feat: new grpc call for subscribring alerts such as low balance (#864)

lib/cli/commands/subscribealerts.ts

@@ -0,0 +1,63 @@
+import { ServiceError, status } from 'grpc';
+import { Arguments } from 'yargs';
+import { XudClient } from '../../proto/xudrpc_grpc_pb';
+import * as xudrpc from '../../proto/xudrpc_pb';
+import { setTimeoutPromise } from '../../utils/utils';
+import { loadXudClient } from '../command';
+import { AlertType } from '../../constants/enums';
+
+export const command = 'subscribealerts';
+
+export const describe = 'subscribe alerts such as low balance';
+
+export const builder = {};
+
+export const handler = async (argv: Arguments) => {
+  await ensureConnection(argv, true);
+};
+
+let client: XudClient;
+
+const ensureConnection = async (argv: Arguments, printError?: boolean) => {
+  if (!client) {
+    client = await loadXudClient(argv);
+  }
+  client.waitForReady(Date.now() + 3000, (error: Error | null) => {
+    if (error) {
+      if (error.message === 'Failed to connect before the deadline') {
+        console.error(`could not connect to xud at ${argv.rpchost}:${argv.rpcport}, is xud running?`);
+        process.exit(1);
+      }
+
+      if (printError) console.error(`${error.name}: ${error.message}`);
+      setTimeout(ensureConnection.bind(undefined, argv, printError), 3000);
+    } else {
+      console.log('Successfully connected, subscribing for alerts');
+      subscribeAlerts(argv);
+    }
+  });
+};
+
+const subscribeAlerts = (argv: Arguments<any>) => {
+  const request = new xudrpc.SubscribeAlertsRequest();
+  const alertsSubscription = client.subscribeAlerts(request);
+
+  alertsSubscription.on('data', (alert: xudrpc.Alert) => {
+    console.log(`${AlertType[alert.getType()]}: ${alert.getMessage()}`);
+  });
+  alertsSubscription.on('end', reconnect.bind(undefined, argv));
+  alertsSubscription.on('error', async (err: ServiceError) => {
+    if (err.code === status.UNIMPLEMENTED) {
+      console.error("xud is locked, run 'xucli unlock', 'xucli create', or 'xucli restore' then try again");
+      process.exit(1);
+    }
+    console.warn(`Unexpected error occured: ${err.message}, reconnecting in 1 second`);
+    await setTimeoutPromise(1000);
+    await ensureConnection(argv);
+  });
+};
+
+const reconnect = async (argv: Arguments) => {
+  console.log('Stream has closed, trying to reconnect');
+  await ensureConnection(argv, false);
+};

lib/connextclient/ConnextClient.ts

@@ -46,13 +46,15 @@ interface ConnextClient {
   on(event: 'htlcAccepted', listener: (rHash: string, amount: number, currency: string) => void): this;
   on(event: 'connectionVerified', listener: (swapClientInfo: SwapClientInfo) => void): this;
   on(event: 'depositConfirmed', listener: (hash: string) => void): this;
+  on(event: 'noBalance', listener: (currency: string) => void): this;
   once(event: 'initialized', listener: () => void): this;
   emit(event: 'htlcAccepted', rHash: string, amount: number, currency: string): boolean;
   emit(event: 'connectionVerified', swapClientInfo: SwapClientInfo): boolean;
   emit(event: 'initialized'): boolean;
   emit(event: 'preimage', preimageRequest: ProvidePreimageEvent): void;
   emit(event: 'transferReceived', transferReceivedRequest: TransferReceivedEvent): void;
   emit(event: 'depositConfirmed', hash: string): void;
+  emit(event: 'noBalance', currency: string): boolean;
 }
 
 /**
@@ -332,6 +334,12 @@ class ConnextClient extends SwapClient {
         channelBalancePromises.push(this.channelBalance(currency));
       }
       await Promise.all(channelBalancePromises);
+
+      this.outboundAmounts.forEach((amount, currency) => {
+        if (amount === 0) {
+          this.emit('noBalance', currency);
+        }
+      });
     } catch (e) {
       this.logger.error('failed to update total outbound capacity', e);
     }

lib/constants/enums.ts

@@ -180,3 +180,7 @@ export enum DisconnectionReason {
   AuthFailureInvalidSignature = 12,
   WireProtocolErr = 13,
 }
+
+export enum AlertType {
+  NoBalance = 0,
+}

lib/grpc/GrpcService.ts

@@ -870,6 +870,24 @@ class GrpcService {
     }
   }
 
+  /*
+   * See [[Service.subscribeAlerts]]
+   */
+  public subscribeAlerts: grpc.handleServerStreamingCall<xudrpc.SubscribeAlertsRequest, xudrpc.Alert> = (call) => {
+    if (!this.isReady(this.service, call)) {
+      return;
+    }
+
+    const cancelled$ = getCancelled$(call);
+    this.service.subscribeAlerts((type, message) => {
+      const alert = new xudrpc.Alert();
+      alert.setType(type as number);
+      alert.setMessage(message);
+      call.write(alert);
+    },
+    cancelled$);
+  }
+
   /*
    * See [[Service.subscribeOrders]]
    */

lib/lndclient/LndClient.ts

@@ -23,6 +23,7 @@ interface LndClient {
   on(event: 'channelBackup', listener: (channelBackup: Uint8Array) => void): this;
   on(event: 'channelBackupEnd', listener: () => void): this;
   on(event: 'locked', listener: () => void): this;
+  on(event: 'noBalance', listener: (currency: string) => void): this;
 
   once(event: 'initialized', listener: () => void): this;
 
@@ -32,6 +33,7 @@ interface LndClient {
   emit(event: 'channelBackupEnd'): boolean;
   emit(event: 'locked'): boolean;
   emit(event: 'initialized'): boolean;
+  emit(event: 'noBalance', currency: string): boolean;
 }
 
 const MAXFEE = 0.03;
@@ -233,6 +235,10 @@ class LndClient extends SwapClient {
     await this.channelBalance().catch(async (err) => {
       this.logger.error('failed to update total outbound capacity', err);
     });
+
+    if (this.maxChannelOutboundAmount === 0) {
+      this.emit('noBalance', this.currency);
+    }
   }
 
   private unaryCall = <T, U>(methodName: Exclude<keyof LightningClient, ClientMethods>, params: T): Promise<U> => {