### Setup and Usage of iroh-gossip with iroh

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip

This example demonstrates how to set up and use the iroh-gossip protocol in conjunction with the iroh networking library. It covers creating an iroh endpoint, initializing the gossip protocol, setting up a router, subscribing to a topic, broadcasting messages, and receiving messages.

```rust
use iroh::{protocol::Router, Endpoint, EndpointId, endpoint::presets};
use iroh_gossip::{api::Event, Gossip, TopicId};
use n0_error::{Result, StdResultExt};
use n0_future::StreamExt;

#[tokio::main]
async fn main() -> Result<()> {
    // create an iroh endpoint that includes the standard discovery mechanisms
    // we've built at number0
    let endpoint = Endpoint::bind(presets::N0).await?;

    // build gossip protocol
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // setup router
    let router = Router::builder(endpoint)
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    // gossip swarms are centered around a shared "topic id", which is a 32 byte identifier
    let topic_id = TopicId::from_bytes([23u8; 32]);
    // and you need some bootstrap peers to join the swarm
    let bootstrap_peers = bootstrap_peers();

    // then, you can subscribe to the topic and join your initial peers
    let (sender, mut receiver) = gossip
        .subscribe(topic_id, bootstrap_peers)
        .await? 
        .split();

    // you might want to wait until you joined at least one other peer:
    receiver.joined().await?;

    // then, you can broadcast messages to all other peers!
    sender.broadcast(b"hello world this is a gossip message".to_vec().into()).await?;

    // and read messages from others!
    while let Some(event) = receiver.next().await {
        match event? {
            Event::Received(message) => {
                println!("received a message: {:?}", std::str::from_utf8(&message.content));
            }
            _ => {}
        }
    }

    // clean shutdown makes sure that other peers are notified that you went offline
    router.shutdown().await.std_context("shutdown router")?;
    Ok(())
}

fn bootstrap_peers() -> Vec<EndpointId> {
    // insert your bootstrap peers here, or get them from your environment
    vec![]
}

```

--------------------------------

### Actor Setup

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Performs the initial setup for the actor, including watching for address updates and handling the initial address. Returns a stream of address updates.

```rust
async fn setup(&mut self) -> impl Stream<Item = EndpointAddr> + Send + Unpin + use<> {
        let addr_update_stream = self.endpoint.watch_addr().stream();
        let initial_addr = self.endpoint.addr();
        self.handle_addr_update(initial_addr).await;
        addr_update_stream
    }
```

--------------------------------

### Setting up and Using Iroh Gossip

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/index.html

This example demonstrates how to set up an iroh endpoint, initialize the gossip protocol, and use it to subscribe to a topic, broadcast messages, and receive messages from peers. It requires the 'net' feature flag.

```rust
use iroh::{protocol::Router, Endpoint, EndpointId, endpoint::presets};
use iroh_gossip::{api::Event, Gossip, TopicId};
use n0_error::{Result, StdResultExt};
use n0_future::StreamExt;

#[tokio::main]
async fn main() -> Result<()> {
    // create an iroh endpoint that includes the standard discovery mechanisms
    // we've built at number0
    let endpoint = Endpoint::bind(presets::N0).await?;

    // build gossip protocol
    let gossip = Gossip::builder().spawn(endpoint.clone());

    // setup router
    let router = Router::builder(endpoint)
        .accept(iroh_gossip::ALPN, gossip.clone())
        .spawn();

    // gossip swarms are centered around a shared "topic id", which is a 32 byte identifier
    let topic_id = TopicId::from_bytes([23u8; 32]);
    // and you need some bootstrap peers to join the swarm
    let bootstrap_peers = bootstrap_peers();

    // then, you can subscribe to the topic and join your initial peers
    let (sender, mut receiver) = gossip
        .subscribe(topic_id, bootstrap_peers)
        .await?;
        .split();

    // you might want to wait until you joined at least one other peer:
    receiver.joined().await?;

    // then, you can broadcast messages to all other peers!
    sender.broadcast(b"hello world this is a gossip message".to_vec().into()).await?;

    // and read messages from others!
    while let Some(event) = receiver.next().await {
        match event? {
            Event::Received(message) => {
                println!("received a message: {:?}", std::str::from_utf8(&message.content));
            }
            _ => {}
        }
    }

    // clean shutdown makes sure that other peers are notified that you went offline
    router.shutdown().await.std_context("shutdown router")?;
    Ok(())
}

fn bootstrap_peers() -> Vec<EndpointId> {
    // insert your bootstrap peers here, or get them from your environment
    vec![]
}

```

--------------------------------

### Initializing Connection Loop

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Sets up and starts the connection loop for a peer, initializing both the send and receive loops. This function handles the lifecycle of a single network connection.

```rust
async fn connection_loop(
    from: PublicKey,
    conn: Connection,
    origin: ConnOrigin,
    send_rx: mpsc::Receiver<ProtoMessage>,
    in_event_tx: mpsc::Sender<InEvent>,
    max_message_size: usize,
    queue: Vec<ProtoMessage>,
) -> Result<(), ConnectionLoopError> {
    debug!(?origin, "connection established");

    let mut send_loop = SendLoop::new(conn.clone(), send_rx, max_message_size);
    let mut recv_loop = RecvLoop::new(from, conn, in_event_tx, max_message_size);
}
```

--------------------------------

### Get Topic State Reference

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.State.html

Returns an optional reference to the protocol state for a specific topic.

```rust
pub fn state(&self, topic: &TopicId) -> Option<&State<PI, R>>
```

