P2P: remove peer sync service (#299)

* remove peer sync service

* change `p2p` to not use the peer sync service

* fmt & clippy

* doc updates

* review fixes

* add a little more detail to comment

Cargo.lock

@@ -773,7 +773,6 @@ dependencies = [
  "cuprate-wire",
  "dashmap",
  "futures",
- "hex",
  "indexmap",
  "monero-serai",
  "pin-project",

p2p/p2p-core/src/client.rs

@@ -1,6 +1,6 @@
 use std::{
     fmt::{Debug, Display, Formatter},
-    sync::Arc,
+    sync::{Arc, Mutex},
     task::{ready, Context, Poll},
 };
 
@@ -15,6 +15,7 @@ use tracing::Instrument;
 
 use cuprate_helper::asynch::InfallibleOneshotReceiver;
 use cuprate_pruning::PruningSeed;
+use cuprate_wire::CoreSyncData;
 
 use crate::{
     handles::{ConnectionGuard, ConnectionHandle},
@@ -59,8 +60,17 @@ pub struct PeerInformation<A> {
     pub handle: ConnectionHandle,
     /// The direction of this connection (inbound|outbound).
     pub direction: ConnectionDirection,
-    /// The peers pruning seed.
+    /// The peer's [`PruningSeed`].
     pub pruning_seed: PruningSeed,
+    /// The [`CoreSyncData`] of this peer.
+    ///
+    /// Data across fields are not necessarily related, so [`CoreSyncData::top_id`] is not always the
+    /// block hash for the block at height one below [`CoreSyncData::current_height`].
+    ///
+    /// This value is behind a [`Mutex`] and is updated whenever the peer sends new information related
+    /// to their sync state. It is publicly accessible to anyone who has a peers [`Client`] handle. You
+    /// probably should not mutate this value unless you are creating a custom [`ProtocolRequestHandler`](crate::ProtocolRequestHandler).
+    pub core_sync_data: Arc<Mutex<CoreSyncData>>,
 }
 
 /// This represents a connection to a peer.

p2p/p2p-core/src/client/connection.rs

@@ -22,7 +22,7 @@ use crate::{
     constants::{REQUEST_TIMEOUT, SENDING_TIMEOUT},
     handles::ConnectionGuard,
     AddressBook, BroadcastMessage, CoreSyncSvc, MessageID, NetworkZone, PeerError, PeerRequest,
-    PeerResponse, PeerSyncSvc, ProtocolRequestHandler, ProtocolResponse, SharedError,
+    PeerResponse, ProtocolRequestHandler, ProtocolResponse, SharedError,
 };
 
 /// A request to the connection task from a [`Client`](crate::client::Client).
@@ -71,7 +71,7 @@ const fn levin_command_response(message_id: MessageID, command: LevinCommand) ->
 }
 
 /// This represents a connection to a peer.
-pub(crate) struct Connection<Z: NetworkZone, A, CS, PS, PR, BrdcstStrm> {
+pub(crate) struct Connection<Z: NetworkZone, A, CS, PR, BrdcstStrm> {
     /// The peer sink - where we send messages to the peer.
     peer_sink: Z::Sink,
 
@@ -86,7 +86,7 @@ pub(crate) struct Connection<Z: NetworkZone, A, CS, PS, PR, BrdcstStrm> {
     broadcast_stream: Pin<Box<BrdcstStrm>>,
 
     /// The inner handler for any requests that come from the requested peer.
-    peer_request_handler: PeerRequestHandler<Z, A, CS, PS, PR>,
+    peer_request_handler: PeerRequestHandler<Z, A, CS, PR>,
 
     /// The connection guard which will send signals to other parts of Cuprate when this connection is dropped.
     connection_guard: ConnectionGuard,
@@ -94,12 +94,11 @@ pub(crate) struct Connection<Z: NetworkZone, A, CS, PS, PR, BrdcstStrm> {
     error: SharedError<PeerError>,
 }
 
-impl<Z, A, CS, PS, PR, BrdcstStrm> Connection<Z, A, CS, PS, PR, BrdcstStrm>
+impl<Z, A, CS, PR, BrdcstStrm> Connection<Z, A, CS, PR, BrdcstStrm>
 where
     Z: NetworkZone,
     A: AddressBook<Z>,
     CS: CoreSyncSvc,
-    PS: PeerSyncSvc<Z>,
     PR: ProtocolRequestHandler,
     BrdcstStrm: Stream<Item = BroadcastMessage> + Send + 'static,
 {
@@ -108,7 +107,7 @@ where
         peer_sink: Z::Sink,
         client_rx: mpsc::Receiver<ConnectionTaskRequest>,
         broadcast_stream: BrdcstStrm,
-        peer_request_handler: PeerRequestHandler<Z, A, CS, PS, PR>,
+        peer_request_handler: PeerRequestHandler<Z, A, CS, PR>,
         connection_guard: ConnectionGuard,
         error: SharedError<PeerError>,
     ) -> Self {

p2p/p2p-core/src/client/connector.rs

@@ -16,7 +16,7 @@ use tower::{Service, ServiceExt};
 
 use crate::{
     client::{handshaker::HandShaker, Client, DoHandshakeRequest, HandshakeError, InternalPeerID},
-    AddressBook, BroadcastMessage, ConnectionDirection, CoreSyncSvc, NetworkZone, PeerSyncSvc,
+    AddressBook, BroadcastMessage, ConnectionDirection, CoreSyncSvc, NetworkZone,
     ProtocolRequestHandler,
 };
 
@@ -32,27 +32,24 @@ pub struct ConnectRequest<Z: NetworkZone> {
 }
 
 /// The connector service, this service connects to peer and returns the [`Client`].
-pub struct Connector<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr> {
-    handshaker: HandShaker<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>,
+pub struct Connector<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr> {
+    handshaker: HandShaker<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>,
 }
 
-impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
-    Connector<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+impl<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
+    Connector<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
 {
     /// Create a new connector from a handshaker.
-    pub const fn new(
-        handshaker: HandShaker<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>,
-    ) -> Self {
+    pub const fn new(handshaker: HandShaker<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>) -> Self {
         Self { handshaker }
     }
 }
 
-impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>
-    Service<ConnectRequest<Z>> for Connector<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+impl<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>
+    Service<ConnectRequest<Z>> for Connector<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
 where
     AdrBook: AddressBook<Z> + Clone,
     CSync: CoreSyncSvc + Clone,
-    PSync: PeerSyncSvc<Z> + Clone,
     ProtoHdlr: ProtocolRequestHandler + Clone,
     BrdcstStrm: Stream<Item = BroadcastMessage> + Send + 'static,
     BrdcstStrmMkr: Fn(InternalPeerID<Z::Addr>) -> BrdcstStrm + Clone + Send + 'static,

p2p/p2p-core/src/client/handshaker.rs

@@ -8,7 +8,7 @@ use std::{
     future::Future,
     marker::PhantomData,
     pin::Pin,
-    sync::Arc,
+    sync::{Arc, Mutex},
     task::{Context, Poll},
 };
 
@@ -40,10 +40,9 @@ use crate::{
         PING_TIMEOUT,
     },
     handles::HandleBuilder,
-    services::PeerSyncRequest,
     AddressBook, AddressBookRequest, AddressBookResponse, BroadcastMessage, ConnectionDirection,
     CoreSyncDataRequest, CoreSyncDataResponse, CoreSyncSvc, NetZoneAddress, NetworkZone,
-    PeerSyncSvc, ProtocolRequestHandler, SharedError,
+    ProtocolRequestHandler, SharedError,
 };
 
 pub mod builder;
@@ -87,13 +86,11 @@ pub struct DoHandshakeRequest<Z: NetworkZone> {
 
