RSDK-2866: add disconnection and reconnection events (#119)

Co-authored-by: Maxim Pertsov <[email protected]>

examples/vanilla/src/main.ts

@@ -34,8 +34,8 @@ function button() {
   return <HTMLButtonElement>document.getElementById('main-button');
 }
 
-// This function runs a motor component with a given named on your robot.
-// Feel free to replace it whatever logic you want to test out!
+// This function runs a motor component with a given name on your robot.
+// Feel free to replace it with whatever logic you want to test out!
 async function run(client: VIAM.RobotClient) {
   // Replace with the name of a motor on your robot.
   const name = '<MOTOR NAME>';
@@ -52,12 +52,26 @@ async function run(client: VIAM.RobotClient) {
   }
 }
 
+// This function is called when the robot is disconnected.
+// Feel free to replace it with whatever logic you want to test out!
+async function disconnected(event) {
+  console.log('The robot has been disconnected. Trying reconnect...');
+}
+
+// This function is called when the robot is reconnected.
+// Feel free to replace it with whatever logic you want to test out!
+async function reconnected(event) {
+  console.log('The robot has been reconnected. Work can be continued.');
+}
+
 async function main() {
   // Connect to client
   let client: VIAM.RobotClient;
   try {
     client = await connect();
     console.log('connected!');
+    client.on('disconnected', disconnected);
+    client.on('reconnected', reconnected);
   } catch (error) {
     console.log(error);
     return;

src/events.ts

@@ -1,5 +1,8 @@
 type Callback = (args: unknown) => void;
 
+export const RECONNECTED = 'reconnected';
+export const DISCONNECTED = 'disconnected';
+
 export class EventDispatcher {
   listeners: Record<string, Set<Callback>> = {};
 

src/robot/client.ts

@@ -4,6 +4,7 @@ import type { Credentials, DialOptions } from '@viamrobotics/rpc/src/dial';
 import { Duration } from 'google-protobuf/google/protobuf/duration_pb';
 import { dialDirect, dialWebRTC } from '@viamrobotics/rpc';
 import type { grpc } from '@improbable-eng/grpc-web';
+import { DISCONNECTED, EventDispatcher, events, RECONNECTED } from '../events';
 import proto from '../gen/robot/v1/robot_pb';
 import type {
   PoseInFrame,
@@ -29,7 +30,6 @@ import { SLAMServiceClient } from '../gen/service/slam/v1/slam_pb_service';
 import { SensorsServiceClient } from '../gen/service/sensors/v1/sensors_pb_service';
 import { ServoServiceClient } from '../gen/component/servo/v1/servo_pb_service';
 import { VisionServiceClient } from '../gen/service/vision/v1/vision_pb_service';
-import { events } from '../events';
 import { ViamResponseStream } from '../responses';
 import SessionManager from './session-manager';
 import type { Robot, RobotStatusStream } from './robot';
@@ -55,7 +55,7 @@ abstract class ServiceClient {
  *
  * @group Clients
  */
-export class RobotClient implements Robot {
+export class RobotClient extends EventDispatcher implements Robot {
   private readonly serviceHost: string;
   private readonly webrtcOptions: WebRTCOptions | undefined;
   private readonly sessionOptions: SessionOptions | undefined;
@@ -114,6 +114,7 @@ export class RobotClient implements Robot {
     webrtcOptions?: WebRTCOptions,
     sessionOptions?: SessionOptions
   ) {
+    super();
     this.serviceHost = serviceHost;
     this.webrtcOptions = webrtcOptions;
     this.sessionOptions = sessionOptions;
@@ -126,6 +127,35 @@ export class RobotClient implements Robot {
         return this.transportFactory(opts);
       }
     );
+
+    events.on(RECONNECTED, () => {
+      this.emit(RECONNECTED, {});
+    });
+    events.on(DISCONNECTED, () => {
+      this.emit(DISCONNECTED, {});
+      if (this.webrtcOptions?.noReconnect) {
+        return;
+      }
+
+      let retries = 0;
+      // eslint-disable-next-line no-console
+      console.debug('connection closed, will try to reconnect');
+      void backOff(() =>
+        this.connect().then(
+          () => {
+            // eslint-disable-next-line no-console
+            console.debug('reconnected successfully!');
+            events.emit(RECONNECTED, {});
+          },
+          (error) => {
+            // eslint-disable-next-line no-console
+            console.debug(`failed to reconnect - retries count: ${retries}`);
+            retries += 1;
+            throw error;
+          }
+        )
+      );
+    });
   }
 
   get sessionId() {
@@ -284,6 +314,10 @@ export class RobotClient implements Robot {
     this.sessionManager.reset();
   }
 
+  public isConnected(): boolean {
+    return this.peerConn?.iceConnectionState === 'connected';
+  }
+
   public async connect(
     authEntity = this.savedAuthEntity,
     creds = this.savedCreds
@@ -353,31 +387,11 @@ export class RobotClient implements Robot {
            * connection getting closed, so restarting ice is not a valid way to
            * recover.
            */
-          if (this.peerConn?.iceConnectionState === 'closed') {
-            if (this.webrtcOptions?.noReconnect) {
-              return;
-            }
-
-            let retries = 0;
-            // eslint-disable-next-line no-console
-            console.debug('connection closed, will try to reconnect');
-            void backOff(() =>
-              this.connect().then(
-                () => {
-                  // eslint-disable-next-line no-console
-                  console.debug('reconnected successfully!');
-                  events.emit('reconnected', {});
-                },
-                (error) => {
-                  // eslint-disable-next-line no-console
-                  console.debug(
-                    `failed to reconnect - retries count: ${retries}`
-                  );
-                  retries += 1;
-                  throw error;
-                }
-              )
-            );
+          if (this.peerConn?.iceConnectionState === 'connected') {
+            events.emit(RECONNECTED, {});
+          } else if (this.peerConn?.iceConnectionState === 'closed') {
+            console.log('emit disconnected');
+            events.emit(DISCONNECTED, {});
           }
         });
 

src/robot/robot.ts

@@ -4,11 +4,14 @@ import type {
   Transform,
 } from '../gen/common/v1/common_pb';
 import type { StructType } from '../types';
+import { DISCONNECTED, RECONNECTED } from '../events';
 import type proto from '../gen/robot/v1/robot_pb';
 import type { ResponseStream } from '../gen/robot/v1/robot_pb_service';
 
 export type RobotStatusStream = ResponseStream<proto.Status[]>;
 
+type Callback = (args: unknown) => void;
+
 export interface Robot {
   /**
    * Get the list of operations currently running on the robot.
@@ -146,4 +149,19 @@ export interface Robot {
     resourceNames?: ResourceName.AsObject[],
     durationMs?: number
   ): RobotStatusStream;
+
+  /**
+   * Call a function when an event of either 'reconnected' or 'disconnected' is
+   * triggered. Note that these events will only be triggered on WebRTC
+   * connections.
+   *
+   * @param type - The event ('reconnected' or 'disconnected') that was
+   *   triggered.
+   * @param listener - The function to call
+   * @alpha
+   */
+  on: (
+    type: typeof RECONNECTED | typeof DISCONNECTED,
+    listener: Callback
+  ) => void;
 }