--------------------------------

### Get TypeId of GossipSender

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipSender.html

Gets the TypeId of the GossipSender, useful for runtime type identification.

```rust
fn type_id(&self) -> TypeId
```

--------------------------------

### Create a new Simulator instance

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Initializes a new simulator with a given configuration and network settings. It sets up the network and prepares for simulation.

```rust
pub fn new(
        simulator_config: SimulatorConfig,
        network_config: impl Into<NetworkConfig>,
    ) -> Self {
        let network_config = network_config.into();
        info!("start {simulator_config:?} {network_config:?}");
        let rng = rand::rngs::ChaCha12Rng::seed_from_u64(simulator_config.rng_seed);
        Self {
            network: Network::new(network_config, rng),
            config: simulator_config,
            round_stats: Default::default(),
        }
    }
```

--------------------------------

### Get Endpoint

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Retrieves the address of the local endpoint.

```APIDOC
## pub fn endpoint(&self) -> &PI

The address of your local endpoint.
```

--------------------------------

### State::state

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/state.rs.html

Gets a reference to the protocol state for a specific topic.

```APIDOC
## State::state

### Description

Retrieves a reference to the protocol state associated with a given [`TopicId`].

### Parameters

- **topic** (&TopicId): A reference to the [`TopicId`] for which to get the state.

### Returns

- **Option<&topic::State<PI, R>>**: An `Option` containing a reference to the topic's state if it exists, otherwise `None`.
```

--------------------------------

### Simulator::new

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Creates a new simulator instance with the specified configuration.

```APIDOC
## Simulator::new

### Description
Creates a new simulator instance with the specified configuration.

### Signature
```rust
pub fn new(simulator_config: SimulatorConfig, network_config: impl Into<NetworkConfig>) -> Self
```

### Parameters
* `simulator_config`: Configuration for the simulator.
* `network_config`: Configuration for the network, convertible into `NetworkConfig`.
```

--------------------------------

### Get Statistics

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Retrieves statistics on the number of messages sent and received.

```APIDOC
## pub fn stats(&self) -> &Stats

Get stats on how many messages were sent and received.
```

--------------------------------

### Bootstrap the network with Set mode

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Boots the network by first establishing a set of initial nodes, then connecting the remaining nodes to random peers within that set. This provides a more distributed initial connection.

```rust
self.network.insert_and_join(0, TOPIC, vec![]);
                for i in 1..count {
                    self.network.insert_and_join(i, TOPIC, vec![0]);
                }

                self.network.run_trips(7);

                for i in count..node_count {
                    let contact = self.network.rng.random_range(0..count);
                    self.network.insert_and_join(i, TOPIC, vec![contact]);
                }

                self.network.run_trips(20);
```

--------------------------------

### fold

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipReceiver.html

Accumulates a computation over the items of a stream, starting with an initial value.

```APIDOC
## fn fold<T, F>(self, init: T, f: F) -> FoldFuture<Self, F, T>

### Description
Accumulates a computation over the stream.

### Method
`fold` is a method on streams.

### Parameters
- `init`: The initial value for the accumulator.
- `f`: A closure that takes the current accumulator value and the next stream item, returning the updated accumulator value.

### Type Parameters
- `T`: The type of the accumulator and the stream items.
```

--------------------------------

### Bootstrap the network with Single mode

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Boots the network by connecting a single initial node and then connecting all other nodes to it. This is a simple bootstrapping strategy.

```rust
self.network.insert_and_join(0, TOPIC, vec![]);
                for i in 1..node_count {
                    self.network.insert_and_join(i, TOPIC, vec![0]);
                }
                self.network.run_trips(20);
```

--------------------------------

### Get Gossip Statistics

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Retrieves statistics specifically for the gossip broadcast state.

```APIDOC
## pub fn gossip_stats(&self) -> &Stats

Get statistics for the gossip broadcast state
TODO: Remove/replace with metrics?
```

--------------------------------

### Get Local PeerIdentity

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.State.html

Retrieves a reference to the local node's PeerIdentity.

```rust
pub fn me(&self) -> &PI
```

--------------------------------

### Simulator::bootstrap

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Bootstraps the network according to the specified mode.

```APIDOC
## Simulator::bootstrap

### Description
Bootstraps the network according to the specified mode. This method sets up the initial network connections and allows it to stabilize.

See [`BootstrapMode`] for details.

### Signature
```rust
pub fn bootstrap(&mut self, bootstrap_mode: BootstrapMode) -> NetworkReport<PeerId>
```

### Parameters
* `bootstrap_mode`: The mode to use for bootstrapping the network (e.g., `Single`, `Set`).

### Returns
The [`NetworkReport`] after finishing the bootstrap process.
```

--------------------------------

### Gossip::type_id

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/net/struct.Gossip.html

Gets the `TypeId` of the Gossip instance, as part of the `Any` trait implementation.

```APIDOC
## Gossip::type_id

### Description
Gets the `TypeId` of `self`.

### Signature
```rust
fn type_id(&self) -> TypeId
```
```

--------------------------------

### Create Simulator Config from Environment

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Creates a `SimulatorConfig` by reading values from environment variables. Specifically, `PEERS` is read for the number of peers, defaulting to 100 if not set.

```rust
impl SimulatorConfig {
    /// Creates a [`SimulatorConfig`] by reading from environment variables.
    ///
    /// [`Self::peers`] is read from `PEERS`, defaulting to `100` if unset.