 /// The peer handshaking service.
 #[derive(Debug, Clone)]
-pub struct HandShaker<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr> {
+pub struct HandShaker<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr> {
     /// The address book service.
     address_book: AdrBook,
     /// The core sync data service.
     core_sync_svc: CSync,
-    /// The peer sync service.
-    peer_sync_svc: PSync,
     /// The protocol request handler service.
     protocol_request_svc: ProtoHdlr,
 
@@ -109,13 +106,12 @@ pub struct HandShaker<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstSt
     _zone: PhantomData<Z>,
 }
 
-impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
-    HandShaker<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+impl<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
+    HandShaker<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
 {
     /// Creates a new handshaker.
     const fn new(
         address_book: AdrBook,
-        peer_sync_svc: PSync,
         core_sync_svc: CSync,
         protocol_request_svc: ProtoHdlr,
         broadcast_stream_maker: BrdcstStrmMkr,
@@ -124,7 +120,6 @@ impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     ) -> Self {
         Self {
             address_book,
-            peer_sync_svc,
             core_sync_svc,
             protocol_request_svc,
             broadcast_stream_maker,
@@ -135,13 +130,11 @@ impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     }
 }
 
-impl<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>
-    Service<DoHandshakeRequest<Z>>
-    for HandShaker<Z, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+impl<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>
+    Service<DoHandshakeRequest<Z>> for HandShaker<Z, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
 where
     AdrBook: AddressBook<Z> + Clone,
     CSync: CoreSyncSvc + Clone,
-    PSync: PeerSyncSvc<Z> + Clone,
     ProtoHdlr: ProtocolRequestHandler + Clone,
     BrdcstStrm: Stream<Item = BroadcastMessage> + Send + 'static,
     BrdcstStrmMkr: Fn(InternalPeerID<Z::Addr>) -> BrdcstStrm + Clone + Send + 'static,
@@ -161,7 +154,6 @@ where
         let address_book = self.address_book.clone();
         let protocol_request_svc = self.protocol_request_svc.clone();
         let core_sync_svc = self.core_sync_svc.clone();
-        let peer_sync_svc = self.peer_sync_svc.clone();
         let our_basic_node_data = self.our_basic_node_data.clone();
 
         let connection_parent_span = self.connection_parent_span.clone();
@@ -176,7 +168,6 @@ where
                     broadcast_stream_maker,
                     address_book,
                     core_sync_svc,
-                    peer_sync_svc,
                     protocol_request_svc,
                     our_basic_node_data,
                     connection_parent_span,
@@ -231,15 +222,13 @@ pub async fn ping<N: NetworkZone>(addr: N::Addr) -> Result<u64, HandshakeError>
 }
 
 /// This function completes a handshake with the requested peer.
-#[expect(clippy::too_many_arguments)]
-async fn handshake<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>(
+async fn handshake<Z: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr, BrdcstStrm>(
     req: DoHandshakeRequest<Z>,
 
     broadcast_stream_maker: BrdcstStrmMkr,
 
     mut address_book: AdrBook,
     mut core_sync_svc: CSync,
-    mut peer_sync_svc: PSync,
     protocol_request_handler: ProtoHdlr,
     our_basic_node_data: BasicNodeData,
     connection_parent_span: Span,
@@ -247,7 +236,6 @@ async fn handshake<Z: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmM
 where
     AdrBook: AddressBook<Z> + Clone,
     CSync: CoreSyncSvc + Clone,
-    PSync: PeerSyncSvc<Z> + Clone,
     ProtoHdlr: ProtocolRequestHandler,
     BrdcstStrm: Stream<Item = BroadcastMessage> + Send + 'static,
     BrdcstStrmMkr: Fn(InternalPeerID<Z::Addr>) -> BrdcstStrm + Send + 'static,
@@ -458,17 +446,6 @@ where
         })
         .await?;
 
-    // Tell the core sync service about the new peer.
-    peer_sync_svc
-        .ready()
-        .await?
-        .call(PeerSyncRequest::IncomingCoreSyncData(
-            addr,
-            handle.clone(),
-            peer_core_sync,
-        ))
-        .await?;
-
     // Set up the connection data.
     let error_slot = SharedError::new();
     let (connection_tx, client_rx) = mpsc::channel(1);
@@ -478,18 +455,18 @@ where
         handle,
         direction,
         pruning_seed,
+        core_sync_data: Arc::new(Mutex::new(peer_core_sync)),
     };
 
     let request_handler = PeerRequestHandler {
         address_book_svc: address_book.clone(),
         our_sync_svc: core_sync_svc.clone(),
-        peer_sync_svc: peer_sync_svc.clone(),
         protocol_request_handler,
         our_basic_node_data,
         peer_info: info.clone(),
     };
 
-    let connection = Connection::<Z, _, _, _, _, _>::new(
+    let connection = Connection::<Z, _, _, _, _>::new(
         peer_sink,
         client_rx,
         broadcast_stream_maker(addr),
@@ -509,13 +486,11 @@ where
     let semaphore = Arc::new(Semaphore::new(1));
 
     let timeout_handle = tokio::spawn(connection_timeout_monitor_task(
-        info.id,
-        info.handle.clone(),
+        info.clone(),
         connection_tx.clone(),
         Arc::clone(&semaphore),
         address_book,
         core_sync_svc,
-        peer_sync_svc,
     ));
 
     let client = Client::<Z>::new(

p2p/p2p-core/src/client/handshaker/builder.rs

@@ -7,13 +7,11 @@ use cuprate_wire::BasicNodeData;
 
 use crate::{
     client::{handshaker::HandShaker, InternalPeerID},
-    AddressBook, BroadcastMessage, CoreSyncSvc, NetworkZone, PeerSyncSvc, ProtocolRequestHandler,
+    AddressBook, BroadcastMessage, CoreSyncSvc, NetworkZone, ProtocolRequestHandler,
 };
 
 mod dummy;
-pub use dummy::{
-    DummyAddressBook, DummyCoreSyncSvc, DummyPeerSyncSvc, DummyProtocolRequestHandler,
-};
+pub use dummy::{DummyAddressBook, DummyCoreSyncSvc, DummyProtocolRequestHandler};
 
 /// A [`HandShaker`] [`Service`](tower::Service) builder.
 ///
@@ -28,7 +26,6 @@ pub struct HandshakerBuilder<
     N: NetworkZone,
     AdrBook = DummyAddressBook,
     CSync = DummyCoreSyncSvc,
-    PSync = DummyPeerSyncSvc,
     ProtoHdlr = DummyProtocolRequestHandler,
     BrdcstStrmMkr = fn(
         InternalPeerID<<N as NetworkZone>::Addr>,
@@ -38,8 +35,6 @@ pub struct HandshakerBuilder<
     address_book: AdrBook,
     /// The core sync data service.
     core_sync_svc: CSync,
-    /// The peer sync service.
-    peer_sync_svc: PSync,
     /// The protocol request service.
     protocol_request_svc: ProtoHdlr,
     /// Our [`BasicNodeData`]
@@ -59,7 +54,6 @@ impl<N: NetworkZone> HandshakerBuilder<N> {
         Self {
             address_book: DummyAddressBook,
             core_sync_svc: DummyCoreSyncSvc::static_mainnet_genesis(),
-            peer_sync_svc: DummyPeerSyncSvc,
             protocol_request_svc: DummyProtocolRequestHandler,
             our_basic_node_data,
             broadcast_stream_maker: |_| stream::pending(),
@@ -69,8 +63,8 @@ impl<N: NetworkZone> HandshakerBuilder<N> {
     }
 }
 
-impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
-    HandshakerBuilder<N, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+impl<N: NetworkZone, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
+    HandshakerBuilder<N, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
 {
     /// Changes the address book to the provided one.
     ///
@@ -83,13 +77,12 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     pub fn with_address_book<NAdrBook>(
         self,
         new_address_book: NAdrBook,
-    ) -> HandshakerBuilder<N, NAdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+    ) -> HandshakerBuilder<N, NAdrBook, CSync, ProtoHdlr, BrdcstStrmMkr>
     where
         NAdrBook: AddressBook<N> + Clone,
     {
         let Self {
             core_sync_svc,
-            peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             broadcast_stream_maker,
@@ -100,7 +93,6 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
         HandshakerBuilder {
             address_book: new_address_book,
             core_sync_svc,
-            peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             broadcast_stream_maker,
@@ -125,13 +117,12 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     pub fn with_core_sync_svc<NCSync>(
         self,
         new_core_sync_svc: NCSync,
-    ) -> HandshakerBuilder<N, AdrBook, NCSync, PSync, ProtoHdlr, BrdcstStrmMkr>
+    ) -> HandshakerBuilder<N, AdrBook, NCSync, ProtoHdlr, BrdcstStrmMkr>
     where
         NCSync: CoreSyncSvc + Clone,
     {
         let Self {
             address_book,
-            peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             broadcast_stream_maker,
@@ -142,43 +133,6 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
         HandshakerBuilder {
             address_book,
             core_sync_svc: new_core_sync_svc,
-            peer_sync_svc,
-            protocol_request_svc,
-            our_basic_node_data,
-            broadcast_stream_maker,
-            connection_parent_span,
-            _zone: PhantomData,
-        }
-    }
-
-    /// Changes the peer sync service, which keeps track of peers sync states.
-    ///
-    /// ## Default Peer Sync Service
-    ///
-    /// The default peer sync service will be used if this method is not called.
-    ///
-    /// The default peer sync service will not keep track of peers sync states.
-    pub fn with_peer_sync_svc<NPSync>(
-        self,
-        new_peer_sync_svc: NPSync,
-    ) -> HandshakerBuilder<N, AdrBook, CSync, NPSync, ProtoHdlr, BrdcstStrmMkr>
-    where
-        NPSync: PeerSyncSvc<N> + Clone,
-    {
-        let Self {
-            address_book,
-            core_sync_svc,
-            protocol_request_svc,
-            our_basic_node_data,
-            broadcast_stream_maker,
-            connection_parent_span,
-            ..
-        } = self;
-
-        HandshakerBuilder {
-            address_book,
-            core_sync_svc,
-            peer_sync_svc: new_peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             broadcast_stream_maker,
@@ -197,14 +151,13 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     pub fn with_protocol_request_handler<NProtoHdlr>(
         self,
         new_protocol_handler: NProtoHdlr,
-    ) -> HandshakerBuilder<N, AdrBook, CSync, PSync, NProtoHdlr, BrdcstStrmMkr>
+    ) -> HandshakerBuilder<N, AdrBook, CSync, NProtoHdlr, BrdcstStrmMkr>
     where
         NProtoHdlr: ProtocolRequestHandler + Clone,
     {
         let Self {
             address_book,
             core_sync_svc,
-            peer_sync_svc,
             our_basic_node_data,
             broadcast_stream_maker,
             connection_parent_span,
@@ -214,7 +167,6 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
         HandshakerBuilder {
             address_book,
             core_sync_svc,
-            peer_sync_svc,
             protocol_request_svc: new_protocol_handler,
             our_basic_node_data,
             broadcast_stream_maker,
@@ -233,7 +185,7 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     pub fn with_broadcast_stream_maker<NBrdcstStrmMkr, BrdcstStrm>(
         self,
         new_broadcast_stream_maker: NBrdcstStrmMkr,
-    ) -> HandshakerBuilder<N, AdrBook, CSync, PSync, ProtoHdlr, NBrdcstStrmMkr>
+    ) -> HandshakerBuilder<N, AdrBook, CSync, ProtoHdlr, NBrdcstStrmMkr>
     where
         BrdcstStrm: Stream<Item = BroadcastMessage> + Send + 'static,
         NBrdcstStrmMkr: Fn(InternalPeerID<N::Addr>) -> BrdcstStrm + Clone + Send + 'static,
@@ -241,7 +193,6 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
         let Self {
             address_book,
             core_sync_svc,
-            peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             connection_parent_span,
@@ -251,7 +202,6 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
         HandshakerBuilder {
             address_book,
             core_sync_svc,
-            peer_sync_svc,
             protocol_request_svc,
             our_basic_node_data,
             broadcast_stream_maker: new_broadcast_stream_maker,
@@ -274,10 +224,9 @@ impl<N: NetworkZone, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr>
     }
 
     /// Builds the [`HandShaker`].
-    pub fn build(self) -> HandShaker<N, AdrBook, CSync, PSync, ProtoHdlr, BrdcstStrmMkr> {
+    pub fn build(self) -> HandShaker<N, AdrBook, CSync, ProtoHdlr, BrdcstStrmMkr> {
         HandShaker::new(
             self.address_book,
-            self.peer_sync_svc,
             self.core_sync_svc,
             self.protocol_request_svc,
             self.broadcast_stream_maker,

p2p/p2p-core/src/client/handshaker/builder/dummy.rs

@@ -10,32 +10,10 @@ use cuprate_wire::CoreSyncData;
 use crate::{
     services::{
         AddressBookRequest, AddressBookResponse, CoreSyncDataRequest, CoreSyncDataResponse,
-        PeerSyncRequest, PeerSyncResponse,
     },
     NetworkZone, ProtocolRequest, ProtocolResponse,
 };
 
-/// A dummy peer sync service, that doesn't actually keep track of peers sync states.
-#[derive(Debug, Clone)]
-pub struct DummyPeerSyncSvc;
-
-impl<N: NetworkZone> Service<PeerSyncRequest<N>> for DummyPeerSyncSvc {
-    type Response = PeerSyncResponse<N>;
-    type Error = tower::BoxError;
-    type Future = Ready<Result<Self::Response, Self::Error>>;
-
-    fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        Poll::Ready(Ok(()))
-    }
-
-    fn call(&mut self, req: PeerSyncRequest<N>) -> Self::Future {
-        ready(Ok(match req {
-            PeerSyncRequest::PeersToSyncFrom { .. } => PeerSyncResponse::PeersToSyncFrom(vec![]),
-            PeerSyncRequest::IncomingCoreSyncData(_, _, _) => PeerSyncResponse::Ok,
-        }))
-    }
-}
-
 /// A dummy core sync service that just returns static [`CoreSyncData`].
 #[derive(Debug, Clone)]
 pub struct DummyCoreSyncSvc(CoreSyncData);

p2p/p2p-core/src/client/request_handler.rs

@@ -14,10 +14,8 @@ use crate::{
     constants::MAX_PEERS_IN_PEER_LIST_MESSAGE,
     services::{
         AddressBookRequest, AddressBookResponse, CoreSyncDataRequest, CoreSyncDataResponse,
-        PeerSyncRequest,
     },
-    AddressBook, CoreSyncSvc, NetworkZone, PeerRequest, PeerResponse, PeerSyncSvc,
-    ProtocolRequestHandler,
+    AddressBook, CoreSyncSvc, NetworkZone, PeerRequest, PeerResponse, ProtocolRequestHandler,
 };
 
