[3/n] Stub networking and network sender

This also introduces metadata manager's machinery for sending metadata updates and accepting metadata fetch requests across nodes

crates/core/src/metadata/manager.rs

@@ -8,13 +8,22 @@
 // the Business Source License, use of this software will be governed
 // by the Apache License, Version 2.0.
 
+use std::ops::Deref;
 use std::sync::Arc;
 
+use restate_node_protocol::MessageEnvelope;
+use restate_node_protocol::MetadataUpdate;
+use restate_node_protocol::NetworkMessage;
+use restate_types::GenerationalNodeId;
+use restate_types::Version;
 use tokio::sync::mpsc;
 use tokio::sync::oneshot;
+use tracing::debug;
 use tracing::info;
 
 use crate::cancellation_watcher;
+use crate::network_sender::NetworkSender;
+use crate::task_center;
 use restate_types::nodes_config::NodesConfiguration;
 
 use super::Metadata;
@@ -28,6 +37,7 @@ pub(super) type CommandReceiver = mpsc::UnboundedReceiver<Command>;
 
 pub(super) enum Command {
     UpdateMetadata(MetadataContainer, Option<oneshot::Sender<()>>),
+    SendMetadataToPeer(GenerationalNodeId, MetadataKind, Option<Version>),
 }
 
 /// Handle to access locally cached metadata, request metadata updates, and more.
@@ -53,16 +63,25 @@ pub struct MetadataManager {
     self_sender: CommandSender,
     inner: Arc<MetadataInner>,
     inbound: CommandReceiver,
+    networking: Arc<dyn NetworkSender>,
+    // Handle inbound network messages to update our metadata and to respond to
+    // external metadata fetch requests
+    network_inbound: mpsc::Receiver<MessageEnvelope>,
+    network_inbound_sender: mpsc::Sender<MessageEnvelope>,
 }
 
 impl MetadataManager {
-    pub fn build() -> Self {
-        let (self_sender, inbound) = tokio::sync::mpsc::unbounded_channel();
+    pub fn build(networking: Arc<dyn NetworkSender>) -> Self {
+        let (self_sender, inbound) = mpsc::unbounded_channel();
+        let (network_inbound_sender, network_inbound) = mpsc::channel(1);
 
         Self {
             inner: Arc::new(MetadataInner::default()),
             inbound,
+            networking,
             self_sender,
+            network_inbound,
+            network_inbound_sender,
         }
     }
 
@@ -74,6 +93,10 @@ impl MetadataManager {
         MetadataWriter::new(self.self_sender.clone(), self.inner.clone())
     }
 
+    pub fn network_inbound_sender(&self) -> mpsc::Sender<MessageEnvelope> {
+        self.network_inbound_sender.clone()
+    }
+
     /// Start and wait for shutdown signal.
     pub async fn run(mut self) -> anyhow::Result<()> {
         info!("Metadata manager started");
@@ -88,6 +111,9 @@ impl MetadataManager {
                 Some(cmd) = self.inbound.recv() => {
                     self.handle_command(cmd)
                 }
+                Some(envelope) = self.network_inbound.recv() => {
+                    self.handle_network_message(envelope).await
+                }
             }
         }
         Ok(())
@@ -96,9 +122,23 @@ impl MetadataManager {
     fn handle_command(&mut self, cmd: Command) {
         match cmd {
             Command::UpdateMetadata(value, callback) => self.update_metadata(value, callback),
+            Command::SendMetadataToPeer(peer, kind, min_version) => {
+                self.send_metadata(peer, kind, min_version)
+            }
         }
     }
 
+    async fn handle_network_message(&mut self, envelope: MessageEnvelope) {
+        let (peer, msg) = envelope.split();
+        match msg {
+            NetworkMessage::MetadataUpdate(update) => self.update_metadata(update.container, None),
+            NetworkMessage::GetMetadataRequest(request) => {
+                debug!("Received GetMetadataRequest from peer {}", peer);
+                self.send_metadata(peer, request.metadata_kind, request.min_version);
+            }
+        };
+    }
+
     fn update_metadata(&mut self, value: MetadataContainer, callback: Option<oneshot::Sender<()>>) {
         match value {
             MetadataContainer::NodesConfiguration(config) => {
@@ -107,6 +147,62 @@ impl MetadataManager {
         }
     }
 