```

--------------------------------

### Get Topic Statistics

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/topic.rs.html

Retrieves statistics related to message sending and receiving for the topic.

```APIDOC
## stats

### Description
Get stats on how many messages were sent and received.

### Method
`GET`

### Endpoint
`/topic/stats`

### Returns
- `Stats` (Stats) - Statistics object containing `messages_sent` and `messages_received`.
```

--------------------------------

### Create SimulatorConfig from Environment Variables

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Loads simulator configuration from environment variables. Defaults are provided if variables are not set.

```rust
pub fn from_env() -> Self {
        let peer = read_var("PEERS", 100);
        Self {
            rng_seed: read_var("SEED", 0),
            peers: peer,
            gossip_round_timeout: Duration::from_secs(read_var("GOSSIP_ROUND_TIMEOUT", 5)),
        }
    }
```

--------------------------------

### Time-Bound Cache Operations

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/util.rs.html

Demonstrates the usage of a `TimeBoundCache`, including inserting key-value pairs with expiration times, retrieving values, checking cache size, and expiring entries based on a given time threshold. It also shows how to update the expiration time of an existing entry.

```rust
        let mut cache = TimeBoundCache::default();

        let t0 = Instant::now();
        let t1 = t0 + Duration::from_secs(1);
        let t2 = t0 + Duration::from_secs(2);

        cache.insert(1, 10, t0);
        cache.insert(2, 20, t1);
        cache.insert(3, 30, t1);
        cache.insert(4, 40, t2);

        assert_eq!(cache.get(&2), Some(&20));
        assert_eq!(cache.len(), 4);
        let removed = cache.expire_until(t1);
        assert_eq!(removed, 3);
        assert_eq!(cache.len(), 1);
        assert_eq!(cache.get(&2), None);
        assert_eq!(cache.get(&4), Some(&40));

        let t3 = t2 + Duration::from_secs(1);
        cache.insert(5, 50, t2);
        assert_eq!(cache.expires(&5), Some(&t2));
        cache.insert(5, 50, t3);
        assert_eq!(cache.expires(&5), Some(&t3));
        cache.expire_until(t2);
        assert_eq!(cache.get(&4), None);
        assert_eq!(cache.get(&5), Some(&50));
```

--------------------------------

### Message Size Method

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/state.rs.html

Provides a method to get the postcard encoded size of a Message.

```rust
impl<PI: Serialize> Message<PI> {
    /// Get the encoded size of this message
    pub fn size(&self) -> postcard::Result<usize> {
        postcard::experimental::serialized_size(&self)
    }
}
```

--------------------------------

### Network::insert_with_config

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Inserts a new peer with a specific protocol configuration. Panics if the peer already exists.

```APIDOC
## Network::insert_with_config

### Description
Inserts a new peer with the specified protocol config.

Panics if the peer already exists.

### Signature
```rust
pub fn insert_with_config(&mut self, peer_id: PI, config: Config)
```

### Parameters
- **peer_id** (PI) - The identifier of the peer to insert.
- **config** (Config) - The protocol configuration for the new peer.
```

--------------------------------

### Get Local Endpoint Address

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Returns a reference to the address of the local endpoint for the State.

```rust
pub fn endpoint(&self) -> &PI
```

--------------------------------

### Get Message Kind

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.Message.html

Retrieves the kind of the Message. This method is available for any Message instance.

```rust
pub fn kind(&self) -> MessageKind
```

--------------------------------

### Create New Network Instance

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Creates a new simulated network instance. Requires a NetworkConfig and a random number generator.

```rust
pub fn new(config: NetworkConfig, rng: R) -> Self
```

--------------------------------

### Policy Combination: AND

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Creates a new `Policy` that requires both the original policy and the provided `other` policy to return `Action::Follow`.

```APIDOC
## fn and<P, B, E>(self, other: P) -> And<T, P>

### Description
Creates a new `Policy` that returns `Action::Follow` only if `self` and `other` return `Action::Follow`.

### Method
Policy Combination

### Parameters
#### Path Parameters
- `other` (P): The other policy to combine with.

### Response
#### Success Response
- Returns a new `And<T, P>` policy.
```

--------------------------------

### Network::elapsed

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Returns the total time elapsed since the network simulation started.

```APIDOC
## Network::elapsed

### Description
Returns the time elapsed since starting the network.

### Signature
```rust
pub fn elapsed(&self) -> Duration
```

### Returns
A `Duration` representing the time elapsed.
```

--------------------------------

### Network::insert_and_join

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Inserts a new peer and makes it join a topic using provided bootstrap nodes. Panics if the peer already exists.

```APIDOC
## Network::insert_and_join

### Description
Inserts a new peer and joins a topic with a set of bootstrap nodes.

Panics if the peer already exists.

### Signature
```rust
pub fn insert_and_join( &mut self, peer_id: PI, topic: TopicId, bootstrap: Vec<PI>, )
```

### Parameters
- **peer_id** (PI) - The identifier of the peer to insert.
- **topic** (TopicId) - The ID of the topic to join.
- **bootstrap** (Vec<PI>) - A list of bootstrap peer identifiers.
```

--------------------------------

### Get Max Message Size

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Retrieves the maximum message size configured for this gossip actor.

```rust
pub fn max_message_size(&self) -> usize {
    self.inner.max_message_size
}
```