 #[derive(thiserror::Error, Debug, Copy, Clone, Eq, PartialEq)]
@@ -28,13 +26,11 @@ enum PeerRequestHandlerError {
 
 /// The peer request handler, handles incoming [`PeerRequest`]s to our node.
 #[derive(Debug, Clone)]
-pub(crate) struct PeerRequestHandler<Z: NetworkZone, A, CS, PS, PR> {
+pub(crate) struct PeerRequestHandler<Z: NetworkZone, A, CS, PR> {
     /// The address book service.
     pub address_book_svc: A,
     /// Our core sync service.
     pub our_sync_svc: CS,
-    /// The peer sync service.
-    pub peer_sync_svc: PS,
 
     /// The handler for [`ProtocolRequest`](crate::ProtocolRequest)s to our node.
     pub protocol_request_handler: PR,
@@ -46,12 +42,11 @@ pub(crate) struct PeerRequestHandler<Z: NetworkZone, A, CS, PS, PR> {
     pub peer_info: PeerInformation<Z::Addr>,
 }
 
-impl<Z, A, CS, PS, PR> PeerRequestHandler<Z, A, CS, PS, PR>
+impl<Z, A, CS, PR> PeerRequestHandler<Z, A, CS, PR>
 where
     Z: NetworkZone,
     A: AddressBook<Z>,
     CS: CoreSyncSvc,
-    PS: PeerSyncSvc<Z>,
     PR: ProtocolRequestHandler,
 {
     /// Handles an incoming [`PeerRequest`] to our node.
@@ -104,18 +99,7 @@ where
     ) -> Result<TimedSyncResponse, tower::BoxError> {
         // TODO: add a limit on the amount of these requests in a certain time period.
 
-        let peer_id = self.peer_info.id;
-        let handle = self.peer_info.handle.clone();
-
-        self.peer_sync_svc
-            .ready()
-            .await?
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                peer_id,
-                handle,
-                req.payload_data,
-            ))
-            .await?;
+        *self.peer_info.core_sync_data.lock().unwrap() = req.payload_data;
 
         let AddressBookResponse::Peers(peers) = self
             .address_book_svc

p2p/p2p-core/src/client/timeout_monitor.rs

@@ -15,35 +15,31 @@ use tracing::instrument;
 use cuprate_wire::{admin::TimedSyncRequest, AdminRequestMessage, AdminResponseMessage};
 
 use crate::{
-    client::{connection::ConnectionTaskRequest, InternalPeerID},
+    client::{connection::ConnectionTaskRequest, PeerInformation},
     constants::{MAX_PEERS_IN_PEER_LIST_MESSAGE, TIMEOUT_INTERVAL},
-    handles::ConnectionHandle,
-    services::{AddressBookRequest, CoreSyncDataRequest, CoreSyncDataResponse, PeerSyncRequest},
-    AddressBook, CoreSyncSvc, NetworkZone, PeerRequest, PeerResponse, PeerSyncSvc,
+    services::{AddressBookRequest, CoreSyncDataRequest, CoreSyncDataResponse},
+    AddressBook, CoreSyncSvc, NetworkZone, PeerRequest, PeerResponse,
 };
 
 /// The timeout monitor task, this task will send periodic timed sync requests to the peer to make sure it is still active.
 #[instrument(
     name = "timeout_monitor",
     level = "debug",
-    fields(addr = %id),
+    fields(addr = %peer_information.id),
     skip_all,
 )]
-pub async fn connection_timeout_monitor_task<N: NetworkZone, AdrBook, CSync, PSync>(
-    id: InternalPeerID<N::Addr>,
-    handle: ConnectionHandle,
+pub async fn connection_timeout_monitor_task<N: NetworkZone, AdrBook, CSync>(
+    peer_information: PeerInformation<N::Addr>,
 
     connection_tx: mpsc::Sender<ConnectionTaskRequest>,
     semaphore: Arc<Semaphore>,
 
     mut address_book_svc: AdrBook,
     mut core_sync_svc: CSync,
-    mut peer_core_sync_svc: PSync,
 ) -> Result<(), tower::BoxError>
 where
     AdrBook: AddressBook<N>,
     CSync: CoreSyncSvc,
-    PSync: PeerSyncSvc<N>,
 {
     let connection_tx_weak = connection_tx.downgrade();
     drop(connection_tx);
@@ -125,15 +121,6 @@ where
             ))
             .await?;
 
-        // Tell the peer sync service about the peers core sync data
-        peer_core_sync_svc
-            .ready()
-            .await?
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                id,
-                handle.clone(),
-                timed_sync.payload_data,
-            ))
-            .await?;
+        *peer_information.core_sync_data.lock().unwrap() = timed_sync.payload_data;
     }
 }

p2p/p2p-core/src/lib.rs

@@ -192,30 +192,6 @@ pub trait NetworkZone: Clone + Copy + Send + 'static {
 // Below here is just helper traits, so we don't have to type out tower::Service bounds
 // everywhere but still get to use tower.
 
-pub trait PeerSyncSvc<Z: NetworkZone>:
-    tower::Service<
-        PeerSyncRequest<Z>,
-        Response = PeerSyncResponse<Z>,
-        Error = tower::BoxError,
-        Future = Self::Future2,
-    > + Send
-    + 'static
-{
-    // This allows us to put more restrictive bounds on the future without defining the future here
-    // explicitly.
-    type Future2: Future<Output = Result<Self::Response, Self::Error>> + Send + 'static;
-}
-
-impl<T, Z: NetworkZone> PeerSyncSvc<Z> for T
-where
-    T: tower::Service<PeerSyncRequest<Z>, Response = PeerSyncResponse<Z>, Error = tower::BoxError>
-        + Send
-        + 'static,
-    T::Future: Future<Output = Result<Self::Response, Self::Error>> + Send + 'static,
-{
-    type Future2 = T::Future;
-}
-
 pub trait AddressBook<Z: NetworkZone>:
     tower::Service<
         AddressBookRequest<Z>,

p2p/p2p-core/src/services.rs

@@ -6,28 +6,6 @@ use crate::{
     NetworkZone,
 };
 
-/// A request to the service that keeps track of peers sync states.
-pub enum PeerSyncRequest<N: NetworkZone> {
-    /// Request some peers to sync from.
-    ///
-    /// This takes in the current cumulative difficulty of our chain and will return peers that
-    /// claim to have a higher cumulative difficulty.
-    PeersToSyncFrom {
-        current_cumulative_difficulty: u128,
-        block_needed: Option<usize>,
-    },
-    /// Add/update a peer's core sync data.
-    IncomingCoreSyncData(InternalPeerID<N::Addr>, ConnectionHandle, CoreSyncData),
-}
-
-/// A response from the service that keeps track of peers sync states.
-pub enum PeerSyncResponse<N: NetworkZone> {
-    /// The return value of [`PeerSyncRequest::PeersToSyncFrom`].
-    PeersToSyncFrom(Vec<InternalPeerID<N::Addr>>),
-    /// A generic ok response.
-    Ok,
-}
-
 /// A request to the core sync service for our node's [`CoreSyncData`].
 pub struct CoreSyncDataRequest;
 

p2p/p2p/Cargo.toml

@@ -30,7 +30,6 @@ thiserror = { workspace = true }
 bytes = { workspace = true, features = ["std"] }
 rand = { workspace = true, features = ["std", "std_rng"] }
 rand_distr = { workspace = true, features = ["std"] }
-hex = { workspace = true, features = ["std"] }
 tracing = { workspace = true, features = ["std", "attributes"] }
 borsh = { workspace = true, features = ["derive", "std"] }
 