+    fn send_metadata(
+        &mut self,
+        peer: GenerationalNodeId,
+        metadata_kind: MetadataKind,
+        min_version: Option<Version>,
+    ) {
+        match metadata_kind {
+            MetadataKind::NodesConfiguration => self.send_nodes_config(peer, min_version),
+            _ => {
+                todo!("Can't send metadata '{}' to peer", metadata_kind)
+            }
+        };
+    }
+
+    fn send_nodes_config(&self, to: GenerationalNodeId, version: Option<Version>) {
+        let config = self.inner.nodes_config.load_full();
+        let Some(config) = config else {
+            return;
+        };
+        if version.is_some_and(|min_version| min_version > config.version()) {
+            // We don't have the version that the peer is asking for. Just ignore.
+            debug!(
+                "Peer requested nodes config version {} but we have {}, ignoring their request",
+                version.unwrap(),
+                config.version()
+            );
+            return;
+        }
+        info!(
+            "Sending nodes config {} to peer, requested version? {:?}",
+            config.version(),
+            version,
+        );
+        let _ = task_center().spawn_child(
+            crate::TaskKind::Disposable,
+            "send-metadata-to-peer",
+            None,
+            {
+                let networking = self.networking.clone();
+                async move {
+                    networking
+                        .send(
+                            to.into(),
+                            &NetworkMessage::MetadataUpdate(MetadataUpdate {
+                                container: MetadataContainer::NodesConfiguration(
+                                    config.deref().clone(),
+                                ),
+                            }),
+                        )
+                        .await?;
+                    Ok(())
+                }
+            },
+        );
+    }
+
     fn update_nodes_configuration(
         &mut self,
         config: NodesConfiguration,
@@ -124,6 +220,11 @@ impl MetadataManager {
             }
             Some(current) => {
                 /* Do nothing, current is already newer */
+                debug!(
+                    "Ignoring nodes config update {} because we are at {}",
+                    config.version(),
+                    current.version(),
+                );
                 maybe_new_version = current.version();
             }
         }
@@ -153,18 +254,33 @@ mod tests {
 
     use super::*;
 
+    use async_trait::async_trait;
     use googletest::prelude::*;
     use restate_test_util::assert_eq;
     use restate_types::nodes_config::{AdvertisedAddress, NodeConfig, Role};
-    use restate_types::{GenerationalNodeId, Version};
+    use restate_types::{GenerationalNodeId, NodeId, Version};
 
     use crate::metadata::spawn_metadata_manager;
-    use crate::TaskCenterFactory;
+    use crate::{NetworkSendError, TaskCenterFactory};
+
+    struct MockNetworkSender;
+
+    #[async_trait]
+    impl NetworkSender for MockNetworkSender {
+        async fn send(
+            &self,
+            _to: NodeId,
+            _message: &NetworkMessage,
+        ) -> std::result::Result<(), NetworkSendError> {
+            Ok(())
+        }
+    }
 
     #[tokio::test]
     async fn test_nodes_config_updates() -> Result<()> {
+        let network_sender = Arc::new(MockNetworkSender);
         let tc = TaskCenterFactory::create(tokio::runtime::Handle::current());
-        let metadata_manager = MetadataManager::build();
+        let metadata_manager = MetadataManager::build(network_sender);
         let metadata_writer = metadata_manager.writer();
         let metadata = metadata_manager.metadata();
 
@@ -219,8 +335,9 @@ mod tests {
 
     #[tokio::test]
     async fn test_watchers() -> Result<()> {
+        let network_sender = Arc::new(MockNetworkSender);
         let tc = TaskCenterFactory::create(tokio::runtime::Handle::current());
-        let metadata_manager = MetadataManager::build();
+        let metadata_manager = MetadataManager::build(network_sender);
         let metadata_writer = metadata_manager.writer();
         let metadata = metadata_manager.metadata();
 

crates/core/src/task_center.rs

@@ -8,22 +8,25 @@
 // the Business Source License, use of this software will be governed
 // by the Apache License, Version 2.0.
 
