pub async fn init<S, C>(
    config: Config,
    inbound_service: S,
    latest_chain_tip: C,
) -> (
    Buffer<BoxService<Request, Response, BoxError>, Request>,
    Arc<std::sync::Mutex<AddressBook>>,
)
where
    S: Service<Request, Response = Response, Error = BoxError> + Clone + Send + 'static,
    S::Future: Send + 'static,
    C: ChainTip + Clone + Send + 'static,
{
    // If we want Zebra to operate with no network,
    // we should implement a `zebrad` command that doesn't use `zebra-network`.
    assert!(
        config.peerset_initial_target_size > 0,
        "Zebra must be allowed to connect to at least one peer"
    );

    let (tcp_listener, listen_addr) = open_listener(&config.clone()).await;

    let (address_book, address_book_updater, address_metrics, address_book_updater_guard) =
        AddressBookUpdater::spawn(&config, listen_addr);

    // Create a broadcast channel for peer inventory advertisements.
    // If it reaches capacity, this channel drops older inventory advertisements.
    //
    // When Zebra is at the chain tip with an up-to-date mempool,
    // we expect to have at most 1 new transaction per connected peer,
    // and 1-2 new blocks across the entire network.
    // (The block syncer and mempool crawler handle bulk fetches of blocks and transactions.)
    let (inv_sender, inv_receiver) = broadcast::channel(config.peerset_total_connection_limit());

    // Construct services that handle inbound handshakes and perform outbound
    // handshakes. These use the same handshake service internally to detect
    // self-connection attempts. Both are decorated with a tower TimeoutLayer to
    // enforce timeouts as specified in the Config.
    let (listen_handshaker, outbound_connector) = {
        use tower::timeout::TimeoutLayer;
        let hs_timeout = TimeoutLayer::new(constants::HANDSHAKE_TIMEOUT);
        use crate::protocol::external::types::PeerServices;
        let hs = peer::Handshake::builder()
            .with_config(config.clone())
            .with_inbound_service(inbound_service)
            .with_inventory_collector(inv_sender)
            .with_address_book_updater(address_book_updater.clone())
            .with_advertised_services(PeerServices::NODE_NETWORK)
            .with_user_agent(crate::constants::USER_AGENT.to_string())
            .with_latest_chain_tip(latest_chain_tip.clone())
            .want_transactions(true)
            .finish()
            .expect("configured all required parameters");
        (
            hs_timeout.layer(hs.clone()),
            hs_timeout.layer(peer::Connector::new(hs)),
        )
    };

    // Create an mpsc channel for peer changes,
    // based on the maximum number of inbound and outbound peers.
    let (peerset_tx, peerset_rx) =
        futures::channel::mpsc::channel::<DiscoveredPeer>(config.peerset_total_connection_limit());

    let discovered_peers = peerset_rx
        // Discover interprets an error as stream termination,
        // so discard any errored connections...
        .filter(|result| future::ready(result.is_ok()))
        .map_ok(|(address, client)| Change::Insert(address, client.into()));

    // Create an mpsc channel for peerset demand signaling,
    // based on the maximum number of outbound peers.
    let (mut demand_tx, demand_rx) =
        futures::channel::mpsc::channel::<MorePeers>(config.peerset_outbound_connection_limit());

    // Create a oneshot to send background task JoinHandles to the peer set
    let (handle_tx, handle_rx) = tokio::sync::oneshot::channel();

    // Connect the rx end to a PeerSet, wrapping new peers in load instruments.
    let peer_set = PeerSet::new(
        &config,
        discovered_peers,
        demand_tx.clone(),
        handle_rx,
        inv_receiver,
        address_metrics,
        MinimumPeerVersion::new(latest_chain_tip, config.network),
    );
    let peer_set = Buffer::new(BoxService::new(peer_set), constants::PEERSET_BUFFER_SIZE);

    // Connect peerset_tx to the 3 peer sources:
    //
    // 1. Incoming peer connections, via a listener.
    let listen_fut = accept_inbound_connections(
        config.clone(),
        tcp_listener,
        listen_handshaker,
        peerset_tx.clone(),
    );
    let listen_guard = tokio::spawn(listen_fut.instrument(Span::current()));

    // 2. Initial peers, specified in the config.
    let initial_peers_fut = add_initial_peers(
        config.clone(),
        outbound_connector.clone(),
        peerset_tx.clone(),
        address_book_updater,
    );
    let initial_peers_join = tokio::spawn(initial_peers_fut.instrument(Span::current()));