--------------------------------

### Policy Combination: OR

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Creates a new `Policy` that returns `Action::Follow` if either the original policy or the provided `other` policy returns `Action::Follow`.

```APIDOC
## fn or<P, B, E>(self, other: P) -> Or<T, P>

### Description
Creates a new `Policy` that returns `Action::Follow` if either `self` or `other` returns `Action::Follow`.

### Method
Policy Combination

### Parameters
#### Path Parameters
- `other` (P): The other policy to combine with.

### Response
#### Success Response
- Returns a new `Or<T, P>` policy.
```

--------------------------------

### Get Local Endpoint Address

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/topic.rs.html

Returns a reference to the local endpoint's peer identity.

```rust
impl<PI, R> State<PI, R> {
    /// The address of your local endpoint.
    pub fn endpoint(&self) -> &PI {
        &self.me
    }
}
```

--------------------------------

### Insert Peer and Join Topic

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Inserts a new peer and immediately joins a specified topic using a list of bootstrap nodes. Panics if the peer ID already exists.

```rust
pub fn insert_and_join( &mut self, peer_id: PI, topic: TopicId, bootstrap: Vec<PI>, )
```

--------------------------------

### Get Message Statistics

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Retrieves statistics related to the number of messages sent and received by the State.

```rust
pub fn stats(&self) -> &Stats
```

--------------------------------

### Get Maximum Message Size

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.State.html

Retrieves the maximum message size configured for the gossip protocol.

```rust
pub fn max_message_size(&self) -> usize
```

--------------------------------

### Create SimulatorConfig from Environment Variables

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.SimulatorConfig.html

Constructs a SimulatorConfig by reading values from environment variables like PEERS, SEED, and GOSSIP_ROUND_TIMEOUT. Defaults are provided if variables are not set.

```rust
pub fn from_env() -> Self
Creates a `SimulatorConfig` by reading from environment variables.
`Self::peers` is read from `PEERS`, defaulting to `100` if unset. `Self::rng_seed` is read from `SEED`, defaulting to `0` if unset. `Self::gossip_round_timeout` is read, as seconds, from `GOSSIP_ROUND_TIMEOUT`, defaulting to `5` if unset.
```

--------------------------------

### Create 'And' Policy

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.RoundStatsAvg.html

Creates a new Policy that requires both self and other policies to return Action::Follow.

```rust
fn and<P, B, E>(self, other: P) -> And<T, P>
where T: Policy<B, E>, P: Policy<B, E>,
```

--------------------------------

### Get Active Connections

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Returns a vector of tuples representing all active connections between peers in the network.

```rust
pub fn conns(&self) -> Vec<(PI, PI)>
```

--------------------------------

### CloneToUninit

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/net/struct.Gossip.html

Performs copy-assignment from self to a destination pointer. This is a nightly-only experimental API.

```APIDOC
## unsafe fn clone_to_uninit(&self, dest: *mut u8)

### Description
Performs copy-assignment from `self` to `dest`.

### Method
`clone_to_uninit`

### Parameters
- `dest` (*mut u8) - The destination pointer.

### Safety
This function is unsafe as it involves raw pointer manipulation.
```

--------------------------------

### Get Maximum Latency

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/enum.LatencyConfig.html

Retrieves the maximum possible latency from a LatencyConfig. This is relevant for dynamic configurations.

```rust
pub fn max(&self) -> Duration
```

--------------------------------

### take

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipTopic.html

Creates a new stream that yields at most `n` items from the underlying stream. After `n` items, the stream will yield `None`.

```APIDOC
## fn take(self, n: usize) -> Take<Self>

### Description
Creates a new stream of at most `n` items of the underlying stream. After `n` items have been yielded, the stream will end.

### Constraints
Requires `Self: Sized`.

### Parameters
* `n`: The maximum number of items to yield.

### Returns
A `Take` stream that yields at most `n` items.
```

--------------------------------

### Get Gossip Broadcast Statistics

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/topic.rs.html

Retrieves specific statistics for the gossip broadcast state within the topic.

```APIDOC
## gossip_stats

### Description
Get statistics for the gossip broadcast state.

### Method
`GET`

### Endpoint
`/topic/gossip_stats`

### Returns
- `plumtree::Stats` (plumtree::Stats) - Statistics specific to the gossip module.
```

--------------------------------

### Network::new

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Creates a new simulated network instance with the given configuration and random number generator.

```APIDOC
## Network::new

### Description
Creates a new network.

### Signature
```rust
pub fn new(config: NetworkConfig, rng: R) -> Self
```

### Parameters
- **config** (NetworkConfig) - The configuration for the network.
- **rng** (R) - The random number generator to use for the simulation.
```

--------------------------------

### Get Direct Neighbors

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipReceiver.html

Lists the current direct neighbors of the GossipReceiver. This method returns an iterator over EndpointIds.

```rust
pub fn neighbors(&self) -> impl Iterator<Item = EndpointId> + '_
Lists our current direct neighbors.
```

--------------------------------

### PolicyExt::or

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipApi.html

Creates a new Policy that returns Action::Follow if either self or other policies return Action::Follow.

```APIDOC
## PolicyExt::or

### Description
Creates a new `Policy` that returns `Action::Follow` if either `self` or `other` returns `Action::Follow`.

### Method
(Implicitly a method call on a Policy object)

### Parameters
- **other**: Policy - The other policy to combine with.

### Returns
- A new Policy object representing the combined logic.
```

