Cluster state types

Summary:
Types used by nodes to share cluster state

crates/types/protobuf/restate/common.proto

@@ -73,6 +73,8 @@ enum TargetName {
   // Node
   NODE_GET_PARTITIONS_PROCESSORS_STATE_REQUEST = 60;
   NODE_GET_PARTITIONS_PROCESSORS_STATE_RESPONSE = 61;
+  NODE_PING = 62;
+  NODE_PONG = 63;
 
   // Remote Scanner
   REMOTE_QUERY_SCANNER_OPEN = 80;

crates/types/src/cluster/cluster_state.rs

@@ -58,7 +58,6 @@ impl ClusterState {
         })
     }
 
-    #[cfg(any(test, feature = "test-util"))]
     pub fn empty() -> Self {
         ClusterState {
             last_refreshed: None,

crates/types/src/net/cluster_state.rs

@@ -0,0 +1,28 @@
+// Copyright (c) 2023 - 2025 Restate Software, Inc., Restate GmbH.
+// All rights reserved.
+//
+// Use of this software is governed by the Business Source License
+// included in the LICENSE file.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0.
+
+use super::{define_rpc, TargetName};
+use serde::{Deserialize, Serialize};
+
+define_rpc! {
+    @request= NodePing,
+    @response= NodePong,
+    @request_target=TargetName::NodePing,
+    @response_target=TargetName::NodePong,
+}
+
+/// Gossip Push message. Is pushed from each node to every other known node
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NodePing {
+    //todo(azmy): share latest metadata versions?
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NodePong {}

crates/types/src/net/mod.rs

@@ -8,6 +8,7 @@
 // the Business Source License, use of this software will be governed
 // by the Apache License, Version 2.0.
 
+pub mod cluster_state;
 pub mod codec;
 mod error;
 pub mod log_server;