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

Author: rsercano

docs/api.md

@@ -0,0 +1,72 @@
+import { ServiceError, status } from 'grpc';
+import { Arguments, Argv } 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 [--pretty]';
+
+export const describe = 'subscribe alerts such as low balance';
+
+export const builder = (argv: Argv) => argv
+    .option('pretty', {
+      type: 'boolean',
+    })
+    .example('$0 subscribealerts', 'prints alert payload in a JSON structure')
+    .example('$0 closechannel --pretty', 'prints alert message only');
+
+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}: ${error.message}`);
+      setTimeout(ensureConnection.bind(undefined, argv, printError), 3000);
+    } else {
+      console.log('Successfully connected, subscribing for alerts');
+      subscribeAlerts(argv);
+    }
+  });
+};
+
+const subscribeAlerts = (argv: Arguments<any>) => {
+  const request = new xudrpc.SubscribeAlertsRequest();
+  const alertsSubscription = client.subscribeAlerts(request);
+
+  alertsSubscription.on('data', (alert: xudrpc.Alert) => {
+    if (argv.pretty) {
+      console.log(`${AlertType[alert.getType()]}: ${alert.getMessage()}`);
+    } else {
+      console.log(JSON.stringify(alert, undefined, 2));
+    }
+  });
+  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/cli/commands/subscribealerts.ts

@@ -1,6 +1,6 @@
 import assert from 'assert';
 import http from 'http';
-import { SwapClientType, SwapRole, SwapState } from '../constants/enums';
+import { ChannelBalanceSide, SwapClientType, SwapRole, SwapState } from '../constants/enums';
 import { CurrencyInstance } from '../db/types';
 import { XudError } from '../types';
 import Logger from '../Logger';
@@ -14,7 +14,7 @@ import SwapClient, {
   PaymentStatus,
   WithdrawArguments,
 } from '../swaps/SwapClient';
-import { SwapDeal, CloseChannelParams, OpenChannelParams, SwapCapacities } from '../swaps/types';
+import { SwapDeal, CloseChannelParams, OpenChannelParams, SwapCapacities, ChannelBalanceAlert } from '../swaps/types';
 import { UnitConverter } from '../utils/UnitConverter';
 import errors, { errorCodes } from './errors';
 import {
@@ -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: 'lowBalance', listener: (alert: ChannelBalanceAlert) => 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: 'lowBalance', alert: ChannelBalanceAlert): boolean;
 }
 
 /**
@@ -332,6 +334,35 @@ class ConnextClient extends SwapClient {
         channelBalancePromises.push(this.channelBalance(currency));
       }
       await Promise.all(channelBalancePromises);
+
+      for (const [currency, address] of this.tokenAddresses) {
+        const remoteBalance = this.inboundAmounts.get(currency) || 0;
+        const localBalance = this.outboundAmounts.get(currency) || 0;
+        const totalBalance = remoteBalance + localBalance;
+        const alertThreshold = totalBalance * 0.1;
+
+        if (localBalance < alertThreshold) {
+          this.emit('lowBalance', {
+            totalBalance,
+            currency,
+            channelPoint: address,
+            side: ChannelBalanceSide.Local,
+            sideBalance: localBalance,
+            bound: 10,
+          });
+        }
+
+        if (remoteBalance < alertThreshold) {
+          this.emit('lowBalance', {
+            totalBalance,
+            currency,
+            channelPoint: address,
+            side: ChannelBalanceSide.Remote,
+            sideBalance: remoteBalance,
+            bound: 10,
+          });
+        }
+      }
     } catch (e) {
       this.logger.error('failed to update total outbound capacity', e);
     }

lib/connextclient/ConnextClient.ts

@@ -180,3 +180,12 @@ export enum DisconnectionReason {
   AuthFailureInvalidSignature = 12,
   WireProtocolErr = 13,
 }
+
+export enum AlertType {
+  LowBalance = 0,
+}
+
+export enum ChannelBalanceSide {
+  Remote = 0,
+  Local = 1,
+}

lib/constants/enums.ts

@@ -2,13 +2,13 @@
 import grpc, { ServerWritableStream, status } from 'grpc';
 import { fromEvent } from 'rxjs';
 import { take } from 'rxjs/operators';
-import { SwapFailureReason } from '../constants/enums';
+import { AlertType, SwapFailureReason } from '../constants/enums';
 import { LndInfo } from '../lndclient/types';
 import { isOwnOrder, Order, OrderPortion, PlaceOrderEventType, PlaceOrderResult } from '../orderbook/types';
 import * as xudrpc from '../proto/xudrpc_pb';
 import Service from '../service/Service';
 import { ServiceOrder, ServicePlaceOrderEvent } from '../service/types';
-import { SwapAccepted, SwapFailure, SwapSuccess } from '../swaps/types';
+import { ChannelBalanceAlert, SwapAccepted, SwapFailure, SwapSuccess } from '../swaps/types';
 import getGrpcError from './getGrpcError';
 
 /**
@@ -870,6 +870,31 @@ class GrpcService {
     }
   }
 
+  /*
+   * See [[Service.subscribeAlerts]]
+   */
+  public subscribeAlerts: grpc.handleServerStreamingCall<xudrpc.SubscribeAlertsRequest, xudrpc.Alert> = (call) => {
+    if (!this.isReady(this.service, call)) {
+      return;
+    }
+
+    const cancelled$ = getCancelled$(call);
+    this.service.subscribeAlerts((type: AlertType, message: string, payload: ChannelBalanceAlert) => {
+      const alert = new xudrpc.Alert();
+      alert.setType(type as number);
+      alert.setMessage(message);
+      const channelBalanceAlert = new xudrpc.ChannelBalanceAlert();
+      channelBalanceAlert.setBound(payload.bound);
+      channelBalanceAlert.setChannelPoint(payload.channelPoint);
+      channelBalanceAlert.setSide(payload.side as number);
+      channelBalanceAlert.setSideBalance(payload.sideBalance);
+      channelBalanceAlert.setTotalBalance(payload.totalBalance);
+      alert.setBalanceAlert(channelBalanceAlert);
+      call.write(alert);
+    },
+    cancelled$);
+  }
+
   /*
    * See [[Service.subscribeOrders]]
    */