--------------------------------

### Get TopicId as Bytes

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.TopicId.html

Returns a reference to the 32-byte array representing the TopicId. This is useful for serialization or comparison.

```rust
pub fn as_bytes(&self) -> &[u8; 32]
```

--------------------------------

### Network::insert method

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Inserts a new peer into the network using the default protocol configuration.

```rust
impl<PI: PeerIdentity + fmt::Display, R: Rng + SeedableRng> Network<PI, R> {
    /// Inserts a new peer.
    ///
    /// Panics if the peer already exists.
    pub fn insert(&mut self, peer_id: PI) {
        let config = self.config.proto.clone();
        self.insert_with_config(peer_id, config);
    }

    /// Inserts a new peer with the specified protocol config.
    ///
    /// Panics if the peer already exists.
    pub fn insert_with_config(&mut self, peer_id: PI, config: Config) {
        assert!(

```

--------------------------------

### Build and Test Network with Message Broadcasting

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto.rs.html

Sets up a network of 6 nodes, connects them in sections, broadcasts messages, and verifies reception. It then connects the sections and broadcasts again, asserting wider reception.

```rust
let mut network = Network::new(network_config, rng);
// build a network with 6 nodes
for i in 0..6 {
    network.insert(i);
}

let t = [0u8; 32].into();

// let node 0 join the topic but do not connect to any peers
network.command(0, t, Command::Join(vec![]));
// connect nodes 1 and 2 to node 0
(1..3).for_each(|i| network.command(i, t, Command::Join(vec![0])));
// connect nodes 4 and 5 to node 3
network.command(3, t, Command::Join(vec![]));
(4..6).for_each(|i| network.command(i, t, Command::Join(vec![3])));
// run ticks and drain events

network.run_trips(4);

let _ = network.events();
assert!(network.check_synchronicity());

// now broadcast a first message
network.command(
    1,
    t,
    Command::Broadcast(b"hi1".to_vec().into(), Scope::Swarm),
);

network.run_trips(4);

let events = network.events();
let received = events.filter(|x| matches!(x, (_, _, Event::Received(_))));
// message should be received by two other nodes
assert_eq!(received.count(), 2);
assert!(network.check_synchronicity());

// now connect the two sections of the swarm
network.command(2, t, Command::Join(vec![5]));
network.run_trips(3);
let _ = network.events();
println!("{}", network.report());

// now broadcast again
network.command(
    1,
    t,
    Command::Broadcast(b"hi2".to_vec().into(), Scope::Swarm),
);
network.run_trips(5);
let events = network.events();
let received = events.filter(|x| matches!(x, (_, _, Event::Received(_))));
// message should be received by all 5 other nodes
assert_eq!(received.count(), 5);
assert!(network.check_synchronicity());
println!("{}", network.report());
```

--------------------------------

### Get Peer Information

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/hyparview.rs.html

Retrieves the PeerInfo for a given peer ID. Returns PeerInfo with optional peer data.

```rust
fn peer_info(&self, id: &PI) -> PeerInfo<PI> {
        let data = self.peer_data.get(id).cloned();
        PeerInfo { id: *id, data }
    }
```

--------------------------------

### Insert Peer with Custom Configuration

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Inserts a new peer with a specific protocol configuration. Panics if the peer ID already exists.

```rust
pub fn insert_with_config(&mut self, peer_id: PI, config: Config)
```

--------------------------------

### Get Neighbors from GossipReceiver

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/api.rs.html

Provides an iterator over the current direct neighbors known to the `GossipReceiver`. The neighbors are stored in a `HashSet`.

```rust
pub fn neighbors(&self) -> impl Iterator<Item = EndpointId> + '_ {
        self.neighbors.iter().copied()
    }
```

--------------------------------

### Get Neighbors from GossipTopic

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/api.rs.html

Returns an iterator over the current direct neighbors of the gossip topic. This information is provided by the `GossipReceiver`.

```rust
pub fn neighbors(&self) -> impl Iterator<Item = EndpointId> + '_ {
        self.receiver.neighbors()
    }
```

--------------------------------

### State::new

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/state.rs.html

Creates a new instance of the protocol state. It requires the local node's PeerIdentity, initial PeerData, configuration, and a random number generator.

```APIDOC
## State::new

### Description

Creates a new instance of the protocol state. It requires the local node's [`PeerIdentity`], initial [`PeerData`] (which can be updated over time), [`Config`], and a random number generator.

### Parameters

- **me** (PI): The [`PeerIdentity`] of the local node.
- **me_data** (PeerData): The initial [`PeerData`] for the local node.
- **config** (Config): The configuration for the gossip protocol. For optimal performance, this should be identical across all nodes.
- **rng** (R): A random number generator implementing `Rng + SeedableRng`.

### Panics

Panics if [`Config::max_message_size`] is below [`MIN_MAX_MESSAGE_SIZE`].
```

--------------------------------

### Handle Incoming Connection

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Spawns a new asynchronous task to manage an incoming network connection. It sets up channels for sending and receiving messages and initiates the connection loop.

```rust
fn handle_connection(&mut self, peer_id: EndpointId, origin: ConnOrigin, conn: Connection) {
        let (send_tx, send_rx) = mpsc::channel(SEND_QUEUE_CAP);
        let conn_id = conn.stable_id();

        let queue = match self.peers.entry(peer_id) {
            Entry::Occupied(mut entry) => entry.get_mut().accept_conn(send_tx, conn_id),
            Entry::Vacant(entry) => {
                entry.insert(PeerState::Active {
                    active_send_tx: send_tx,
                    active_conn_id: conn_id,
                    other_conns: Vec::new(),
                });
                Vec::new()
            }
        };

        let max_message_size = self.state.max_message_size();
        let in_event_tx = self.in_event_tx.clone();

        // Spawn a task for this connection
        self.connection_tasks.spawn(
            async move {
                let res = connection_loop(
                    peer_id,
                    conn.clone(),
                    origin,
                    send_rx,
                    in_event_tx,
                    max_message_size,
                    queue,
                )
                .await;
                (peer_id, conn, res)
            }
            .instrument(error_span!("conn", peer = %peer_id.fmt_short()))
        );
    }
```

