossip instance for topic subscription
• async_bootstrap - If false, awaits until bootstrap completes

pub async fn split(&self) -> Result<(GossipSender, GossipReceiver)>

Split into sender and receiver for message exchange.

Examples found in repository

examples/simple.rs (line 48)

async fn main() -> Result<()> {
    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with discovery enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher = RecordPublisher::new(
        topic_id.clone(),
        signing_key.clone(),
        None,
        initial_secret,
        Config::default(),
    );

    let topic = gossip
        .subscribe_and_join_with_auto_discovery(record_publisher)
        .await?;

    println!("[joined topic]");

    // Do something with the gossip topic
    // (bonus: GossipSender and GossipReceiver are safely clonable)
    let (_gossip_sender, _gossip_receiver) = topic.split().await?;

    Ok(())
}

examples/full_config.rs (line 113)

async fn main() -> Result<()> {
    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with discovery enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher =
        RecordPublisher::builder(topic_id.clone(), signing_key.clone(), initial_secret)
            .config(config_builder())
            .secret_rotation(RotationHandle::new(DefaultSecretRotation))
            .build();

    let topic = gossip
        .subscribe_and_join_with_auto_discovery(record_publisher)
        .await?;

    println!("[joined topic]");

    // Do something with the gossip topic
    // (bonus: GossipSender and GossipReceiver are safely clonable)
    let (_gossip_sender, _gossip_receiver) = topic.split().await?;

    Ok(())
}

examples/without_mergers.rs (line 59)

async fn main() -> Result<()> {
    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with discovery enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher = RecordPublisher::new(
        topic_id.clone(),
        signing_key.clone(),
        None,
        initial_secret,
        // [!] Disable merge workers (BubbleMerge and MessageOverlapMerge)
        Config::builder()
            .merge_config(
                MergeConfig::builder()
                    .bubble_merge(BubbleMergeConfig::Disabled)
                    .message_overlap_merge(MessageOverlapMergeConfig::Disabled)
                    .build(),
            )
            .build(),
    );

    let topic = gossip
        .subscribe_and_join_with_auto_discovery(record_publisher)
        .await?;

    println!("[joined topic]");

    // Do something with the gossip topic
    // (bonus: GossipSender and GossipReceiver are safely clonable)
    let (_gossip_sender, _gossip_receiver) = topic.split().await?;

    Ok(())
}

examples/e2e_test.rs (line 43)

async fn main() -> Result<()> {
    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = mainline::SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with address lookup enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher = RecordPublisher::new(
        topic_id.clone(),
        signing_key.clone(),
        None,
        initial_secret,
        Config::default(),
    );
    let (gossip_sender, mut gossip_receiver) = gossip
        .subscribe_and_join_with_auto_discovery(record_publisher)
        .await?
        .split()
        .await?;

    tokio::spawn(async move {
        while let Ok(event) = gossip_receiver.next().await {
            println!("event: {event:?}");
        }
        println!("\nGossip receiver stream ended");
    });

    tokio::time::sleep(std::time::Duration::from_secs(3)).await;
    gossip_sender
        .broadcast(format!("hi from {}", endpoint.id()).into())
        .await?;

    println!("[joined topic]");

    tokio::time::sleep(std::time::Duration::from_secs(10)).await;

    println!("[finished]");

    // successfully joined
    // exit with code 0
    Ok(())
}

examples/secret_rotation.rs (line 62)

async fn main() -> Result<()> {
    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with discovery enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher = RecordPublisher::new(
        topic_id.clone(),
        signing_key.clone(),
        Some(RotationHandle::new(MySecretRotation)),
        initial_secret,
        Config::default(),
    );
    let (gossip_sender, mut gossip_receiver) = gossip
        .subscribe_and_join_with_auto_discovery(record_publisher)
        .await?
        .split()
        .await?;

    println!("Joined topic");

    // Spawn listener for incoming messages
    tokio::spawn(async move {
        while let Ok(event) = gossip_receiver.next().await {
            if let Event::Received(msg) = event {
                println!(
                    "\nMessage from {}: {}",
                    &msg.delivered_from.to_string()[0..8],
                    String::from_utf8(msg.content.to_vec()).unwrap()
                );
            } else if let Event::NeighborUp(peer) = event {
                println!("\nJoined by {}", &peer.to_string()[0..8]);
            }
        }
        println!("\nGossip receiver stream ended");
    });

    // Main input loop for sending messages
    let mut buffer = String::new();
    let stdin = std::io::stdin();
    loop {
        print!("\n> ");
        stdin.read_line(&mut buffer).unwrap();
        gossip_sender
            .broadcast(buffer.clone().replace("\n", "").into())
            .await
            .unwrap();
        println!(" - (sent)");
        buffer.clear();
    }
}

examples/chat_no_wait.rs (line 53)

async fn main() -> Result<()> {
    tracing_subscriber::fmt()
        .with_thread_ids(true)
        .with_ansi(true)
        .with_env_filter(
            EnvFilter::try_from_default_env()
                .unwrap_or_else(|_| EnvFilter::new("distributed_topic_tracker=debug")),
        )
        .init();

    // Generate a new random secret key
    let secret_key = SecretKey::generate(&mut rand::rng());
    let signing_key = SigningKey::from_bytes(&secret_key.to_bytes());

    // Set up endpoint with discovery enabled
    let endpoint = Endpoint::builder(iroh::endpoint::presets::N0)
        .secret_key(secret_key.clone())
        .bind()
        .await?;

    // Initialize gossip with auto-discovery
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // Set up protocol router
    let _router = iroh::protocol::Router::builder(endpoint.clone())
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    let topic_id = TopicId::new("my-iroh-gossip-topic".to_string());
    let initial_secret = b"my-initial-secret".to_vec();

    let record_publisher = RecordPublisher::new(
        topic_id.clone(),
        signing_key.clone(),
        None,
        initial_secret,
        Config::default(),
    );
    let (gossip_sender, mut gossip_receiver) = gossip
        .subscribe_and_join_with_auto_discovery_no_wait(record_publisher)
        .await?
        .split()
        .await?;

    println!("Joined topic");

    // Spawn listener for incoming messages
    tokio::spawn(async move {
        while let Ok(event) = gossip_receiver.next().await {
            if let Event::Received(msg) = event {
                println!(
                    "\nMessage from {}: {}",
                    &msg.delivered_from.to_string()[0..8],
                    String::from_utf8(msg.content.to_vec()).unwrap()
                );
            } else if let Event::NeighborUp(peer) = event {
                println!("\nJoined by {}", &peer.to_string()[0..8]);
            }
        }
        println!("\nGossip receiver stream ended");
    });

    // Main input loop for sending messages
    let mut buffer = String::new();
    let stdin = std::io::stdin();
    loop {
        print!("\n> ");
        stdin.read_line(&mut buffer).unwrap();
        gossip_sender
            .broadcast(
                buffer
                    .trim_end_matches(&['\r', '\n'][..])
                    .as_bytes()
                    .to_vec(),
            )
            .await
            .unwrap();
        println!(" - (sent)");
        buffer.clear();
    }
}

Additional examples can be found in:

• examples/chat.rs

pub async fn gossip_sender(&self) -> Result<GossipSender>

Get the gossip sender for this topic.

pub async fn gossip_receiver(&self) -> Result<GossipReceiver>

Get the gossip receiver for this topic.

pub async fn record_creator(&self) -> Result<RecordPublisher>

Get the record publisher for this topic.

Trait Implementations

impl Clone for Topic

fn clone(&self) -> Topic

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Topic

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.