p2p/p2p/src/block_downloader.rs

@@ -22,11 +22,7 @@ use tower::{Service, ServiceExt};
 use tracing::{instrument, Instrument, Span};
 
 use cuprate_async_buffer::{BufferAppender, BufferStream};
-use cuprate_p2p_core::{
-    handles::ConnectionHandle,
-    services::{PeerSyncRequest, PeerSyncResponse},
-    NetworkZone, PeerSyncSvc,
-};
+use cuprate_p2p_core::{handles::ConnectionHandle, NetworkZone};
 use cuprate_pruning::{PruningSeed, CRYPTONOTE_MAX_BLOCK_HEIGHT};
 
 use crate::{
@@ -137,14 +133,12 @@ pub enum ChainSvcResponse {
 /// The block downloader may fail before the whole chain is downloaded. If this is the case you can
 /// call this function again, so it can start the search again.
 #[instrument(level = "error", skip_all, name = "block_downloader")]
-pub fn download_blocks<N: NetworkZone, S, C>(
+pub fn download_blocks<N: NetworkZone, C>(
     client_pool: Arc<ClientPool<N>>,
-    peer_sync_svc: S,
     our_chain_svc: C,
     config: BlockDownloaderConfig,
 ) -> BufferStream<BlockBatch>
 where
-    S: PeerSyncSvc<N> + Clone,
     C: Service<ChainSvcRequest, Response = ChainSvcResponse, Error = tower::BoxError>
         + Send
         + 'static,
@@ -152,13 +146,8 @@ where
 {
     let (buffer_appender, buffer_stream) = cuprate_async_buffer::new_buffer(config.buffer_size);
 
-    let block_downloader = BlockDownloader::new(
-        client_pool,
-        peer_sync_svc,
-        our_chain_svc,
-        buffer_appender,
-        config,
-    );
+    let block_downloader =
+        BlockDownloader::new(client_pool, our_chain_svc, buffer_appender, config);
 
     tokio::spawn(
         block_downloader
@@ -195,12 +184,10 @@ where
 /// - request the next chain entry
 /// - download an already requested batch of blocks (this might happen due to an error in the previous request
 ///   or because the queue of ready blocks is too large, so we need the oldest block to clear it).
-struct BlockDownloader<N: NetworkZone, S, C> {
+struct BlockDownloader<N: NetworkZone, C> {
     /// The client pool.
     client_pool: Arc<ClientPool<N>>,
 
-    /// The service that holds the peer's sync states.
-    peer_sync_svc: S,
     /// The service that holds our current chain state.
     our_chain_svc: C,
 
@@ -238,9 +225,8 @@ struct BlockDownloader<N: NetworkZone, S, C> {
     config: BlockDownloaderConfig,
 }
 
-impl<N: NetworkZone, S, C> BlockDownloader<N, S, C>
+impl<N: NetworkZone, C> BlockDownloader<N, C>
 where
-    S: PeerSyncSvc<N> + Clone,
     C: Service<ChainSvcRequest, Response = ChainSvcResponse, Error = tower::BoxError>
         + Send
         + 'static,
@@ -249,16 +235,12 @@ where
     /// Creates a new [`BlockDownloader`]
     fn new(
         client_pool: Arc<ClientPool<N>>,
-
-        peer_sync_svc: S,
         our_chain_svc: C,
         buffer_appender: BufferAppender<BlockBatch>,
-
         config: BlockDownloaderConfig,
     ) -> Self {
         Self {
             client_pool,
-            peer_sync_svc,
             our_chain_svc,
             amount_of_blocks_to_request: config.initial_batch_size,
             amount_of_blocks_to_request_updated_at: 0,
@@ -495,22 +477,10 @@ where
             panic!("Chain service returned wrong response.");
         };
 
-        let PeerSyncResponse::PeersToSyncFrom(peers) = self
-            .peer_sync_svc
-            .ready()
-            .await?
-            .call(PeerSyncRequest::PeersToSyncFrom {
-                current_cumulative_difficulty,
-                block_needed: None,
-            })
-            .await?
-        else {
-            panic!("Peer sync service returned wrong response.");
-        };
-
-        tracing::debug!("Response received from peer sync service");
-
-        for client in self.client_pool.borrow_clients(&peers) {
+        for client in self
+            .client_pool
+            .clients_with_more_cumulative_difficulty(current_cumulative_difficulty)
+        {
             pending_peers
                 .entry(client.info.pruning_seed)
                 .or_default()
@@ -621,12 +591,8 @@ where
 
     /// Starts the main loop of the block downloader.
     async fn run(mut self) -> Result<(), BlockDownloadError> {
-        let mut chain_tracker = initial_chain_search(
-            &self.client_pool,
-            self.peer_sync_svc.clone(),
-            &mut self.our_chain_svc,
-        )
-        .await?;
+        let mut chain_tracker =
+            initial_chain_search(&self.client_pool, &mut self.our_chain_svc).await?;
 
         let mut pending_peers = BTreeMap::new();
 

p2p/p2p/src/block_downloader/request_chain.rs

@@ -1,16 +1,12 @@
 use std::{mem, sync::Arc};
 
-use rand::prelude::SliceRandom;
-use rand::thread_rng;
 use tokio::{task::JoinSet, time::timeout};
 use tower::{Service, ServiceExt};
 use tracing::{instrument, Instrument, Span};
 
 use cuprate_p2p_core::{
-    client::InternalPeerID,
-    handles::ConnectionHandle,
-    services::{PeerSyncRequest, PeerSyncResponse},
-    NetworkZone, PeerRequest, PeerResponse, PeerSyncSvc, ProtocolRequest, ProtocolResponse,
+    client::InternalPeerID, handles::ConnectionHandle, NetworkZone, PeerRequest, PeerResponse,
+    ProtocolRequest, ProtocolResponse,
 };
 use cuprate_wire::protocol::{ChainRequest, ChainResponse};
 
@@ -83,13 +79,11 @@ pub(crate) async fn request_chain_entry_from_peer<N: NetworkZone>(
 ///
 /// We then wait for their response and choose the peer who claims the highest cumulative difficulty.
 #[instrument(level = "error", skip_all)]
-pub async fn initial_chain_search<N: NetworkZone, S, C>(
+pub async fn initial_chain_search<N: NetworkZone, C>(
     client_pool: &Arc<ClientPool<N>>,
-    mut peer_sync_svc: S,
     mut our_chain_svc: C,
 ) -> Result<ChainTracker<N>, BlockDownloadError>
 where
-    S: PeerSyncSvc<N>,
     C: Service<ChainSvcRequest, Response = ChainSvcResponse, Error = tower::BoxError>,
 {
     tracing::debug!("Getting our chain history");
@@ -108,29 +102,9 @@ where
 
     let our_genesis = *block_ids.last().expect("Blockchain had no genesis block.");
 