--------------------------------

### Get Cache Size

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/util/struct.TimeBoundCache.html

Returns the current number of entries stored in the TimeBoundCache. Useful for monitoring cache usage.

```rust
pub fn len(&self) -> usize
```

--------------------------------

### try_fold

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipReceiver.html

Accumulates a fallible computation over the items of a stream, starting with an initial value. The computation stops if an error occurs.

```APIDOC
## fn try_fold<T, E, F, B>( &mut self, init: B, f: F, ) -> TryFoldFuture<'_, Self, F, B>

### Description
Accumulates a fallible computation over the stream.

### Method
`try_fold` is a method on fallible streams.

### Parameters
- `init`: The initial value for the accumulator.
- `f`: A closure that takes the current accumulator value and the next stream item, returning a `Result` with the updated accumulator value or an error.

### Type Parameters
- `T`: The type of items in the stream.
- `E`: The type of error that can occur.
- `B`: The type of the accumulator.
```

--------------------------------

### Create 'Or' Policy

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.RoundStatsAvg.html

Creates a new Policy that returns Action::Follow if either self or other policies return Action::Follow.

```rust
fn or<P, B, E>(self, other: P) -> Or<T, P>
where T: Policy<B, E>, P: Policy<B, E>,
```

--------------------------------

### Connect to RPC Server

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipApi.html

Establishes a connection to a remote gossip network as an RPC client. This method requires the 'rpc' crate feature to be enabled.

```rust
pub async fn connect(endpoint: Endpoint, addr: SocketAddr) -> Self
```

--------------------------------

### Get Peers from Connection ID

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Retrieves the two peer identifiers associated with a connection. This is useful for identifying the participants of a connection.

```rust
fn peers(&self) -> [PI; 2] {
        self.0
    }
```

--------------------------------

### Get Expiration Time of an Item

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/util/struct.TimeBoundCache.html

Retrieves the expiration Instant for a specific key in the cache. Returns None if the key is not present.

```rust
pub fn expires(&self, key: &K) -> Option<&Instant>
```

--------------------------------

### Subscribe to Gossip Topic (Default Options)

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipApi.html

Joins a gossip topic with default options. This method does not wait for bootstrap endpoints to become available. Use `GossipTopic::joined` or `Self::subscribe_and_join` to ensure a connection.

```rust
pub async fn subscribe( &self, topic_id: TopicId, bootstrap: Vec<EndpointId>, ) -> Result<GossipTopic, ApiError>
```

--------------------------------

### Get Elapsed Network Time

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Returns the total time elapsed since the network simulation was initialized, as a `Duration` object.

```rust
pub fn elapsed(&self) -> Duration
```

--------------------------------

### Test Peer Disconnection with Quit Command

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto.rs.html

Creates a network of 4 nodes, asserts initial peer connections, then simulates a node leaving using the `Quit` command and verifies that the departed peer is no longer listed in connections.

```rust
let rng = ChaCha12Rng::seed_from_u64(read_var("SEED", 0));
let mut config = Config::default();
config.membership.active_view_capacity = 2;
let mut network = Network::new(config.into(), rng);
let num = 4;
for i in 0..num {
    network.insert(i);
}

let t: TopicId = [0u8; 32].into();

// join all nodes
network.command(0, t, Command::Join(vec![]));
network.command(1, t, Command::Join(vec![0]));
network.command(2, t, Command::Join(vec![1]));
network.command(3, t, Command::Join(vec![2]));
network.run_trips(2);

// assert all peers appear in the connections
let all_conns: HashSet<u64> = HashSet::from_iter((0u64..4).flat_map(|p| {
    network
        .neighbors(&p, &t)
        .into_iter()
        .flat_map(|x| x.into_iter())
}));
assert_eq!(all_conns, HashSet::from_iter([0, 1, 2, 3]));
assert!(network.check_synchronicity());

//  let node 3 leave the swarm
network.command(3, t, Command::Quit);
network.run_trips(4);
assert!(network.peer(&3).unwrap().state(&t).is_none());

// assert all peers without peer 3 appear in the connections
let all_conns: HashSet<u64> = HashSet::from_iter((0..num).flat_map(|p| {
    network
        .neighbors(&p, &t)
        .into_iter()
        .flat_map(|x| x.into_iter())
}));
assert_eq!(all_conns, HashSet::from_iter([0, 1, 2]));
assert!(network.check_synchronicity());
```

--------------------------------

### Get Gossip Broadcast Statistics

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Retrieves statistics specifically for the gossip broadcast state. This might be replaced by a metrics system in the future.

```rust
pub fn gossip_stats(&self) -> &Stats
```

--------------------------------

### take

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipTopic.html

Creates a new stream that yields at most `n` items from the underlying stream. Once `n` items are yielded, the new stream will end.

```APIDOC
## fn take(self, n: usize) -> Take<Self>

### Description
Creates a new stream of at most `n` items of the underlying stream.

### Source
[Source Link]
```