-use futures::FutureExt;
-use restate_types::identifiers::PartitionId;
 use std::collections::HashMap;
 use std::panic::AssertUnwindSafe;
 use std::sync::atomic::{AtomicBool, AtomicI32, AtomicU64, Ordering};
 use std::sync::{Arc, Mutex, OnceLock};
 use std::time::{Duration, Instant};
 
-use futures::Future;
+use async_trait::async_trait;
+use futures::{Future, FutureExt};
+use restate_types::NodeId;
 use tokio::task::JoinHandle;
 use tokio::task_local;
 use tokio_util::sync::{CancellationToken, WaitForCancellationFutureOwned};
 use tracing::{debug, error, info, instrument, trace, warn};
 
+use restate_node_protocol::NetworkMessage;
+use restate_types::identifiers::PartitionId;
+
 use crate::metadata::{spawn_metadata_manager, Metadata, MetadataManager};
-use crate::{TaskId, TaskKind};
+use crate::{NetworkSendError, NetworkSender, TaskId, TaskKind};
 
 static NEXT_TASK_ID: AtomicU64 = AtomicU64::new(0);
 const EXIT_CODE_FAILURE: i32 = 1;
@@ -32,6 +35,20 @@ const EXIT_CODE_FAILURE: i32 = 1;
 #[error("system is shutting down")]
 pub struct ShutdownError;
 
+// TEMPORARY. REMOVED IN NEXT PR(s)
+struct MockNetworkSender;
+
+#[async_trait]
+impl NetworkSender for MockNetworkSender {
+    async fn send(
+        &self,
+        _to: NodeId,
+        _message: &NetworkMessage,
+    ) -> std::result::Result<(), NetworkSendError> {
+        Ok(())
+    }
+}
+
 /// Used to create a new task center. In practice, there should be a single task center for the
 /// entire process but we might need to create more than one in integration test scenarios.
 pub struct TaskCenterFactory {}
@@ -56,7 +73,8 @@ pub fn create_test_task_center() -> TaskCenter {
 
     let tc = TaskCenterFactory::create(tokio::runtime::Handle::current());
 
-    let metadata_manager = MetadataManager::build();
+    let networking = Arc::new(MockNetworkSender);
+    let metadata_manager = MetadataManager::build(networking);
     let metadata = metadata_manager.metadata();
     metadata_manager
         .writer()

crates/core/src/task_center_types.rs

@@ -70,6 +70,8 @@ pub enum TaskKind {
     /// A background task that the system needs for its operation. The task requires a system
     /// shutdown on errors and the system will wait for its graceful cancellation on shutdown.
     BifrostBackgroundHighPriority,
+    #[strum(props(OnCancel = "abort", OnError = "log"))]
+    Disposable,
 }
 
 impl TaskKind {

crates/network/Cargo.toml

@@ -10,15 +10,18 @@ publish = false
 [dependencies]
 restate-core = { workspace = true }
 restate-errors = { workspace = true }
+restate-node-protocol = { workspace = true }
 restate-types = { workspace = true }
 restate-wal-protocol = { workspace = true }
 
 anyhow = { workspace = true }
+async-trait = { workspace = true }
 bytes = { workspace = true }
 drain = { workspace = true }
 futures = { workspace = true }
 http = { workspace = true }
 pin-project = { workspace = true }
+static_assertions = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true }
 tonic = { workspace = true }

crates/network/src/lib.rs

@@ -14,6 +14,9 @@ use std::fmt::Debug;
 use std::future::Future;
 use tokio::sync::mpsc;
 
+mod v2;
+pub use v2::*;
+
 mod routing;
 mod unbounded_handle;
 pub mod utils;