    // 3. Outgoing peers we connect to in response to load.
    let mut candidates = CandidateSet::new(address_book.clone(), peer_set.clone());

    // Wait for the initial seed peer count
    let mut active_outbound_connections = initial_peers_join
        .await
        .expect("unexpected panic in spawned initial peers task")
        .expect("unexpected error connecting to initial peers");
    let active_initial_peer_count = active_outbound_connections.update_count();

    // We need to await candidates.update() here,
    // because zcashd rate-limits `addr`/`addrv2` messages per connection,
    // and if we only have one initial peer,
    // we need to ensure that its `Response::Addr` is used by the crawler.
    //
    // TODO: cache the most recent `Response::Addr` returned by each peer.
    //       If the request times out, return the cached response to the caller.

    info!(
        ?active_initial_peer_count,
        "sending initial request for peers"
    );
    let _ = candidates.update_initial(active_initial_peer_count).await;

    // Compute remaining connections to open.
    let demand_count = config
        .peerset_initial_target_size
        .saturating_sub(active_outbound_connections.update_count());

    for _ in 0..demand_count {
        let _ = demand_tx.try_send(MorePeers);
    }

    let crawl_fut = crawl_and_dial(
        config,
        demand_tx,
        demand_rx,
        candidates,
        outbound_connector,
        peerset_tx,
        active_outbound_connections,
    );
    let crawl_guard = tokio::spawn(crawl_fut.instrument(Span::current()));

    handle_tx
        .send(vec![listen_guard, crawl_guard, address_book_updater_guard])
        .unwrap();

    (peer_set, address_book)
}
/// Initialize a peer set, using a network `config`, `inbound_service`,
/// and `latest_chain_tip`.
///
/// The peer set abstracts away peer management to provide a
/// [`tower::Service`] representing "the network" that load-balances requests
/// over available peers.  The peer set automatically crawls the network to
/// find more peer addresses and opportunistically connects to new peers.
///
/// Each peer connection's message handling is isolated from other
/// connections, unlike in `zcashd`.  The peer connection first attempts to
/// interpret inbound messages as part of a response to a previously-issued
/// request.  Otherwise, inbound messages are interpreted as requests and sent
/// to the supplied `inbound_service`.
///
/// Wrapping the `inbound_service` in [`tower::load_shed`] middleware will
/// cause the peer set to shrink when the inbound service is unable to keep up
/// with the volume of inbound requests.
///
/// Use [`NoChainTip`] to explicitly provide no chain tip receiver.
///
/// In addition to returning a service for outbound requests, this method
/// returns a shared [`AddressBook`] updated with last-seen timestamps for
/// connected peers. The shared address book should be accessed using a
/// [blocking thread](https://docs.rs/tokio/1.15.0/tokio/task/index.html#blocking-and-yielding),
/// to avoid async task deadlocks.
///
/// # Panics
///
/// If `config.config.peerset_initial_target_size` is zero.
/// (zebra-network expects to be able to connect to at least one peer.)


The peer set abstracts away peer management to provide a
[`tower::Service`] representing "the network" that load-balances requests
over available peers.  The peer set automatically crawls the network to
find more peer addresses and opportunistically connects to new peers.

Each peer connection's message handling is isolated from other
connections, unlike in `zcashd`.  The peer connection first attempts to
interpret inbound messages as part of a response to a previously-issued
request.  Otherwise, inbound messages are interpreted as requests and sent
to the supplied `inbound_service`.

Wrapping the `inbound_service` in [`tower::load_shed`] middleware will
cause the peer set to shrink when the inbound service is unable to keep up
with the volume of inbound requests.

Use [`NoChainTip`] to explicitly provide no chain tip receiver.