--------------------------------

### Creating a New Gossip Address Lookup Instance

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net/address_lookup.rs.html

Initializes a new GossipAddressLookup with default retention options. This is the simplest way to create an instance.

```rust
pub(crate) fn new() -> Self {
    Self::with_opts(Default::default())
}
```

--------------------------------

### Get Encoded Message Size

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.Message.html

Calculates the encoded size of the Message. This requires the generic type PI to implement the Serialize trait.

```rust
pub fn size(&self) -> Result<usize>
```

--------------------------------

### Publish and Subscribe to Gossip Topic

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Demonstrates setting up two endpoints, joining a gossip topic, publishing messages from one endpoint, and receiving them on the other. Asserts that the correct number of messages are received.

```rust
        let topic: TopicId = blake3::hash(b"foobar").into();

        let addr1 = EndpointAddr::new(pi1).with_relay_url(relay_url.clone());
        let addr2 = EndpointAddr::new(pi2).with_relay_url(relay_url);
        memory_lookup.add_endpoint_info(addr1.clone());
        memory_lookup.add_endpoint_info(addr2.clone());

        debug!("----- joining  -----");
        // join the topics and wait for the connection to succeed
        let [sub1, mut sub2, mut sub3] = [ 
            go1.subscribe_and_join(topic, vec![]),
            go2.subscribe_and_join(topic, vec![pi1]),
            go3.subscribe_and_join(topic, vec![pi2]),
        ]
        .try_join()
        .await
        .unwrap();

        let (sink1, _stream1) = sub1.split();

        let len = 2;

        // publish messages on endpoint1
        let pub1 = spawn(async move {
            for i in 0..len {
                let message = format!("hi{i}");
                info!("go1 broadcast: {message:?}");
                sink1.broadcast(message.into_bytes().into()).await.unwrap();
                tokio::time::sleep(Duration::from_micros(1)).await;
            }
        });

        // wait for messages on endpoint2
        let sub2 = spawn(async move {
            let mut recv = vec![];
            loop {
                let ev = sub2.next().await.unwrap().unwrap();
                info!("go2 event: {ev:?}");
                if let Event::Received(msg) = ev {
                    recv.push(msg.content);
                }
                if recv.len() == len {
                    return recv;
                }
            }
        });

        // wait for messages on endpoint3
        let sub3 = spawn(async move {
            let mut recv = vec![];
            loop {
                let ev = sub3.next().await.unwrap().unwrap();
                info!("go3 event: {ev:?}");
                if let Event::Received(msg) = ev {
                    recv.push(msg.content);
                }
                if recv.len() == len {
                    return recv;
                }
            }
        });

        timeout(Duration::from_secs(10), pub1)
            .await
            .unwrap()
            .unwrap();
        let recv2 = timeout(Duration::from_secs(10), sub2)
            .await
            .unwrap()
            .unwrap();
        let recv3 = timeout(Duration::from_secs(10), sub3)
            .await
            .unwrap()
            .unwrap();

        // We assert the received messages, but not their order.
        // While commonly they will be received in-order, for go3 it may happen
        // that the second message arrives before the first one, because it managed to
        // forward-join go1 before the second message is published.
        let expected: HashSet<Bytes> = (0..len)
            .map(|i| Bytes::from(format!("hi{i}").into_bytes()))
            .collect();
        assert_eq!(HashSet::from_iter(recv2), expected);
        assert_eq!(HashSet::from_iter(recv3), expected);

        cancel.cancel();
        for t in tasks {
            timeout(Duration::from_secs(10), t)
                .await
                .unwrap()
                .unwrap()
                .unwrap();
        }
```

--------------------------------

### fold

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipTopic.html

Applies an asynchronous accumulating function to the stream's items, starting with an initial value, and returns the final accumulated value.

```APIDOC
## fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F>

### Description
Execute an accumulating asynchronous computation over a stream, collecting all the values into one final result.

### Method
`fold`

### Parameters
- `self`: The stream to fold.
- `init`: The initial value for the accumulator.
- `f`: An asynchronous closure that takes the current accumulator value and the next item, returning the updated accumulator value.
```

--------------------------------

### Get Other Peer from Connection ID

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Given one peer of a connection, returns the other peer. Returns None if the provided peer is not part of the connection.

```rust
fn other(&self, other: PI) -> Option<PI> {
        if self.0[0] == other {
            Some(self.0[1])
        } else if self.0[1] == other {
            Some(self.0[0])
        } else {
            None
        }
    }
```

--------------------------------

### connect

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipApi.html

Connect to a remote as a RPC client. Requires the `rpc` feature.

```APIDOC
## connect

### Description
Connect to a remote as a RPC client.

### Method
`pub fn connect(endpoint: Endpoint, addr: SocketAddr) -> Self`

### Parameters
- **endpoint** (Endpoint) - Description not available
- **addr** (SocketAddr) - Description not available

### Returns
- `Self` (GossipApi) - Description not available
```

--------------------------------

### Get a random peer ID

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Returns the PeerId of a randomly selected peer from the network. This is useful for targeting random nodes in simulation operations.

```rust
pub fn random_peer(&mut self) -> PeerId {
        *self
            .network
            .peers
            .keys()
            .choose(&mut self.network.rng)
            .unwrap()
    }
```

