add Ping to RpcMessage

packages/rpc/src/RpcClient.ts

@@ -28,7 +28,7 @@ import type { Mutable } from "effect/Types"
 import type * as Rpc from "./Rpc.js"
 import type * as RpcGroup from "./RpcGroup.js"
 import type { FromClient, FromClientEncoded, FromServer, FromServerEncoded } from "./RpcMessage.js"
-import { RequestId } from "./RpcMessage.js"
+import { constPing, RequestId } from "./RpcMessage.js"
 import * as RpcSchema from "./RpcSchema.js"
 import * as RpcSerialization from "./RpcSerialization.js"
 
@@ -529,6 +529,13 @@ export const makeProtocolSocket = Effect.gen(function*() {
     Effect.forkScoped
   )
 
+  yield* Effect.suspend(() => write(parser.encode(constPing))).pipe(
+    Effect.delay("30 seconds"),
+    Effect.ignore,
+    Effect.forever,
+    Effect.forkScoped
+  )
+
   return Protocol.of({
     responses,
     send(request) {
@@ -582,7 +589,7 @@ const decodeDefectExit = Schema.decodeSync(Schema.Exit({
 const transformBigInt = (request: FromClientEncoded) => {
   if (request._tag === "Request") {
     ;(request as any).id = request.id.toString()
-  } else {
+  } else if (request._tag !== "Ping") {
     ;(request as any).requestId = request.requestId.toString()
   }
 }

packages/rpc/src/RpcMessage.ts

@@ -16,7 +16,7 @@ export type FromClient<A extends Rpc.Any> = Request<A> | Ack | Interrupt | Eof
  * @since 1.0.0
  * @category request
  */
-export type FromClientEncoded = RequestEncoded | Ack | Interrupt
+export type FromClientEncoded = RequestEncoded | Ack | Interrupt | Ping
 
 /**
  * @since 1.0.0
@@ -99,12 +99,26 @@ export interface Eof {
   readonly _tag: "Eof"
 }
 
+/**
+ * @since 1.0.0
+ * @category request
+ */
+export interface Ping {
+  readonly _tag: "Ping"
+}
+
 /**
  * @since 1.0.0
  * @category request
  */
 export const constEof: Eof = { _tag: "Eof" }
 
+/**
+ * @since 1.0.0
+ * @category request
+ */
+export const constPing: Ping = { _tag: "Ping" }
+
 /**
  * @since 1.0.0
  * @category response
@@ -119,7 +133,7 @@ export type FromServer<A extends Rpc.Any> =
  * @since 1.0.0
  * @category response
  */
-export type FromServerEncoded = ResponseChunkEncoded | ResponseExitEncoded | ResponseDefectEncoded
+export type FromServerEncoded = ResponseChunkEncoded | ResponseExitEncoded | ResponseDefectEncoded | Pong
 
 /**
  * @since 1.0.0
@@ -208,3 +222,17 @@ export interface ClientEnd {
   readonly _tag: "ClientEnd"
   readonly clientId: number
 }
+
+/**
+ * @since 1.0.0
+ * @category response
+ */
+export interface Pong {
+  readonly _tag: "Pong"
+}
+
+/**
+ * @since 1.0.0
+ * @category response
+ */
+export const constPong: Pong = { _tag: "Pong" }

packages/rpc/src/RpcServer.ts

@@ -28,6 +28,7 @@ import type * as Rpc from "./Rpc.js"
 import type * as RpcGroup from "./RpcGroup.js"
 import {
   constEof,
+  constPong,
   type FromClient,
   type FromClientEncoded,
   type FromServer,
@@ -566,6 +567,10 @@ export const makeEncoded: <Rpcs extends Rpc.Any>(
               )
               break
             }
+            case "Ping": {
+              yield* send(client.id, client.parser.encode(constPong))
+              break
+            }
             default: {
               if (!serialization.supportsBigInt) {
                 ;(request as any).requestId = BigInt(request.requestId) as any