In addition to returning a service for outbound requests, this method
returns a shared [`AddressBook`] updated with last-seen timestamps for
connected peers. The shared address book should be accessed using a
[blocking thread],
to avoid async task deadlocks.
The peer set abstracts away peer management to provide a [ ` tower :: Service ` ] representing " the network " that load - balances requests over available peers . The peer set automatically crawls the network to find more peer addresses and opportunistically connects to new peers . Each peer connection ' s message handling is isolated from other connections unlike in ` zcashd ` . The peer connection first attempts to interpret inbound messages as part of a response to a previously - issued request . Otherwise inbound messages are interpreted as requests and sent to the supplied ` inbound_service ` . Wrapping the ` inbound_service ` in [ ` tower :: load_shed ` ] middleware will cause the peer set to shrink when the inbound service is unable to keep up with the volume of inbound requests . Use [ ` NoChainTip ` ] to explicitly provide no chain tip receiver . In addition to returning a service for outbound requests this method returns a shared [ ` AddressBook ` ] updated with last - seen timestamps for connected peers . The shared address book should be accessed using a [ blocking thread ] to avoid async task deadlocks .
pub async fn init<S, C>(
    config: Config,
    inbound_service: S,
    latest_chain_tip: C,
) -> (
    Buffer<BoxService<Request, Response, BoxError>, Request>,
    Arc<std::sync::Mutex<AddressBook>>,
)
where
    S: Service<Request, Response = Response, Error = BoxError> + Clone + Send + 'static,
    S::Future: Send + 'static,
    C: ChainTip + Clone + Send + 'static,
{
    // If we want Zebra to operate with no network,
    // we should implement a `zebrad` command that doesn't use `zebra-network`.
    assert!(
        config.peerset_initial_target_size > 0,
        "Zebra must be allowed to connect to at least one peer"
    );
    let (tcp_listener, listen_addr) = open_listener(&config.clone()).await;
    let (address_book, address_book_updater, address_metrics, address_book_updater_guard) =
        AddressBookUpdater::spawn(&config, listen_addr);
    // Create a broadcast channel for peer inventory advertisements.
    // If it reaches capacity, this channel drops older inventory advertisements.
    //
    // When Zebra is at the chain tip with an up-to-date mempool,
    // we expect to have at most 1 new transaction per connected peer,
    // and 1-2 new blocks across the entire network.
    // (The block syncer and mempool crawler handle bulk fetches of blocks and transactions.)
    let (inv_sender, inv_receiver) = broadcast::channel(config.peerset_total_connection_limit());
    // Construct services that handle inbound handshakes and perform outbound
    // handshakes. These use the same handshake service internally to detect
    // self-connection attempts. Both are decorated with a tower TimeoutLayer to
    // enforce timeouts as specified in the Config.
    let (listen_handshaker, outbound_connector) = {
        use tower::timeout::TimeoutLayer;
        let hs_timeout = TimeoutLayer::new(constants::HANDSHAKE_TIMEOUT);
        use crate::protocol::external::types::PeerServices;
        let hs = peer::Handshake::builder()
            .with_config(config.clone())
            .with_inbound_service(inbound_service)
            .with_inventory_collector(inv_sender)
            .with_address_book_updater(address_book_updater.clone())
            .with_advertised_services(PeerServices::NODE_NETWORK)
            .with_user_agent(crate::constants::USER_AGENT.to_string())
            .with_latest_chain_tip(latest_chain_tip.clone())
            .want_transactions(true)
            .finish()
            .expect("configured all required parameters");
        (
            hs_timeout.layer(hs.clone()),
            hs_timeout.layer(peer::Connector::new(hs)),
        )
    };
    // Create an mpsc channel for peer changes,
    // based on the maximum number of inbound and outbound peers.
    let (peerset_tx, peerset_rx) =
        futures::channel::mpsc::channel::<DiscoveredPeer>(config.peerset_total_connection_limit());
    let discovered_peers = peerset_rx
        // Discover interprets an error as stream termination,
        // so discard any errored connections...
        .filter(|result| future::ready(result.is_ok()))
        .map_ok(|(address, client)| Change::Insert(address, client.into()));
    // Create an mpsc channel for peerset demand signaling,
    // based on the maximum number of outbound peers.
    let (mut demand_tx, demand_rx) =