--------------------------------

### Initialize SendLoop

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net/util.rs.html

Creates a new `SendLoop` instance. It requires a `Connection`, a receiver for `ProtoMessage`s, and the maximum message size.

```rust
pub(crate) fn new(
        conn: Connection,
        send_rx: mpsc::Receiver<ProtoMessage>,
        max_message_size: usize,
    ) -> Self {
        Self {
            conn,
            max_message_size,
            buffer: Default::default(),
            streams: Default::default(),
            finishing: Default::default(),
            send_rx,
        }
    }
```

--------------------------------

### Get Earliest Entry Timestamp

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/util.rs.html

Returns a reference to the Instant of the earliest entry in the TimerMap without removing it. Returns None if the TimerMap is empty.

```rust
pub fn first(&self) -> Option<&Instant> {
        self.heap.peek().map(|x| &x.time)
    }
```

--------------------------------

### subscribe_with_opts

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.GossipApi.html

Join a gossip topic with options. Returns a `GossipTopic` instantly. To wait for at least one connection to be established, you can await `GossipTopic::joined`. Messages will be queued until a first connection is available. If the internal channel becomes full, the oldest messages will be dropped from the channel.

```APIDOC
## subscribe_with_opts

### Description
Join a gossip topic with options. Returns a `GossipTopic` instantly. To wait for at least one connection to be established, you can await `GossipTopic::joined`. Messages will be queued until a first connection is available. If the internal channel becomes full, the oldest messages will be dropped from the channel.

### Method
`pub async fn subscribe_with_opts( &self, topic_id: TopicId, opts: JoinOptions, ) -> Result<GossipTopic, ApiError>`

### Parameters
- **topic_id** (TopicId) - Description not available
- **opts** (JoinOptions) - Description not available

### Returns
- `Result<GossipTopic, ApiError>` - Description not available
```

--------------------------------

### Handle IHave Message

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/plumtree.rs.html

Marks a message as missing when an IHave message is received and starts a timer for it. This is a placeholder for the actual logic described in the paper.

```rust
/// Handle receiving a [`Message::IHave`].
///
/// > When a node receives a IHAVE message, it simply marks the corresponding message as
/// > missing It then starts a timer, with a predefined timeout value, and waits for the missing
```

--------------------------------

### Dialer Initialization

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/net.rs.html

Creates a new dialer instance for a given endpoint. Initializes the pending connections and pending dials maps.

```rust
impl Dialer {
    /// Create a new dialer for a [`Endpoint`]
    fn new(endpoint: Endpoint) -> Self {
        Self {
            endpoint,
            pending: Default::default(),
            pending_dials: Default::default(),
        }
    }
// ...
}
```

--------------------------------

### Get the number of peers in the network

Source: https://docs.rs/iroh-gossip/latest/src/iroh_gossip/proto/sim.rs.html

Returns the current count of peers connected to the simulated network. Provides a quick status check of the network size.

```rust
pub fn peer_count(&self) -> usize {
        self.network.peers.len()
    }
```

--------------------------------

### Creating JoinOptions with Bootstrap Endpoints

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/api/struct.JoinOptions.html

Instantiates JoinOptions with specified bootstrap endpoints, using the default subscription capacity. This is useful for initiating connections to a gossip network.

```rust
pub fn with_bootstrap(endpoints: impl IntoIterator<Item = EndpointId>) -> Self
```

--------------------------------

### Queue and Perform Network Command

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Queues a command to be performed by a specific peer on a given topic. This method is used to send instructions to peers within the simulation.

```rust
pub fn command(&mut self, peer: PI, topic: TopicId, command: Command<PI>)
```

--------------------------------

### Get PeerData Bytes

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/struct.PeerData.html

Retrieves a reference to the internal bytes::Bytes stored within the PeerData. This allows for direct access to the underlying byte buffer.

```rust
pub fn inner(&self) -> &Bytes>
```

--------------------------------

### Get Formatted Elapsed Network Time

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Returns the elapsed time of the network simulation, formatted as a string representing seconds with limited decimal places.

```rust
pub fn elapsed_fmt(&self) -> String
```

--------------------------------

### State Initialization

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/topic/struct.State.html

Initializes the local state for a topic with a default random number generator.

```APIDOC
## pub fn new(me: PI, me_data: Option<PeerData>, config: Config) -> Self

Initialize the local state with the default random number generator.

### Panics

Panics if `Config::max_message_size` is below `MIN_MAX_MESSAGE_SIZE`.
```

--------------------------------

### State::new

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/state/struct.State.html

Creates a new instance of the protocol state. It requires the local node's PeerIdentity, initial PeerData, configuration, and a random number generator. Panics if the max message size in the config is too small.

```APIDOC
## State::new

### Description
Creates a new protocol state instance.

`me` is the `PeerIdentity` of the local node, `peer_data` is the initial `PeerData` (which can be updated over time). For the protocol to perform as recommended in the papers, the `Config` should be identical for all nodes in the network.

### Method
`new(me: PI, me_data: PeerData, config: Config, rng: R) -> Self`

### Panics
Panics if `Config::max_message_size` is below `MIN_MAX_MESSAGE_SIZE`.
```

--------------------------------

### Get Specific Peer State

Source: https://docs.rs/iroh-gossip/latest/iroh_gossip/proto/sim/struct.Network.html

Retrieves the `State` object for a given peer ID, if that peer exists in the network. Returns `None` if the peer is not found.

```rust
pub fn peer(&self, peer: &PI) -> Option<&State<PI, R>>
```