-    tracing::debug!("Getting a list of peers with higher cumulative difficulty");
-
-    let PeerSyncResponse::PeersToSyncFrom(mut peers) = peer_sync_svc
-        .ready()
-        .await?
-        .call(PeerSyncRequest::PeersToSyncFrom {
-            block_needed: None,
-            current_cumulative_difficulty: cumulative_difficulty,
-        })
-        .await?
-    else {
-        panic!("peer sync service sent wrong response.");
-    };
-
-    tracing::debug!(
-        "{} peers claim they have a higher cumulative difficulty",
-        peers.len()
-    );
-
-    // Shuffle the list to remove any possibility of peers being able to prioritize getting picked.
-    peers.shuffle(&mut thread_rng());
-
-    let mut peers = client_pool.borrow_clients(&peers);
+    let mut peers = client_pool
+        .clients_with_more_cumulative_difficulty(cumulative_difficulty)
+        .into_iter();
 
     let mut futs = JoinSet::new();
 

p2p/p2p/src/block_downloader/tests.rs

@@ -2,7 +2,7 @@ use std::{
     fmt::{Debug, Formatter},
     future::Future,
     pin::Pin,
-    sync::Arc,
+    sync::{Arc, Mutex},
     task::{Context, Poll},
     time::Duration,
 };
@@ -20,13 +20,14 @@ use tower::{service_fn, Service};
 use cuprate_fixed_bytes::ByteArrayVec;
 use cuprate_p2p_core::{
     client::{mock_client, Client, InternalPeerID, PeerInformation},
-    services::{PeerSyncRequest, PeerSyncResponse},
-    ClearNet, ConnectionDirection, NetworkZone, PeerRequest, PeerResponse, ProtocolRequest,
-    ProtocolResponse,
+    ClearNet, ConnectionDirection, PeerRequest, PeerResponse, ProtocolRequest, ProtocolResponse,
 };
 use cuprate_pruning::PruningSeed;
 use cuprate_types::{BlockCompleteEntry, TransactionBlobs};
-use cuprate_wire::protocol::{ChainResponse, GetObjectsResponse};
+use cuprate_wire::{
+    protocol::{ChainResponse, GetObjectsResponse},
+    CoreSyncData,
+};
 
 use crate::{
     block_downloader::{download_blocks, BlockDownloaderConfig, ChainSvcRequest, ChainSvcResponse},
@@ -52,19 +53,14 @@ proptest! {
             timeout(Duration::from_secs(600), async move {
                 let client_pool = ClientPool::new();
 
-                let mut peer_ids = Vec::with_capacity(peers);
-
                 for _ in 0..peers {
                     let client = mock_block_downloader_client(Arc::clone(&blockchain));
 
-                    peer_ids.push(client.info.id);
-
                     client_pool.add_new_client(client);
                 }
 
                 let stream = download_blocks(
                     client_pool,
-                    SyncStateSvc(peer_ids) ,
                     OurChainSvc {
                         genesis: *blockchain.blocks.first().unwrap().0
                     },
@@ -255,31 +251,19 @@ fn mock_block_downloader_client(blockchain: Arc<MockBlockchain>) -> Client<Clear
         handle: connection_handle,
         direction: ConnectionDirection::Inbound,
         pruning_seed: PruningSeed::NotPruned,
+        core_sync_data: Arc::new(Mutex::new(CoreSyncData {
+            cumulative_difficulty: u64::MAX,
+            cumulative_difficulty_top64: u64::MAX,
+            current_height: 0,
+            pruning_seed: 0,
+            top_id: [0; 32],
+            top_version: 0,
+        })),
     };
 
     mock_client(info, connection_guard, request_handler)
 }
 
-#[derive(Clone)]
-struct SyncStateSvc<Z: NetworkZone>(Vec<InternalPeerID<Z::Addr>>);
-
-impl Service<PeerSyncRequest<ClearNet>> for SyncStateSvc<ClearNet> {
-    type Response = PeerSyncResponse<ClearNet>;
-    type Error = tower::BoxError;
-    type Future =
-        Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static>>;
-
-    fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        Poll::Ready(Ok(()))
-    }
-
-    fn call(&mut self, _: PeerSyncRequest<ClearNet>) -> Self::Future {
-        let peers = self.0.clone();
-
-        async move { Ok(PeerSyncResponse::PeersToSyncFrom(peers)) }.boxed()
-    }
-}
-
 struct OurChainSvc {
     genesis: [u8; 32],
 }

p2p/p2p/src/client_pool.rs

@@ -127,6 +127,32 @@ impl<N: NetworkZone> ClientPool<N> {
     ) -> impl Iterator<Item = ClientPoolDropGuard<N>> + sealed::Captures<(&'a (), &'b ())> {
         peers.iter().filter_map(|peer| self.borrow_client(peer))
     }
+
+    /// Borrows all [`Client`]s from the pool that have claimed a higher cumulative difficulty than
+    /// the amount passed in.
+    ///
+    /// The [`Client`]s are wrapped in [`ClientPoolDropGuard`] which
+    /// will return the clients to the pool when they are dropped.
+    pub fn clients_with_more_cumulative_difficulty(
+        self: &Arc<Self>,
+        cumulative_difficulty: u128,
+    ) -> Vec<ClientPoolDropGuard<N>> {
+        let peers = self
+            .clients
+            .iter()
+            .filter_map(|element| {
+                let peer_sync_info = element.value().info.core_sync_data.lock().unwrap();
+
+                if peer_sync_info.cumulative_difficulty() > cumulative_difficulty {
+                    Some(*element.key())
+                } else {
+                    None
+                }
+            })
+            .collect::<Vec<_>>();
+
+        self.borrow_clients(&peers).collect()
+    }
 }
 
 mod sealed {

p2p/p2p/src/constants.rs

@@ -16,6 +16,7 @@ pub(crate) const MAX_SEED_CONNECTIONS: usize = 3;
 pub(crate) const OUTBOUND_CONNECTION_ATTEMPT_TIMEOUT: Duration = Duration::from_secs(5);
 
 /// The durations of a short ban.
+#[cfg_attr(not(test), expect(dead_code))]
 pub(crate) const SHORT_BAN: Duration = Duration::from_secs(60 * 10);
 
 /// The durations of a medium ban.

p2p/p2p/src/lib.rs

@@ -5,11 +5,7 @@
 use std::sync::Arc;
 
 use futures::FutureExt;
-use tokio::{
-    sync::{mpsc, watch},
-    task::JoinSet,
-};
-use tokio_stream::wrappers::WatchStream;
+use tokio::{sync::mpsc, task::JoinSet};
 use tower::{buffer::Buffer, util::BoxCloneService, Service, ServiceExt};
 use tracing::{instrument, Instrument, Span};
 
@@ -17,7 +13,7 @@ use cuprate_async_buffer::BufferStream;
 use cuprate_p2p_core::{
     client::Connector,
     client::InternalPeerID,
-    services::{AddressBookRequest, AddressBookResponse, PeerSyncRequest},
+    services::{AddressBookRequest, AddressBookResponse},
     CoreSyncSvc, NetworkZone, ProtocolRequestHandler,
 };
 
@@ -28,7 +24,6 @@ pub mod config;
 pub mod connection_maintainer;
 mod constants;
 mod inbound_server;
-mod sync_states;
 
 use block_downloader::{BlockBatch, BlockDownloaderConfig, ChainSvcRequest, ChainSvcResponse};
 pub use broadcast::{BroadcastRequest, BroadcastSvc};
@@ -63,12 +58,6 @@ where
         config.max_inbound_connections + config.outbound_connections,
     );
 