        futures::channel::mpsc::channel::<MorePeers>(config.peerset_outbound_connection_limit());
    // Create a oneshot to send background task JoinHandles to the peer set
    let (handle_tx, handle_rx) = tokio::sync::oneshot::channel();
    // Connect the rx end to a PeerSet, wrapping new peers in load instruments.
    let peer_set = PeerSet::new(
        &config,
        discovered_peers,
        demand_tx.clone(),
        handle_rx,
        inv_receiver,
        address_metrics,
        MinimumPeerVersion::new(latest_chain_tip, config.network),
    );
    let peer_set = Buffer::new(BoxService::new(peer_set), constants::PEERSET_BUFFER_SIZE);
    // Connect peerset_tx to the 3 peer sources:
    //
    // 1. Incoming peer connections, via a listener.
    let listen_fut = accept_inbound_connections(
        config.clone(),
        tcp_listener,
        listen_handshaker,
        peerset_tx.clone(),
    );
    let listen_guard = tokio::spawn(listen_fut.instrument(Span::current()));
    // 2. Initial peers, specified in the config.
    let initial_peers_fut = add_initial_peers(
        config.clone(),
        outbound_connector.clone(),
        peerset_tx.clone(),
        address_book_updater,
    );
    let initial_peers_join = tokio::spawn(initial_peers_fut.instrument(Span::current()));
    // 3. Outgoing peers we connect to in response to load.
    let mut candidates = CandidateSet::new(address_book.clone(), peer_set.clone());
    // Wait for the initial seed peer count
    let mut active_outbound_connections = initial_peers_join
        .await
        .expect("unexpected panic in spawned initial peers task")
        .expect("unexpected error connecting to initial peers");
    let active_initial_peer_count = active_outbound_connections.update_count();
    // We need to await candidates.update() here,
    // because zcashd rate-limits `addr`/`addrv2` messages per connection,
    // and if we only have one initial peer,
    // we need to ensure that its `Response::Addr` is used by the crawler.
    //
    // TODO: cache the most recent `Response::Addr` returned by each peer.
    //       If the request times out, return the cached response to the caller.
    info!(
        ?active_initial_peer_count,
        "sending initial request for peers"
    );
    let _ = candidates.update_initial(active_initial_peer_count).await;
    // Compute remaining connections to open.
    let demand_count = config
        .peerset_initial_target_size
        .saturating_sub(active_outbound_connections.update_count());
    for _ in 0..demand_count {
        let _ = demand_tx.try_send(MorePeers);
    }
    let crawl_fut = crawl_and_dial(
        config,
        demand_tx,
        demand_rx,
        candidates,
        outbound_connector,
        peerset_tx,
        active_outbound_connections,
    );
    let crawl_guard = tokio::spawn(crawl_fut.instrument(Span::current()));
    handle_tx
        .send(vec![listen_guard, crawl_guard, address_book_updater_guard])
        .unwrap();
    (peer_set, address_book)
}
pub async fn init < S , C > ( config : Config , inbound_service : S , latest_chain_tip : C , ) -> ( Buffer < BoxService < Request , Response , BoxError > , Request > , Arc < std :: sync :: Mutex < AddressBook > > , ) where S : Service < Request , Response = Response , Error = BoxError > + Clone + Send + ' static , S :: Future : Send + ' static , C : ChainTip + Clone + Send + ' static , { // If we want Zebra to operate with no network, // we should implement a `zebrad` command that doesn't use `zebra-network`. assert ! ( config peerset_initial_target_size 0 " " ) ; let ( tcp_listener , listen_addr ) = open_listener ( & config . clone ( ) ) . await ; let ( address_book , address_book_updater , address_metrics , address_book_updater_guard ) = AddressBookUpdater :: spawn ( & config , listen_addr ) ; // Create a broadcast channel for peer inventory advertisements. // If it reaches capacity, this channel drops older inventory advertisements. // // When Zebra is at the chain tip with an up-to-date mempool, // we expect to have at most 1 new transaction per connected peer, // and 1-2 new blocks across the entire network. // (The block syncer and mempool crawler handle bulk fetches of blocks and transactions.) let ( inv_sender , inv_receiver ) = broadcast :: channel ( config . peerset_total_connection_limit ( ) ) ; // Construct services that handle inbound handshakes and perform outbound // handshakes. These use the same handshake service internally to detect // self-connection attempts. Both are decorated with a tower TimeoutLayer to // enforce timeouts as specified in the Config. let ( listen_handshaker , outbound_connector ) = { use tower :: timeout :: TimeoutLayer ; let hs_timeout = TimeoutLayer :: new ( constants :: HANDSHAKE_TIMEOUT ) ; use crate :: protocol :: external :: types :: PeerServices ; let hs = peer :: Handshake :: builder ( ) . with_config ( config . clone ( ) ) . with_inbound_service ( inbound_service ) . with_inventory_collector ( inv_sender ) . with_address_book_updater ( address_book_updater . clone ( ) ) . with_advertised_services ( PeerServices :: NODE_NETWORK ) . with_user_agent ( crate :: constants :: USER_AGENT . to_string ( ) ) . with_latest_chain_tip ( latest_chain_tip . clone ( ) ) . want_transactions ( true ) . finish ( ) . expect ( " " ) ; ( hs_timeout . layer ( hs . clone ( ) ) , hs_timeout . layer ( peer :: Connector :: new ( hs ) ) , ) } ; // Create an mpsc channel for peer changes, // based on the maximum number of inbound and outbound peers. let ( peerset_tx , peerset_rx ) = futures :: channel :: mpsc :: channel :: < DiscoveredPeer > ( config . peerset_total_connection_limit ( ) ) ; let discovered_peers = peerset_rx // Discover interprets an error as stream termination, // so discard any errored connections... . filter ( | result | future :: ready ( result . is_ok ( ) ) ) . map_ok ( | ( address , client ) | Change :: Insert ( address , client . into ( ) ) ) ; // Create an mpsc channel for peerset demand signaling, // based on the maximum number of outbound peers. let ( mut demand_tx , demand_rx ) = futures :: channel :: mpsc :: channel :: < MorePeers > ( config . peerset_outbound_connection_limit ( ) ) ; // Create a oneshot to send background task JoinHandles to the peer set let ( handle_tx , handle_rx ) = tokio :: sync :: oneshot :: channel ( ) ; // Connect the rx end to a PeerSet, wrapping new peers in load instruments. let peer_set = PeerSet :: new ( & config , discovered_peers , demand_tx . clone ( ) , handle_rx , inv_receiver , address_metrics , MinimumPeerVersion :: new ( latest_chain_tip , config . network ) , ) ; let peer_set = Buffer :: new ( BoxService :: new ( peer_set ) , constants :: PEERSET_BUFFER_SIZE ) ; // Connect peerset_tx to the 3 peer sources: // // 1. Incoming peer connections, via a listener. let listen_fut = accept_inbound_connections ( config . clone ( ) , tcp_listener , listen_handshaker , peerset_tx . clone ( ) , ) ; let listen_guard = tokio :: spawn ( listen_fut . instrument ( Span :: current ( ) ) ) ; // 2. Initial peers, specified in the config. let initial_peers_fut = add_initial_peers ( config . clone ( ) , outbound_connector . clone ( ) , peerset_tx . clone ( ) , address_book_updater , ) ; let initial_peers_join = tokio :: spawn ( initial_peers_fut . instrument ( Span :: current ( ) ) ) ; // 3. Outgoing peers we connect to in response to load. let mut candidates = CandidateSet :: new ( address_book . clone ( ) , peer_set . clone ( ) ) ; // Wait for the initial seed peer count let mut active_outbound_connections = initial_peers_join . await . expect ( " " ) . expect ( " " ) ; let active_initial_peer_count = active_outbound_connections . update_count ( ) ; // We need to await candidates.update() here, // because zcashd rate-limits `addr`/`addrv2` messages per connection, // and if we only have one initial peer, // we need to ensure that its `Response::Addr` is used by the crawler. // // TODO: cache the most recent `Response::Addr` returned by each peer. //       If the request times out, return the cached response to the caller. info ! ( active_initial_peer_count " " ) ; let _ = candidates . update_initial ( active_initial_peer_count ) . await ; // Compute remaining connections to open. let demand_count = config . peerset_initial_target_size . saturating_sub ( active_outbound_connections . update_count ( ) ) ; for _ in 0 .. demand_count { let _ = demand_tx . try_send ( MorePeers ) ; } let crawl_fut = crawl_and_dial ( config , demand_tx , demand_rx , candidates , outbound_connector , peerset_tx , active_outbound_connections , ) ; let crawl_guard = tokio :: spawn ( crawl_fut . instrument ( Span :: current ( ) ) ) ; handle_tx . send ( vec ! [ listen_guard crawl_guard address_book_updater_guard ] ) . unwrap ( ) ; ( peer_set , address_book ) }
Initialize a peer set, using a network `config`, `inbound_service`,
and `latest_chain_tip`.
Initialize a peer set using a network ` config ` ` inbound_service ` and ` latest_chain_tip ` .
config
Config
inbound_service
S
latest_chain_tip
C
panics
If `config.config.peerset_initial_target_size` is zero.
(zebra-network expects to be able to connect to at least one peer.)
If ` config . config . peerset_initial_target_size ` is zero . ( zebra - network expects to be able to connect to at least one peer . )