-    let (sync_states_svc, top_block_watch) = sync_states::PeerSyncSvc::new();
-    let sync_states_svc = Buffer::new(
-        sync_states_svc,
-        config.max_inbound_connections + config.outbound_connections,
-    );
-
     // Use the default config. Changing the defaults affects tx fluff times, which could affect D++ so for now don't allow changing
     // this.
     let (broadcast_svc, outbound_mkr, inbound_mkr) =
@@ -83,7 +72,6 @@ where
     let outbound_handshaker_builder =
         cuprate_p2p_core::client::HandshakerBuilder::new(basic_node_data)
             .with_address_book(address_book.clone())
-            .with_peer_sync_svc(sync_states_svc.clone())
             .with_core_sync_svc(core_sync_svc)
             .with_protocol_request_handler(protocol_request_handler)
             .with_broadcast_stream_maker(outbound_mkr)
@@ -136,9 +124,7 @@ where
     Ok(NetworkInterface {
         pool: client_pool,
         broadcast_svc,
-        top_block_watch,
         make_connection_tx,
-        sync_states_svc,
         address_book: address_book.boxed_clone(),
         _background_tasks: Arc::new(background_tasks),
     })
@@ -151,16 +137,11 @@ pub struct NetworkInterface<N: NetworkZone> {
     pool: Arc<client_pool::ClientPool<N>>,
     /// A [`Service`] that allows broadcasting to all connected peers.
     broadcast_svc: BroadcastSvc<N>,
-    /// A [`watch`] channel that contains the highest seen cumulative difficulty and other info
-    /// on that claimed chain.
-    top_block_watch: watch::Receiver<sync_states::NewSyncInfo>,
     /// A channel to request extra connections.
     #[expect(dead_code, reason = "will be used eventually")]
     make_connection_tx: mpsc::Sender<MakeConnectionRequest>,
     /// The address book service.
     address_book: BoxCloneService<AddressBookRequest<N>, AddressBookResponse<N>, tower::BoxError>,
-    /// The peer's sync states service.
-    sync_states_svc: Buffer<sync_states::PeerSyncSvc<N>, PeerSyncRequest<N>>,
     /// Background tasks that will be aborted when this interface is dropped.
     _background_tasks: Arc<JoinSet<()>>,
 }
@@ -183,17 +164,7 @@ impl<N: NetworkZone> NetworkInterface<N> {
             + 'static,
         C::Future: Send + 'static,
     {
-        block_downloader::download_blocks(
-            Arc::clone(&self.pool),
-            self.sync_states_svc.clone(),
-            our_chain_service,
-            config,
-        )
-    }
-
-    /// Returns a stream which yields the highest seen sync state from a connected peer.
-    pub fn top_sync_stream(&self) -> WatchStream<sync_states::NewSyncInfo> {
-        WatchStream::from_changes(self.top_block_watch.clone())
+        block_downloader::download_blocks(Arc::clone(&self.pool), our_chain_service, config)
     }
 
     /// Returns the address book service.

p2p/p2p/src/sync_states.rs

@@ -1,420 +0,0 @@
-//! # Sync States
-//!
-//! This module contains a [`PeerSyncSvc`], which keeps track of the claimed chain states of connected peers.
-//! This allows checking if we are behind and getting a list of peers who claim they are ahead.
-use std::{
-    cmp::Ordering,
-    collections::{BTreeMap, HashMap, HashSet},
-    future::{ready, Ready},
-    task::{Context, Poll},
-};
-
-use futures::{stream::FuturesUnordered, StreamExt};
-use tokio::sync::watch;
-use tower::Service;
-
-use cuprate_p2p_core::{
-    client::InternalPeerID,
-    handles::ConnectionHandle,
-    services::{PeerSyncRequest, PeerSyncResponse},
-    NetworkZone,
-};
-use cuprate_pruning::{PruningSeed, CRYPTONOTE_MAX_BLOCK_HEIGHT};
-use cuprate_wire::CoreSyncData;
-
-use crate::{client_pool::disconnect_monitor::PeerDisconnectFut, constants::SHORT_BAN};
-
-/// The highest claimed sync info from our connected peers.
-#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct NewSyncInfo {
-    /// The peers chain height.
-    pub chain_height: u64,
-    /// The peers top block's hash.
-    pub top_hash: [u8; 32],
-    /// The peers cumulative difficulty.
-    pub cumulative_difficulty: u128,
-}
-
-/// A service that keeps track of our peers blockchains.
-///
-/// This is the service that handles:
-/// 1. Finding out if we need to sync
-/// 1. Giving the peers that should be synced _from_, to the requester
-pub(crate) struct PeerSyncSvc<N: NetworkZone> {
-    /// A map of cumulative difficulties to peers.
-    cumulative_difficulties: BTreeMap<u128, HashSet<InternalPeerID<N::Addr>>>,
-    /// A map of peers to cumulative difficulties.
-    peers: HashMap<InternalPeerID<N::Addr>, (u128, PruningSeed)>,
-    /// A watch channel for *a* top synced peer info.
-    new_height_watcher: watch::Sender<NewSyncInfo>,
-    /// The handle to the peer that has data in `new_height_watcher`.
-    last_peer_in_watcher_handle: Option<ConnectionHandle>,
-    /// A [`FuturesUnordered`] that resolves when a peer disconnects.
-    closed_connections: FuturesUnordered<PeerDisconnectFut<N>>,
-}
-
-impl<N: NetworkZone> PeerSyncSvc<N> {
-    /// Creates a new [`PeerSyncSvc`] with a [`Receiver`](watch::Receiver) that will be updated with
-    /// the highest seen sync data, this makes no guarantees about which peer will be chosen in case of a tie.
-    pub(crate) fn new() -> (Self, watch::Receiver<NewSyncInfo>) {
-        let (watch_tx, mut watch_rx) = watch::channel(NewSyncInfo {
-            chain_height: 0,
-            top_hash: [0; 32],
-            cumulative_difficulty: 0,
-        });
-
-        watch_rx.mark_unchanged();
-
-        (
-            Self {
-                cumulative_difficulties: BTreeMap::new(),
-                peers: HashMap::new(),
-                new_height_watcher: watch_tx,
-                last_peer_in_watcher_handle: None,
-                closed_connections: FuturesUnordered::new(),
-            },
-            watch_rx,
-        )
-    }
-
-    /// This function checks if any peers have disconnected, removing them if they have.
-    fn poll_disconnected(&mut self, cx: &mut Context<'_>) {
-        while let Poll::Ready(Some(peer_id)) = self.closed_connections.poll_next_unpin(cx) {
-            tracing::trace!("Peer {peer_id} disconnected, removing from peers sync info service.");
-            let (peer_cum_diff, _) = self.peers.remove(&peer_id).unwrap();
-
-            let cum_diff_peers = self
-                .cumulative_difficulties
-                .get_mut(&peer_cum_diff)
-                .unwrap();
-            cum_diff_peers.remove(&peer_id);
-            if cum_diff_peers.is_empty() {
-                // If this was the last peer remove the whole entry for this cumulative difficulty.
-                self.cumulative_difficulties.remove(&peer_cum_diff);
-            }
-        }
-    }
-
-    /// Returns a list of peers that claim to have a higher cumulative difficulty than `current_cum_diff`.
-    fn peers_to_sync_from(
-        &self,
-        current_cum_diff: u128,
-        block_needed: Option<usize>,
-    ) -> Vec<InternalPeerID<N::Addr>> {
-        self.cumulative_difficulties
-            .range((current_cum_diff + 1)..)
-            .flat_map(|(_, peers)| peers)
-            .filter(|peer| {
-                if let Some(block_needed) = block_needed {
-                    // we just use CRYPTONOTE_MAX_BLOCK_HEIGHT as the blockchain height, this only means
-                    // we don't take into account the tip blocks which are not pruned.
-                    self.peers[peer]
-                        .1
-                        .has_full_block(block_needed, CRYPTONOTE_MAX_BLOCK_HEIGHT)
-                } else {
-                    true
-                }
-            })
-            .copied()
-            .collect()
-    }
-
-    /// Updates a peers sync state.
-    fn update_peer_sync_info(
-        &mut self,
-        peer_id: InternalPeerID<N::Addr>,
-        handle: ConnectionHandle,
-        core_sync_data: &CoreSyncData,
-    ) -> Result<(), tower::BoxError> {
-        tracing::trace!(
-            "Received new core sync data from peer, top hash: {}",
-            hex::encode(core_sync_data.top_id)
-        );
-
-        let new_cumulative_difficulty = core_sync_data.cumulative_difficulty();
-
-        if let Some((old_cum_diff, _)) = self.peers.get_mut(&peer_id) {
-            match (*old_cum_diff).cmp(&new_cumulative_difficulty) {
-                Ordering::Equal => {
-                    // If the cumulative difficulty of the peers chain hasn't changed then no need to update anything.
-                    return Ok(());
-                }
-                Ordering::Greater => {
-                    // This will only happen if a peer lowers its cumulative difficulty during the connection.
-                    // This won't happen if a peer re-syncs their blockchain as then the connection would have closed.
-                    tracing::debug!(
-                        "Peer's claimed cumulative difficulty has dropped, closing connection and banning peer for: {} seconds.", SHORT_BAN.as_secs()
-                    );
-                    handle.ban_peer(SHORT_BAN);
-                    return Err("Peers cumulative difficulty dropped".into());
-                }
-                Ordering::Less => (),
-            }
-
-            // Remove the old cumulative difficulty entry for this peer
-            let old_cum_diff_peers = self.cumulative_difficulties.get_mut(old_cum_diff).unwrap();
-            old_cum_diff_peers.remove(&peer_id);
-            if old_cum_diff_peers.is_empty() {
-                // If this was the last peer remove the whole entry for this cumulative difficulty.
-                self.cumulative_difficulties.remove(old_cum_diff);
-            }
-            // update the cumulative difficulty
-            *old_cum_diff = new_cumulative_difficulty;
-        } else {
-            // The peer is new so add it the list of peers.
-            self.peers.insert(
-                peer_id,
-                (
-                    new_cumulative_difficulty,
-                    PruningSeed::decompress_p2p_rules(core_sync_data.pruning_seed)?,
-                ),
-            );
-
-            // add it to the list of peers to watch for disconnection.
-            self.closed_connections.push(PeerDisconnectFut {
-                closed_fut: handle.closed(),
-                peer_id: Some(peer_id),
-            });
-        }
-
-        self.cumulative_difficulties
-            .entry(new_cumulative_difficulty)
-            .or_default()
-            .insert(peer_id);
-
-        // If the claimed cumulative difficulty is higher than the current one in the watcher
-        // or if the peer in the watch has disconnected, update it.
-        if self.new_height_watcher.borrow().cumulative_difficulty < new_cumulative_difficulty
-            || self
-                .last_peer_in_watcher_handle
-                .as_ref()
-                .is_some_and(ConnectionHandle::is_closed)
-        {
-            tracing::debug!(
-                "Updating sync watcher channel with new highest seen cumulative difficulty: {new_cumulative_difficulty}"
-            );
-            #[expect(
-                clippy::let_underscore_must_use,
-                reason = "dropped receivers can be ignored"
-            )]
-            let _ = self.new_height_watcher.send(NewSyncInfo {
-                top_hash: core_sync_data.top_id,
-                chain_height: core_sync_data.current_height,
-                cumulative_difficulty: new_cumulative_difficulty,
-            });
-            self.last_peer_in_watcher_handle.replace(handle);
-        }
-
-        Ok(())
-    }
-}
-
-impl<N: NetworkZone> Service<PeerSyncRequest<N>> for PeerSyncSvc<N> {
-    type Response = PeerSyncResponse<N>;
-    type Error = tower::BoxError;
-    type Future = Ready<Result<Self::Response, Self::Error>>;
-
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.poll_disconnected(cx);
-
-        Poll::Ready(Ok(()))
-    }
-
-    fn call(&mut self, req: PeerSyncRequest<N>) -> Self::Future {
-        let res = match req {
-            PeerSyncRequest::PeersToSyncFrom {
-                current_cumulative_difficulty,
-                block_needed,
-            } => Ok(PeerSyncResponse::PeersToSyncFrom(self.peers_to_sync_from(
-                current_cumulative_difficulty,
-                block_needed,
-            ))),
-            PeerSyncRequest::IncomingCoreSyncData(peer_id, handle, sync_data) => self
-                .update_peer_sync_info(peer_id, handle, &sync_data)
-                .map(|()| PeerSyncResponse::Ok),
-        };
-
-        ready(res)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use tower::{Service, ServiceExt};
-
-    use cuprate_p2p_core::{
-        client::InternalPeerID, handles::HandleBuilder, services::PeerSyncRequest,
-    };
-    use cuprate_wire::CoreSyncData;
-
-    use cuprate_p2p_core::services::PeerSyncResponse;
-    use cuprate_test_utils::test_netzone::TestNetZone;
-
-    use super::PeerSyncSvc;
-
-    #[tokio::test]
-    async fn top_sync_channel_updates() {
-        let (_g, handle) = HandleBuilder::new().build();
-
-        let (mut svc, mut watch) = PeerSyncSvc::<TestNetZone<true, true, true>>::new();
-
-        assert!(!watch.has_changed().unwrap());
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(0),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 1_000,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [0; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert!(watch.has_changed().unwrap());
-
-        assert_eq!(watch.borrow().top_hash, [0; 32]);
-        assert_eq!(watch.borrow().cumulative_difficulty, 1000);
-        assert_eq!(watch.borrow_and_update().chain_height, 0);
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(1),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 1_000,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [0; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert!(!watch.has_changed().unwrap());
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(2),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 1_001,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [1; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert!(watch.has_changed().unwrap());
-
-        assert_eq!(watch.borrow().top_hash, [1; 32]);
-        assert_eq!(watch.borrow().cumulative_difficulty, 1001);
-        assert_eq!(watch.borrow_and_update().chain_height, 0);
-    }
-
-    #[tokio::test]
-    async fn peer_sync_info_updates() {
-        let (_g, handle) = HandleBuilder::new().build();
-
-        let (mut svc, _watch) = PeerSyncSvc::<TestNetZone<true, true, true>>::new();
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(0),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 1_000,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [0; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert_eq!(svc.peers.len(), 1);
-        assert_eq!(svc.cumulative_difficulties.len(), 1);
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(0),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 1_001,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [0; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert_eq!(svc.peers.len(), 1);
-        assert_eq!(svc.cumulative_difficulties.len(), 1);
-
-        svc.ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::IncomingCoreSyncData(
-                InternalPeerID::Unknown(1),
-                handle.clone(),
-                CoreSyncData {
-                    cumulative_difficulty: 10,
-                    cumulative_difficulty_top64: 0,
-                    current_height: 0,
-                    pruning_seed: 0,
-                    top_id: [0; 32],
-                    top_version: 0,
-                },
-            ))
-            .await
-            .unwrap();
-
-        assert_eq!(svc.peers.len(), 2);
-        assert_eq!(svc.cumulative_difficulties.len(), 2);
-
-        let PeerSyncResponse::PeersToSyncFrom(peers) = svc
-            .ready()
-            .await
-            .unwrap()
-            .call(PeerSyncRequest::PeersToSyncFrom {
-                block_needed: None,
-                current_cumulative_difficulty: 0,
-            })
-            .await
-            .unwrap()
-        else {
-            panic!("Wrong response for request.")
-        };
-
-        assert!(
-            peers.contains(&InternalPeerID::Unknown(0))
-                && peers.contains(&InternalPeerID::Unknown(1))
-        );
-    }
-}